Dissertations / Theses: 'Lactose'

1

Oliveira, Sofia Sá. "Intolerância à lactose e persistência da lactase." Bachelor's thesis, [s.n.], 2018. http://hdl.handle.net/10284/7363.

Full text

Abstract:

Trabalho Complementar apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de licenciada em Ciências da Nutrição
A intolerância à lactose é um assunto amplamente estudado até à data e, por isso, consensual em termos de causa primária, fenótipos clínicos e estratégia terapêutica. Não obstante, subsistem aspetos sob investigação que necessitam de uma maior consolidação científica. Com o objetivo de contribuir para uma melhor compreensão sobre o paradigma da intolerância à lactose e da persistência da lactase, o presente trabalho efetua uma revisão descritiva da informação científica. A sua análise ampla e integrada sublinha a importância da continuidade da investigação e da difusão do conhecimento sobre este tema.
Lactose intolerance is a topic that has been widely studied untill now and, therefore, consensual in terms of primary cause, clinical phenotypes and therapeutic strategy. Nevertheless, there are areas under investigation which require further scientific consolidation. In order to contribute to a better understanding of the paradigm of lactose intolerance and the persistence of lactase, the present paper carries out a descriptive review of the scientific information. Its comprehensive and integrated analysis underlines the importance of continuing research and dissemination of knowledge on this subject.
N/A

APA, Harvard, Vancouver, ISO, and other styles

2

Peuhkuri, Katri. "Lactose, lactase, and bowel disorders : reducing hypolactasia-related gastrointestinal symptoms by improving the digetibility og lactose." Helsinki : University of Helsinki, 2000. http://ethesis.helsinki.fi/julkaisut/laa/biola/vk/peuhkuri/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Gimenez, Vidal Marc. "Isomérisation du lactose en lactulose par électro-activation." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/29776/29776.pdf.

Full text

Abstract:

Dans le présent travail, l’électro-isomérisation du lactose en lactulose a été étudiée. Les variables indépendantes mises à l’étude dans ce projet sont : 1) l’effet de la concentration du lactose (5 et 10%), l’effet de la densité du champ électrique appliqué au réacteur d’électro-activation (100 et 200 mA). L’électro-isomérisation du lactose à 5% a été également comparée à celle observée dans du lactosérum ayant une concentration de lactose  5%. Les variables réponse principales (variables dépendantes) mises à l’étude étaient le taux de conversion du lactose en lactulose, le taux de formation de sous-produits de la réaction et l'efficacité du procédé exprimée en termes de résistance électrique globale du système d’électro-activation. Une surface totale de l’aire cathodique de 21,5 cm2 a été utilisée, donnant ainsi des densités de courant électrique de 4,65 et 9,30 mA/cm2, respectivement. Les analyses statistiques des données obtenues ont montré que l’effet du temps d’électro-activation sur le taux d’électro-isomérisation du lactose (rendement de formation de lactulose) ainsi que la résistance électrique du réacteur électro-activation était significatif. Le processus d’électro-activation a été réalisé pendant 60 min et des échantillons ont été prélevés chaque 10 min. Les résultats obtenus ont montré la grande efficacité de l'électro-activation, en tant qu’approche novatrice, pour transformer le lactose en lactulose. Après 60 min d’électro-activation à température ambiante (23  1  C), 25% de rendement d’électro-isomérisation a été obtenu. En excluant le lactose, la pureté du produit final était de 96,28  0,18%. En outre, aucune formation d’epilactose n’a été observée. De façon non systématique, du galactose a été détecté dans certains échantillons (<1,5%) et seulement quelques traces de fructose ont été observées (<0,31%). La résistance électrique globale du réacteur d’électro-activation diminuait avec l’augmentation du temps d'électro-activation, indiquant une grande efficacité énergétique de cette nouvelle technologie d’isomérisation du lactose en lactulose.
In the present work, electro-isomerization of lactose into lactulose has been studied. Effects of lactose concentration (5 and 10%) and applied DC-electric field (100 and 200 mA) on the electro-isomerization of lactose into lactulose and on process efficiency were investigated. Total cathode area of 21.5 cm2 was used; giving electric current density of 4.65 mA/cm2 and 9.30 mA/cm2, respectively. Milk whey permeate (4.7  0.15% lactose) obtained by ultrafiltration was also used as feed solution in the electro-activation reactor. The effect of processing time on lactose electro-isomerization rate (lactulose formation yield), by-product (glucose, galactose, epilactose and fructose) formation, and global electric resistance of the electro-activation reactor has been investigated. The process was run during 60 min and samples were taken every 10 min. Obtained results showed the high effectiveness of the developed electro-activation technology to convert lactose into lactulose. After 60 min electro-activation at ambient temperature (23  1 C), 25% electro-isomerisation yield was obtained. By excluding lactose, the end product purity was 96.28  0.18%, which is similar to the pharmakopoeia requirements for lactulose powder. Moreover, no epilactose was formed. Not systematically, galactose was detected in some samples (<1.5%) and only some traces of fructose were detected (<0.31%). The global electric resistance of the electro-activation reactor decreased as the electro-activation time was increased indicating the high energetic effectiveness of this new electro-isomerization technology.

APA, Harvard, Vancouver, ISO, and other styles

4

MARTINEAU, LAURE. "Valorisation du lactose par voie chimique : synthese du lactulose." Rennes 1, 1989. http://www.theses.fr/1989REN10033.

Full text

Abstract:

Synthese du lactalose par isomerisation du lactose en milieu basique. Un procede de cristallisation du lactalose a ete mis au point. Apres isomerisation d'une partie lactospe contenue dans les permeats de lait, il est possible de reconstituer le lait par ajout des retentats d'ultrafiltration. Des essais en quart de grand, apres demineralisation partielle, permettent de penser que ces laits supporteront les traitements thermiques habituels

APA, Harvard, Vancouver, ISO, and other styles

5

Mattanna, Paula. "DESENVOLVIMENTO DE REQUEIJÃO CREMOSO COM BAIXO TEOR DE LACTOSE PRODUZIDO POR ACIDIFICAÇÃO DIRETA E COAGULAÇÃO ENZIMÁTICA." Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/5696.

Full text

Abstract:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Much of the world population has problems in consuming milk and dairy products because some people are lactose intolerant. To be absorbed in the intestine lactose needs to be hydrolyzed by lactase enzyme. People with lactose intolerance do not produce lactase and therefore can not enjoy milk and dairy products benefits. This work aim to prepare requeijões cremosos by two different processes (direct acidification and enzymatic coagulation) by adding lactase enzyme at different concentrations (0.2; 0.5 and 0.8 g of lactase enzyme per liter of milk, respectively) and evaluating their physico-chemical, microbiological and sensory properties compared with requeijões control sample. In relation to physical and chemical characteristics the requeijões prepared are in accordance with current law. The lactose was hydrolyzed in more than 70 % for the treatments with adding of the lactase enzyme, enough to alleviate symptoms of intolerance in people who not well absorb lactose. Lactose found in "requeijões" with added lactase are considered low, within the standards regulated by the laws of foods for special purposes. The requeijões were sensoring accepted, no difference was detected statistic by Tukey test (p<0.05) in testing by a hedonic scale among treatments. The lipid profile of requeijões , the total saturated fatty acids ranged from 62.76% to 64.70%, while total unsaturated ranged from 34.36% to 38.36%. In the texture profile analysis only the firmness and elasticity parameters differed significantly (p< 0,05) during the storage period (60 days). Considering the results it is possible conclude that the enzyme lactase used in the experiment efficiently hydrolyzed the lactose of the requeijões , and, did not affect the physico-chemical and sensory characteristics of the product, then this is a viable option for the lactose intolerant people.
Grande parte da população mundial tem problemas em consumir leite e seus derivados por serem intolerantes à lactose. Para ser absorvida, a lactose necessita ser hidrolisada no intestino pela enzima lactase. As pessoas intolerantes à lactose não produzem a lactase e, portanto, não podem desfrutar dos benefícios do leite e de seus derivados. O presente estudo teve como objetivo elaborar requeijões cremosos com baixo teor de lactose obtidos por dois diferentes processos (acidificação direta e coagulação enzimática) a partir de leites adicionados de enzima lactase em diferentes concentrações (0,2; 0,5 e 0,8g de enzima por litro de leite) e avaliar as suas características físico-químicas, microbiológicas e sensoriais em comparação com requeijões cremosos controle. Quanto às características físicoquímicas os requeijões elaborados estão de acordo com a legislação vigente. A lactose foi hidrolisada em mais de 70% para os tratamentos com adição de enzima lactase, suficiente para amenizar os sintomas de intolerância em pessoas que possuem má absorção da lactose. Os teores de lactose encontrados nos requeijões com adição de lactase foram considerados baixos, dentro dos padrões regulamentados pela legislação de alimentos para fins especiais. As contagens de micro-organismos se mantiveram dentro do exigido pela legislação brasileira. Os requeijões foram aceitos sensorialmente, não sendo detectada diferença estatística entre os tratamentos pelo teste de Tukey (p< 0,05) no teste por escala hedônica. No perfil lipídico dos requeijões, o total de ácidos graxos saturados variou 62,76% a 64,70%, enquanto o total de insaturados variou de 34,36% a 38,36%. Na análise do perfil de textura apenas os parâmetros firmeza e elasticidade diferiram significativamente (p<0,05) durante o período de armazenamento (60 dias). Considerando os resultados obtidos pode-se concluir que a enzima lactase utilizada hidrolisou eficientemente a lactose dos requeijões e não comprometeu as características físico-químicas e sensoriais do produto, sendo este então uma opção viável para indivíduos intolerantes a lactose.

APA, Harvard, Vancouver, ISO, and other styles

6

Horner, Trenton W. "Beta Galactosidose Activity of Commercial Lactase Samples in Raw and Pasteurized Milk at Refrigerated Temperatures." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2590.

Full text

Abstract:

Many consumers are unable to enjoy the benefits of milk, due to lactose-intolerance. Lactose-free milk is available, but at about 2 times the cost of regular milk or greater, it may be difficult for consumers to afford. The high cost of lactose-free milk is in part due to the added cost of the lactose hydrolysis process. Hydrolysis at refrigerated temperatures, possibly in the bulk tank or package, could increase the flexibility of the process, and potentially reduce the cost. A rapid β-galactosidase assay was used to determine the relative activity of commercially available lactase samples at different temperatures. Four enzymes exhibited low-temperature activity and were added to refrigerated raw and pasteurized milk at various concentrations and allowed to react for various lengths of time. The degree of lactose hydrolysis by each of the enzymes as a function of time and enzyme concentration was determined by HPLC. The two most active enzymes, as determined by the β-galactosidase assay, hydrolyzed over 98% of the lactose in 24 hours at 2°C using the supplier recommended dosage. The other two enzymes hydrolyzed over 95% of the lactose in 24 hours at two times the supplier recommended dosage at 2°C. Results were consistent in all milk types tested. The results show that it is feasible to hydrolyze lactose during refrigerated storage of milk using currently available enzymes.

APA, Harvard, Vancouver, ISO, and other styles

7

Bulhões, Andréia Cristina da Silva. "Análise molecular do gene da lactase-florizina hidrolase em indivíduos tolerantes e intolerantes à lactose." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2006. http://hdl.handle.net/10183/11355.

Full text

Abstract:

Objetivo: Verificar a relação entre a presença das mutações C/T-13910 e G/A-22018 no gene da lactase-florizina hidrolase e a absorção de lactose em indivíduos residentes no município de Porto Alegre. Casuística e Métodos: Foi realizado um estudo transversal que incluiu 20 indivíduos adultos, sadios, com idade superior a 18 anos, procedentes do município de Porto Alegre. Os participantes foram classificados segundo o relato da quantidade de leite consumida, habitualmente, por dia e quanto à presença ou ausência de sintomas relacionados à ingestão de leite. A má absorção de lactose foi diagnosticada através do teste de hidrogênio expirado após a ingestão de 50 g de lactose diluída em solução aquosa a 20%. O teste teve duração de 3 horas e foi considerado positivo quando o aumento foi superior a 20 partes por milhão na concentração de H2 em relação ao nível basal. Os voluntários também foram classificados como indivíduos com lactase persistente e lactase não persistente através da análise molecular dos dois polimorfismos (C/T-13910 e G/A-22018) responsáveis pela persistência ou não da Lactase Florizina Hidrolase no adulto pelo método da Reação em Cadeia da Polimerase (PCR). Resultados: Foram estudados 20 indivíduos com média de idade de 32,7 ± 7,3 anos. 9/20 sujeitos apresentaram o genótipo CCGG – não persistência de lactase em concordância com o teste do hidrogênio expirado positivo. 11/20 indivíduos apresentaram o teste H2 expirado negativo, sendo que 10/20 apresentaram genótipos de persistência de lactase (1/20 CTAA, 3/20 TTAA e 6/20 CTGA) e 1 sujeito com o genótipo de não persistência de lactase (CCGG). Obteve-se um coeficiente de concordância kappa = - 0,9 entre os testes, molecular e de H2 expirado com p < 0,001. Conclusões: Os resultados do trabalho permitem concluir que a análise dos polimorfismos C/T-13910 e G/A-22018 no gene da Lactase Florizina Hidrolase podem ser considerados um bom indicador para o diagnóstico de má absorção de lactose, visto que é um método bastante sensível e específico com ótima concordância com o teste de hidrogênio expirado.
Objective: to verify the relation between the presence of mutations C/T–13910 and G/A–22018 in the gene of lactase-phlorizin hydrolase and the absorption of lactose in individuals who live in the city of Porto Alegre. Methods: It consists of a transversal study which included 20 healthy adult individuals over eighteen years old, from the city of Porto Alegre. The participants were classified according to reports on the quantity of milk they habitually consumed per day and in regard to the presence or absence of symptoms related to lactose intolerance. Lactose malabsorption was diagnosed through the hydrogen breath test after the ingestion of 50g of lactose diluted in watery solution. The test lasted 3 hours and it was considered positive when the increase was higher than 20 parts per million on concentration of H2 in relation to the basal level. The volunteers were also classified as individuals with persistent and nonpersistent lactase through the analysis of the presence of both polyformisms (C/T–13910 and G/A–22018), which are responsible for the persistence or not of Lactase Phlorizin Hydrolase in adults. The analysis was made through the Polymerase Chain Reaction method (PCR). Results: Twenty individuals were studied with mean age of 32.7 ± 7.3 years. 9/20 subjects presented with the CCGG genotype – non-persistence of lactase accordingly to the positive hydrogen breath test (HBT). 11/20 individuals presented with negative HBT, whereas 10/20 presented with genotypes of lactase persistence (1/20 CTAA, 3/20 TTAA e 6/20 CTGA) and one subject with genotype of non-persistence of lactase (CCGG). An agreement coefficient kappa = - 0.9 was obtained between the molecular and the hydrogen breath test with p < 0,001. Conclusions: This project results make it possible to conclude that the analysis of the polyformisms C/T–13910 and G/A–22018 in the gene of Lactase Phlorizin Hydrolase can be considered a good indicator for the diagnosis for lactose malabsorption, since it is a very sensible and specific method, as it was demonstrated in recent studies. It also has an excellent agreement with the expired hydrogen.

APA, Harvard, Vancouver, ISO, and other styles

8

Stievenard, Sylvain. "Hydrolyse industrielle du lactose : mise au point au stade laboratoire d'un réacteur à lactase immobilisée." Lille 1, 1986. http://www.theses.fr/1986LIL10172.

Full text

Abstract:

L'existence d'une activité lactasique chez un micro-organisme non pathogène nous a conduit à envisager la mise au point d'un procédé d'hydrolyse industrielle du lactose contenu dans le lait et les lactosérums. Notre démarche s'est appuyée sur plusieurs points : le procédé doit être facile à mettre en oeuvre industirellement et doit pouvoir se réaliser en continu. Il doit être en outre peu coûteux et conforme à la législation. La purification de la lactase est procédé qui s'est révélé être trop onéreux et déstabilisateur de l'activité enzymatique. Les cellules de ce microorganisme ont été incluses à l'intérieur d'un polymère d'origine naturelle. Nous avons comparé les paramétres enzymatiques de l'enzyme "libre" et "immobilisée". Le procédé mis au point au laboratoire est décrit, ses performances sont comparées à celles des autres systèmes existant déjà sur le marché.

APA, Harvard, Vancouver, ISO, and other styles

9

Gao, Kai-Ping, Takahiro Mitsui, Kotoyo Fujiki, Hiroshi Ishiguro, and Takaharu Kondo. "Effect of lactase preparations in asymptomatic individuals with lactase deficiency : gastric digestion of lactose and breath hydrogen analysis." Nagoya University School of Medicine, 2002. http://hdl.handle.net/2237/5376.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Listiohadi, Yuanita D. "The caking of lactose." Thesis, View thesis, 2004. http://handle.uws.edu.au:8081/1959.7/25753.

Full text

Abstract:

This project has investigated the mechanism of caking of lactose and identified some possible solutions to minimise caking of lactose and dairy powders, additional to those suggested in the literature. A background to lactose and caking is given. The problems of caking are identified and discussed. The project adds information to the knowledge on the polymorphic forms of lactose and their inter-relationships due to moisture sorption and processes such as milling. This information and many others in the literature are used to complete the simplified lactose conversion diagram developed by King [1965] and improved by Walstra, et al. [1999], which has been widely used in the literature as a guide for lactose manufacturing, processing, and storage.

APA, Harvard, Vancouver, ISO, and other styles

11

Listiohadi, Yuanita D. "The caking of lactose /." View thesis, 2004. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20041108.084200/index.html.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Dincer, Tuna. "Mechanims of lactose crystallisation." Thesis, Curtin University, 2000. http://hdl.handle.net/20.500.11937/1958.

Full text

Abstract:

Lactose is the major carbohydrate in milk. The presence of lactose in whey constitutes a significant pollution problem for dairy factories. At the same time, there is an increasing market for high quality crystalline lactose. The main problem of lactose crystallisation, compared to sucrose, which is also a disaccharide, is that it is very slow, unpredictable and cannot easily be controlled. Compared to sucrose crystallisation, which has been extensively studied, lactose crystallisation lacks the fundamental research to identify the mechanisms of growth and effect of additives. An important difference from most other crystal growth systems is that ([alpha]-lactose hydrate crystals never grow from a pure environment; their growth environment always contains beta lactose. [alpha]-lactose monohydrate crystallises much more slowly because of the presence of [beta]- lactose in all solutions. Although there have been some studies on growth rates and the effect of additives, there has not been any reported work on the fundamentals of lactose crystallisation and the mechanisms that operate on the molecular level. The aim of this thesis is to gain a greater understanding at the fundamental processes, which occur at the molecular level during the crystallisation of lactose, in order to improve control at a macroscopic level.The growth rates of the dominant crystallographic faces have been measured in situ, at three temperatures and over a wide range of supersaturation. The mean growth rates of faces were proportional to the power of between 2.5-3.1 of the relative supersaturation. The rate constants and the activation energies were calculated for four faces. The [alpha]-lactose monohydrate crystals grown in aqueous solutions exhibited growth rate dispersion. Crystals of similar size displayed almost 10 fold difference in the growth rate grown under identical conditions for all the faces. Growth rate dispersion increases with increasing growth rate and supersaturation for all the faces. The variance in the GRD for the (0 10) face is twice the variance of the GRD of the (110) and (100) faces and ten times higher than the (0 11) face at different supersaturations and temperatures. The influence of [beta]-lactose on the morphology of [alpha]-lactose monohydrate crystals has been investigated by crystallising [alpha]-lactose monohydrate from supersaturated DMSO ethanol solutions. The slowness of mutarotation in DMSO allowed preparation of saturated solutions with a fixed, chosen [beta]-lactose content. It was found that [beta]-lactose significantly influences the morphology of [alpha]- lactose monohydrate crystals grown from DMSO solution. At low concentrations of [beta]-lactose, the fastest growing face is the (011) face resulting in long thin prismatic crystals. At higher [beta]-lactose concentrations, the main growth occurs in the b direction and the (020) face becomes the fastest growing face (since the (011) face is blocked by [beta]-lactose), producing pyramid and tomahawk shaped crystals.Molecular modeling was used to calculate morphologies of lactose crystals, thereby defining the surface energies of specific faces, and to calculate the energies of interactions between these faces and [beta]-lactose molecules. It was found that as the replacement energy of [beta]-lactose increased, the likelihood of [beta]-lactose to dock onto faces decreased and therefore the growth rate increased. The attachment energy of a new layer of [alpha]-lactose monohydrate to the faces containing [beta]-lactose was calculated for the (010) and (011) faces. For the (0 10) face, the attachment energy of a new layer was found to be lower than the attachment energy onto a pure lactose surface, meaning slower growth rates when [beta]-lactose was incorporated into the surface. For the (011) face, attachment energy calculations failed to predict the slower growth rates of this face in the presence of [beta]-lactose. AFM investigation of [alpha]-lactose monohydrate crystals produced very useful information about the surface characteristics of the different faces of the [alpha]-lactose monohydrate crystal. The growth of the (010) face of the crystal occurs by the lateral addition of growth layers. Steps are 2 nm high (unit cell height in the b direction) and emanate from double spirals, which usually occurred at the centre of the face. Double spirals rotate clockwise on the (010) face, while the direction of spirals is counterclockwise on the (010) face. A polygonised double spiral, showing anisotropy in the velocity of stepswas observed at the centre of the prism-shaped a-lactose monohydrate crystals grown in the presence of 5 and 10 % [beta]-lactose.The mean spacing of the steps parallel to the (011) face is larger than those parallel to the (100) face, indicating higher growth rates of the (011 )face. The edge free energy of the (011) face is 6.6 times larger than the (100) face in the presence of 5% [beta]-lactose. Increase of [beta]-lactose content from 5% to 10 % decreases the edge free energy of the growth unit on a step parallel to the (011) face by 10 %. Tomahawk-shaped [alpha]-lactose monohydrate crystals produced from aqueous solutions where the [beta]-lactose content of the growth solution is about 60 % have shown clockwise double spirals as the source of unit cell high steps on the (010) face of the crystal. However , the spirals are more circular than polygonised, unlike the prism shaped crystals and the mean step spacing of the (011) face is less than the steps parallel to the (110) face, indicating the growth rate reducing effect of [beta]-lactose on the (011) face. The (100) face of the [alpha]-lactose monohydrate crystal grows by step advancement in relative supersaturations of up to 3.1. Steps are 0.8 nm high and parallel to the c rection. Above this supersaturation, rectangular shaped two-dimensional nuclei, 10 nm high, were observed. The (011) face of the crystal grown at low supersaturations (s= 2.1) displayed a very rough surface with no steps, covered by 4-10nm high and 100-200[micro]m wide formations. Triangular shaped macrosteps were observed when the crystal was grown in solutions with s=3.1. In situ AFM investigation of the (010) face (T = 20[degree]C and s = 1.18) has shown that growth occurs by lateral addition of growth units into steps emanated by double spirals.The growth rate of the (010) face from in situ AFM growth experiments was calculated to be 1.25 gm/min. The growth rate of crystals grown in the in situ optical growth cell under identical conditions was 0.69 pm/min. The difference in growth rates can be attributed to the size difference of seed c stals used. The (010) face of a [alpha]-lactosemonohydrate crystal grown at 22.4 C and s=1.31 displayed triangular-shaped growth fronts parallel to the (011) face. The steps parallel to the (O11) face grow in a triangular shape, and spaces between triangles are filled by growth units until the end of the macrosteps is reached. No such formations were observed on steps parallel to the (110) face. Formation of macrosteps, 4-6 nm high, emanating from another spiral present on the surface was also observed on the (010) face of a crystal grown under these conditions.

APA, Harvard, Vancouver, ISO, and other styles

13

Dincer, Tuna. "Mechanims of lactose crystallisation." Curtin University of Technology, School of Applied Chemistry, 2000. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=14562.

Full text

Abstract:

Lactose is the major carbohydrate in milk. The presence of lactose in whey constitutes a significant pollution problem for dairy factories. At the same time, there is an increasing market for high quality crystalline lactose. The main problem of lactose crystallisation, compared to sucrose, which is also a disaccharide, is that it is very slow, unpredictable and cannot easily be controlled. Compared to sucrose crystallisation, which has been extensively studied, lactose crystallisation lacks the fundamental research to identify the mechanisms of growth and effect of additives. An important difference from most other crystal growth systems is that ([alpha]-lactose hydrate crystals never grow from a pure environment; their growth environment always contains beta lactose. [alpha]-lactose monohydrate crystallises much more slowly because of the presence of [beta]- lactose in all solutions. Although there have been some studies on growth rates and the effect of additives, there has not been any reported work on the fundamentals of lactose crystallisation and the mechanisms that operate on the molecular level. The aim of this thesis is to gain a greater understanding at the fundamental processes, which occur at the molecular level during the crystallisation of lactose, in order to improve control at a macroscopic level.
The growth rates of the dominant crystallographic faces have been measured in situ, at three temperatures and over a wide range of supersaturation. The mean growth rates of faces were proportional to the power of between 2.5-3.1 of the relative supersaturation. The rate constants and the activation energies were calculated for four faces. The [alpha]-lactose monohydrate crystals grown in aqueous solutions exhibited growth rate dispersion. Crystals of similar size displayed almost 10 fold difference in the growth rate grown under identical conditions for all the faces. Growth rate dispersion increases with increasing growth rate and supersaturation for all the faces. The variance in the GRD for the (0 10) face is twice the variance of the GRD of the (110) and (100) faces and ten times higher than the (0 11) face at different supersaturations and temperatures. The influence of [beta]-lactose on the morphology of [alpha]-lactose monohydrate crystals has been investigated by crystallising [alpha]-lactose monohydrate from supersaturated DMSO ethanol solutions. The slowness of mutarotation in DMSO allowed preparation of saturated solutions with a fixed, chosen [beta]-lactose content. It was found that [beta]-lactose significantly influences the morphology of [alpha]- lactose monohydrate crystals grown from DMSO solution. At low concentrations of [beta]-lactose, the fastest growing face is the (011) face resulting in long thin prismatic crystals. At higher [beta]-lactose concentrations, the main growth occurs in the b direction and the (020) face becomes the fastest growing face (since the (011) face is blocked by [beta]-lactose), producing pyramid and tomahawk shaped crystals.
Molecular modeling was used to calculate morphologies of lactose crystals, thereby defining the surface energies of specific faces, and to calculate the energies of interactions between these faces and [beta]-lactose molecules. It was found that as the replacement energy of [beta]-lactose increased, the likelihood of [beta]-lactose to dock onto faces decreased and therefore the growth rate increased. The attachment energy of a new layer of [alpha]-lactose monohydrate to the faces containing [beta]-lactose was calculated for the (010) and (011) faces. For the (0 10) face, the attachment energy of a new layer was found to be lower than the attachment energy onto a pure lactose surface, meaning slower growth rates when [beta]-lactose was incorporated into the surface. For the (011) face, attachment energy calculations failed to predict the slower growth rates of this face in the presence of [beta]-lactose. AFM investigation of [alpha]-lactose monohydrate crystals produced very useful information about the surface characteristics of the different faces of the [alpha]-lactose monohydrate crystal. The growth of the (010) face of the crystal occurs by the lateral addition of growth layers. Steps are 2 nm high (unit cell height in the b direction) and emanate from double spirals, which usually occurred at the centre of the face. Double spirals rotate clockwise on the (010) face, while the direction of spirals is counterclockwise on the (010) face. A polygonised double spiral, showing anisotropy in the velocity of stepswas observed at the centre of the prism-shaped a-lactose monohydrate crystals grown in the presence of 5 and 10 % [beta]-lactose.
The mean spacing of the steps parallel to the (011) face is larger than those parallel to the (100) face, indicating higher growth rates of the (011 )face. The edge free energy of the (011) face is 6.6 times larger than the (100) face in the presence of 5% [beta]-lactose. Increase of [beta]-lactose content from 5% to 10 % decreases the edge free energy of the growth unit on a step parallel to the (011) face by 10 %. Tomahawk-shaped [alpha]-lactose monohydrate crystals produced from aqueous solutions where the [beta]-lactose content of the growth solution is about 60 % have shown clockwise double spirals as the source of unit cell high steps on the (010) face of the crystal. However , the spirals are more circular than polygonised, unlike the prism shaped crystals and the mean step spacing of the (011) face is less than the steps parallel to the (110) face, indicating the growth rate reducing effect of [beta]-lactose on the (011) face. The (100) face of the [alpha]-lactose monohydrate crystal grows by step advancement in relative supersaturations of up to 3.1. Steps are 0.8 nm high and parallel to the c rection. Above this supersaturation, rectangular shaped two-dimensional nuclei, 10 nm high, were observed. The (011) face of the crystal grown at low supersaturations (s= 2.1) displayed a very rough surface with no steps, covered by 4-10nm high and 100-200[micro]m wide formations. Triangular shaped macrosteps were observed when the crystal was grown in solutions with s=3.1. In situ AFM investigation of the (010) face (T = 20[degree]C and s = 1.18) has shown that growth occurs by lateral addition of growth units into steps emanated by double spirals.
The growth rate of the (010) face from in situ AFM growth experiments was calculated to be 1.25 gm/min. The growth rate of crystals grown in the in situ optical growth cell under identical conditions was 0.69 pm/min. The difference in growth rates can be attributed to the size difference of seed c stals used. The (010) face of a [alpha]-lactosemonohydrate crystal grown at 22.4 C and s=1.31 displayed triangular-shaped growth fronts parallel to the (011) face. The steps parallel to the (O11) face grow in a triangular shape, and spaces between triangles are filled by growth units until the end of the macrosteps is reached. No such formations were observed on steps parallel to the (110) face. Formation of macrosteps, 4-6 nm high, emanating from another spiral present on the surface was also observed on the (010) face of a crystal grown under these conditions.

APA, Harvard, Vancouver, ISO, and other styles

14

Araujo, Bellido Katherine Cristy, Cahuas Juan Andres Echevarria, Flores Camila Luciana Echevarria, Otoya Jacqueline Ursula Lleren, and Achata Magib Jesus Olortegui. "Batidos 4Lite." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2019. http://hdl.handle.net/10757/626525.

Full text

Abstract:

Actualmente, las personas optan por alimentos más saludables y buscan alimentos que complementen sus comidas, es decir, sean más balanceados. Por ello, el presente proyecto consiste de nutri batidos a base de avena y quinua, leche de almendras y frutas como Arándanos, Lúcuma y Fresa, este producto destaca principalmente por ser natural, saludable y no contiene lactosa, además que puedes consumirlo en cualquier momento del día. Al analizar la viabilidad de este proyecto, se pudo identificar que nuestro tamaño de mercado se encuentra en las zonas 6 y 7 de Lima Metropolitana en los NSE A y B, que permitió detectar un público poco satisfecho debido a la falta de productos sin lactosa, frutados naturalmente y sean saludables por el contenido de quinua y avena. Por ello, 4Lite se presenta ante nuestro público objetivo como una opción bebible y de fácil consumo debido a su presentación de 300ml y su botella de material eco amigable. Para poner en marcha este proyecto, se requerirá una inversión inicial de 14,500 soles, financiado básicamente por el aporte de los cinco accionistas que cuenta 4Lite. Se estima recuperar el dinero invertido al segundo año de operación.
Nowadays, people opt for healthier foods and look for foods that complement their meals, something more balanced. Therefore, the present project consists of nutri smothies based on oats and quinoa, almond milk and fruits such as Blueberries, Lucuma and Strawberry, this product stands out mainly for being natural, healthy and lactose-free, also you can consume it at any time of the day. When analyzing the viability of this project, it was possible to identify that our market size is located in zones 6 and 7 of Metropolitan Lima in NSE A and B, which allowed us to detect an unhappy public due to the lack of products without lactose, naturally fruity and healthy due to the content of quinoa and oats. Therefore, 4Lite is presented to our target audience as a drinkable and easy to consume option due to its presentation of 300ml and its bottle of eco-friendly material. To start up this project, an initial investment of 14,500 soles will be required, basically financed by the contribution of the five shareholders that 4Lite has. It is estimated to recover the money invested in the second year of operation.
Trabajo de investigación

APA, Harvard, Vancouver, ISO, and other styles

15

Diniz, Raphael Hermano Santos. "Metabolismo de lactose em Kluyveromyces marxianus UFV-3 e Kluyveromyces lactis JA6." Universidade Federal de Viçosa, 2009. http://locus.ufv.br/handle/123456789/5305.

Full text

Abstract:

Made available in DSpace on 2015-03-26T13:51:45Z (GMT). No. of bitstreams: 1 texto completo.pdf: 402071 bytes, checksum: f514861e3699db83508ed828b9260676 (MD5) Previous issue date: 2009-02-17
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The fermentative metabolism of lactose in Kluyveromyces marxianus UFV-3 was compared to the Kluyveromyces lactis JA6 under aerobic and hypoxia through the analysis of kinetics of growth, consumption of substrate, production of ethanol and formation of biomass, depending on the concentration of lactose. It was determinated the gene expression and activity of key enzymes of metabolism of lactose under aerobic and hypoxia. In fermentations carried out under aerobic and hypoxia in lactose concentrations of 0.25 to 64 mM, K. marxianus UFV-3 showed higher specific growth rate and higher concentration of biomass after 24 hours of cultivation, for K. lactis JA6. In fermentations with 64 mM lactose under aerobic and hypoxia K. marxianus UFV-3 showed higher yield to ethanol by K. lactis JA6, demonstrating that high concentrations of substrate metabolism favors fermentation in K. marxianus UFV-3. Under aerobic K. marxianus UFV-3 has more activity of pyruvate dehydrogenase that K. lactis JA6, justifying the formation of higher biomass and higher growth rate observed in K. marxianus UFV-3. Under hypoxia the highest activities of pyruvate decarboxylase and β- galactosidase of K. marxianus UFV-3 in relation to K. lactis JA6 seem to be the factors that contribute to the increased formation of ethanol in K. marxianus UFV-3 when compared to K. lactis JA6. In hypoxia K. marxianus showed higher expression of genes that encode enzymes β-galactosidase, pyruvate decarboxylase and the Leilor pathway for when compared to aerobic. Indicating that these genes are important for the metabolism of lactose in hypoxia. Already in K. lactis JA6 none of these genes showed increased expression in hypoxia. It appears the higher expression of genes encoding key enzymes of metabolism of lactose as the major enzymatic activity is responsible for fermentation potential of K. marxianus UFV-3.
O metabolismo fermentativo de lactose em Kluyveromyces marxianus UFV-3 foi comparado ao de Kluyveromyces lactis JA6 em aerobiose e hipoxia por meio da análise de cinéticas de crescimento, consumo de substrato, produção de etanol e formação de biomassa, em função da concentração de lactose. Determinou-se ainda a expressão gênica e atividade de enzimas-chave do metabolismo de lactose em aerobiose e hipoxia. Nas fermentações conduzidas em aerobiose e hipoxia em concentrações de lactose de 0,25 a 64 mM, K. marxianus UFV-3 apresentou maior velocidade específica de crescimento e maior concentração de biomassa após 24 horas de cultivo, em relação a K. lactis JA6. Nas fermentações com 64 mM de lactose em aerobiose e hipoxia K. marxianus UFV-3 mostrou maior rendimento de etanol por lactose que K. lactis JA6, demonstrando que alta concentração de substrato favorece metabolismo fermentativo em K. marxianus UFV-3. Sob aerobiose K. marxianus UFV-3 possui maior atividade de piruvato desidrogenase que K. lactis JA6, justificando a maior formação de biomassa e maior velocidade de crescimento verificada em K. marxianus UFV-3 em aerobiose. Sob hipoxia as maiores atividades de β-galactosidase e de piruvato descarboxilase de K. marxianus UFV-3 em relação à K. lactis JA6 parecem ser os fatores que contribuem para a maior formação de etanol de K. marxianus UFV-3 quando comparado a K. lactis JA6. Em hipoxia K. marxianus apresentou maior expressão de genes que codificam enzimas para a via de Leilor, para a enzima β-gal e piruvato descarboxilase quando comparado à aerobiose. Indicando que estes genes são importantes para o metabolismo de lactose em hipoxia. Já em K. lactis JA6 nenhum destes genes apresentou expressão aumentada em hipoxia. Tanto a maior expressão de genes que codificam enzimas chaves do metabolismo de lactose quanto à maior atividade enzimática parecem ser os responsáveis pela capacidade fermentativa de K. marxianus UFV-3.

APA, Harvard, Vancouver, ISO, and other styles

16

Trevisan, Ana Paula. "INFLUÊNCIA DE DIFERENTES CONCENTRAÇÕES DE ENZIMAS LACTASE E TEMPERATURAS SOBRE A HIDRÓLISE DA LACTOSE EM LEITE PASTEURIZADO." Universidade Federal de Santa Maria, 2008. http://repositorio.ufsm.br/handle/1/5654.

Full text

Abstract:

The intolerance to lactose is the most common intolerance to carbohydrates among people of all ages and it affects about 70% of the adult population worldwide. Due to the prevalence of this condition on the world population, the commercial interest on milk and derivatives with reduced amount of lactose has increased. Such product can be obtained through lactose hydrolysis, mainly through the enzymatic method, using lactase enzyme. The level of lactose hydrolysis depends on the dosage of J-galactosidase in milk, as well as on its processing conditions and, for this reason, it is extremely important to evaluate the influence of such conditions concerning obtainment of milk with reduced amount of lactose, such as temperature during hydrolysis and lactase concentration, over the efficiency of the hydrolysis process and over the physical, chemical and microbiological characteristics of the fina product. The aim of the present study was to observe the influence of different temperatures and concentrations of lactase enzymes over the lactose hydrolysis in pasteurized milks. Samples of pasteurized milks from the Usina Escola de Laticínios (UFSM) were used. Lactase enzyme, supplied by two companies, was added to the milk in different quantities (0.1g/L; 0.2g/L; 0.5g/L; 0.8g/L e 0.9g/L) and hydrolysis was accomplished in different temperatures (7.9ºC; 12ºC; 22ºC; 32ºC e 36.1ºC). These two variables were combined through Response Surface Methodology (RSM) by rotational composed central delineation. Hydrolysis was followed by crioscopy until it reached stabilization. Physical, chemical and microbiological analysis were carried out before and after lactose hydrolysis, and sensorial analysis was carried out after hydrolysis. Lactase enzyme input modified physical and chemical properties and characteristics of milk, reducing pH, crioscopy, fat and lactose levels and increasing density, total dry extract (TDE), free-fat dry extract (FDE), glucose and protein levels. There was a difference between the efficiency of the two enzymes on the reduction of the lactose level. Lactose hydrolysis reached values in between 80% and 100%, reducing lactose level to less than 1g/100g, thus enabling milk ingestion by individuals who are intolerant to this carbohydrate. Higher percentages of hydrolysis and, consequently, lower lactose levels were verified in temperatures in between 15 and 30°C, using enzyme concentrations in between 0.6 and 1.0 g/L. The average total count after hydrolysis was beyond the limit established by law, but concerning the count per milk sample, using enzyme 1 and 2, treatments three and seven did not exceed this limit, respectively. Higher values of total count were found at the highest temperatures and using lowest enzyme concentrations. Differences among milk samples with different lactose levels were not sensorially perceived through triangular test.
A intolerância à lactose é a intolerância a carboidrato mais comum entre pessoas de todas as faixas etárias e afeta cerca de 70% dos adultos do mundo. Devido à prevalência desta condição na população mundial, tem aumentado o interesse comercial nos leites e derivados com teor reduzido de lactose. E isto pode ser obtido através da hidrólise da lactose, principalmente pelo método enzimático, com a utilização da enzima lactase. O grau de hidrólise da lactose depende da dosagem da J-galactosidase no leite e das condições de processamento e por isto, é extremamente importante avaliar a influência dessas condições para obtenção do leite com teor reduzido de lactose, como temperatura durante a hidrólise e concentração da lactase, sobre a eficiência do processo de hidrólise e sobre as características físico-químicas e microbiológicas do produto final. O objetivo do presente estudo foi observar a influência de diferentes temperaturas e concentrações de enzimas lactase sobre a hidrólise da lactose em leites pasteurizados. Foram utilizadas amostras de leite pasteurizado, proveniente da Usina Escola de Laticínios (UFSM). A enzima lactase, fornecida por duas empresas, foi adicionada ao leite em diferentes concentrações (0,1g/L; 0,2g/L; 0,5g/L; 0,8g/L e 0,9g/L) e a hidrólise foi realizada a diferentes temperaturas (7,9ºC; 12ºC; 22ºC; 32ºC e 36,1ºC), sendo estas duas variáveis combinadas entre si através da Metodologia de Superfície de Resposta (MSR) por delineamento central composto rotacional. A hidrólise foi acompanhada por crioscopia até que esta se estabilizasse. Foram realizadas análises físicoquímicas e microbiológicas antes e após a hidrólise da lactose e análise sensorial após. A adição da enzima lactase modificou características e propriedades físico-químicas do leite, reduzindo pH, crioscopia, teores de gordura e lactose e aumentando densidade, extrato seco total (EST), extrato seco desengordurado (ESD), teores de proteína e glicose. Houve diferença entre a eficiência das duas enzimas na redução do teor de lactose. A hidrólise da lactose atingiu valores de 80% a 100%, reduzindo o teor de lactose para menos de 1g/100g, possibilitando a ingestão do leite por indivíduos intolerantes a este carboidrato. As maiores porcentagens de hidrólise e, conseqüentemente, os menores teores de lactose foram verificados em temperaturas de 15 a 30ºC e com o uso de concentrações de enzima de 0,6 a 1,0 g/L. A média da contagem total após a hidrólise ultrapassou o limite estabelecido pela legislação, porém, nas contagens realizadas por amostra de leite, com o uso da enzima 1, três tratamentos não excederam esse limite e com o uso da enzima 2, sete. Os maiores valores de contagem total foram encontrados nas maiores temperaturas e com o uso de menores concentrações de enzimas. As diferenças entre amostras de leite com teores de lactose diferentes, não foram sensorialmente percebidas através do teste triangular.

APA, Harvard, Vancouver, ISO, and other styles

17

Quiroga, Espitia Lenny Maritza. "Isomérisation du lactose en lactulose en solution modèle de lactose et dans du perméat de lactosérum par électro-activation supportée par échange ionique sur résine." Master's thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/26958.

Full text

Abstract:

L'isomérisation alcaline du lactose en lactulose a été effectuée électro-chimiquement à l’aide d’un réacteur d'électro-activation en combinaison avec des résines échangeuses d'anions de polystyrène de trois types; à savoir Lewatit VP-OC-1065 faible-acide, Lewatit MP-64 moyenne-acide et Lewatit Monoplus M500 forte-acide. Les paramètres opératoires qui ont fait l’objet de cette étude ont été étudiés sur trois blocs expérimentaux pour optimiser le système. Dans le Premier bloc, les paramètres étudiés sont : (1) ratio lactose-5%(p/v) : résine échangeuse d'anions (1:0.5, 1:1 et 1:2), (2) intensité du champ électrique : 50 mA, 100 mA et 200 mA et (3) type de résines : faible, moyenne et forte. Dans le Deuxième bloc, les paramètres mis à l’étude comprenaient : (1) l’intensité du champ électrique : 300 mA, 450 mA et 550 mA, (2) le débit de la solution traitée : 25 ml / min, 50 ml/ min et 100 ml/min et (3) la surface active de la membrane adjacente au compartiment cathodique : 0.78 cm2, 7.06 cm2 et 18.1 cm2. Le Troisième bloc expérimental a été effectué sur la base de la distance entre la membrane et l'électrode : 3.1 cm, 5.6 cm et 9 cm. Le même modèle expérimental a était également réalisé avec du perméat du lactosérum d’une concentration de 7% (p/v). Les résultats obtenus ont révélé que le meilleur rendement de l’isomérisation du lactose en lactulose était obtenu après 30 minutes d’électroactivation en utilisant une solution modèle de lactose-5% avec une valeur d’environ 20.1%. Les conditions opératoires qui ont permis d’avoir ce taux de conversion sont une intensité du courant de 550 mA, un débit de la solution de 25 ml/min, une surface active de la membrane de 7.06 cm2 et une distance de 9 cm entre la cathode et la membrane qui lui y est adjacente. En utilisant le perméat de lactosérum-7%, un taux de conversion de lactose en lactulose de 8.34% a était obtenu avec une intensité du courant de 200 mA, un débit de 120 ml/min, une surface active de de 18.1cm2 et une distance de 9 cm entre la membrane et l’électrode dans le compartiment cathodique. Les analyses de variance ont indiqué un effet catalytique significatif du type de la résine. En effet, la résine-forte a permis d’avoir les plus hauts rendements de la réaction d’isomérisation par électro-activation. La résistance électrique globale du système d’électroactivation dépendait de la valeur de l’intensité du courant. Le produit final était d’une grande pureté, car il ne présentait que quelques traces de galactose (< 4%).
The isomerization of lactose to lactulose in alkaline conditions was carried out electrochemically using an electro-activation reactor in combination with three types of anion-exchange polystyrene resins, namely Lewatit VPOC 1065 weak acid, Lewatit MP-64 medium acid, and Lewatit Monoplus M500 strong acid. The operational parameters evaluated in this study have been adjusted to three blocks to optimize the system: first block: a) ratio lactose- 5% (w /v): anionexchange resin (1:0.5, 1:1 and 1:2), b) electric field intensity of 50 mA, 100 mA, and 200 mA, and c) resin type; second block: a) electric field intensity of 300 mA, 450 mA, and 550 mA, b) flow rate (25 ml / min, 50 ml / min, and 100 ml / min); and c) area of the membrane adjacent to the cathode compartment (0.78 cm2,7.06 cm2, and 18.1 cm2); and third block: distance between the membrane and the electrode (3.1 cm, 5.6 cm, and 9 cm). The same experimental model was used with whey permeat at a concentration of 7% (w/v). Obtained results revealed that the best yield was obtained after 30 minutes of electro-activation using a typical solution based on 20.1% of lactose-5% under a current intensity of 550 mA, a flow rate of 25 ml / min, a membrane area of 7.06 cm2, and a distance of 9 cm between the membrane and the electrode. The use of whey permeate-7% resulted in 8.34% of lactulose under a current intensity of 200 mA, a flow rate of 120 ml / min, a membrane area of 18.1 cm2, and a distance of 9 cm in the cathodic compartment. The analysis of variance indicated a significant catalytic effect on the resin type since the strong acid resin allowed obtaining the highest yields of the isomerization reaction by electro-activation. The overall electrical resistance of the electro-activation system depends on the current intensity. The final product was of high purity since it contains only few traces of galactose (< 4%).

APA, Harvard, Vancouver, ISO, and other styles

18

Wang, Hua. "Physical and Functional Events Involved in Conjugal Transfer of Lactose Utilization in Lactococcus lactis subsp. lactis." DigitalCommons@USU, 1992. https://digitalcommons.usu.edu/etd/5386.

Full text

Abstract:

The nature of the cell surface components involved in donor cell clumping (Clu+) and the relationship of Clu+ to high frequency conjugal transfer of lactose utilization (Lac) in Lactococcus lactis subsp. lactis ML3 was examined. Lactose positive (Lac+), Clu+ transconjugants, containing a novel 104 kilobase Lac plasmid, were obtained by mating ML3 with LM2301. When used as Lac+ donors in second round matings, these transconjugants transferred Lac at high frequencies ranging from 10-2 to 10-4 transconjugants per donor CFU. Treatment of donor cells with EDTA and EGTA containing solutions or proteolytic enzymes (proteinase K and chymotrypsin A) resulted in a loss of Clu+. By using a direct plate conjugation technique, these treatments also decreased the capacity for transferring Lac at high frequency. Analysis of cell-surface proteins by SOS-PAGE identified a novel protein of approximately 125 kDa which was present in Clu+ transconjugants, but not in non-clumping transconjugants. These results suggest that Clu+ is required for high frequency Lac transfer in ML3 transconjugants, and at least one large protein is involved in Clu+. De novo synthesis requirements of donor cells for conjugal transfer of Lac were tested on direct plate conjugation technique. Results indicate that de novo protein synthesis and RNA synthesis are not required for conjugal transfer of Lac.

APA, Harvard, Vancouver, ISO, and other styles

19

Cachon, Rémy. "Etude du comportement cinétique d'une bactérie lactique modèle en culture libre ou immobilisée dans des billes de gel." dijon, 1993. http://www.theses.fr/1993DIJOS030.

Full text

Abstract:

Le travail porte sur l'étude de la croissance, la fermentation lactique et l'utilisation de l'acide citrique par lactococcus lactis ssp. Lactis bv. Diacetylactis en culture libre et en culture immobilisée dans des billes de gel. Un modèle est proposé pour la croissance, la fermentation lactique et l'utilisation de l'acide citrique en réacteur à cellules libres. Ce modèle est généralise a l'effet du ph sur ces métabolismes, il simule correctement des fermentations a ph régule (6,5; 6,0; 5,5; 5,0; 4,5) et une fermentation a ph non régulé. L'acide lactique non dissocie a été identifie comme l'inhibiteur principal de la croissance et de la fermentation lactique. L'évolution physiologique des cellules a été introduite dans le modèle. Pour les cellules immobilisées, le Co métabolisme lactose-citrate à été étudié en réacteur continu a ph constant. Un modèle dynamique de diffusion-réaction-croissance est développe. Il précise les gradients du lactose, de l'acide lactique, du ph, et de l'acide citrique dans les billes et leur incidence sur la croissance et la bioconversion du citrate.

APA, Harvard, Vancouver, ISO, and other styles

20

Back, Daniele. "DESENVOLVIMENTO DE QUEIJO MINAS FRESCAL PROBIÓTICO COM TEOR REDUZIDO DE LACTOSE." Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/5705.

Full text

Abstract:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
In recent years, there has been an increasing demand for foods with some functional property, being the dairy products the largest range of functional products manufactured on the market today. Nevertheless, a large part of the world population is restricted to the consumption of dairy by having a deficiency or absence in the production of lactase in the gut. Thus, this study aimed to develop a probiotic Minas fresh cheese with low-lactose content and evaluate their physico-chemical, sensorial and technological characteristics as well as the viability of probiotic bacteria during storage. Six cheese formulations (T1 to T6) were prepared with milk treated with lactase enzyme (β-galactosidase) at concentrations of 0,3, 0,6 and 0,9 g / L in reaction times of 12 and 24 hours, all of which added by 1% of probiotic culture (Lactobacillus acidophilus e Bifidobacterium sp.). Two other formulations, T7 and T8, were both developed without the addition of lactose and only T7 containing probiotic. The lactose was reduced more than 70% for all treatments added lactase, reaching 93,23% in the treatment with larger amount of enzyme. The physico-chemical evaluation showed that all the cheeses were developed in accordance with current legislation regarding the parameters of moisture and fat. It was observed that the acidity values were significantly lower (ρ <0,05) for cheese with less lactose content and for chesse without probiotic culture to the values found for the other treatments. Although the counts of Lactobacillus acidophilus were below the established minimum, the counts of Bifidobacterium sp. always remained above 106 CFU g-1, regardless of the amount of enzyme lactase added. In the analysis of instrumental texture, there were no significant differences (ρ> 0.05) among treatments for the parameters of firmness, cohesiveness and gumminess. In the sensory analysis, panelists found the taste more sweet and less acid in the sample with higher hydrolysis of lactose, and found no difference in texture compared to controls. Based on the results obtained, it can be said that the enzyme lactase effectively reduced the lactose content in the developed cheeses, and did not change the physico-chemical, sensorial and technological neither the probiotic viability, being a positive option for the dairy market, especially for being able to reduce lactose intolerance symptoms.
Nos últimos anos, houve um aumento na procura por alimentos com alguma propriedade funcional, sendo os derivados lácteos a maior gama de produtos funcionais industrializados atualmente disponíveis no mercado. Porém uma grande parte da população mundial está restringida ao consumo de lácteos por possuir uma deficiência ou ausência na produção de enzima lactase no intestino. Desta forma, o presente trabalho teve como objetivo desenvolver queijos Minas Frescal probióticos com baixo teor de lactose e avaliar suas características físico-químicas, sensoriais e tecnológicas bem como a viabilidade das bactérias probióticas durante o armazenamento. Seis formulações de queijo (T1 a T6) foram elaboradas com leite tratado com a enzima lactase (β-galactosidade) nas concentrações de 0,3, 0,6 e 0,9 g/L em tempos de reação de 12 e 24 horas, sendo todas adicionadas de 1% de cultura probiótica (Lactobacillus acidophilus e Bifidobacterium sp.). Outras duas formulações, T7 e T8, foram desenvolvidas ambas sem adição de lactase e somente T7 contendo probiótico. A lactose foi diminuída em mais de 70% em todos os queijos adicionados de enzima lactase, chegando a atingir 93,23% no tratamento com maior quantidade da enzima. A avaliação físico-química demonstrou que todos os queijos desenvolvidos estavam de acordo com a legislação vigente quanto aos parâmetros de umidade e gordura no extrato seco. Observou-se que os valores de acidez foram significativamente menores (ρ<0,05) para o queijo com menor teor de lactose e para o queijo sem adição de probiótico que os valores encontrados para os demais tratamentos. Apesar das contagens de Lactobacillus acidophilus ficarem abaixo do mínimo estabelecido, as contagens de Bifidobacterium sp. mantiveram-se sempre acima de 106 UFC.g-1, independente da quantidade de enzima lactase adicionada. Na análise do perfil de textura instrumental, não foram detectadas diferenças significativas (ρ>0,05) entre os tratamentos quanto aos parâmetros de firmeza, coesividade e gomosidade. Quanto à análise sensorial, os provadores detectaram o menor gosto ácido e maior gosto doce na amostra com maior hidrólise de lactose, e não observaram diferença quanto à textura em relação aos controles. Com base nos resultados obtidos, pode se concluir que a enzima lactase reduziu de maneira eficaz o teor de lactose nos queijos desenvolvidos, não alterando as características físico-químicas, sensoriais e tecnológicas e nem a viabilidade probiótica, mostrando-se como uma opção positiva para o mercado de laticínios, especialmente por poder reduzir os sintomas da intolerância à lactose.

APA, Harvard, Vancouver, ISO, and other styles

21

Carmichael, C. S. J. "Decomposition of the lactose operon." Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/13315.

Full text

Abstract:

The immediate aims of the project, as set out in the introduction, were 1) to separate the lacZ and lacY genes of the lactose operon such that they could be controlled/induced independently 2) to maintain the expression construct in the E.coli chromosome. The lacY gene was subcloned into plasmid PBN372 downstream of the S.marsescens trp promoter. The flanking E.coli trp genes were exploited to integrate the construct into the E.coli chromosome at the trpB locus via homologous recombination. Homologous recombinants should be trp^{-}. Two approaches were employed to achieve integration: 1) transformation of a recD strain (which was also a lacY deletion) 2) transduction with phage lambda. The first method was unsuccessful, only spontaneous trp^- mutations were isolated. The second method yielded several integrants, one of which was used in subsequent growth experiments. Since the constructed strain was rendered trp^-, the internal tryptophan concentration could be influenced by the concentration of tryptophan in the medium and the level of induction could be set by the addition of differing amounts of the antirepressor, IAA. The growth rate of the constructed strain in minimal lactose media was comparable with that of wild type E.coli. The permease activity of the constructed strain was seen to vary when assayed in the presence of varying amounts of IAA. The expression of permease was also demonstrated to be independent of galactosidase activity. The constructed strain therefore met all the initial requirements for the experimental system set out in this thesis. Difficulties were encountered during the analysis of permease induction in batch culture. This was due to the competition between antirepressor (IAA) and corepressor (tryptophan). These difficulties would have been minimal had the analysis been carried out in chemostat experiments. It would then have been possible to maintain a constant, low level of tryptophan throughout the experiment. In batch culture, the tryptophan level is constantly changing, initially being relatively high and becoming depleted as the experiment progresses.

APA, Harvard, Vancouver, ISO, and other styles

22

Friedrich, Deise Cristine. "A diversidade do gene LCT e a persistência da lactase na população brasileira." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/84942.

Full text

Abstract:

A hipolactasia do tipo adulto é o fenótipo determinado pela diminuição da expressão da lactase após o período de lactação. Ela ocorre em um grande número de adultos em todo o mundo. A lactase é produzida pelos enterócitos e sua função principal é hidrolisar a lactose, que é o carboidrato do leite. Os indivíduos intolerantes à lactose irão apresentar sintomas como inchaço, flatulência, náusea e diarreia causados pela fermentação da lactose. A persistência da lactase (PL) é o fenótipo no qual a expressão da lactase se mantém elevada durante toda a vida. Na Europa, a PL foi relacionada a um polimorfismo de base única (SNP) localizado a aproximadamente 14 Kb do sítio de início da transcrição do LCT (gene da lactase), dentro de um íntron do gene MCM6, sendo este SNP uma troca de C para T na posição -13910 (rs4988235). Na África e Oriente Médio os seguintes SNPs foram relacionados a PL: - 13907C>G (rs41525747), -13915T>G (rs41380347), -14010G>C (rs145946881). O gene LCT também possui SNPs na região codificadora e na região promotora que não estão envolvidos com a PL. Estes SNPs apresentam alto desequilíbrio de ligação formando haplótipos, sendo que os haplótipos A, B, C e U são os mais frequentes na maioria das populações. No Brasil, dados sobre os alelos relacionados com a persistência da lactase são escassos. Além disso, dados populacionais relacionados à diversidade do gene LCT ainda não foram descritos para nossas populações. Portanto, o objetivo deste trabalho foi estudar a diversidade do gene LCT, da região codificadora do gene, da região promotora proximal e da região enhancer população brasileira. Um total de 1297 indivíduos foram analisados. As populações estudadas foram nativos brasileiros (Kaingang N=72, Xavante N=101, Guarani-Kaiowá N=84 e Guarani-Ñandeva N=59), eurodescendentes de Porto Alegre (Rio Grande do Sul, N=337), afrodescendentes de Porto Alegre (N=182), miscigenados de Belém (Pará, N=200) e de Recife (Pernambuco, N=262). Doze SNPs foram analisados, 10 nas regiões codificadora e promotora do LCT e 2 na região enhancer. As metodologias utilizadas na genotipagem destes SNPs foram PCR-RFLP, discriminação alélica pelo sistema TaqMan e sequenciamento. O sequenciamento também foi utilizado na busca de novos alelos da região enhancer. Com relação à população nativa, o único alelo de PL encontrado foi o -13910*T, variando de 0,5% em Xavante a 7,6% nos GuaraniÑandeva. O gene LCT foi altamente polimórfico apresentando 15 haplótipos com distribuição heterogênea nas populações nativas. Na população brasileira em geral, a frequência do alelo -13910*T foi maior (0,295) nos eurodescendentes de Porto Alegre e menor (0,175) na população de Belém. Nos grupos de afrodescendentes de Porto Alegre, Belém e Recife, 4 outras variantes, previamente descritas, da região enhancer foram encontradas: - 13779G>C, -13937G>A, -14010G>C, -14011C>T. Vinte e seis haplótipos previamente descritos foram identificados. O estudo de associação da presença do alelo -13910*T com a presença da síndrome metabólica nos eurodescendentes de Porto Alegre demonstrou que os indivíduos persistentes apresentam menor risco do que os não persistente de ter síndrome metabólica (OR=0,47; p=0,023). Na tentativa de auxiliar no entendimento das causas da PL foi realizado um estudo funcional da variante -13937G>A. Os resultados demonstraram que o alelo derivado não direciona maior expressão do gene repórter em células em cultura. Considerando os dados obtidos no presente trabalho e os disponíveis na literatura, ressaltamos a importância dos estudos que buscam compreender a PL pela busca de novos alelos, por estudos de correlação fenótipo-genótipo e também pelos estudos funcionais para a caracterização das variantes encontradas em relação ao fenótipo da lactase.
Adult-type hypolactasia is the phenotype determined by the decreased lactase expression after weaning. It occurs in a high number of adults in the world. Lactase is produced by the enterocytes and its major function is to hydrolyze lactose, the milk carbohydrate. The lactose intolerant individuals will have symptoms like bloating, flatulence, nausea and diarrhea caused by the lactose fermentation. Lactase persistence (LP) is the high lactase expression during adulthood. In Europe, the LP was related to a single nucleotide polymorphism (SNP) located approximately 14 Kb from the LCT (lactase gene) transcription initiation site, within a MCM6 gene intron, and this SNP is a C to T mutation in the -13910 position (rs4988235). In Africa and Middle East, the following SNPs were related to LP: - 13907C>G (rs41525747), -13915T>G (rs41380347), -14010G>C (rs145946881). LCT gene also has SNPs in the coding and promoter region that are not involved in the LP. These SNPs have high linkage disequilibrium forming haplotypes, with the A, B, C and U being the most frequent haplotypes in the majority of the populations. In Brazil, data about the LP related alleles are rare. Moreover, population data related to LCT gene diversity was not described for our population. Hence, the aim of this work was to study the LCT gene diversity in the coding region, in the proximal promoter region, and in the enhancer region in the Brazilian population. In total, 1297 individuals were investigated. The populations studied were Brazilian natives (Kaingang N=72, Xavante N=101, Guarani-Kaiowá N=84 and Guarani-Ñandeva N=59), Eurodescendants from Porto Alegre (Rio Grande do Sul state N=337), Afrodescendants from Porto Alegre (N=182), admixed individuals from Belém (Pará state, N=200) and from Recife (Pernambuco state, N=262). We analyzed 12 SNPs, 10 in the coding and promoter region of the LCT gene and 2 in the enhancer region. The genotyping methodologies applied were PCRRFLP, allelic discrimination by TaqMan system and sequencing. Sequencing was also employed for new alleles identification in the enhancer region. In relation to the native population, the only LP allele found was -13910*T, and the frequency ranged from 0.5% in Xavante to 7.6% in Guarani-Ñandeva. The LCT gene was highly polymorphic showing 15 haplotypes with heterogeneous distribution in the native populations. In the general population, the frequency of the -13910*T was higher (0.295) in Eurodescendants from Porto Alegre and lower (0.175) in the Belém population. In the groups of Afrodescendants from Porto Alegre, Belém and Recife, 4 other previously described variants in the enhancer region were found: -13779G>C, - 13937G>A, -14010G>C, -14011C>T. Twenty-six haplotypes previously described were found in the Brazilian population. The association study of the -13910*T allele and of the presence of the metabolic syndrome in the Eurodescendants from Porto Alegre showed that the persistent individuals have lower risk than the non-persistent of developing metabolic syndrome (OR=0.47, p=0.023). In an attempt to disclose LP causality, a functional study of the -13937G>A variant was performed. The results showed that the derived allele does not drive a higher expression of the reporter gene in cells in culture. Considering the results of this study and the data available in the literature, we emphasize the importance of the studies that try to determine the LP looking for new alleles, phenotype-genotype studies, and functional studies to characterize the variants found related to the lactase phenotype.

APA, Harvard, Vancouver, ISO, and other styles

23

Allagui, Molka. "Contribution au développement d'un procédé pour la neutralisation du lactosérum électro-activé in situ du réacteur par un mode électrolytique." Master's thesis, Université Laval, 2021. http://hdl.handle.net/20.500.11794/70317.

Full text

Abstract:

L'électro-activation (EA) est une approche novatrice qui permet l'isomérisation du lactose en lactulose directement in situ du lactosérum. Cependant, le lactosérum électro-activé (LAEA) possède un pH hautement alcalin. Alors, l'objectif de ce travail est de contribuer au développement d'un procédé électrolytique pour la neutralisation du LA-EA. La détermination de l'effet des paramètres opératoires et physico-chimiques du milieu électro-activé sur la formation du lactulose a montré qu'un rendement maximum en lactulose de 34,71% est obtenu en utilisant une solution de lactosérum d'une concentration de 7% et 60 min de temps d'électro-activation sous une intensité du courant de 1000 mA après un temps de relaxation de 48 h. Trois configurations électrolytiques ont été étudiées pour la neutralisation de la solution du lactosérum: (1) en neutralisant avec l'anolyte généré dans le compartiment anodique; (2) en inversant les deux électrodes (cathode et anode) et (3) en introduisant le LA-EA dans le compartiment central du réacteur. Les résultats ont montré la faisabilité du processus d'électro-neutralisation. En effet, le pH de la solution a diminué soit en ajoutant des ions H+ (cas des configurations 1 et 2), ou en éliminant les ions OH- de la solution (cas de la configuration 3). De plus, il a été révélé que l'électro-neutralisation est ralentie lorsque (I) augmente pour les deux configurations 1 et 2, tandis que pour la configuration 3, elle est accélérée. Les résultats de l'évaluation de l'effet de ce processus sur les propriétés du LA-EA ont montré que la neutralisation de la solution après un temps de relaxation de 48 h n'a pas affecté la composition glucidique du LA-EA, notamment le lactulose. De plus, elle a permis d'améliorer les propriétés techno-fonctionnelles des poudres résultantes en particulier en termes de reconstitution instantanée.
Electro activation (EA) is a novel approach that allows the isomerization of lactose to lactulose in situ from whey. However, electro-activated whey (LA-EA) has a highly alkaline pH. Therefore, the objective of this work is to contribute to the development of an electrolytic process for the neutralization of LA-EA. The determination of the effect of physico-chemical parameters on the formation of lactulose showed that the maximum lactulose yield (34.71%) is obtained for a feed concentration of 7% at 60 min of electro-activation, under a current intensity of 1000 mA after a relaxation time of 48 h. Three electrolytic configurations were studied for neutralization of the whey solution: (1) neutralizing with the anolyte generated at the anode compartment; (2) reversing the two electrodes (cathode and anode) and (3) introducing LA-EA into the central compartment of the reactor. The results showed the feasibility of the electro-neutralization process. Indeed, the pH of the solution decreased either by adding H+ ions (case of configurations 1 and 2), or by removing OH- ions from the solution (case of configuration 3). Furthermore, it was revealed that electro-neutralization is slowed down when (I) increases for both configurations 1 and 2, while for configuration 3, it is accelerated. The results of the evaluation of the effect of this process on the properties of LA-EA showed that the neutralization of the solution after a relaxation time of 48 h did not affect the carbohydrate composition of LA-EA, especially lactulose. Moreover, it improved the technofunctional properties of the resulting powder in particular in terms of instant reconstitution

APA, Harvard, Vancouver, ISO, and other styles

24

Moura, Erly Catarina de. "Tolerancia a lactose em adultos : dose limite e uso de leite com baixo teor de lactose." [s.n.], 1989. http://repositorio.unicamp.br/jspui/handle/REPOSIP/322544.

Full text

Abstract:

Orientador : Debora de Queiroz Tavares
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-07-14T04:05:32Z (GMT). No. of bitstreams: 1 Moura_ErlyCatarinaDe_M.PDF: 4420157 bytes, checksum: 1da543f9035c70c11e882fc53e4d39ec (MD5) Previous issue date: 1989
Resumo: O resumo poderá ser visualizado no texto completo da tese digital
Abstract: The abstract is available with the full electronic document
Mestrado
Mestre em Ciência da Nutrição

APA, Harvard, Vancouver, ISO, and other styles

25

Fernandes, Tatiana Alves Rigamonte. "Internalização da permease de lactose de Kluyveromyces lactis em resposta a fontes de carbono." Universidade Federal de Viçosa, 2010. http://www.locus.ufv.br/handle/123456789/6584.

Full text

Abstract:

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2015-11-09T13:45:39Z No. of bitstreams: 1 texto completo.pdf: 600665 bytes, checksum: ee26156d6dc7124f99efde31caf1f198 (MD5)
Made available in DSpace on 2015-11-09T13:45:39Z (GMT). No. of bitstreams: 1 texto completo.pdf: 600665 bytes, checksum: ee26156d6dc7124f99efde31caf1f198 (MD5) Previous issue date: 2010-04-12
Fundação de Amparo à Pesquisa do Estado de Minas Gerais
A permease de lactose de Kluyveromyces lactis, Lac12, media o transporte de lactose e o de galactose de baixa afinidade. Aqui é apresentado o estudo do efeito de fontes de carbono na internalização de Lac12 através do uso de linhagens contendo o gene quimérico LAC12-GFP. Quando células de K. lactis pré-cultivadas em galactose ou lactose foram transferidas para um novo meio, Lac12-GFP foi removida da membrana plasmática e localizada intracelularmente. Surpreendentemente, mesmo a presença de galactose ou lactose no novo meio de transferência causou essa internalização, e a resposta celular foi diferente para esse dois açúcares. Os resultados obtidos revelam que o processo de internalização é dependente do tipo de açúcar presente e de sua concentração. A internalização de Lac12-GFP causou redução nas taxas de captação de lactose[C14] e também foi observada em uma linhagem mutante Klsnf1; portanto, esse evento independe da atividade de KlSnf1. Evidências indicam que glicose-6-fosfato é o sinal intracelular, uma vez que a internalização foi induzida por 2-deoxiglicose, e a inibição da atividade da enzima fosfoglimutase por lítio impediu a internalização por galactose, mas não por lactose ou glicose. A internalização não ocorreu em 6-deoxiglicose, e, em ausência de síntese protéica, o evento foi irreversível.
Kluyveromyces lactis Lac12 permease mediates lactose and low-affinity galactose transports. In this study we have investigated the effects of carbon sources on internalization of Lac12 by using a LAC12-GFP fusion construct. When galactose- or lactose-grown cells are shifted to a fresh sugar medium, Lac12-GFP is removed from the plasma membrane and localized intracellularly. Surprisingly, even galactose or lactose in the new media caused the internalization, and cells responded differently to theses two sugars. Our results reveal that this process is dependent of sugar species and also sugar concentration. Lac12-GFP internalization causes reduction on [C14]lactose uptake rates and also occurs in a Klsnf1 mutant strain; thereby, it is independent of KlSnf1 activity. We suggest that glucose-6-phosphate is the intracellular signal, since internalization was induced by 2-deoxyglucose and inhibition of phosphoglucomutase by lithium prevented galactose- but not lactose- or glucose-induced internalization. Lac12-GFP internalization was not triggered by 6-deoxyglucose, and was irreversible in absence of protein synthesis.

APA, Harvard, Vancouver, ISO, and other styles

26

Eadala, Praveen. "Lactose sensitivity and inflammatory bowel disease." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/53992/.

Full text

Abstract:

Controversy still exists as to the incidence, role and impact of lactose sensitivity in inflammatory bowel disease. The thesis shows that there is a higher than previously reported incidence of lactose sensitivity determined by a combination of genotype, breath test and symptoms after a lactose challenge. Lactose sensitivity in patients with inflammatory bowel disease who are in remission is 70%. There was no difference compared to healthy volunteers in terms of lactase genotyping; however there was a significantly greater prevalence of positive breath test and symptoms after lactose challenge. This suggests that lactose sensitivity in inflammatory bowel disease is related to the disease itself or a consequence of it and not due to a genetic predisposition. A significant proportion of inflammatory bowel disease patients [16%] are methane producers which warrants further investigation. A pilot study of reduced lactose intake in patients with Crohn’s disease and lactose sensitivity, who were in remission, showed a promising improvement in symptoms reported and quality of life scores. The Real-Time Polymerase Chain Reaction is simple and quick compared to Restrictive Fragment Length Polymorphism for assessing the lactase genotype. The Quintron MicroLyzer to assess breath samples after lactose challenge is preferred to the hand held Micro H2 meter. This detects methane in addition to hydrogen and without this a number of cases of lactose sensitivity would be II missed. It may be possible to predict a negative breath test with the absence of any GI symptoms after a breath test and vice-versa a positive breath test is very likely if multiple GI symptoms are reported. The ‘hidden’ lactose in drugs used to treat inflammatory bowel disease and co-existing conditions should be considered as it is present in many drugs and can make a significant contribution to the amount of lactose ingested; lactose free alternatives are widely available.

APA, Harvard, Vancouver, ISO, and other styles

27

Lima, Helena Santos. "AIDS, diarreia e malabsorção de lactose." [s.n.], 1989. http://repositorio.unicamp.br/jspui/handle/REPOSIP/309235.

Full text

Abstract:

Orientador : Adriana Seva-Pereira
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
Made available in DSpace on 2018-07-14T22:40:55Z (GMT). No. of bitstreams: 1 Lima_HelenaSantos_M.pdf: 1042138 bytes, checksum: ff56989989a009b866d2c4fbfc4fb96d (MD5) Previous issue date: 1989
Resumo: Com o objetivo de pesquisar a diarréia e a malabsorção de lactose na síndrome da imunodeficiência adquirida, foram estudados 25 aidéticos brancos e comparados com 40 caucasóides normais (grupo controle) . Foi verificado que 50% dos pacientes com AlDS apresentaram história de diarréia em algum momento da doença. A freqüência de malabsorção de lactose nesta síndrome foi de 50%, estatisticamente igual à do grupo controle, não sendo então, a AlDS causa de deficiência secundária de lactase. A história de intolerância ao leite na síndrome da imunodeficiência adquirida foi de 44%, diferente estatisticamente do grupo controle (12%). A freqüência de consumo grande de leite nos pacientes com AlDS (75%) foi estatisticamente igual à do grupo controle (70%), Foram também discutidos, neste trabalho, aspectos fisiopatologia da diarréia na AIDS e sua relação com a malabsorção lactose.
Abstract: In order to Investigate diarrhea and lactose malabsorption in acquired immunodeficiency syndrome, 25 white patients with AIDS were studied and compared to 40 healthy Caucasoids individuals (control group). 60% of patients with AIDS showed history of diarrhea in some point of their illness. The frequency of lactose malabsorption in this syndrome was 60%, statistically equal to the control group. Therefore, AIDS is not cause of secondary lactase deficiency. The history of milk intolerance in acquired immunodeficiency syndrome was about 44%, statistically different from the control group (12%). The frequency of high m11k Intake In AIDS patients (76%) was statistically similar to the control group (70%). Physiopathological aspects of diarrhea in AIDS as well as their relationship with lactose malabsorption were also discussed.
Mestrado
Mestre em Ciências Médicas

APA, Harvard, Vancouver, ISO, and other styles

28

Matak, Kristen Erica. "Lactose Hydrolysis by Fungal and Yeast Lactase: Influence on Freezing Point and Dipping Characteristics of Ice Cream." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/30998.

Full text

Abstract:

Two studies were conducted to examine the effects of lactose hydrolysis on freezing point and dipping characteristics of ice cream. The overall research objective was to determine changes in freezing point, texture and ease of dipping ice cream as a result of lactose hydrolysis. It was also the goal of this research to relate observations from the sensory dippability study with hardness and yield stress data to determine if the latter methods could be used as an alternative to human testing of dippability. In the first experiment, ice cream mixes were treated with lactase (EC 3.2.1.23) to cause 0 to 83% lactose hydrolysis. Lactose hydrolysis decreased the freezing point from -1.63oC in the control (0% hydrolysis) to -1.74oC in the 83% hydrolyzed sample (p < 0.05). Firmness decreased from 0.35 J in the control sample to 0.08 J in the 83% hydrolyzed sample. Lactose hydrolyzed samples melted at a faster rate than the control. There was a difference (p < 0.05) in ease of dipping between samples treated with lactase and the control. There were no perceived differences in sweetness and coldness. In the second study, ice cream mixes were treated with lactase (EC 3.2.1.23) from the microbial sources Kluyveromyces lactis and Aspergillus oryzae to cause 0 to 100% lactose hydrolysis. Compression measurements and yield stress as measured by the vane method were both affected by the temperature of the samples. R2 values for compression measurements as related to lactose hydrolysis were higher then those obtained for yield stress measurements. Human evaluation determined a difference (p < 0.05) between the control samples (0% hydrolyzed) and the treatment groups (80% and 100% hydrolyzed). This research demonstrated a relationship between lactose hydrolysis and ease of dipping ice cream. The results implied that the effect of lactose hydrolysis on the dipping characteristics could be evaluated successfully by three different methods: the vane method, compression measurements, and human evaluation. Changes in freezing point due to lactose hydrolysis were minimal, implying that monitoring freezing point is not enough to determine textural characteristics.
Master of Science

APA, Harvard, Vancouver, ISO, and other styles

29

Houssin, Christine. "La lactose perméase de E. Coli : étude structurale de la protéine solubilisée en détergent." Paris 11, 1985. http://www.theses.fr/1985PA112020.

Full text

Abstract:

Le lactose perméase de E. Coli, produit du gène y de l’opéron lactose, est la protéine membranaire responsable du transport des β-galactosides. Selon l’hypothèse chimiosmotique de Mitchell, la lactose perméase catalyse un co-transport proton(s)/lactose. Récemment, la lactose perméase a été purifiée dans un détergent non ionique : l’octyl-glucoside, puis reconstituée dans des protéoliposomes. Ce résultat nous a permis d’aborder une étude structurale de la protéine purifiée, et en particulier de déterminer l’état d’association de la perméase solubilisée dans un détergent non dénaturant. Dans un premier temps, nous avons échangé l’octyl glucoside, dans lequel la perméase est peu stable, pour un autre détergent non ionique : le C₁₂E₈ (dodécyloctaéthylène glycol monoéther). Le complexe protéine/détergent/phospholipides a été caractérisé chimiquement : il contient 17 molécules de détergent et 9 phospholipides liés par chaine polypeptidique de perméase. Une étude par filtration sur gel (chromatographie liquide conventionnelle) a montré l’existence d’une espèce majoritaire dont nous avons déterminé le rayon de Stokes. L’utilisation d’une technique chromatographique plus résolutive : l’HPLC nous a permis de séparer 2 espèces moléculaires de lactose perméase. Nous avons effectué sur chacune d’elles une étude par ultracentrifugation analytique. L’ensemble de nos résultats indiquent clairement que la lactose perméase est essentiellement dimérique dans le C₁₂E₈ : la forme monomérique existe également dans ce détergent mais en très faible proportion. Pour plusieurs raisons, mais essentiellement parce que le C₁₂E₈ est non dénaturant, nous pensons que la prépondérance de l’état dimérique de la perméase, observée dans ce détergent, pourrait refléter l’état d’association natif de la protéine dans la membrane. Nous avons également pu montrer que le C₁₂E₈ se fixait sur la perméase sous forme d’une monocouche et non d’une micelle. Ce résultat conforte ceux précédemment obtenus pour d’autres détergents non ioniques, concernant leur mode de fixation sur les protéines hydrophobes.

APA, Harvard, Vancouver, ISO, and other styles

30

Carminatti, Claudimir Antonio. "Ensaios de hidrólise enzimática da lactose em reator a membrana utilizando beta-galactosidase Kluyveromyces lactis." Florianópolis, SC, 2001. http://repositorio.ufsc.br/xmlui/handle/123456789/81434.

Full text

Abstract:

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Química.
Made available in DSpace on 2012-10-19T03:56:53Z (GMT). No. of bitstreams: 1 206490.pdf: 398163 bytes, checksum: f16a7b92b0c01916305100970df09783 (MD5)
O soro de leite é o subproduto principal da indústria laticínia. Devido ao seu elevado poder poluente e a dificuldade de sua eliminação, as empresas estão buscando alternativas para o reaproveitamento dos componentes do soro, principalmente das proteínas e da lactose. A lactose é um dissacarídeo que pode ser hidrolisado através dos métodos ácido ou enzimático, fornecendo como produtos glicose e galactose. No processo enzimático é utilizada b-D-galactosidase, que pode ser extraída de plantas, animais, fungos, bactérias e leveduras. Neste trabalho, a lactose presente no permeado do soro de leite foi hidrolisada em um reator a membrana utilizando-se lactase (b-D-galactosidase) Kluyveromyces lactis Maxilact® L-5000. O grau de hidrólise foi determinado para diversas condições operacionais de temperatura (30, 35, 40, 45 e 50 ºC), pH (4, 5, 6 e 7) e concentração de enzima (400, 1250 e 2000 mg.L-1). Foram obtidas conversões entre 90 e 100% para temperaturas entre 30 e 40 ºC, pH 6 e concentração de enzima de 1250 mg.L-1. A hidrólise foi realizada em um reator utilizando uma membrana de PVDF-DMF com alta porosidade que permitiu a passagem de compostos com baixa massa molecular, como a glicose, galactose e lactose, e impediu a permeação das enzimas, moléculas com alta massa molecular. A possibilidade da interação entre a enzima e a membrana foi verificada através das análises de FTIR # Espectroscopia de Absorção na Região do Infravermelho com Transformada de Fourier e MEV # Microscopia Eletrônica de Varredura, realizadas na membrana nova e após sua utilização na célula de ultrafiltração. Ensaios foram realizados para comparar a hidrólise da lactose do soro de leite utilizando dois modelos de reator: reator operado em batelada e reator a membrana. As condições operacionais nos dois experimentos foram as mesmas, temperatura de 40 ºC, pH 6 e concentração de enzima de 1250 mg.L-1. O reator a membrana mostrou-se mais eficiente, convertendo 92% da lactose em glicose e galactose, contra 82% do reator operado em batelada.

APA, Harvard, Vancouver, ISO, and other styles

31

Frère, Jacques, and Georges Novel. "Isolement et caracterisation de la region de replication du plasmide lactose-protease pucl22 de lactococcus lactis subsp. Lactis cnrz270." Caen, 1993. http://www.theses.fr/1993CAEN2033.

Full text

Abstract:

Le replicon minimum rep22 du plasmide lactose-protease pucl22 (54 kb) de lactococcus lactis subsp. Lactis crnz270 a ete isole sur un fragment de 1812 pb. Il est constitue de deux regions essentielles a la replication: l'origine (ori) portant deux sequences homologues aux boites dnaa d'e. Coli et trois iterons suivis d'un quatrieme incomplet; le gene rep22a codant la proteine rep22a (388 a. A. ) active en trans. La replication est initiee dans la region ori et progresse de facon bidirectionnelle suivant un mecanisme theta. Rep22a inhibe l'expression du gene cat de pc194 chez lc. Lactis en se fixant sur sa region promotrice, et doit inhiber sa propre expression. De nombreux plasmides de bacteries lactiques hybrident avec une sonde specifique rep22; certains sont coresidents. Des plasmides possedant une forte similarite de sequence avec rep22 sont compatibles avec ce replicon. Cette compatibilite plasmidique pourrait resulter d'une adaptation du couple iteron-proteine de replication de chaque plasmide permettant l'existence de souches multiplasmidiques portant plusieurs replicons de cette famille. Le nombre de copies par cellule du replicon rep22 varie suivant la souche de lactocoque qui l'abrite. Ce replicon segrege au hasard, ou moins bien qu'au hasard suivant la souche de lactocoque qui l'abrite, signifiant l'absence d'un systeme de partition active dans cette region d'adn. Un tel systeme est detecte chez le plasmide lactose-protease parental qui possede un nombre de copies voisin de celui du chromosome

APA, Harvard, Vancouver, ISO, and other styles

32

Giraldi, Catiucia. "Aplicação de concentrado proteico de soro de leite com lactose hidrolisada em iogurte com baixo teor de lactose." Universidade Tecnológica Federal do Paraná, 2014. http://repositorio.utfpr.edu.br/jspui/handle/1/1131.

Full text

Abstract:

O soro de leite é uma importante fonte de proteínas. Porém, no Brasil ainda há um grande número de laticínios que realizam o descarte deste subproduto da fabricação de queijos, gerando assim, desperdícios e um problema socioambiental. A busca por novas aplicações ao soro de leite pode aumentar o uso potencial deste subproduto como ingrediente lácteo em diversos alimentos. Este trabalho teve como objetivo a hidrólise da lactose do concentrado proteico de soro de leite (CPS) para aplicação como ingrediente lácteo em iogurte cremoso para intolerantes à lactose. A metodologia de superfície de resposta foi utilizada para investigar o efeito de dois parâmetros (tempo e concentração de enzima) na hidrólise da lactose do CPS e do leite para produção de iogurte com redução de lactose. A experimentação teve como objetivo definir as faixas ótimas de operação para as variáveis do processo, visando à maximização da hidrólise da lactose. As condições ótimas para a hidrólise da lactose foram: para o CPS, concentração de enzima 0,22% por 1680 minutos e para o leite, 0,13% de enzima por 120 minutos. Depois de hidrolisado, o CPS foi submetido à secagem por atomização e apresentou os valores de lactose, glicose, galactose e proteínas iguais a 2,98; 19,41; 15,89 e 36,7g. 100 g-1 de amostra, respectivamente; 5,00% de umidade e 8,06% de cinzas. Após a hidrólise, as amostras de leite foram fortificadas com diferentes concentrações de CPS e leite em pó desnatado (LPD) para produção de iogurte cremoso. A amostra controle e as amostras fortificadas com 2 e 4% de CPS apresentaram os menores valores de lactose: 0,05; 0,09 e 0,13 g. 100 g-1 de iogurte, respectivamente. Foram realizadas análises microbiológicas e físico-químicas no CPS em pó e nas amostras de iogurtes, e ambos estavam dentro dos padrões da legislação vigente. A partir da pesquisa, verificou-se ser possível o uso potencial do CPS hidrolisado na produção de iogurte com baixo teor de lactose, beneficiando os intolerantes à lactose, à indústria e o meio ambiente.

APA, Harvard, Vancouver, ISO, and other styles

33

Ghazi, Alexandre. "La lactose perméase d'Escherichia coli : cotransport proton lactose et théorie chimiosmotique localisée, inactivation in vivo de la protéine." Paris 11, 1987. http://www.theses.fr/1987PA112307.

Full text

Abstract:

Le lactose perméase d’E. Coli est une protéine membranaire qui catalyse le transport actif du lactose en symport avec un proton. Le travail présenté ici comporte deux parties distinctes correspondant à des thèmes utilisant tous deux le lactose perméase comme système expérimental. La théorie chimiosmotique, dans sa formation initiale (dite délocalisée), est en contradiction, au moins apparente, avec un certain nombre de tests expérimentaux. Parmi ceux-ci, ceux qui traitent des relations flux-force sont les plus contraignants. La validité de ce test a néanmoins été remise en cause récemment dans un cas particulier. Nous examinons d’abord, au plan théorique, le bien-fondé de cette critique. Au plan expérimental, l’étude des relations flux-force en bioénergétique a jusqu’ici concerné uniquement la phosphorylation oxydative et phosphorylation, il n’existe pas de relation unique entre le flux (ici vitesse de transport du lactose catalysé par le lactose perméase) ou accumulation d’une part, et force (force promotrice) d’autre part. Ce résultat est compatible avec un mécanisme chimiosmotique localisé. Nous avons mis en évidence un phénomène d’inactivation du lactose perméase in vivo (dans la membrane). Les caractéristiques au niveau de la perméase ainsi que les conditions de cette inactivation sont décrites. On montre en particulier que ce phénomène met en jeu l’activité de la chaine respiratoire d’E. Coli et certaines protéases. L’inactivation du lactose perméase pourrait refléter un mécanisme physiologique

APA, Harvard, Vancouver, ISO, and other styles

34

Ghazi, Alexandre. "La Lactose perméase d'Escherichia coli cotransport lactose proton et théorie chimiosmotique localisée : inactivation in vivo de la protéine /." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb376054042.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Van, Griethuysen Evin Griethuysen-Dilber Evin van. "Etude de la cinétique de la lactase de Aspergillus oryzae et de son application à l'hydrolyse du lactose /." [S.l.] : [s.n.], 1987. http://library.epfl.ch/theses/?nr=678.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Berwig, Karina Hammel. "Produção bacteriana de poli(3-hidroxibutirato) a partir de lactose e soro de leite." reponame:Repositório Institucional da UCS, 2016. https://repositorio.ucs.br/handle/11338/1192.

Full text

Abstract:

Polihidroxialcanoatos são polímeros 100% biodegradáveis produzidos intracelularmente por bactérias, que possuem características semelhantes às de polímeros de origem petrolífera e configuram uma alternativa a estes polímeros, os quais devido ao seu crescente acúmulo na natureza vêm se tornando um grave problema ambiental. O poli(3-hidroxibutirato) (PHB) é um poliéster que faz parte deste grupo, sendo o mais amplamente estudado. Visando o aproveitamento do soro de leite, que é gerado em volumes elevados na produção de queijo, e ainda uma possível redução de custos do processo de produção de PHB, este trabalho avaliou a produção deste polímero por meio das bactérias Alcaligenes latus e Bacillus megaterium. Inicialmente investigou-se o efeito de diferentes concentrações iniciais de lactose e de diferentes tempos de processo, em ensaio realizado em agitador orbital a 35 °C e 200 rpm. Definiu-se também qual das bactérias apresentou melhor desempenho e a concentração inicial de lactose por meio de ensaio em agitador orbital com as mesmas condições mencionadas anteriormente. Estes resultados foram avaliados por meio de planejamento experimental fatorial 2³ sem ponto central. Avaliou-se o efeito da neutralização do meio de cultivo preparado com o sobrenadante obtido após a precipitação ácida das proteínas do soro de leite com hidróxido de amônio (NH4OH), hidróxido de potássio (KOH) e hidróxido de sódio (NaOH) (soluções 10% m/v) por meio de análise estatística de um fator a vários níveis (ANOVA). Ainda, foram comparados (por meio de ANOVA) quatro meios de cultivo (produzidos com lactose, soro de leite, sobrenadante obtido após a precipitação ácida das proteínas do soro de leite, lactose extraída por processos de separação por membranas) por meio de ensaio em agitador orbital nas mesmas condições previamente mencionadas. O meio que proporcionou maior concentração final de PHB foi utilizado em ensaio em biorreator de bancada, a 35 °C e pH controlado em 6,5. Na primeira fase, identificou-se que para a bactéria A. latus a concentração inicial de lactose mais adequada foi a de 20 g.L-1, com produção máxima de PHB de 0,55 g.L-1 em 12 horas, enquanto que para a bactéria B. megaterium foi de 16 g.L-1, com produção máxima de PHB de 0,095 g.L-1 também em 12 horas. Com a posterior análise estatística, verificou-se que não houve diferença significativa na geração de produto com as concentrações iniciais de lactose de 16 e 20 g.L-1. A bactéria que proporcionou maior produção de polímero foi a A. latus, enquanto o meio foi o composto pelo sobrenadante obtido após a precipitação ácida das proteínas do soro de leite (neutralizado com hidróxido de amônio - melhor resultado na neutralização). No ensaio em biorreator de bancada (TecBio 7,5, Tecnal, Brasil), constatou-se que o tempo total de processo foi de 11,6 horas, com máxima velocidade específica de crescimento de 0,428 h-1, máxima velocidade específica de formação de produto de 0,026 g.L-1.h-1, máxima velocidade específica de consumo de substrato de 1,036 g.L-1.h-1, fator de rendimento em células de 0,211 g.g-1, fator de rendimento em produto de 0,024 g.g-1 e produtividade volumétrica de 0,014 g.L-1.h-1. Ainda, por meio de caracterização do PHB extraído e do PHB padrão por calorimetria exploratória diferencial, termogravimetria e espectroscopia no infravermelho com transformada de Fourier, verificou-se que o polímero produzido possui propriedades semelhantes às do padrão, demonstrando que a produção de PHB por A. latus e B. megaterium utilizando soro de leite é factível.
Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2016-07-01T14:29:10Z No. of bitstreams: 1 Dissertacao Karina Hammel Berwig.pdf: 2733803 bytes, checksum: fc3f784dd87e48cbeb45f4a3784a5219 (MD5)
Made available in DSpace on 2016-07-01T14:29:11Z (GMT). No. of bitstreams: 1 Dissertacao Karina Hammel Berwig.pdf: 2733803 bytes, checksum: fc3f784dd87e48cbeb45f4a3784a5219 (MD5) Previous issue date: 2016-07-01
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES.
Polyhydroxyalkanoates are 100% biodegradable polymers produced intracellularly by bacteria, and have characteristics similar to petroleum-based polymers. They emerge as an alternative to recalcitrant polymers, that because of its growing accumulation in nature are becoming a serious environmental problem. Poly(3-hydroxybutyrate) (PHB) is a polyester which is part of this group, being the most studied. In order to utilize whey, which is generated in large volumes in cheese production, and also to enable a possible cost reduction of the PHB production process, this study evaluated the production of this polymer by Alcaligenes latus e Bacillus megaterium. First of all, the effect of different initial lactose concentrations and different process times were investigated in an orbital shaker at 35 °C and 200 rpm. In addition, it was defined which bacteria showed best results and also the appropriate initial lactose concentration in an orbital shaker in the same conditions mentioned. The results were evaluated by a factorial 2³ (without central point) experimental design. The neutralization of the medium (prepared with the supernatant obtained after the acid protein precipitation of whey) with ammonium hydroxide (NH4OH), potassium hydroxide (KOH) and sodium hydroxide (NaOH) (10% w/v solutions) was evaluated by a one factor statistical analysis (ANOVA). Also, four culture mediums (lactose, whey, supernatant obtained after acid protein precipitation of whey, lactose obtained by membrane filtration of whey) were compared through an experiment in orbital shaker in the same conditions used before. The results were also evaluated by a one factor statistical analysis. The medium with the best results was used in a bioreactor experiment, at 35 °C and pH controlled at 6.5. For A. latus the most appropriate initial lactose concentration was 20 g.L-1, with a maximum PHB concentration of 0.55 g.L-1 in 12 hours. For B. megaterium, the initial lactose concentration was 16 g.L-1, and a maximum PHB concentration of 0.095 g.L-1 also in 12 hours. With the posterior statistical analysis it was seen that there was no significant difference in PHB production with initial lactose concentrations of 16 and 20 g.L-1. A. latus showed better results for PHB production, while the best medium was the one produced with the supernatant obtained after acid protein precipitation of whey (neutralized with ammonium hydroxide - best neutralization results). In the bioreactor experiment was observed that the total process time was 11.6 hours, with a maximum specific growth rate of 0.428 h-1, maximum specific product formation rate of 0.026 g.L-1.h-1, maximum specific substrate consumption rate of 1.036 g.L-1.h-1, cell yield of 0.211 g.g-1, PHB yield of 0.024 g.g-1 and volumetric productivity of 0.014 g.L-1.h-1. Finally, it was seen, through the polymer characterization by differential scanning calorimetry, thermogravimetry and Infrared Spectroscopy with Fourier transform, that the produced polymer has similar characteristics to those of the standard PHB, showing that the production of PHB by A. latus and B. megaterium using milk whey is feasible.

APA, Harvard, Vancouver, ISO, and other styles

37

Kauter, Michael D. "The effects of impurities on lactose crystallization /." St. Lucia, Qld, 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17844.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Hediger, Thomas. "Die enzymatische Hydrolyse der Lactose mit Hohlfaserreaktoren /." [S.l.] : [s.n.], 1985. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=7933.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Rampanti, Giorgia. "Lactose crystallization assisted by Static Electric Field." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.

Find full text

Abstract:

Il lattosio ha varie applicazioni nell’industria alimentare grazie alle sue proprietà funzionali. È recuperato dal siero, il principale sottoprodotto della caseificazione. Il processo di produzione è ancora lontano dall’essere ottimizzato, anche a causa della mancanza di comprensione del processo di cristallizzazione. Per migliorarlo sono utilizzati nuovi design degli impianti e tecniche come l’inseminazione di germi cristallini. Negli ultimi anni è stato studiato l’utilizzo di sistemi innovativi, come campi elettrici e/o magnetici, ultrasuoni e alte pressioni per controllare la cristallizzazione. L’obiettivo del progetto è stato quello di investigare la cristallizzazione del lattosio e di valutare l’effetto del SEF sul processo. A tale scopo sono stati utilizzati due dispositivi sviluppati presso ONIRIS-GEPEA (Nantes, FR). Il principio del “SET-UP 1” era di rilevare l’aumento di temperatura che si verifica con la cristallizzazione. Dal confronto dei grafici tempo-temperatura delle soluzioni controllo e trattate con SEF non sono state riscontrate differenze, tranne che con l’applicazione di 8 kV-SEF, in cui il segnale è stato interpretato come un continuo innesco della cristallizzazione della soluzione nella zona di supersaturazione. I cristalli sono stati analizzati tramite SEM e XRD. La microstruttura dei cristalli formati durante l’applicazione del SEF è apparsa più liscia e lineare. Gli spettri XRD consentono di studiare i polimorfi del lattosio (Lα∙H2O, Lβ, LαS, LαH); la forma LαH è più igroscopica e meno ricercata e non è stata trovata nei cristalli derivanti da cristallizzazione assistita da SEF. Attraverso il “SET-UP 2” è stato possibile monitorare la cristallizzazione durante l’applicazione del SEF, che ha permesso una riduzione significativa del tempo di nucleazione. Il SEF è risultato un mezzo rilevante per innescare la cristallizzazione del lattosio e per cambiare il comportamento stocastico della nucleazione rendendolo più ripetibile e prevedibile.

APA, Harvard, Vancouver, ISO, and other styles

40

Lajoie, Denis. "Lactose hydrolases de Trichoderma reesei MCG-80." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq26227.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Kirk, Joanne H. "Fundamental structural aspects of crystalline lactose polymorphs." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/12527.

Full text

Abstract:

Excipients are used in pharmaceutical formulations as fillers and drug carriers. Their successful function is inextricably linked to their physicochemical properties and, in turn, these properties are directly related to their structure. This thesis is concerned with the structural and spectroscopic characterisation of a selection of excipients by powder and single crystal X-ray diffraction, Raman and IR spectroscopy and MASNMR and an investigation of their stability as a function of temperature, humidity and particle size. As well as being a well-known excipient used in the pharmaceutical industry, lactose is also a common food additive. The diverse usage of lactose has led to a wealth of contradictory information relating to both structure and properties of this material. The first part of experimental work in this thesis identifies the four real lactose polymorphs; the naturally occurring a-lactose monohydrate; the anhydrous stable form of a-lactose; the hygroscopic unstable form of a-lactose; and the anomeric equivalent, p-lactose using powder X-ray diffraction. The work shows that anhydrous lactose formed by solvent dehydration often termed aM is simply the anhydrous stable form of a-lactose formed via a different route. Simple methods for discerning between the polymorphs using standard laboratory equipment are suggested. IlC MASNMR data were collected on all four forms of lactose for the first time and illustrate key differences between the four structures. Single crystal data were successfully collected on the a-lactose monohydrate and refinement carried at low temperature to determine the hydrogen bonded arrangement for the first time. Rietveld refmement of the hygroscopic unstable form of a-lactose using in-situ temperature resolved X-ray diffraction has shown that the hygroscopic form can be produced as a single phase. Refinement of Plactose using the Rietveld method has shown that powder diffraction data were comparable with single crystal data, with respect to structure refinement but attempts at both crystallisation and refinement of the stable anhydrous a-lactose polymorph were unsuccessful due to the complexity of the structure. Powder X-ray diffraction analysis was shown to be an effective tool in the quantification of mixed phase lactose samples with respect to both mixed phase stable anhydrous a-lactose and a-lactose monohydrate; and mixed p-Iactose and a-lactose monohydrate samples. The accuracy of the technique was determined to be at least 5%. Quantification was carried out using relative intensities of a well resolved unique reflection for each phase within the system. Dehydration techniques applied to lactose were applied to other hydrated pharmaceutical sugars; trehalose dihydrate and raffmose pentabydrate. Solid state techniques; powder X-ray diffraction, Raman and IR spectroscopy; showed that discrimination of other sugar hydrates became more complex with increasing levels of hydration.

APA, Harvard, Vancouver, ISO, and other styles

42

Shah, Ajay. "Interaction of water with maltodextrins and lactose." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404592.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Pires, Ana Carolina Moreira da Silva. "Desenvolvimento de petit suisse simbiótico sem lactose /." Araraquara, 2018. http://hdl.handle.net/11449/154963.

Full text

Abstract:

Orientador: Kátia Sivieri
Banca: Adilson Cesar Abreu Bernardi
Banca: Valéria de Carvalho Santos Ebinuma
Resumo: Introdução: A intolerância à lactose atinge 70% da população mundial e é uma desordem gastrointestinal caracterizada pela deficiência da enzima lactase. Indivíduos intolerantes a lactose tendem a parar de consumir produtos lácteos ou buscam por opções sem lactose para suprir as necessidades diária de nutrientes e cálcio. Uma das alternativas no desenvolvimento de produtos lácteos com baixo ou ausência de lactose é o uso da tecnologia de membrana, principalmente a ultrafiltração (UF) e a diafiltração (DF). Objetivo: Desenvolver um petit suisse simbiótico sem lactose utilizando leite com alto teor de proteína e sem lactose obtidos por tecnologia de UF e DF. Métodos: Este trabalho foi desenvolvido em duas etapas, sendo que na primeira etapa foram obtidos os leites a serem utilizados na produção do queijo petit suisse. Para obtenção do leite com maior teor de proteína - leite proteico (LP) foi realizado a operação de ultrafiltração do leite UHT desnatado, utilizando um fator de concentração igual a dois. Em seguida, para a obtenção de leite sem lactose foram realizadas três diafiltrações para a remoção da lactose do leite proteico, produzindo o leite proteico sem lactose (LPSL). Nos leites LP e PPSL foram avaliados os teores de proteína e lactose. Na segunda etapa foram realizados os processos de obtenção dos queijos Quarks e petit suisses. A partir do LP foi desenvolvido o queijo Quark proteico (QQP), com o LPSL foi desenvolvido o queijo Quark proteico sem lactose (QQPSL) e como... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Introduction: Lactose intolerance affects 70% of the world population and is a gastrointestinal disorder characterized by a deficiency of the enzyme lactase. Individuals intolerant to lactose tend to stop consuming dairy products or search for lactose-free options to meet the daily needs of nutrients and calcium. One of the alternatives in the development of dairy products with low or no lactose is the use of membrane technology, mainly ultrafiltration (UF) and diafiltration (DF). Objective: To develop a symbiotic petit suisse without lactose using milk with high protein content and without lactose obtained by UF and DF technology. Methods: This work was developed in two stages, and in the first stage the milks to be used in the production of petit suisse cheese were obtained. To obtain the milk with the highest protein - protein (LP) milk, the ultrafiltration operation of the skimmed UHT milk was performed, using a concentration factor of two. Then, to obtain lactose-free milk, three diafiltrations were carried out to remove lactose from protein milk, producing lactose-free protein milk (LPSL). In the LP and PPSL milks the protein and lactose contents were evaluated. In the second stage the processes of obtaining Quarks and petit suisses cheeses were carried out. From the LP, the protein Quark cheese (QQP) was developed, with the LPSL was developed the protein Quark cheese without lactose (QQPSL) and as control was produced the cheese Quark control (QQC) obtained through the skim milk UHT control (LC), without membrane processing. For the Quarks cheeses were also evaluated the levels of protein and lactose. Then the petit suisse cheeses were produced. With the QQP, the probiotic and proteic symbiotic petit suisses (PPP and PPS) were produced. From the QQPSL, the probiotic and... (Complete abstract click electronic access below)
Mestre

APA, Harvard, Vancouver, ISO, and other styles

44

Blyth, Kristy Michelle. "Causes of growth rate inhibition in lactose." Thesis, Curtin University, 2013. http://hdl.handle.net/20.500.11937/1723.

Full text

Abstract:

Lactose, a by-product of dairy processing, crystallizes slowly and unreliably. Purified lactose was obtained for baseline crystal growth behaviour. A new method to achieve this was developed. The impact of process-relevant impurities on crystal growth relative to the baseline was studied. Sugar phosphates were found to inhibit growth. Using inorganic salts it was found that ion pairs can have an impact on crystal habit. This may explain some of the discrepancies in the literature.

APA, Harvard, Vancouver, ISO, and other styles

45

Dwivedi, Sarvajna Kumar. "Anomeric composition and solid state properties of lactose." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/27872.

Full text

Abstract:

Lactose is a widely used excipient in capsules and tablets. It has two anomeric forms, ⍺ (usually a monohydrate) and β (anhydrous). Lactose NF XVI is usually ⍺-lactose monohydrate. Physical properties, such as thermal behavior, x-ray diffraction characteristics, and true density of the anomers are different and not clearly understood. Pure samples of each anomer are difficult to prepare and all commercial lactose samples, especially the directly compressible grades, contain a certain amount of each anomer. It is not clearly established in what physical form the two anomers are present in a commercial sample. The physical form, and also certain differences in the physical properties, may depend upon the anomeric composition. An accurate and rapid gas chromatographic (GC) method for the determination of anomeric composition was developed. It involved derivatization of the lactose samples using trimethylsilylimidazole (TSIM). A mixture of TSIM in dimethylsulfoxide (DMSO) and pyridine (PYR) was used. DMSO dissolved the samples and PYR stabilized the solutions by preventing a phase separation which occurred if only TSIM and DMSO were used. Alpha-rich samples were dissolved directly into the mixture. Beta-rich samples were first dissolved in DMSO and then derivatized using a mixture of TSIM and PYR. An OV-225 column with helium as carrier gas was used for separating the anomers. The relative response of the anomers at a flame ionization detector was equal. Thus, the relative anomeric peak areas could be used as relative anomeric amounts. This avoided the use of an internal standard. The anomeric composition of a number of lactose samples was determined and was found to vary from 1.9 to 98.4% ⍺. A study of the thermal behavior of commercial lactose samples using differential scanning calorimetry and thermal microscopy showed that all ⍺-lactose monohydrate rich samples exhibited a dehydration peak followed by a melting peak when heated in an open pan. In sealed pans, the dehydration peak split into two components because of an overlap of an exotherm (due to dissolution of anhydrous lactose in the liquid water formed in the sealed pan, and recrystallization of β-lactose from the solution) with the endothermic dehydration peak. The extent of the split varied with the heating rate (which controls the extent of dissolution). Two new peaks, an endotherm and an exotherm, also appeared after the dehydration peak. The endotherm is due to anomeric conversion (determined using the GC method) rather than melting, and the exotherm is due to recrystallization into a new crystal lattice as the sample became β-rich. Since β-rich samples normally have a higher melting point than ⍺-rich samples, the melting peak shifted to a higher temperature when sealed pans were used. An unstable anhydrous a-lactose sample also showed the endotherm (anomeric conversion) and the exotherm (recrystallization of the β-rich form). On the basis of their powder x-ray diffraction patterns, the lactose samples can be classified into three types: 1. ⍺-lactose monohydrate rich, 2. β-rich, and, 3. samples showing peaks of both ⍺-lactose monohydrate and β-lactose. It was shown using quantitative x-ray diffraction that samples did not contain their anomeric impurity as a simple physical mixture. The true density of the lactose samples also varied with their anomeric composition. Beta-rich samples had greater true density than a-rich samples. This can be attributed to: 1. a simple physical mixture of ⍺-lactose monohydrate and β-lactose crystals, 2. a continuous substitutional solid solution, 3. an interstitial solid solution, or, 4. a mixture of two solid solutions. The first possibility was ruled out using quantitative x-ray diffraction because the relative anomeric x-ray peak intensities did not match the anomeric composition determined by GC. The second possibility was ruled out because there was no gradual shift of peaks in the x-ray diffraction patterns with the anomeric composition. The formation of an interstitial solid solution was not possible because this occurs only if the solute and solvent have very different molecular sizes. The quantitative x-ray diffraction experiments suggest that most samples contain a mixture of two solid solutions. Sorbed-moisture and surface area are important factors in tabletting. Various commercial lactose samples had specific surface areas ranging from 0.108 to 0.574 m²/g- Moisture-desorption and sorption were found to depend more on the relative crystallinities of the samples than on their surface areas.
Pharmaceutical Sciences, Faculty of
Graduate

APA, Harvard, Vancouver, ISO, and other styles

46

Costa, Ricardo Calvo. "Obtenção de lactose a partir de permeado de soro de queijo e permeado de leite." [s.n.], 1995. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255587.

Full text

Abstract:

Orientador: Salvador M. Roig
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-07-20T23:21:40Z (GMT). No. of bitstreams: 1 Costa_RicardoCalvo_M.pdf: 2710464 bytes, checksum: 2f1749d07b2a3e39917bedff151f819f (MD5) Previous issue date: 1995
Resumo: Neste trabalho foi estudada a extração de lactose a partir de permeado de leite e de permeado de soro de queijo, obtidos por ultrafiltração de leite e soro de queijo. A antecipação da etapa de descoloração foi estudada com o objetivo de eliminar a etapa de refino no processo tradicional e obter uma lactose de alto teor de pureza. A pasta descorante composta de 750/0 de carvão ativo e negro de ossos e 25% de ácido clorídrico concentrado foi adicionada aos permeados de leite e de soro de queijo, e somente resultou em descoloração quando foram utilizados teores de pasta superiores a 8% da massa de lactose presente no permeado. Os melhores resultados foram obtidos a partir de permeado de leite, obtido através de ultrafiltração de leite em um sistema de ultrafiltração dotado de membranas minerais, sem descoloracão do permeado. Os compostos coloridos foram retidos durante o processo de ultrafiltração resultando em um permeado límpido. O melhor processo obtido para extração de lactose a partir de permeado foi ultrafiltração do leite em membrana mineral, seguido de concentração à vácuo do permeado, cristalização, separação, lavagem dos cristais com água a 5°e e secagem. A partir de permeado de leite com 0,027% de nitrogênio total 0,49% de cinzas e 4,71 % de lactose foi obtida lactose com 99,3% de pureza 0,66% de cinzas e 0,07% de nitrogênio total
Abstract: The lactose extraction by ultrafiltration from milk and whey permeates was studied. The aim of this work was to eliminate the refining step of the traditional process and produce a high purity level lactose yield before the discolouring step. The discolouring paste which is made of 75% of a mixture of active carbon and black bone and 25% of concentrated hydrogen chloride was added to milk and whey permeates resulting in discolouring only when the paste concentration was higher than 8% in relation to the lactose mass in the permeate. The best results carne from milk permeate processed in a mineral membranes milk ultrafiltration system without the discolouring step. The colouring compounds were retained in the ultrafiltration process resulting in a cleaned permeate. The best process to lactose extraction from permeate was milk ultrafiltration in a mineral membrane system followed by permeate vacuum concentration, crystallization, separation and crystal washing with 't\1Iter at 5°e and drying. From mill permeate with 0,027% total nitrogen, 0,49% ash and 4,71% of lactose it was possible to obtain lactose with a purity of 99,3%, 0.660% ash and 0,07% total nitrogen contents
Mestrado
Mestre em Tecnologia de Alimentos

APA, Harvard, Vancouver, ISO, and other styles

47

Duluc, Isabelle. "Structure de la lactase-phlorizine hydrolase du rat et expression au cours du développement post-natal et le long du tractus intestinal." Aix-Marseille 3, 1992. http://www.theses.fr/1992AIX30092.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Worthen, Denise Lynne. "Lactose binding to the E. coli symport protein Lac permease." Diss., Pasadena, Calif. : California Institute of Technology, 1989. http://resolver.caltech.edu/CaltechTHESIS:11242009-093118312.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Sparvoli, Antonio Cardoso. "Malabsorção de lactose do adulto. Prevalencia na população sulina. Aspectos geneticos e evolutivos do polimorfismo da atividade da lactose." [s.n.], 1990. http://repositorio.unicamp.br/jspui/handle/REPOSIP/313701.

Full text

Abstract:

Orientador: Adriana Seva-Pereira
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
Made available in DSpace on 2018-07-14T01:47:14Z (GMT). No. of bitstreams: 1 Sparvoli_AntonioCardoso_D.pdf: 2483442 bytes, checksum: 557646058e7d68cd786d24e96a225f93 (MD5) Previous issue date: 1990
Resumo: A prevalência da malabsorcão de lactose do adulto na Região Sul do Brasil permanecia desconhecida. Este trabalho objetivou a sua determinação e o estabelecimento das associações desta condição com o consumo de leite, a história de intolerância ao leite e a intolerância à lactose. Para tal setenta indivíduos adultos, sadios, nascidos na Região Sul do Brasil (48 caucasóides e 22 negróides), sem deficiência secundária de lactase, submeteram-se ao teste de sobrecarga com lactose. A distribuição de frequência dos caucasóides de acordo com o aumento máximo da glicemia em relação ao jejum apresentou aspecto trimodal, com uma antimoda no intervalo entre 14 e 17mg% e outra entre 33 e 36mg%. A trimodalidade desta distribuição sugere que a primeira antimoda divide os mal absorvedores dos absorvedores e a segunda separa os absorvedores heterozigotos dos absorvedores homozigotos. Desse modo, a malabsorcão de lactose do adulto Abstract: A lactose loading test was applied to seventy healthy adults, well nourished, from Southern Brazil (48 caucasoids and 22 negroids) with no secondary lactase deficiency. The distribution of the examined individuals according to race and to maximum blood glucose rise after the lactose loading test showed an antimode at the interval bet ween 14 and 17 mg% and another antimode between 33 and 36 mg%. It seems, therefore, that a maximum blood glucose rise of less than 17 mg% after the lactose loading test should indicate lactose malabsorption. On the basis of this criterion, adult type lactose malabsorption was manifested by 18 caucasoids (37,5%) and 15 negroids (6B,l8Ji). It was not demonstrated significant association among adult type lactase malabsorption and milk consumption or history of milk intolerance. However, lactose malabsorption was associated with lactose intolerance. Moreover, it seems attractive to suppose that a maximum blood glucose rise between 17 and 36 mg% would indicate heterozygous lactose absorbers, while a maximum blood glucose rise of 36 mg% or more would indicate homozygous lactose absorbers. There is an indication drawn from population genetics which favors this hypothesis. The variability of adult lactase activity represents a genetic polymorph ism. The mechanism by which this polymorphism evolved from the ubiquity of lactose malabsorption in early human populations is controversial. The two most accepted hypothesis, the culture historical and the calcium absorption, were critically analysed and refuted. I propose an alternative hypothesis which seems better suited to explain the evolution of this polymorphism
Doutorado
Doutor em Medicina

APA, Harvard, Vancouver, ISO, and other styles

50

Bottaro, Silvania Moraes. "Leite humano com baixo teor de lactose : uma alternativa no tratamento da intolerancia a lactose em lactentes e crianças." reponame:Repositório Institucional da UFSC, 1998. http://repositorio.ufsc.br/xmlui/handle/123456789/78056.

Full text

Abstract:

Dissertação (Mestrado) - Universidade Federal de Santa Catarina, Centro de Ciencias Agrarias
Made available in DSpace on 2012-10-17T09:57:47Z (GMT). No. of bitstreams: 0
A pesquisa teve como objetivo reduzir a lactose do leite humano para que possa ser usado no tratamento dietético de lactentes ou crianças com intolerância secundária à lactose, evitando a introdução precoce de outro alimento. O processo para cinco tratamentos de hidrólise foi desenvolvido através de uma enzima comercial, do qual obteve-se a média de 75,35% de hidrólise da lactose do leite humano. O valor protéico do leite humano não apresentou variação nos resultados, antes e após o tratamento de hidrólise. O teor médio de lipídios foi inferior para todas as amostras hidrolisadas comparando com as amostras não hidrolisadas. O leite humano hidrolisado comparado com o não hidrolisado apresentou teores equivalentes de sólidos totais, cinzas, acidez total, acidez em ácido láctico, cálcio e fósforo. As condições higiênico-sanitárias do leite humano, mostraram ausência de Salmonella sp e Listeria monocytogenes tanto nas amostras de leite humano não hidrolisadas como nas hidrolisadas. Todas as amostras apresentaram o mesmo índice de coliformes fecais e Sthaphylococcus aureus antes e após a hidrólise. A avaliação do leite humano hidrolisado, através da análise sensorial, mostrou que houve uma variação de aceitabilidade entre as amostras de leite testadas.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Lactose'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles