Bibliografie tematiche / Lactose hydrolysis

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Letteratura scientifica selezionata sul tema "Lactose hydrolysis"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 20 febbraio 2023

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Articoli di riviste sul tema "Lactose hydrolysis"

Xu, Yunli, Guowei Shu, Chunji Dai, Chun Yin, Xu Dong, Yuliang Guo e He Chen. "Screening of lactases suitable for the preparation of low-lactose prebiotic liquid milk and optimisation of their combination". Acta Universitatis Cibiniensis. Series E: Food Technology 25, n. 2 (1 dicembre 2021): 275–84. http://dx.doi.org/10.2478/aucft-2021-0025.

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Abstract (sommario):

Abstract Lactose intolerance is an important factor restricting the consumption of dairy products. Lactase is used to hydrolyze lactose in milk while generating galactooligosaccharides (GOS), thereby reducing the incidence of lactose intolerance. We used cow milk as raw materials, and selected enzyme preparations with high lactose hydrolysis rate and strong GOS generation ability from 14 commercially available lactase enzymes. The lactose hydrolysis rate is 5.85%-81.38%, and the GOS content is 0.03 g/L- 13.10 g/L. The mixing experiment design determined the two lactase enzymes (E10 and E11) ratio and the optimal enzymatic hydrolysis process of low-lactose prebiotic milk: compound lactases (E10:E11=0.756:0.244) addition 0.11%, 55℃for 5h, lactose hydrolysis rate and GOS content were 98.02% and 19.69g/L, respectively, and the remaining lactose content was about 0.97 g/L.

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Rao, D. R., e C. B. Chawan. "Enzyme technologies for alleviating lactose maldigestion / Tecnologías enzimáticas para aliviar la mala digestion de la lactosa". Food Science and Technology International 3, n. 2 (aprile 1997): 81–86. http://dx.doi.org/10.1177/108201329700300202.

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Lactose reduction in milk by β-galactosidase prior to consumption is one of the current modali ties of alleviating lactose maldigestion. However, hydrolysis of lactose results in flavour changes in milk: glucose and galactose are between three and four times sweeter than lactose, and many lactose maldigesters do not like the taste of lactose-hydrolysed milk. The addition of exogenous β-galactosidase to meals has been shown to alleviate lactose maldigestion adequately, and so β-galactosidase could be added to milk if the lactose could be protected from the hydrolytic action of the added enzyme. Liposomes, which have recently shown potential as carriers of enzymes, could be good vehicles for the addition of β-galactosidase to milk. β-galactosidase can be successfully encapsulated in liposomes which have been shown to be very stable when suspended in milk stored at refrigeration temperature. Lactose hydrolysis is minimal when liposomal β-galactosidase is added to milk. In vitro digestibility studies have shown that the liposomal β-galactosidase is available for digesting lactose in milk. Stable blends of β-galactosidase and dry milk powders have also been used. Results have shown that up to 95% of the original activity of the fungal lactase was retained in blends of the enzyme and milk powder when stored under nitrogen at 45 °C for 6 months.

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Zhao, Di, Thao T. Le, Lotte Bach Larsen, Yingqun Nian, Cong Wang, Chunbao Li e Guanghong Zhou. "Interplay between Residual Protease Activity in Commercial Lactases and the Subsequent Digestibility of β-Casein in a Model System". Molecules 24, n. 16 (8 agosto 2019): 2876. http://dx.doi.org/10.3390/molecules24162876.

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One of the conventional ways to produce lactose-hydrolyzed (LH) milk is via the addition of commercial lactases into heat-treated milk in which lactose is hydrolyzed throughout storage. This post-hydrolysis method can induce proteolysis in milk proteins due to protease impurities remaining in commercial lactase preparations. In this work, the interplay between lactose hydrolysis, proteolysis, and glycation was studied in a model system of purified β-casein (β-CN), lactose, and lactases using peptidomic methods. With a lactase presence, the proteolysis of β-CN was found to be increased during storage. The protease side-activities mainly acted on the hydrophobic C-terminus of β-CN at Ala, Pro, Ile, Phe, Leu, Lys, Gln, and Tyr positions, resulting in the formation of peptides, some of which were N-terminal glycated or potentially bitter. The proteolysis in β-CN incubated with a lactase was shown to act as a kind of “pre-digestion”, thus increasing the subsequent in vitro digestibility of β-CN and drastically changing the peptide profiles of the in vitro digests. This model study provides a better understanding of how the residual proteases in commercial lactase preparations affect the quality and nutritional aspects of β-CN itself and could be related to its behavior in LH milk.

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Majore, Kristine, e Inga Ciprovica. "Sensory Assessment of Bi-Enzymatic-Treated Glucose-Galactose Syrup". Fermentation 9, n. 2 (31 gennaio 2023): 136. http://dx.doi.org/10.3390/fermentation9020136.

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There are a variety of ways to make glucose-galactose syrup (GGS) and other products of lactose hydrolysis; therefore, research is still ongoing and will undoubtedly result in improved methods and lower costs. The aim of the study was to use a two-stage fermentation approach to increase the sweetness of glucose-galactose syrup. Comparing lactose hydrolysis with β-galactosidases, the enzyme Ha-Lactase 5200 (K. lactis) showed the highest hydrolysis yield but NOLA™ Fit5500 (B. licheniformis) and GODO-YNL2 (K. lactis) hydrolysis yields varied. After the two-stage fermentation, the syrups from sweet whey permeate had shown the highest sweet taste intensity scores; the sweetest samples were 1NFS and 1HLS with a score of 9.2 and 9.3, respectively. The presence of fructose in the range of 14 ± 3 to 25 ± 1 %, significantly (p < 0.05) increased the sweetness of the syrups. Obtained syrups from whey permeates using enzymes NOLA™ Fit5500 and Ha-Lactase 5200 contained less than 10% lactose. Additionally, results indicate that hydrolysis of lactose and subsequent enhancement of sweetness through glucose isomerisation may provide additional benefits through the production of galacto-oligosaccharides (GOS) in the range of 2 ± 1 to 34 ± 7%.

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Costa, Cleiver Júnio Martins, Camila Alves Moreira, Ricardo Corrêa de Santana, Amado Jésus Silva, Juliana Karla de Souza Teixeira Almeida e Milla Gabriela dos Santos. "Lactose quantification in UHT milk by high-performance liquid chromatography and cryoscopy (freezing point depression)". Research, Society and Development 10, n. 15 (23 novembre 2021): e454101523224. http://dx.doi.org/10.33448/rsd-v10i15.23224.

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Abstract (sommario):

Due to the large number of people with lactose maldigestion, the dairy industries have increased production and diversity of low lactose and lactose-free foods. Consequently, the need to control the lactose hydrolysis process has also risen. This study aimed to correlate freezing point depression (cryoscopy) and lactose concentration, quantified by high-performance liquid chromatography (HPLC), in UHT milk. To accomplish this, UHT milk samples were subjected to seven lactose hydrolysis treatments, using lactase enzyme, resulting in different lactose concentrations. All samples were subjected to HPLC analysis and freezing point measurement, using a cryoscope. The results were plotted on a graph and a linear regression was performed. There was a strong correlation between lactose concentration and freezing point (R = 0,9973) and the coefficient of determination (R2) was 0,9946, which means that 99,46% of the variability of the response data is explained by the linear regression model. Therefore, the results point to the feasibility of estimating the lactose concentration in milk during the hydrolysis process for the production of low lactose milk, by cryoscopy, a quick analysis, with lower cost compared to HPLC and that is already among the analyses commonly performed in dairy industries.

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Buller, H. A., A. G. Van Wassenaer, S. Raghavan, R. K. Montgomery, M. A. Sybicki e R. J. Grand. "New insights into lactase and glycosylceramidase activities of rat lactase-phlorizin hydrolase". American Journal of Physiology-Gastrointestinal and Liver Physiology 257, n. 4 (1 ottobre 1989): G616—G623. http://dx.doi.org/10.1152/ajpgi.1989.257.4.g616.

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Lactase-phlorizin hydrolase, a small intestinal disaccharidase, has been considered mainly an enzyme important only for the hydrolysis of lactose. After weaning in most mammals lactase-specific activity falls markedly, and, functionally, adult mammals are considered to be lactase deficient. However, the persistence of low levels of lactase activity in adulthood has never been explained. In addition, it has been suggested that lactase-phlorizin hydrolase is associated with glycosylceramidase activity when the enzyme is prepared by column chromatography, but it is unclear whether this represents copurified activities or two catalytic sites on one peptide. The developmental patterns of lactase-phlorizin hydrolase and other disaccharidases were investigated in homogenates of total rat small intestine; lactase and several glycosylceramidases were measured in immunoprecipitates from these homogenates using a monoclonal antibody. The developmental pattern of total lactase activity showed a steady 2.3-fold increase to adult levels (specific activity decreased eightfold), whereas total phlorizin-hydrolase activity increased 10.7-fold (specific activity decreased threefold). As expected, levels of both total and specific sucrase and maltase activities increased during development. In lactating rats total lactase activity showed a significant increase compared with adult males. The developmental pattern of the enzyme activities for the glycolipid substrates was similar to that found for lactase, and the immunoprecipitated enzyme showed a 40- to 55-fold higher affinity for the glycolipids than for lactose. Galactosyl- and lactosylceramide inhibited lactose hydrolysis by 38%, without a competitive pattern, suggesting two different active sites for lactose and glycolipid hydrolysis, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

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Høyvik, H., P. B. Gordon, T. O. Berg, P. E. Strømhaug e P. O. Seglen. "Inhibition of autophagic-lysosomal delivery and autophagic lactolysis by asparagine." Journal of Cell Biology 113, n. 6 (15 giugno 1991): 1305–12. http://dx.doi.org/10.1083/jcb.113.6.1305.

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Overall autophagy was measured in isolated hepatocytes as the sequestration and lysosomal hydrolysis of electroinjected [14C]lactose, using HPLC to separate the degradation product [14C]glucose from undegraded lactose. In addition, the sequestration step was measured separately as the transfer from cytosol to sedimentable cell structures of electroinjected [3H]raffinose or endogenous lactate dehydrogenase (LDH; in the presence of leupeptin to inhibit lysosomal proteolysis). Inhibitor effects at postsequestrational steps could be detected as the accumulation of autophaged lactose (which otherwise is degraded intralysosomally), or of LDH in the absence of leupeptin. Asparagine, previously shown to inhibit autophagic but not endocytic protein breakdown, strongly suppressed the autophagic hydrolysis of electroinjected lactose. Vinblastine, which inhibits both types of degradation, likewise suppressed lactose hydrolysis. Asparagine had little or no effect on sequestration, but caused an accumulation of autophaged LDH and lactose, indicating inhibition at a postsequestrational step. Neither asparagine nor vinblastine affected the degradation of intralysosomal lactose preaccumulated in the presence of the reversible lysosome inhibitor propylamine. However, if lactose was preaccumulated in the presence of asparagine, both asparagine and vinblastine suppressed its subsequent degradation. The data thus indicate that autophagic-lysosomal delivery, i.e., the transfer of autophaged material from prelysosomal vacuoles to lysosomes, is inhibited selectively by asparagine and non-selectively by vinblastine.

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Hanauer, Duana Ceciliane, e Alexandre Tadeu Paulino. "Anchoring lactase in pectin-based hydrogels for lactose hydrolysis reactions". Process Biochemistry 122 (novembre 2022): 50–59. http://dx.doi.org/10.1016/j.procbio.2022.08.026.

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Renner, E. "Dietary approaches to alleviation of lactose maldigestion / Efectos de la dieta sobre la digestión de la lactosa". Food Science and Technology International 3, n. 2 (aprile 1997): 71–79. http://dx.doi.org/10.1177/108201329700300201.

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Abstract (sommario):

Because dairy products are a significant source of essential nutrients, elimination of all dairy foods in the diet would be nutritionally unwise and is usually not necessary in the case of lactose maldigestion. About 250 ml milk/d can generally be taken without adverse effects. If milk is taken in combination with solid foods, lactose malabsorption may be reduced by about 50%, probably due to a slower rate of colonic fermentation which may lower gastrointestinal symptoms in lactose malabsorbers. It is well established that, in lactase-deficient subjects, yoghurt is better tolerated than milk. This is only to some extent related to the fact that the lactose content of the products is reduced during fermentation, but is mainly attributed to the fact that the culture organisms- by virtue of being rich in lactase - are able to participate in the hydrolysis of ingested lactose. Up to 20 g of lactose in yoghurt is tolerated well by lactase-deficient persons. The enhanced absorp tion of lactose in yoghurt is explained as a result of the intestinal release of lactase from the yoghurt organisms. Ripened cheese is also tolerated very well by lactose-intolerant persons since virtually all of the lactose present is decomposed to lactic acid and other metabolites.

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Czyzewska, Katarzyna, e Anna Trusek. "Encapsulated NOLA™ Fit 5500 Lactase—An Economically Beneficial Way to Obtain Lactose-Free Milk at Low Temperature". Catalysts 11, n. 5 (21 aprile 2021): 527. http://dx.doi.org/10.3390/catal11050527.

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Abstract (sommario):

The current requirements of industrial biocatalysis are related to economically beneficial and environmentally friendly processes. Such a strategy engages low-temperature reactions. The presented approach is essential, especially in food processes, where temperature affects the quality and nutritional value foodstuffs. The subject of the study is the hydrolysis of lactose with the commercial lactase NOLA™ Fit 5500 (NOLA). The complete decomposition of lactose into two monosaccharides gives a sweeter product, recommended for lactose intolerant people and those controlling a product’s caloric content. The hydrolysis reaction was performed at 15 °C, which is related to milk transportation and storage temperature. The enzyme showed activity over the entire range of substrate concentrations (up to 55 g/L lactose). For reusability and easy isolation, the enzyme was encapsulated in a sodium alginate network. Its stability allows carrying out six cycles of the complete hydrolysis of lactose to monosaccharides, lasting from two to four hours. During the study, the kinetic description of native and encapsulated NOLA was conducted. As a result, the model of competitive galactose inhibition and glucose mixed influence (competitive inhibition and activation) was proposed. The capsule size does not influence the reaction rate; thus, the substrate diffusion into capsules can be omitted from the process description. The prepared 4 mm capsules are easy to separate between cycles, e.g., using sieves.

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Più fonti

Tesi sul tema "Lactose hydrolysis"

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.

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Abstract (sommario):

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

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Kreft, Mary Ellen. "Lactose hydrolysis by sonicated cultures of Lactobacillus delbrueckii subsp. bulgaricus 11842". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ60448.pdf.

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Chaudhary, Manoja Nand, of Western Sydney Hawkesbury University, of Science Technology and Agriculture Faculty e School of Food Science and Technology. "An evaluation of nanofiltration and lactose hydrolysis of milk UF permeate for use in ice cream". THESIS_FSTA_FST_Chaudhary_M.xml, 1997. http://handle.uws.edu.au:8081/1959.7/741.

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This study aimed to obtain 15% total solids and reduced mineral content in milk UF permeate by nanofiltration, hydrolysing the lactose content of nano-concentrate enzymically, partially substituting sucrose in ice cream formulations with hydrolysed lactose nano-concentrate (HLNC), and investigating the effects of HLNC on the physio-chemical and sensory characteristics of ice cream. The desired 15% total solids in the nano-concentrate was achieved after three fold concentration of milk UF permeate. The colour of milk permeate changed, pH and mineral content decreased, and crude protein content, lactose content and titratable acidity increased. The lactose content was hydrolysed by enzyme lactase. HLNC was used to replace 25% and 50% of sucrose in ice cream formulations. Springiness, cohesiveness, chewiness, adhesiveness, hardness, iciness, Ph and colour were not significantly affected. Viscosity, freezing point, glass transition temperature, melting temperature, gumminess and sweetness were significantly decreased, whereas freezing time, saltiness and cooked flavour were significantly increased. The overall acceptability of ice cream significantly decreased at 50% but was insignificantly affected at the 25% level. These results indicate that about one quarter of sucrose could be replaced by HLNC.
Master of Science (Hons) (Food Technology)

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Bury, Dean. "Growth and disruption of Lactobacillus delbrueckii spp. bulgaricus for lactose hydrolysis applications". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0009/MQ60097.pdf.

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Ribeiro, Cátia Vanessa Carvalho. "Ensaios de fabrico de queijo fresco com teor reduzido de lactose". Master's thesis, ISA, 2013. http://hdl.handle.net/10400.5/6463.

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Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia
It can be stated that one third of Portugal’s population suffer of lactose intolerance. The main objective of this study was the development of a new product in our market, originated in Portugal, low lactose fresh cheese. Were tested various enzymatic hydrolysis methodologies, in order to know what is the enzyme’s actuation time on milk or cheese required to hydrolyze the biggest lactose content. The enzyme was added 3 and 18 hours at 6C and 1 hour at 30C, before the beginning of manufacture, and, added at the time of addition of the remaining ingredients, during cheese manufacture. Have also been developed assays with the addition of different amounts of salt, to minimize the predictable effects of lactose hydrolysis, like the increase of sweetness. After 3-4 days of conservation, was achieved a degree of lactose hydrolysis above 90% (93- 97%). Upon reaching concentrations levels less than 0,5g of lactose per 100g of cheese (0,5%, m/m), the product may be considered as low lactose fresh cheese. The different methodologies of manufacture didn’t affect the positive opinion of the tasters, during the sensory evaluation.

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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.

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Abstract (sommario):

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.

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Freitas, Maria de FÃtima Matos de. "ProduÃÃo de β-galactosidase por Kluyveromyces lactis NRRL Y1564 em soro de leite e imobilizaÃÃo em quitosana". Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=9396.

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Abstract (sommario):

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
Neste trabalho, a enzima β-galactosidase, que catalisa a hidrÃlise da lactose em glicose e galactose, foi produzida pelo cultivo do micro-organismo Kluyveromyces lactis NRRL Y1564 em soro de leite suplementado com extrato de levedura. A enzima Ã um metabÃlito intracelular, sendo a liberaÃÃo da enzima para o meio uma condiÃÃo essencial, por isso estudaram-se diferentes mÃtodos quÃmicos e mecÃnicos de extraÃÃo como, agitaÃÃo com pÃrolas de vidro, ruptura em ultrassom com pÃrolas de vidro, adiÃÃo de etanol e tolueno, observando tambÃm, seus efeitos na atividade enzimÃtica. Posteriormente, realizaram-se ensaios para estudar a influÃncia da temperatura (30, 34, 37 e 40 ÂC) na produÃÃo da enzima a partir do soro de queijo. Na extraÃÃo da enzima, o uso de esferas de vidro em vÃrtex foi o mÃtodo mais eficiente quando comparado com os outros avaliados. A enzima, nÃo sofreu inibiÃÃo ou desnaturaÃÃo quando incubadas com etanol, tolueno ou etanol-tolueno. A temperatura Ãtima de produÃÃo da enzima por K. lactis NRRL Y1564 foi 30 ÂC, com atividade enzimÃtica de 4418,37 U/g de cÃlulas em 12 h de fermentaÃÃo. A enzima produzida foi imobilizada em quitosana 2,0% m/v. Diferentes protocolos de ativaÃÃo usando glutaraldeÃdo, epicloridrina ou glicidol foram avaliados. Estudou-se tambÃm, o tempo de contato enzima-suporte (3, 5 e 10 horas) a fim de se obter um biocatalisador que apresentasse alto rendimento, atividade recuperada e tempo de meia-vida, visando a hidrÃlise da lactose em reator batelada e leito fixo. A influÃncia da temperatura e do pH na hidrÃlise da lactose foi avaliada, usando como substrato uma soluÃÃo sintÃtica (lactose 5,0% (m/v) e leite desnatado, contendo 4,3% m/v de lactose. O suporte que apresentou melhores resultados nos parÃmetros de imobilizaÃÃo foi a quitosana 2% reticulada com glutaraldeÃdo no tempo de imobilizaÃÃo de 5 horas. O biocatalisador produzido nesse estudo apresentou um fator de estabilidade de 17,37 vezes maior que a enzima solÃvel, com uma estabilidade de armazenamento de 100% quando armazenada a 4 ÂC por 90 dias. A temperatura Ãtima de hidrÃlise da lactose foi de 40 ÂC e o pH Ãtimo foi 7,0 . A conversÃo da lactose a 40 ÂC para este derivado (3,0 U/g) foi em mÃdia 53% em 10 ciclos (bateladas consecutivas). Em reator batelada, a conversÃo em glicose a partir da hidrÃlise da lactose, usando soluÃÃo sintÃtica, foi aproximadamente 86 % para a enzima solÃvel (3,8 U/mL) e 83 % para a enzima imobilizada (3,8 U/g). A conversÃo obtida na hidrÃlise do leite desnatado foi de 17 % para a enzima solÃvel e 20 % para a enzima imobilizada.
In this work, the enzyme β-galactosidase which catalyzes the hydrolysis of lactose to glucose and galactose, was produced by cultivating the micro-organism Kluyveromyces lactis NRRL Y1564 in whey supplemented with yeast extract. The enzyme is an intracellular metabolite, the release enzyme is very important, therefore were studied various chemical and mechanical methods of extraction and stirring with glass beads, sonication, addition of ethanol and toluene, noting also their effects on enzymatic activity. Subsequently, trials were carried out to study the influence of temperature (30, 34, 37 and 40 Â C) in the production of the enzyme from the cheese whey. In the enzyme extraction, using glass beads by a vÃrtex was more efficient method compared to others evaluated. The enzyme not presented inhibited or denatured when incubated with ethanol, toluene or ethanol-toluene. The optimum temperature for enzyme production by K. lactis NRRL Y1564 was 30 ÂC with enzymatic activity of 4418.37 U/g of cells at 12 h of fermentation. The enzyme produced was immobilized on chitosan 2.0% w/v. Different activation protocols using glutaraldehyde, epichlorohydrin or glycidol were evaluated. Was also studied, the contact time the enzyme-carrier (3, 5, and 10 hours) to obtain a biocatalyst to produce high yield, recovered activity and half-life in order to hydrolysis of lactose in batch reactor and fixed bed. The influence of temperature and pH on the hydrolysis of lactose was evaluated using as substrate a synthetic solution (lactose 5.0% (w/v) in potassium phosphate buffer 100 mM with 0.1 mM MnCl2) and skimmed milk containing 4.3% w/v lactose. The support shows better results in the parameters of immobilization was chitosan 2% actived with glutaraldehyde and contact time of 5 hours. The biocatalyst produced in this study showed a stability factor of 17.37 and a storage stability of 100% when stored at 4 ÂC for 90 days. Temperature optimum hydrolysis of lactose was 40 ÂC and the optimal pH 7.0. The conversion of lactose to 40 ÂC for this derivative (3.0 U/g) was on average 53% in 10 cycles (consecutive batches). In batch reactor, the conversion to glucose by the hydrolysis of lactose using synthetic solution was approximately 86% for the soluble enzyme (3.8 U/mL) and 83% of the immobilized enzyme (3.8 U/g). The conversion obtained in the hydrolysis of skim milk was 17% for the soluble enzyme and 20% for the immobilized enzyme.

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Davidson, Richard H. "Culture enumeration, lactose hydrolysis and sensory changes in stored frozen yogurt fermented with two culture systems". Thesis, Virginia Tech, 1995. http://hdl.handle.net/10919/45071.

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Mioro, Miriam Kanyua. "Designing a Two Component System for Enzyme Immobilization Using a Modified Chitosan Support". Youngstown State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ysu15946615388307.

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West, Christopher Michael. "Bioreaction and separation in preparative batch chromatographic columns : the hydrolysis of lactose to yield glucose, galactose and oligosaccharides". Thesis, Aston University, 1997. http://publications.aston.ac.uk/9614/.

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The initial aim of this project was to improve the performance of a chromatographic bioreactor-separator (CBRS). In such a system, a dilute enzyme solution is pumped continuously through a preparative chromatographic column, while pulses of substrate are periodically injected on to the column. Enzymic reaction and separation are therefore performed in a single unit operation. The chromatographic columns used were jacketed glass columns ranging from 1 to 2 metres long with an internal diameter of 1.5 cm. Linking these columns allowed 1, 2, 3 and 4 metre long CBRS systems to be constructed. The hydrolysis of lactose in the presence of β~galactosidase was the reaction of study. From previous work at Aston University, there appeared to be no difficulties in achieving complete lactose hydrolysis in a CBRS. There did, however, appear to be scope for improving the separative performance, so this was adopted as an initial goal. Reducing the particle size of the stationary phase was identified as a way of achieving this improvement. A cation exchange resin was selected which had an average particle size of around half that previously used when studying this reaction. A CBRS system was developed which overcame the operational problems (such as high pressure drop development) associated with use of such a particle size. A significant improvement in separative power was achieved. This was shown by an increase in the number of theoretical plates (N) from about 500 to about 3000 for a 2 metre long CBRS, coupled with higher resolution. A simple experiment with the 1 metre column showed that combined bioreaction and separation was achievable in this system. Having improved the separative performance of the system, the factors affecting enzymic reaction in a CBRS were investigated; including pulse volume and the degree of mixing between enzyme and substrate. The progress of reaction in a CBRS was then studied. This information was related to the interaction of reaction and separation over the reaction zone. The effect of injecting a pulse over a length of time as in CBRS operation was simulated by fed batch experiments. These experiments were performed in parallel with normal batch experiments where the substrate is mixed almost instantly with the enzyme. The batch experiments enabled samples to be taken every minute and revealed that reaction is very rapid. The hydrodynamic characteristics of the two injector configurations used in CBRS construction were studied using Magnetic Resonance Imaging, combined with hydrodynamic calculations. During the optimisation studies, galactooligosaccharides (GOS) were detected as intermediates in the hydrolysis process. GOS are valuable products with potential and existing applications in food manufacture (as nutraceuticals), medicine and drug targeting. The focus of the research was therefore turned to GOS production. A means of controlling reaction to arrest break down of GOS was required. Raising temperature was identified as a possible means of achieving this within a CBRS. Studies were undertaken to optimise the yield of oligosaccharides, culminating in the design, construction and evaluation of a Dithermal Chromatographic Bioreactor-separator.

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Più fonti

Capitoli di libri sul tema "Lactose hydrolysis"

Zadow, J. Greig. "Lactose Hydrolysis". In Whey and Lactose Processing, 361–408. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2894-0_10.

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Hayes, J. F., I. Mitchell, M. Free e J. G. Zadov. "Lactose Hydrolysis of Dairy Products". In MILK the vital force, 221. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-3733-8_180.

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Mello, Ariane Fátima Murawski de, Luciana Porto de Souza Vandenberghe, Clara Matte Borges Machado, Agnes de Paula Scheer, Aline B. Argenta, Gilberto Vinicius de Melo Pereira, Alexander da Silva Vale e Carlos Ricardo Soccol. "Enzymes for Lactose Hydrolysis and Transformation". In Microbial Enzymes in Production of Functional Foods and Nutraceuticals, 173–94. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003311164-12.

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Plou, Francisco J., Julio Polaina, Julia Sanz-Aparicio e María Fernández-Lobato. "β-Galactosidases for Lactose Hydrolysis and Galactooligosaccharide Synthesis". In Microbial Enzyme Technology in Food Applications, 121–44. Boca Raton, FL : CRC Press, [2016] | Series: Food biology series | “A science publishers book.”: CRC Press, 2017. http://dx.doi.org/10.1201/9781315368405-9.

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Splechtna, Barbara, Inge Petzelbauer, Bernhard Kuhn, Klaus D. Kulbe e Bernd Nidetzky. "Hydrolysis of Lactose by ß-Glycosidase CelB from Hyperthermophilic Archaeon Pyrococcus Furiosus". In Biotechnology for Fuels and Chemicals, 473–88. Totowa, NJ: Humana Press, 2002. http://dx.doi.org/10.1007/978-1-4612-0119-9_39.

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Harju, M. "Hydrolysis of Lactulose and Lactitol with β-Galactosidases". In MILK the vital force, 232. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-3733-8_191.

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Teiber, John F., e Dragomir I. Draganov. "High-Performance Liquid Chromatography Analysis of N-Acyl Homoserine Lactone Hydrolysis by Paraoxonases". In Methods in Molecular Biology, 291–98. Totowa, NJ: Humana Press, 2010. http://dx.doi.org/10.1007/978-1-60761-971-0_21.

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Nakayama, Atsuyoshi, Ioannis Arvanitoyannis, Norioki Kawasaki, Kazuko Hayashi e Noboru Yamamoto. "Hydrolytic Degradation of Poly(L-Lactide-co-ε-Caprolactone)S". In Advanced Biomaterials in Biomedical Engineering and Drug Delivery Systems, 241–42. Tokyo: Springer Japan, 1996. http://dx.doi.org/10.1007/978-4-431-65883-2_57.

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Liu, Jin Fang, Satoshi Hayakawa, Kanji Tsuru, Jian Zhong Jiang e Akiyoshi Osaka. "Preparation of Hydroxyapatite / Titania Double Layer Coating on Poly-I-lactide due to Hydrolysis of Titanium Tetrachloride". In Key Engineering Materials, 687–90. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-422-7.687.

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Hassan, Mohammad K., Jeffrey S. Wiggins, Robson F. Storey e Kenneth A. Mauritz. "Broadband Dielectric Spectroscopic Characterization of the Hydrolytic Degradation of Hydroxyl-Terminated Poly(D,L-lactide) Materials". In ACS Symposium Series, 153–69. Washington, DC: American Chemical Society, 2008. http://dx.doi.org/10.1021/bk-2008-0977.ch009.

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Atti di convegni sul tema "Lactose hydrolysis"

Verner, A. V., e O. V. Chugunova. "TECHNOLOGICAL ASPECTS OF PRODUCTION AND ASSORTMENT OF LACTOSE-FREE DAIRY PRODUCTS". In I International Congress “The Latest Achievements of Medicine, Healthcare, and Health-Saving Technologies”. Kemerovo State University, 2023. http://dx.doi.org/10.21603/-i-ic-21.

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The features of technologies for the production of lactose-free and low-lactose dairy products, which provide for special operations for the hydrolysis of lactose or its removal using ultra- or nanofiltration followed by hydrolysis of the residual amount, are considered. The range of dairy products produced using these technologies in Russia at leading enterprises in this field of production is presented.

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Zolnere, Kristine, e Inga Ciprovica. "Lactose hydrolysis in different solids content whey and milk permeates". In 13th Baltic Conference on Food Science and Technology “FOOD. NUTRITION. WELL-BEING”. Latvia University of Life Sciences and Technologies. Faculty of Food Technology,, 2019. http://dx.doi.org/10.22616/foodbalt.2019.011.

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Cavalcante Fai Buarque de Gusmão, Ana Elizabeth, Haroldo Yukio Kawaguti, Isabela Thomazelli e Glaucia Maria Pastore. "Comparison of galactooligosaccharides synthesis during lactose hydrolysis by immobilized Aspergillus oryzae beta-galactosidase systems". In Simpósio Nacional de Bioprocessos e Simpósio de Hidrólise Enzimática de Biomassa. Campinas - SP, Brazil: Galoá, 2015. http://dx.doi.org/10.17648/sinaferm-2015-33686.

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Abu-Reesh, Ibrahim M. "Application of third-order polynomial approximate solution to enzymatic glucose isomerization and lactose hydrolysis reactions". In 2011 Fourth International Conference on Modeling, Simulation and Applied Optimization (ICMSAO). IEEE, 2011. http://dx.doi.org/10.1109/icmsao.2011.5775507.

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Wilson, James H., Wilson, Edward J., Matak, Kristen E., Duncan, Susan E., Sumner Susan e Hackney C. R. "The Influence of Lactose Hydrolysis on the Strength and Sensory Characteristics of Vanilla Ice Cream". In 2003, Las Vegas, NV July 27-30, 2003. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2003. http://dx.doi.org/10.13031/2013.13907.

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Michael Arlante Teruel, Atma Bhawuk, Daniel McKewn Jenkins e José I Reyes de Corcuera. "Modeling and Validation of an Unusual Kinetic Phenomenon During the Enzymatic Hydrolysis of Lactose to Glucose". In 2007 Minneapolis, Minnesota, June 17-20, 2007. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2007. http://dx.doi.org/10.13031/2013.23399.

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Kopsahelis, Nikolaos, Iliada Lappa, Anthi Stamatiou, Fani Sereti, Aikaterini Papadaki, Vassiliki Kachrimanidou e Effimia Eriotou. "Expanding the Valorization Routes of Cheese Whey: Lactose Hydrolysis Using A. awamori-derived β-Galactosidase for the Subsequent Production of Bacterial Cellulose". In 1st International Electronic Conference on Catalysis Sciences. Basel, Switzerland: MDPI, 2020. http://dx.doi.org/10.3390/eccs2020-07780.

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Theiner, Rick, Christine Dunstan e Leon Zheng. "Cc variances as a result of sophorolipid lactone/lactonic acid ratios". In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/kkku2300.

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Abstract (sommario):

It has been established that the so-called characteristic curvature (Cc) of a surfactant is helpful to formulators of various industries in optimizing systems for wetting, emulsifying, and so forth. Determination of surfactant Cc has been well explored and methods of determination of that characteristic value abound. Sophorolipids present a specific problem, however, as these biosurfactants may take one of two structures and usually a combination of both. The first structure is the ring-like lactone structure, which is nonionic. The second structure, the more linear lactonic acid, is formed when the first structure undergoes hydrolysis and becomes a bolaform surfactant. One side of the bolaform is nonionic, but the other side, terminating with a carboxylic acid function, is anionic above pH 5. Two difficulties in determining the Cc are presented as a result of this transformation. The first is that of combining terms for a nonionic surfactant and an anionic surfactant at various ratios which are often pH dependant. The second problem is that the lactonic acid has been shown exhibit unusual self-assembly properties as a single moiety, let alone as part of a two component system with the lactone.The discussed work examines variances in Cc for a commercial sophorolipid under pH induced ratios and aggregation.

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Ma, Na, Ping Liu, Chao Chen, Aili Zhang e Lisa X. Xu. "Thermal Environmental Effect on Breast Tumor Growth". In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206229.

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Tissue hypoxia is a common and important feature of rapidly growing malignant tumors and their metastases. Tumor cells mainly depend on energy production thru anaerobic glycolysis rather than aerobic oxidative phosphorylation in mitochondria [1]. Intervening the tumor metabolic process via thermal energy infusion is worthy attempting. And hyperthermia, mildly elevated local temperature above the body temperature, is one of such kind. Previously, after being heated for a short period of time, tumor glucose and lactate level increased and ATP level decreased, which suggested energy metabolism was modified following hyperthermia through increased ATP hydrolysis, intensified glycolysis and impaired oxidative phosphorylation [2]. Many researchers designed experiments to determine thermal dose in hyperthermia [3], but few focused on the relationship between tumor and energy, especially for a long-term local hyperthermia treatment. One clinical trial indicated the effective long-term hyperthermo-therapy for maintaining performance status, symptomatic improvement, and prolongation of survival time in patients with peritoneal dissemination [4].

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