Tesi sul tema "Rancidity"

Ketonic rancidity is associated with the lauric acid oils and butterfat. It arises when short and intermediate carbon chain length fatty acids (C6 to C14) are converted into methyl ketones (C5 to C13) by certain fungi. Ketonicrancidity will not occur in fats and oils that do not contain these fatty acids. Fermentation experiments with whole oils and simple triglycerides confirmed that only short and intermediate carbon chain length fatty acids were converted into methyl ketones. Methyl ketones produced contained one carbon atom less than the parent fatty acid. Tetradecanoic acid was the longest fatty acid to undergo conversion into its corresponding methyl ketone. Experiments with free fatty acids established that short and intermediate carbon chain length fatty acids inhibited the growth of Penicillium crustosum, Evidence was presented to demonstrate that the mitochondrion was a site of antifungal activity. It was concluded that the conversion of fatty acids into methyl ketones was a detoxification mechanism for their removal from the environment. Extrinsic factors (temperature, pH, aw, preservatives and O2 removal) were used to control fungal growth and ketonic rancidity. Fungal homeostatic mechanisms often enabled P.crustosum to grow under unfavourable environmental conditions. It was suggested that acombination of preservation measures should be used to prevent ketonic rancidity in the lauric acid oils and their products.

The research in this dissertation focused on determining antioxidant effects of various natural antioxidants in cooked meat systems. Milk mineral (MM), spices, and raisin paste were used in cooked meat systems to verify their potential antioxidant properties. The MM study determined the antioxidant activity of 1.5% MM added to uncured cooked beef meatballs, and possible additive effects of MM in combination with 20-ppm or 40-ppm sodium nitrate in cooked beef sausages . There was no additive inhibition of lipid oxidation in samples containing 20-ppm or 40-ppm sodium nitrite plus 1.5% MM. Cooked meat yield was not different between control meatballs and those containing MM. As expected, treatments containing nitrite had higher redness (a*) values than samples without nitrite. The MM at 1.5% was a very effective antioxidant as compared to controls. The Garam Masala (GM) study determined the antioxidant effects and sensory attributes of the individual spices in an Indian spice blend GM in cooked ground beef, and possible additive antioxidant effects between Type I and Type II antioxidants. All spices had antioxidant effects on cooked ground beef, compared to controls without spices, with cloves being the most effective. All spices at their lowest effective recommended level effectively lowered the perception of rancid odor and rancid flavor in cooked ground beef as compared to control samples. As expected, most spices also imparted distinctive flavors to the cooked ground beef. Type II antioxidants (iron binding phosphate compounds) were more effective than individual Type I antioxidants (spices and butylated hydroxytoluene; BHT) in cooked ground beef. There was a positive additive antioxidant effect seen with rosemary + MM and rosemary + sodium tripolyphosphate (STPP) treatments as compared to individual rosemary treatment. There was no additive antioxidant effect observed for other combinations of spices with phosphate antioxidants. The raisin study was done to determine the antioxidant activity of raisin paste added to cooked ground beef, pork, and chicken. Thiobarbituric acid (TBA) values were measured using the distillation method, on the distillates, to avoid interference from sugar in the raisins. Beef, pork, and chicken flavor intensity, rancid flavor intensity, and raisin flavor intensity were evaluated by a trained sensory panel (n = 6). Addition of 2% raisin paste effectively inhibited rancid flavor development for 14 days after cooking in cooked ground beef, pork, and chicken. Sugar added at levels equivalent to that contributed by the raisins inhibited rancidity, probably due to antioxidant effects of Maillard browning products, suggesting that the antioxidant effect of raisins was due to their sugar content.

Master of Science
Food Science
J. Scott Smith
The objective of this study was to observe the effect of natural cocoa powder versus 200 ppm of tocopherols on delaying the onset of oxidative rancidity in peanuts, peanut butter, and peanut oil. The samples were obtained from a single lot of blended Runner peanuts after roasting, grinding, and pressing. The samples were treated within a week of initial roasting with either 200 ppm of mixed tocopherols or 2.5% cocoa powder. The development of oxidation was monitored by peroxide value (PV) and gas chromatography monitoring of hexanal development. The peanut butter samples were assessed by a professional sensory panel using descriptive analysis for the development of rancidity. The data was analyzed using JMP SAS software. In peanuts, the cocoa powder sample developed significantly lower levels of oxidation identifiers than the tocopherol or control samples. In peanut oil, there was no significant difference in levels of oxidation identifiers between the treatments. In peanut butter, the PV was significantly higher in the tocopherol sample than the cocoa powder or control samples, but no significant difference was observed in hexanal. The results of the sensory analysis indicated that the cocoa powder depressed the perception of both positive and negative attributes compared to the tocopherol and control samples. This study showed that cocoa powder may be a more effective preservative than an untreated sample or a sample treated with 200 ppm of tocopherols in peanuts and peanut butter; however, cocoa powder at 2.5% w/w basis did not perform as a significant antioxidant in peanut oil.

The antioxidants BHA, BHT, and ascorbic acid were added to flaxmeal breads to prevent rancidity. Six types of yeast leavened breads were evaluated: control (100% bread flour), flaxmeal (15%) bread, and flaxmeal (15%) bread that contained 0.01% respectively of BHA, BHT, BHA and BHT, and ascorbic acid. Vital wheat gluten was added in all the flaxmeal breads. Chemical, objective and sensory tests were used to evaluate the breads. The crumb texture of all the experimental breads was significantly softer (p¡à 0.05) than the control breads, but the control breads were significantly moister (p¡à 0.05) than the flaxmeal breads that contained BHA and BHT, separately. No significant differences (p>0.05) were found in loaf volume of the control bread and the experimental breads. The crumb color of the experimental breads was significantly darker (p<0.0001) due to the incorporation of flaxmeal. The acid value of the flaxmeal breads was significantly higher (p¡à 0.05) than the control breads. No significant differences (p>0.05) were found in peroxide values between the control breads and experimental breads after eight weeks. The QDA sensory tests showed that breads containing BHA or in combination with BHT were moister, chewier and had the least noticeable stale taste when compared to the control breads. Ascorbic acid was not as effective as BHA or a combination of BHA and BHT in preventing lipid oxidation, but produced the softest bread. This study showed that flaxmeal breads made with BHA and BHT provided the best protection against lipid oxidation and produced a moist and chewy bread.
Master of Science

This study examined the effects of guar gum and xanthan gum on flax supplemented breads through objective and sensory testing. Breads containing flaxseed and gums were found to have a significantly (p<0.05) higher water activity than the control bread. Control bread was also found to have a higher (p<0.05) volume while flax breads containing guar gum had a significant (p<0.05) decrease in volume. Control bread and bread containing guar gum were significantly (p<0.05) harder in crumb texture. Breads with flax and xanthan gum displayed a significant (p<0.05) amount of springiness. While there was no significant (p>0.05) difference in peroxide values among bread samples, control bread had a lower (p<0.05) anisidine value indicating a decrease in hydroperoxide breakdown. While not significant (p>0.05), bread containing xanthan gum had a lower anisidine value than the other treatments. Sensory analysis found bread with both gums to be moister (p<0.05) and have a strong (p<0.05) yeasty aroma and fresher flavor. Control bread was found to have the least (p<0.05) yeasty aroma and taste significantly (p<0.05) less bitter but more stale.
Master of Science

Shelf life studies of raw Macadamia integrifolia nuts were carried out at different storage temperatures, relative humidities and time. An accelerated shelf life test was conducted, and the influence of water activity on kernel texture was studied. The antioxidants naturally present were identified by the use of thin layer chromatography. Accelerated shelf life tests showed that hydrolytic rancidity followed apparent zero order kinetics within the water activity range of 0.3 to 0.5. Oxidative rancidity measured by peroxide value appeared to follow different orders of reaction at different temperatures. At two months of storage rancidity was detected at which the headspace concentration of hexanal was 0.39 ppm and a peroxide value of 0.37 meq/kg. Headspace gas chromatography was done to find a quick and effective method for measuring oxidative rancidity. The presence of natural antioxidants was verified to explain the shelf life of macadamia nuts. In textural study, correlations were found between subjective and objective measurements. The product became unacceptable organoleptically above water activity 0.415 when stored at 20 degrees C. This level was established as the critical water activity. There is a need to establish a water activity at which the consumer is likely to reject the product.
Master of Science (Hons) (Food Science and Nutrition)

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
Aiming to evaluate the oxidative stability of parboiled rice bran, coconut meal and cashew nut meal during storage and the effects of its use in the feeding of meat quails, were carried three experiments in the period 7 at 42 days of age. For this, a batch of 100 kg of each meal was stored for a period of six months. At the end of that period, were purchased new batches of 100 kg each bran, and meal, fresh and stored, were used to formulate the diets of quail. In the first experiment, 245 quails with seven days of age were distributed in a completely randomized design with five treatments and seven replications of seven birds each and were tested levels of 10 and 20% inclusion of stored parboiled rice bran (SPRB) and new (NPRB). In the second and third experiments, 280 quails with seven days of age were distributed in a completely randomized design with five treatments and seven replications of eight birds each. In these trials, the treatments consisted of a control diet and the other containing 12.5 and 25% of stored coconut bran (SCB) and new (NCB) and stored cashew nut bran (SCNB) and new (NCNB), respectively. The rice bran parboiled stored for six months showed signs of hydrolytic and oxidative reactions observed by the increase in acid value and peroxide, respectively. Regardless of the storage, the inclusion of rice bran parboiled resulted in lower digestibility of dry matter and nitrogen and higher metabolizable energy value of the diet compared to the control diet. The inclusion of 20% SPRB resulted in less metabolizable energy value of feed in relation to the addition of NPRB. Although there have been no differences between treatments in nutrient utilization ration these were not enough to significantly influence the performance, carcass characteristics, relative weight of the liver and pancreas and growth and bone quality. The coconut meal stored for six months showed a higher tendency to hydrolysis reactions, observed by increasing the acidity index. Regardless of the storage, the inclusion of coconut meal resulted in higher metabolizable energy of the ration and reduction in consumption and feed conversion compared to the control diet. Although there have been differences between treatments in some parameters, these were not sufficient to significantly influence carcass characteristics, the relative weights of the liver and pancreas and growth and bone quality. The cashew nut bran stored for six months showed a higher tendency to hydrolysis reactions, observed by increasing the acidity index. Storage independent, inclusion the cashew nut bran resulted in higher metabolizable energy of the ration and reduction in feed intake and feed compared to the control diet. Although there have been differences between treatments in some parameters, these were not sufficient to significantly influence carcass characteristics, the relative weights of the liver and pancreas and growth and bone quality. Although the store for six months promote hydrolytic and oxidative rancidity the bran of parboiled rice and hydrolytic in the coconut bran and cashew nut bran, these can be used to feed meat quails in inclusion levels of up to 20% for the parboiled rice bran and 25% for the coconut bran and cashew nut bran.
Com o objetivo de avaliar a estabilidade oxidativa do farelo integral de arroz parboilizado, do farelo de coco e do farelo de castanha de caju durante o armazenamento e os efeitos do uso desses ingredientes na alimentaÃÃo de codornas de corte, foram realizados trÃs experimentos no perÃodo de 7 a 42 dias de idade. Para isso, um lote de 100 kg de cada farelo foi armazenado durante o perÃodo de seis meses. Ao tÃrmino desse perÃodo, foi adquirido novo lote de 100 kg de cada farelo e tanto os farelos novos e armazenados, foram utilizados para formular as raÃÃes das codornas. No primeiro experimento, 245 codornas com sete dias de idade foram distribuÃdas em um delineamento inteiramente casualizado, com cinco tratamentos e sete repetiÃÃes de sete aves por unidade experimental e foram testados os nÃveis de 10 e 20% de inclusÃo de farelo integral de arroz parboilizado armazenado (FIAPA) e novo (FIAPN). No segundo e terceiro experimentos, 280 codornas com sete dias de idade foram distribuÃdas em um delineamento inteiramente casualizado, com cinco tratamentos e sete repetiÃÃes de oito aves por unidade experimental. Nesses ensaios, os tratamentos consistiram em uma raÃÃo controle e os demais contendo 12,5 e 25% de farelo de coco armazenado (FCA) e novo (FCN) e farelo de castanha de caju armazenado (FCCA) e novo (FCCN), respectivamente. O farelo integral de arroz armazenado por seis meses apresentou sinais de reaÃÃes hidroliticas e oxidativas, observados pelo aumento do Ãndice de acidez e de perÃxido, respectivamente. Independente do armazenamento, a inclusÃo do farelo integral de arroz parboilizado resultou em menor digestibilidade da matÃria seca e do nitrogÃnio e maior valor de energia metabolizÃvel da raÃÃo em relaÃÃo à raÃÃo controle. A inclusÃo de 20% de FIAPA resultou em menor valor de energia metabolizÃvel da raÃÃo em relaÃÃo à adiÃÃo do FIAPN. Embora tenha sido verificadas diferenÃas entre os tratamentos no aproveitamento dos nutrientes da raÃÃo esses nÃo foram suficientes para influenciar significativamente o desempenho, caracterÃsticas da carcaÃa, peso relativo do fÃgado e pÃncreas e o crescimento e a qualidade Ãssea. O farelo de coco armazenado por seis meses apresentou maior tendÃncia a reaÃÃes de hidrÃlise, observado pelo aumento do Ãndice de acidez. Independente do armazenamento, a inclusÃo do FC resultou em maiores valores de energia metabolizÃvel da raÃÃo e em reduÃÃo no consumo e na conversÃo alimentar em relaÃÃo à raÃÃo controle. Embora tenha sido verificadas diferenÃas entre os tratamentos em alguns parÃmetros, esses nÃo foram suficientes para influenciar significativamente as caracterÃsticas de carcaÃa, os pesos relativos do fÃgado e do pÃncreas e o crescimento e a qualidade Ãssea. O farelo de castanha de caju armazenado por seis meses apresentou maior tendÃncia a reaÃÃes de hidrÃlise, observado pelo aumento do Ãndice de acidez. Independente do armazenamento, a inclusÃo do FCC resultou em maiores valores de energia metabolizÃvel da raÃÃo e em reduÃÃo no consumo e conversÃo alimentar em relaÃÃo à raÃÃo controle. Ainda que tenha sido verificadas diferenÃas entre os tratamentos em alguns parÃmetros, esses nÃo foram suficientes para influenciar significativamente as caracterÃsticas de carcaÃa, os pesos relativos do fÃgado e do pÃncreas e o crescimento e a qualidade Ãssea. Ainda que o armazenamento por seis meses promova rancidez hidrolÃtica e oxidativa no farelo integral de arroz parboilizado e hidrolÃtica nos farelos de coco e de castanha de caju, estes podem ser utilizados na alimentaÃÃo de codornas de corte, em nÃveis de inclusÃo de atà 20%, para o farelo integral de arroz parboilizado e 25% para os farelos de coco e de castanha de caju.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 18, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. Jeffre D. Firman. Includes bibliographical references.

The antioxidant properties of various blends of rosemary extract and tocopherols, either alone or with citric and ascorbic acid, were compared in filleted, headed and gutted, and minced rainbow trout (Oncorhynchus mykiss). The filleted and headed and gutted products were stored at -29 degrees C for twelve months, while the minced was stored at the same temperature for 24 weeks. Oxidation was measured by following changes in thiobarbituric reactive substances, conjugated diene hydroperoxides, texture, drip loss, pH, sensory evaluation, and gas chromatographic detection of aldehydes. Natural antioxidants, in particular those that contained citric and ascorbic acids, were effective at retarding the development of conjugated diene hydroperoxides and malonaldehyde (p<0.05). Furthermore, sensory evaluation indicated that treated samples were less oxidized. In subsequent studies, however, it was determined that the herbal flavor notes associated with natural antioxidants complicated the ability of the experienced panel to judge extent of oxidation. Also, using filleted samples, further consumer sensory panels indicated that after 12 months frozen storage, the treated and control samples were equally acceptable. For both the filleted and headed and gutted samples, no texture differences were noted over storage time or between control or variable treatments. When using natural antioxidant products, drip loss and pH were found unreliable predicators of oxidation or muscle degradation.
Master of Science

All-purpose wheat flour is a useful long-term storage commodity, but is subject to off-odor formation. Although flour stored in a low oxygen atmosphere should inhibit rancid odor formation, it elicits consumer complaints about odor. The purpose of this study was to examine off-odor development in all-purpose wheat flour during ambient and elevated storage by determining the effect of low oxygen atmosphere and enrichment-bleaching on quality as measured by, free fatty acids (FFA), flour descriptive sensory analysis, conjugated dienes, headspace volatiles, bread consumer sensory analysis, color, loaf volume, and vitamin analysis. Enriched, bleached (EB) and unenriched, unbleached (UU) flour was stored in a low and normal oxygen atmosphere in no. 10 cans at 22, 30, and 40°C for 24 weeks. Moisture remained constant throughout the study. Headspace oxygen was < 0.1% in flour stored in a low oxygen atmosphere and decreased in flour stored in a normal oxygen atmosphere. FFA increased with storage time and temperature. The "fresh flour" descriptive aroma of flour decreased during storage and decreased more rapidly in a low oxygen atmosphere. The "cardboard/stale" aroma increased in flour stored in a normal oxygen atmosphere. The "acid-metallic" aroma increased in flour stored in a low oxygen atmosphere and was determined to be the off-odor from consumer complaints. Conjugated dienes and volatiles generally increased more rapidly in flour stored in a normal oxygen atmosphere and in EB flour, suggesting that the acid-metallic odor did not result from lipid oxidation. Bread consumer sensory analysis identified EB flour stored in a normal oxygen atmosphere to have the lowest acceptance scores for aroma, overall acceptability, and flavor. The acid-metallic odor dissipated within 24 hours when the container was opened and was not detrimental to consumer acceptance of bread made from the flour. Oxygen absorbers prevented the darkening of flour but not the reddening or yellowing. A low oxygen atmosphere resulted in higher bread loaf volumes. Vitamin degradation is not a concern under normal storage conditions. Bleaching appears to increase flour oxidative rancidity more than enrichment. Although storage at a low oxygen atmosphere results in an off-odor present in newly opened cans, it gave higher quality flour and bread. A low oxygen atmosphere should continue to be used in flour stored long-term, and consumers should be made aware that the off-odor present in cans of flour dissipates after opening.

O objetivo deste trabalho foi estudar o perfil oxidativo de concentrados para bovinos adicionados de óleo de soja, refinado e degomado, em um período de armazenamento de 15 dias, sob as temperaturas de 25ºC e 40ºC. Foram formados cinco grupos de alimentos: controle (C) sem adição de óleo, tratamentos (T) 1, 2, 3 e 4 com adição de 2, 4, 6 e 8%, respectivamente, de óleo de soja refinado ou degomado. Para tal, foram avaliados os índices de peróxidos e de acidez. Com relação à influência da temperatura de estocagem, ao longo do período experimental à 25ºC, não houve alteração com relação aos valores de índice de peróxido quando se adicionou óleo de soja refinado aos concentrados, contudo, à 40ºC, houve aumento observando-se um valor máximo em torno de 0,9 mEq/kg de concentrado. O índice de acidez do óleo refinado extraído dos concentrados armazenados à 25ºC não foi alterado ao longo do período de armazenamento, e à 40ºC resultou em aumento de 19, 25, 44 e 44% para os respectivos T1, T2, T3 e T4 em relação ao controle. Quanto à influência do tipo de óleo processado na oxidação lipídica dos concentrados armazenados à 40ºC, a adição de óleo de soja refinado não alterou os índices de peróxidos dos concentrados ao longo dos 15 dias de experimento, e para o degomado observou-se um aumento no 3º dia de armazenamento em 57%, 44%, 123% e 93% para os respectivos T1, T2, T3 e T4, em relação ao controle. Também, o efeito da adição de óleo de soja degomado resultou em aumento do índice de acidez de 21%, 36%, 43% e 57% a partir do 5º dia de experimento, em relação ao 1º dia. Conclui-se que durante os 15 dias de armazenamento, houve diferença no perfil oxidativo dos concentrados adicionados de óleo de soja quando se comparou as temperaturas de 25ºC e 40ºC, mas se manteve inalterado quando se avaliou os tipos de óleo refinado e degomado em diferentes porcentagens. Assim, a adição de óleo de soja refinado ou degomado não altera o perfil oxidativo do concentrado para bovino sob as condições deste estudo.
The objective of this work was to study the oxidative profile of concentrates for cattle added soybean oil, refined and degummed in a storage period of 15 days, at temperatures of 25ºC and 40ºC. Were formed five food groups: control (C) without addition of oil, treatments (T) 1, 2, 3 and 4 with the addition of 2, 4, 6 and 8%, respectively, of refined or degummed soybean oil. For this purpose ware available index of peroxide and of acidic. Regarding the influence of storage temperature, the addition of refined soybean oil did not alter the values of the peroxide during the trial period at 25ºC, however, at 40ºC of storage of food alter this parameter and was shown a maximum value about 0.9 mEq/kg of concentrate. The acidity of refined oil extracted from concentrates stored at 25ºC was not changed during the storage period, and 40ºC resulted in an increase of 19, 25, 44 and 44% for the respective T1, T2, T3 and T4 compared the control. Regarding the influence of oil processed in lipid oxidation of concentrates stored at 40ºC, the addition of refined soybean oil did not alter the levels of peroxide concentrates over the 15 days of experiment, and the degummed observed an increase in 3rd day of storage in 57%, 44%, 123% and 93% for the respective T1, T2, T3 and T4, compared to control. Also, the effect of addition of crude soybean oil resulted in increased acid value of 21%, 36%, 43% and 57% from the 5th day of experiment, as compared to day 1. Thus, the addition of refined soybean oil or degummed not change profile for bovine oxidative concentrated under the conditions of this study.

The rice bran is obtained from the polishing of husked rice to produce white rice and, despite its high content of protein and vitamin, this by product is still almost entirely used to animal nutrition and less used by the food industry. Due to the large amount of bran produced, there is a big effort to increase the oxidative stability of this material. The aim of this study was to evaluate the stability of rice bran on the known conditions of humidity and temperature and then, propose a procedure for its stabilization, affordable and easily applicable. Therefore, various treatments were employed, such as physical processes (pelleting and irradiation), synthetic antioxidants as well as natural antioxidants. The rice bran was stored for 90 days and analyzed for its chemical composition, acidity and peroxide value. The values of acidity and peroxide value were similar to those found in the literature. The acidity and peroxide value increased during the storage time for almost all treatment combinations. The start and final acidity values of rice bran treated with natural and chemical antioxidants were higher than those obtained from physical processes. The lowest initial acidity values were 7.10, 6.09, and 4.36% for natural antioxidants, chemical antioxidants and physical processes, respectively. The highest total acidity value was observed for natural antioxidants (17.58%) and the lowest, for the treatment with chemical antioxidants combined with pelleting (9.12%). The results indicated that the stabilization of rice bran is affected by environmental conditions such as temperature, relative humidity, and storage time. The chemical composition of rice bran is affected by rice origin, species, harvest period, processing and type of soil. Irradiation and pelleting processes proved to be satisfactory and efficient for the oxidative stabilization of the rice bran in the food industry.
O farelo é proveniente do polimento do arroz descascado para produzir o arroz branco e, apesar do elevado conteúdo proteico e vitamínico, este subproduto ainda é quase totalmente utilizado em formulações para alimentação de animais, especialmente suínos e ruminantes, sendo pouco utilizado na indústria de alimentos. Devido à grande quantidade de farelo produzido, existe um grande esforço para aumentar a sua estabilidade oxidativa. Sendo assim, o objetivo deste estudo foi avaliar a estabilidade do farelo de arroz integral diante de condições conhecidas de umidade e temperatura e, então, propor um procedimento para a estabilização do farelo de arroz, acessível e facilmente aplicável. Para tanto, diferentes tratamentos foram empregados, utilizando processos físicos (irradiação e peletização) e antioxidantes sintéticos e de origem natural. Os farelos de arroz foram armazenados por 90 dias e analisados quanto à composição centesimal, acidez e índice de peróxidos. Os valores de acidez e peróxidos foram semelhantes aos encontrados na literatura para farelo de arroz. A acidez e o índice de peróxidos aumentaram durante o tempo de armazenamento em praticamente todas as combinações de tratamentos. Os valores inicial e final de acidez com antioxidantes naturais e químicos foram mais elevados do que com os processos físicos. O menor valor inicial de acidez para os tratamentos com antioxidantes naturais foi 7,10%, para os antioxidantes químicos foi 6,09% e para os processos físicos foi 4,36%. O maior valor final de acidez foi obtido para os tratamentos com antioxidantes naturais (17,58%), e o menor, para o tratamento com peletização associada a antioxidantes químicos (9,12%). Os resultados indicaram que a estabilização do FAI é afetada pelas condições ambientais na qual ele é beneficiado, principalmente pela temperatura, umidade relativa e tempo de armazenamento do FAI. A composição centesimal do FAI sofre interferência direta da origem do arroz, espécie, período da colheita, tipo de beneficiamento e tipo de solo no qual o arroz é produzido. A irradiação e a peletização atendem de forma satisfatória a indústria de alimentos para a estabilização oxidativa do FAI.

Shelf life studies of raw Macadamia integrifolia nuts were carried out at different storage temperatures, relative humidities and time. An accelerated shelf life test was conducted, and the influence of water activity on kernel texture was studied. The antioxidants naturally present were identified by the use of thin layer chromatography. Accelerated shelf life tests showed that hydrolytic rancidity followed apparent zero order kinetics within the water activity range of 0.3 to 0.5. Oxidative rancidity measured by peroxide value appeared to follow different orders of reaction at different temperatures. At two months of storage rancidity was detected at which the headspace concentration of hexanal was 0.39 ppm and a peroxide value of 0.37 meq/kg. Headspace gas chromatography was done to find a quick and effective method for measuring oxidative rancidity. The presence of natural antioxidants was verified to explain the shelf life of macadamia nuts. In textural study, correlations were found between subjective and objective measurements. The product became unacceptable organoleptically above water activity 0.415 when stored at 20 degrees C. This level was established as the critical water activity. There is a need to establish a water activity at which the consumer is likely to reject the product.

FARIAS, Nadja Naiara Pereira. Farelos de arroz, coco e castanha de caju submetidos a armazenamento prolongado na alimentação de codornas de corte. 2013. 96 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Zootecnia, Fortaleza-CE, 2009
Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-08-09T14:48:59Z No. of bitstreams: 1 2013_dis_nnpfarias.pdf: 1065619 bytes, checksum: 093ec7ddd5e899d3abc93f495204dab9 (MD5)
Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-08-09T14:49:14Z (GMT) No. of bitstreams: 1 2013_dis_nnpfarias.pdf: 1065619 bytes, checksum: 093ec7ddd5e899d3abc93f495204dab9 (MD5)
Made available in DSpace on 2016-08-09T14:49:14Z (GMT). No. of bitstreams: 1 2013_dis_nnpfarias.pdf: 1065619 bytes, checksum: 093ec7ddd5e899d3abc93f495204dab9 (MD5) Previous issue date: 2013
Com o objetivo de avaliar a estabilidade oxidativa do farelo integral de arroz parboilizado, do farelo de coco e do farelo de castanha de caju durante o armazenamento e os efeitos do uso desses ingredientes na alimentação de codornas de corte, foram realizados três experimentos no período de 7 a 42 dias de idade. Para isso, um lote de 100 kg de cada farelo foi armazenado durante o período de seis meses. Ao término desse período, foi adquirido novo lote de 100 kg de cada farelo e tanto os farelos novos e armazenados, foram utilizados para formular as rações das codornas. No primeiro experimento, 245 codornas com sete dias de idade foram distribuídas em um delineamento inteiramente casualizado, com cinco tratamentos e sete repetições de sete aves por unidade experimental e foram testados os níveis de 10 e 20% de inclusão de farelo integral de arroz parboilizado armazenado (FIAPA) e novo (FIAPN). No segundo e terceiro experimentos, 280 codornas com sete dias de idade foram distribuídas em um delineamento inteiramente casualizado, com cinco tratamentos e sete repetições de oito aves por unidade experimental. Nesses ensaios, os tratamentos consistiram em uma ração controle e os demais contendo 12,5 e 25% de farelo de coco armazenado (FCA) e novo (FCN) e farelo de castanha de caju armazenado (FCCA) e novo (FCCN), respectivamente. O farelo integral de arroz armazenado por seis meses apresentou sinais de reações hidroliticas e oxidativas, observados pelo aumento do índice de acidez e de peróxido, respectivamente. Independente do armazenamento, a inclusão do farelo integral de arroz parboilizado resultou em menor digestibilidade da matéria seca e do nitrogênio e maior valor de energia metabolizável da ração em relação à ração controle. A inclusão de 20% de FIAPA resultou em menor valor de energia metabolizável da ração em relação à adição do FIAPN. Embora tenha sido verificadas diferenças entre os tratamentos no aproveitamento dos nutrientes da ração esses não foram suficientes para influenciar significativamente o desempenho, características da carcaça, peso relativo do fígado e pâncreas e o crescimento e a qualidade óssea. O farelo de coco armazenado por seis meses apresentou maior tendência a reações de hidrólise, observado pelo aumento do índice de acidez. Independente do armazenamento, a inclusão do FC resultou em maiores valores de energia metabolizável da ração e em redução no consumo e na conversão alimentar em relação à ração controle. Embora tenha sido verificadas diferenças entre os tratamentos em alguns parâmetros, esses não foram suficientes para influenciar significativamente as características de carcaça, os pesos relativos do fígado e do pâncreas e o crescimento e a qualidade óssea. O farelo de castanha de caju armazenado por seis meses apresentou maior tendência a reações de hidrólise, observado pelo aumento do índice de acidez. Independente do armazenamento, a inclusão do FCC resultou em maiores valores de energia metabolizável da ração e em redução no consumo e conversão alimentar em relação à ração controle. Ainda que tenha sido verificadas diferenças entre os tratamentos em alguns parâmetros, esses não foram suficientes para influenciar significativamente as características de carcaça, os pesos relativos do fígado e do pâncreas e o crescimento e a qualidade óssea. Ainda que o armazenamento por seis meses promova rancidez hidrolítica e oxidativa no farelo integral de arroz parboilizado e hidrolítica nos farelos de coco e de castanha de caju, estes podem ser utilizados na alimentação de codornas de corte, em níveis de inclusão de até 20%, para o farelo integral de arroz parboilizado e 25% para os farelos de coco e de castanha de caju.
Aiming to evaluate the oxidative stability of parboiled rice bran, coconut meal and cashew nut meal during storage and the effects of its use in the feeding of meat quails, were carried three experiments in the period 7 at 42 days of age. For this, a batch of 100 kg of each meal was stored for a period of six months. At the end of that period, were purchased new batches of 100 kg each bran, and meal, fresh and stored, were used to formulate the diets of quail. In the first experiment, 245 quails with seven days of age were distributed in a completely randomized design with five treatments and seven replications of seven birds each and were tested levels of 10 and 20% inclusion of stored parboiled rice bran (SPRB) and new (NPRB). In the second and third experiments, 280 quails with seven days of age were distributed in a completely randomized design with five treatments and seven replications of eight birds each. In these trials, the treatments consisted of a control diet and the other containing 12.5 and 25% of stored coconut bran (SCB) and new (NCB) and stored cashew nut bran (SCNB) and new (NCNB), respectively. The rice bran parboiled stored for six months showed signs of hydrolytic and oxidative reactions observed by the increase in acid value and peroxide, respectively. Regardless of the storage, the inclusion of rice bran parboiled resulted in lower digestibility of dry matter and nitrogen and higher metabolizable energy value of the diet compared to the control diet. The inclusion of 20% SPRB resulted in less metabolizable energy value of feed in relation to the addition of NPRB. Although there have been no differences between treatments in nutrient utilization ration these were not enough to significantly influence the performance, carcass characteristics, relative weight of the liver and pancreas and growth and bone quality. The coconut meal stored for six months showed a higher tendency to hydrolysis reactions, observed by increasing the acidity index. Regardless of the storage, the inclusion of coconut meal resulted in higher metabolizable energy of the ration and reduction in consumption and feed conversion compared to the control diet. Although there have been differences between treatments in some parameters, these were not sufficient to significantly influence carcass characteristics, the relative weights of the liver and pancreas and growth and bone quality. The cashew nut bran stored for six months showed a higher tendency to hydrolysis reactions, observed by increasing the acidity index. Storage independent, inclusion the cashew nut bran resulted in higher metabolizable energy of the ration and reduction in feed intake and feed compared to the control diet. Although there have been differences between treatments in some parameters, these were not sufficient to significantly influence carcass characteristics, the relative weights of the liver and pancreas and growth and bone quality. Although the store for six months promote hydrolytic and oxidative rancidity the bran of parboiled rice and hydrolytic in the coconut bran and cashew nut bran, these can be used to feed meat quails in inclusion levels of up to 20% for the parboiled rice bran and 25% for the coconut bran and cashew nut bran.

Made available in DSpace on 2014-07-29T15:22:56Z (GMT). No. of bitstreams: 1 Diracy.pdf: 1319673 bytes, checksum: 5bee102f59d80260a1c48f1623eed435 (MD5) Previous issue date: 2008-11-06
Rice bran is a by product of the rice milling process. It corresponds to 8% of the total rice grain and is used as feed and fertilizer mainly. The major problem related to its use in human nutrition is the rancification process starting soon after its extraction. The objective of this work was to evaluate the stability of raw rice bran (RRB), extruded rice bran (ERB) and rice bran obtained after parboilization (RBP) when stored at room temperature for 180 days in polyethylene bags as well as to characterize them and the cookies formulated with ERB. Physicochemical, microbiological and stability tests (lipase activity, hydrolytic rancidity and peroxide index) were performed on rice bran from cultivar Primavera (donated by benefited industry) and on the prepared cookies with ERB using a completely randomized design, with a control and four treatments (12.5%, 25%, 37.5% and 50% of ERB). All tests were performed according to standard methodologies. PRB presented the highest contents of protein (17.7 g 100 g-1), lipid (36.03 g 100 g-1), dietary fibers (34.06 g 100 g-1), calcium (99.45 mg 100g-1), zinc (15.58 g 100 g-1), copper (1.45 g 100 g-1) and manganese (17.81 g 100 g-1) and the lowest contents of carbohydrates (5,73 g 100 g-1), ashes (7.01 g 100 g-1) and iron (6.83 mg 100 g-1). Lipase activity and hydrolytic rancidity were higher in NRB during the storage period but the peroxidase index was lower. Cookies were well accepted and did not show any significant diference regarding appearance, texture and flavor. Cookies with 50% of ERB had higher contents of protein (18.9%), dietary fiber (213.3%) and ashes (59.1%) than the control. Forty grams of that formulation supplies more than 10% of daily recommended intakes of magnesium, phosphorus and copper. Cookies also presented acceptable microbiological standards according to Brazilian legislation. Extrusion and parboilization are efficient methods to prevent free fatty acid formation in ERB and PRB, placed in plastic films permeable to oxygen and stored at room temperature, but they contributed to higher concentrations of peroxides in those rice bran. Cookies with 50% ERB had a better nutritional quality than those without rice bran
O farelo de arroz, subproduto resultante do beneficiamento para obtenção do arroz polido, corresponde a 8% do arroz em casca, sendo utilizado principalmente na ração animal e como fertilizante. O maior problema relacionado à utilização do farelo é a rancificação iniciada logo após sua obtenção. Este trabalho objetivou avaliar a estabilidade à rancidez dos farelos de arroz cru (FAC), extrusado (FAE) e obtido após parboilização do arroz (FAP) quando armazenados em sacos de polietileno à temperatura ambiente por 180 dias, bem como caracterizar estes farelos e cookies formulados com FAE. As análises físico-químicas, microbiológicas e de estabilidade (atividade de lipase, rancidez hidrolítica e índice de peróxidos) foram realizadas nos farelos de arroz da cultivar Primavera (doados pela indústria beneficiadora) e nos biscoitos elaborados por delineamento inteiramente casualizado, com um controle e quatro tratamentos (12,5%, 25%, 37,5% e 50% de FAE). As análises foram realizadas conforme métodos validados. O FAP apresentou maior teor de proteínas (17,17 g 100 g-1), lipídios (36,03 g 100 g-1), fibra alimentar (34,06 g 100 g-1), cálcio (99,45 mg 100 g- 1), zinco (15,58 mg 100 g-1), cobre (1,45 g 100 g-1) e manganês (17,81 g 100 g-1) e menor teor de carboidratos (5,73 g 100 g-1), cinzas (7,01 g 100 g-1) e ferro (6,83 mg 100 g-1). A atividade de lipase e a rancidez hidrolítica durante o armazenamento foram maiores no FAC, enquanto que o índice de peróxidos foi menor. Os biscoitos elaborados foram bem aceitos, não apresentando diferenças significativas quanto a aparência, textura e sabor. O biscoito elaborado com 50% de FAE apresentou conteúdo maior de proteínas (18,9%), fibra alimentar (213,3%) e cinzas (59,1%) que o controle, sendo que uma porção de 40 g fornece mais que 10% da recomendação diária de magnésio, fósforo e cobre. Os biscoitos apresentaram padrões microbiológicos aceitáveis conforme legislação brasileira. A extrusão e a parboilização são eficientes para prevenir a formação de ácidos graxos livres nos FAE e FAP embalados em filme plástico permeável ao oxigênio e armazenados à temperatura ambiente, entretanto, promovem maior formação de peróxidos nestes farelos. Biscoitos com 50% de FAE possuem melhor qualidade nutricional que os biscoitos sem farelo

Submitted by Clebson Anjos (clebson.leandro54@gmail.com) on 2016-03-04T20:58:30Z No. of bitstreams: 1 arquivototal.pdf: 4279867 bytes, checksum: cc6bcf7dbfdbba66c85512e2c1a25a45 (MD5)
Made available in DSpace on 2016-03-04T20:58:31Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 4279867 bytes, checksum: cc6bcf7dbfdbba66c85512e2c1a25a45 (MD5) Previous issue date: 2015-11-27
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
“Manteiga da terra” is a traditional product in the northeast of Brazil that consists of a form of anhydrous cow’s milk fat. This product is susceptible to hydrolytic and oxidative rancidity, responsible for undesirable sensory changes, decreases in nutritional quality and economic impact for the industry. In this study, thermal stability and changes in the physicochemical and sensory profiles were evaluated during storage temperatures of 5, 30, 45 and 60°C at 0, 14, 28, 42 and 56 days. Physicochemical analyses were carried out to evaluate chemical composition and fatty acids profile in the initial time and the storage effects on acidity, peroxide value, TBARS value and objective color. From these results, the activation energy and the induction period were estimated. Microbiological analyses were performed for total and fecal coliforms. Quantitative Descriptive Analysis (QDA) was used to the sensory evaluation of appearance (yellow color, opacity, uniformity and visual viscosity), odor (characteristic of the product and rancid), flavor (characteristic of the product, acid and rancid) and texture (viscosity and granularity). The “manteiga da terra” produced to this study met the standards established by the brazilian legislation with results of 98.96% for fat, 0.07% for moisture, 0.97% for non-fat solids and 0.78% for acidity. The major fatty acids found in the product were oleic (22.66%), palmitic (21.18%) and stearic (13.86%). Saturated fatty acids accounted for 53.72% and unsaturated for 32.24% of the total. There were significant differences for acidity between samples stored at 30, 45 and 60°C, with final values of 0.89, 1.0 and 1.11%, respectively. The peroxide values showed significant increases from 0.50 to 1.30 and 3.99 mEq.kg-1 in samples stored at 45 and 60°C, in this order. The TBARS value was 0.08 mgMDA.kg-1 in the initial time and there were significant increases in the samples stored at 45 and 60°C, with values of 0.12 and 0.19 mgMDA.kg-1, respectively, at the end of 56 days. The parameters L*, a* and b* for objective color characterized the yellow color of the product, with decrease in yellow tone during storage, especially at higher temperatures. The activation energy found for the system was 50.2 kJ.mol-1 and the induction period (in days) was 616 to 5°C, 103 to 30°C, 52 to 45°C and 26 to 60°C. Microbiological analysis indicated the absence of contamination for all samples. In the sensory analysis, the samples kept at 60°C for 56 days had the lowest scores for yellow tone color, opacity, characteristic odor and taste, visual viscosity and viscosity felt at the mouth. On the other hand, they showed a significant increase for the characteristic odor and taste of rancid. The results indicated that the “manteiga da terra” is a stable product for a long period under normal storage conditions.
A manteiga da terra é um produto característico da região nordeste brasileira e consiste de uma forma de gordura anidra proveniente do leite de vaca. Este produto é susceptível às rancificações hidrolítica e oxidativa, responsáveis por alterações sensoriais indesejáveis, diminuição na qualidade nutricional e impacto econômico para a indústria. Neste estudo, foram avaliadas a estabilidade térmica e alterações nos perfis físico-químicos e sensoriais durante o armazenamento em temperaturas de 5, 30, 45 e 60ºC nos tempos 0, 14, 28, 42 e 56 dias. Nas análises físico-químicas, foram realizadas a composição centesimal e o perfil de ácidos graxos no tempo inicial e a avaliação dos efeitos do armazenamento nos parâmetros de acidez, índice de peróxidos, valor de TBARS e cor objetiva. Com estes dados, foram estimados a energia de ativação e o período de indução da amostra. Foram realizadas análises microbiológicas para coliformes a 35 e a 45ºC. A Análise Descritiva Quantitativa (ADQ) foi utilizada na avaliação sensorial dos atributos: aparência (cor amarela, opacidade, homogeneidade e viscosidade visual), odor (característico de manteiga da terra e de ranço), sabor (característico de manteiga da terra, ácido e de ranço) e textura (viscosidade e granulosidade). A manteiga da terra elaborada atendeu aos parâmetros estabelecidos pela legislação com resultados de 98,96% de matéria gorda, 0,07% de umidade, 0,97% de sólidos não gordurosos e 0,78% de acidez. Os ácidos graxos majoritários do produto foram o oleico (22,66%), o palmítico (21,18%) e o esteárico (13,86%). Os ácidos graxos saturados corresponderam a 53,72% e os insaturados a 32,24% do total. No índice de acidez, houve diferença significativa nas amostras armazenadas a 30, 45 e 60ºC, com teores finais de 0,89, 1,01 e 1,11%, respectivamente. Quanto ao índice de peróxidos, inicialmente com 0,50 mEq.kg-1, houve aumentos significativos para as amostras armazenadas a 45 e 60ºC, com índices finais de 1,30 e 3,99 mEq.kg-1, nesta ordem. O valor de TBARS inicial foi de 0,08 mgMDA.kg-1, com aumento significativo nas amostras armazenadas a 45 e 60ºC, com valores de 0,12 e 0,19 mgMDA.kg-1, respectivamente, ao final dos 56 dias. Quanto à cor objetiva, os parâmetros L*, a* e b* caracterizam a cor amarela da amostra que, durante o armazenamento, apresentou um clareamento na tonalidade do amarelo, em especial nas temperaturas mais elevadas. A energia de ativação encontrada para o sistema foi de 50,2 kJ.mol-1 e o período de indução (em dias) foi de 616 para 5ºC, 103 para 30ºC, 52 para 45ºC e de 26 para 60ºC. As análises microbiológicas indicaram ausência de contaminação para todas as amostras. Na análise sensorial, as amostras armazenadas a 60ºC por 56 dias foram as que obtiveram os menores escores para a tonalidade da cor amarela, opacidade, odor e sabor característicos de manteiga da terra, viscosidade visual e viscosidade sentida na boca. Em contrapartida, apresentaram também aumento significativo para o odor e o sabor característicos do ranço. Os resultados do estudo indicaram que a manteiga da terra é um produto que se mantém estável por um longo período, sem alterações importantes antes dos 103 dias de estocagem à temperatura ambiente.