962 resultados para continuous process, fermentation
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The aim of this study was to determine the optimal temperature and baking time to obtain a Madeira wine considered typical by an expert panel. For this purpose simultaneous descriptive analyses of typical Madeira wines were performed, and seven descriptors were selected: “dried fruit”, “nutty”, “musty”, “baked”, “oak”, “mushroom”, and “brown sugar”. Up to 10 odor-active zones were the most frequently cited by the members of the GC-olfactometry panel as corresponding to the panel’s descriptors. The odor importance of each of the zones reported by the GC-O analysis was ranked by AEDA. Three odor zones were identified as common to both Malvasia and Sercial wines and had retention indices (RI) of 1993 (“brown sugar” and “toasted”), 2151 (“brown sugar”), and 2174 (“nutty”, “driedfruits”);sotolonwasidentifiedasresponsibleforthislastaroma.Severalmoleculeswereselected to be quantified on baked wines on the basis of AEDA results and expected Maillard volatiles, such as sotolon, furfural, 5-methylfurfural, 5-ethoximethylfurfural, methional, and phenylacetaldehyde. It was observed that typicity scores were positively correlated with the concentrations of sotolon and sugar and baking time and negatively with the fermentation length.
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A mandioca, apesar de ser nativa do Brasil, ainda é sub-utilizada principalmente quando a questão é o aproveitamento da sua parte aérea. Com o objetivo de estudar o potencial da mandioca para alimentação animal, o presente trabalho avaliou as características da parte aérea da planta quando submetida os processos de ensilagem e fenação. Os tratamentos consistiram de: parte aérea ensilada sem emurchecimento (PAS); parte aérea ensilada após 24 horas de emurchecimento (PAE) e parte aérea fenada (PAF). As análises químicas foram realizadas a fim de avaliar os parâmetros que determinam o valor nutritivo da silagem e do feno. O emurchecimento elevou o teor de matéria seca de 25% no material in natura para 27.7%, sem alterar o teor de carboidratos solúveis (33.3 e 35.5% de MS na PAS e PAE respectivamente), bem como o poder tampão (204 mmol kg-1 MS na PAS e 195 mmol kg-1 MS na PAE). Nem o pH (3.57 na silagem in natura e 3.60 na PAE) nem os teores de NIDA (11.32% do nitrogênio total na MS na PAS e 9.99% do nitrogênio total na MS na PAE) diferiram entre as silagens, mas o NIDA foi maior na forragem fenada (15.39%). Contudo, o emurchecimento provocou aumento no nitrogênio amoniacal (de 6.5% do nitrogênio total na MS da PAS para 13.0 do nitrogênio total na MS da PAE). Os teores de ácidos graxos voláteis não sofreram alterações com o emurchecimento. O processo de ensilagem reduziu os teores de ácido cianídrico livre (HCN), sem, contudo, alterar a cianidrina.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The use of sugarcane bagasse and grass as low cost raw material for xylanase production by Bacillus circulans D1 in submerged fermentation was investigated. The microorganism was cultivated in a mineral medium containing hydrolysate of bagasse or grass as carbon source. High production of enzyme was obtained during growth in media with bagasse hydrolysates (8.4 U/mL) and in media with grass hydrolysates (7.5 U/mL). Xylanase production in media with hydrolysates was very close to that obtained in xylan containing media (7.0 U/ mL) and this fact confirm the feasibility of using this agro-industrial byproducts by B. circulans D1 as an alternative to save costs on the enzyme production process. (c) 2005 Elsevier Ltd. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The pectinolytic enzyme obtained from Penicillium viridicatum RFC by solid-state fermentation was purified to homogeneity by pretreatment with kaolin (40 mg mL(-1) ) and ultrafiltration. followed by chromatography on a Sephadex G50 column. The apparent molecular weight of the enzyme was 24 kDa. Maximal activity occurred at pH 6.0 and at 60 degrees C. The enzyme proved to be an exo-polygalacturonase, releasing galacturonic acid by hydrolysis of highly esterified pectin. The presence of 10 mM Ba2+ increased the enzyme activity by 96% and its thermal stability by 30%. besides increasing its stability at acid pH. The apparent K-m with apple pectin as substrate was 1.82 mg mL(-1) and the V-max was 81 mu mol min(-1). (c) 2007 Elsevier Ltd. All rights reserved.
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Endo-polygalacturonase (endo-PG), exo-polygalacturonase (exo-PG) and pectin liase (PL) were produced by solid-state fermentation of a mixture of orange bagasse and wheat bran (1:1) with the filamentous fungus Penicillium viridicatum RFC3. This substrate was prepared with two moisture contents, 70% and 80%, and each was fermented in two types of container, Erlenmeyer flask and polypropylene pack. When Erlenmeyer flasks were used, the medium containing 80% of initial moisture afforded higher PL production while neither exo- nor endo-PG production was influenced by substrate moisture. The highest enzyme activities obtained were 0.70 U mL(-1) for endo-PG, 8.90 U mL(-1) for exo-PG, and 41.30 U mL(-1) for PL. However, when the fermentation was done in polypropylene packs, higher production of all three enzymes was obtained at 70% moisture (0.7 and 8.33 U mL(-1) for endo- and exo-PG and 100 U mL(-1) for PL). An increase in the pH and decrease in the reducing sugar content of the medium was observed. The fungus was able to produce pectin esterase and other depolymerizing enzymes such as xylanase, CMCase, protease and amylase. (c) 2005 Elsevier Ltd. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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In this work, a 3(3) factorial design was performed with the aim of optimizing the culture conditions for xylanase production by an alkalophilic thermophilic strain of Bacillus circulans, using response surface methodology. The variables involved in this study were xylan concentration (X-1), pH (X-2) and cultivation time (X-3). The optimal response region was approached without using paths of steepest ascent. Statistical analysis of results showed that, in the range studied, only pH did not have a significant effect on xylanase production. A second-order model was proposed to represent the enzymic activity as a function of xylan concentration (X-1) and cultivation time (X-3). The optimum xylan concentration and cultivation time were 5 g/l and 48 h, respectively. Under these conditions, the model predicted a xylanase activity of 19.1 U/ml. (C) 2002 Elsevier B.V. Ltd. All rights reserved.
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The effect of continuous emission hypothesis on the two-pion Bose-Einstein correlation is discussed and compared with the corresponding results based on the usual freeze-out ansatz. Sizable differences in the correlation function are observed when comparing these two scenarios of the decoupling process. They could lead to entirely different interpretation of properties of the hot matter formed in high-energy heavy-ion collisions.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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This work investigated the effects of increasing temperature from 30 degrees C to 47 degrees C on the physiological and genetic characteristics of Saccharomyces cerevisiae strain 63M after continuous fermentation with cell recycling in a system of five reactors in series. Steady state was attained at 30 degrees C, and then the temperature of the system was raised so it ranged from 35 degrees C in the last reactor to 43 degrees C in the first reactor or feeding reactor with a 2 degrees C difference between reactors. After 15 days at steady state, the temperature was raised from 37 degrees C to 45 degrees C for 25 days at steady state, then from 39 degrees C to 47 degrees C for 20 days at steady state. Starter strain 63M was a hybrid strain constructed to have a MAT a/alpha, LYS/lys, URA/ura genotype. This hybrid yeast showed vigorous growth on plates at 40 degrees C, weak growth at 41 degrees C, positive assimilation of melibiose, positive fermentation of galactose, raffinose and sucrose. of 156 isolates obtained from this system at the end of the fermentation process, only 17.3% showed the same characteristics as starter strain 63M. Alterations in mating type reaction and in utilization of raffinose, melibiose, and sucrose were identified. Only 1.9% of the isolates lost the ability to grow at 40 degrees C. Isolates showing requirements for lysine and uracil were also obtained. In addition, cell survival was observed at 39-47 degrees C, but no isolates showing growth above 41 degrees C were obtained.
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Maintenance of high cell viability was the main characteristic of our new strains of thermotolerant Saccharomyces. Total sugar conversion to ethanol was observed for sugarcane juice fermentation at 38-40-degrees-C in less than 10 h and without continuous aeration of the culture. Invertase activity differed among the selected strains and increased during fermentation but was not dependent on cell viability. Invertase activity of the cells and optimum temperature for growth, as well as velocity of ethanol formation, were dependent on medium composition and the type of strain used. At high sugarcane syrup concentrations, the best temperature for ethanol formation by strain 781 was 35-degrees-C. Distinct differences among the velocities of ethanol production using selected strains were also observed in sugarcane syrup at 35-38-degrees-C.