Mathematical modeling of the ethanol fermentation of cashew apple juice by a flocculent yeast: the effect of initial substrate concentration and temperature.

In this work, the effect of initial sugar concentration and temperature on the production of ethanol by Saccharomyces cerevisiae CCA008, a flocculent yeast, using cashew apple juice in a 1L-bioreactor was studied. The experimental results were used to develop a kinetic model relating biomass, ethanol production and total reducing sugar consumption. Monod, Andrews, Levenspiel and Ghose and Tyagi models were investigated to represent the specific growth rate without inhibition, with inhibition by substrate and with inhibition by product, respectively. Model validation was performed using a new set of experimental data obtained at 34 °C and using 100 g L-1 of initial substrate concentration. The model proposed by Ghose and Tyagi was able to accurately describe the dynamics of ethanol production by S. cerevisiae CCA008 growing on cashew apple juice, containing an initial reducing sugar concentration ranging from 70 to 170 g L-1 and temperature, from 26 to 42 °C. The model optimization was also accomplished based on the following parameters: percentage volume of ethanol per volume of solution (%V ethanol/V solution), efficiency and reaction productivity. The optimal operational conditions were determined using response surface graphs constructed with simulated data, reaching an efficiency and a productivity of 93.5% and 5.45 g L-1 h-1, respectively.

Qualidade microbiológica e fisico-química da polpa e mix de açaí armazenada sob congelamento / Microbiological quality and physical-chemical characteristics of the frozen pulp and blended açai

Polpas e mix de açaí (Euterpe oleracea Mart) congeladas e comercializadas na região de São Carlos, SP foram analisadas quanto às características microbiológicas e físico-químicas. Nas amostras sob congelamento durante 0, 3, 6 e 9 meses foram investigadas a contaminação Salmonella, coliformes totais e fecais. Os parâmetros físico-químicos avaliados foram lipídeos totais, pH, umidade, cinzas, proteínas, sólidos totais, açúcares redutores e não redutores. Todas as amostras de diferentes marcas e tempo de armazenamento investigadas demonstraram ausência de bactéria. Nos parâmetros físico-químicos, constatou-se diferença significativa entre as marcas de produtos, bem como entre amostras em diferentes tempos de armazenamento; contudo, para pH não houve variação significativa entre as amostras estocadas em diferentes períodos de tempo. As amostras analisadas apresentaram conformidade com a legislação no aspecto higiênico sanitário e as variações encontradas nas análises físico-químicas evidenciam que, mesmo sob congelamento, as reações químicas continuam a ocorrer no alimento.

This study aimed at assessing the microbiological and physical-chemical parameters of frozen pulp and blended açai (Euterpe oleracea Mart) from brands marketed in São Carlos, São Paulo State. The samples kept frozen for 0, 3, 6 and 9 months were analyzed on Salmonella, total/fecal coliforms contamination, and on parameters as total lipids, pH, humidity, ash, proteins, total solids, reducing and non-reducing sugars. No Salmonella and total/fecal coliforms were found in samples from all products brands and stored atdifferent period of months, being in compliance with Brazilian legislation. On physical-chemical analyses, a significant difference among the product brands and storage times was found; but for pH, no significant difference was found in the product storing time. All of the samples were in accordance with the hygienic standards parameters, and the alterations verified on the physical-chemical analysis evidenced that evenunder freezing storage, the chemical reactions still continue to occur in the food.

Amino acid composition of single and mixed fungal cultures grown in sugar cane vinasse

Foi avaliada a composiçäo de aminoácidos de culturas puras e mista de Cryptococus laurentii e Aspergillus niger desenvolvidas em meio de vinhaça. Os perfis de aminoácidos, determinados por cromatografia de troca iônica, mostraram que a biomassa de A.niger apresentou valores superiores aqueles apresentados por Cr. laurentii para cada aminoácido. No entanto, a cultura mista destes microrganismos apresentou teores ainda mais elevados de aminoácidos. A biomassa da cultura mista foi deficiente em cistina em comparaçäo com o padräo de proteína recomendado pela FAO; ácido glutâmico e prolina em comparaçäo com a caseína; e metionina em comparaçäo com as proteínas da carne, trigo, leite e ovo. Os resultados mostraram ser a cultura mista de A.niger and Cr.laurenti uma boa fonte de proteína