A large number of advantages are obtained from the use of highly concentrated worts during the production of beer in a process referred to as "high-gravity". However, problems related to slow or stuck fermentations, which cause the lower productivity and possibility of contamination, are encountered. This study examines the influence of factors pH, percentage of corn syrup, initial wort concentration and fermentation temperature on the fermentation parameters, namely productivity, wort attenuation and the yield coefficient for sugar-to-ethanol conversion. The results show that productivity increased when the higher temperature, the higher wort concentration and the lower syrup percentage were used, while wort attenuation increased when lower wort concentration and no syrup were used. The yield coefficient for sugar-to-ethanol conversion was not influenced by any of the factors studied.

A eucalyptus hemicellulose fraction was hydrolysed by treating eucalyptus wood chips with sulfuric acid. The hydrolysate was used as the substrate to grow Paecilomyces variotii IOC-3764 cultured for 72 or 96 hours. The influence of the inhibitors, nutrients and fermentation time was verified by a 28-4 and, subsequently, a 25-1 fractional factorial design. The effects of the inhibitors (acetic acid and furfural), nutrients (rice bran, urea, potassium nitrate, ammonium sulfate, magnesium sulfate and sodium phosphate) and fermentation time were investigated. The highest yield (10.59 g/L of biomass) was obtained when the microorganisms were cultivated for 72 hours in a medium composed of 30 g/L rice bran, 9.4 g/L ammonium sulfate (2 g/L nitrogen) and 2 g/L sodium phosphate.

O presente trabalho visou ao estudo do comportamento da fração lipídica de castanhas do Pará em casca e descascadas, conservadas por 4 meses em sacos de papel Kraft, nas seguintes condições: ao ambiente, a 2°C e -15°C. Nas castanhas em casca, mantidas ao ambiente, a formação de peróxidos somente ocorreu a partir do 2° mês, alcançando o valor de 0,16 meq O2/kg de óleo. Dentro do mesmo período, a 2°C e -15°C, isto ocorreu de forma mais lenta, chegando a 0,10 meq O2/kg, nos dois tratamentos. As castanhas descascadas apresentaram, no início, 9,18 meq O2/Kg de índice de peróxido e l mg KOH/g de óleo de índice de acidez. Após 4 meses ao ambiente, o índice de peróxido chegou a 23,3 meq O2/Kg e a acidez a 2 mg KOH/g, com redução do índice de iodo. Para as castanhas a 2°C, os índices se mantiveram estáveis, enquanto que, para aquelas a -15°C, ocorreu redução no índice de peróxido, no 1° mês para 7,5 meq O2/Kg de amostra, mantido até o final do experimento. Os índices de iodo e de acidez se mantiveram estáveis e o exame espectrofotométrico na faixa ultravioleta confirmaram estes dados. De uma maneira geral, observou-se que o abaixamento da temperatura de armazenamento contribuiu para aumentar o tempo de conservação das castanhas, que será ainda maior se forem armazenadas em casca.

The objective of this study on whole and shelled Brazil nuts was to determine the changes in the lipid fraction when stored for four months in ordinary paper bags, at ambient temperature, 2°C and -15°C. Whole nuts kept at room temperature had an increase in peroxide formation in the second month of storage, reaching 0.16 meq O2/kg oil. The nuts kept at 2°C and -15°C, had a lower increase, reaching 0.10 meq O2/kg in both treatments, within the same period. Shelled nuts had an initial peroxide value of 9.18 meq O2/kg oil and 1 mg KOH/g oil of acid value. After four months at room temperature, the peroxide value reached 23.3 meq O2/kg and acidity, 2 mg KOH/g, with a reduction in iodine number. The nuts at 2°C showed minor changes. The nuts at -15° showed reduction in peroxide value to 7.5 meq O2/kg in the first month which was mantained until the end of the experiment. Iodine numbers and acid values were relatively stable as confirmed by spectrophotometric determinations. The conclusion is that the reduction in storage temperature contributed to the increase in time of conservation of the Brazil nuts, specially if they are not shelled.