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The production of volatile fatty acids (VFAs), intermediates in the anaerobic degradation process of organic matter from waste water, was evaluated in this work. A batch reactor was used to investigate the effect of temperature, and alkalinity in the production of VFAs, from the fermentation of industrial cassava waste water. Peak production of total volatile fatty acids (TVFAs) was observed in the first two days of acidogenesis. A central composite design was performed, and the highest yield (3400 mg L(-1) of TVFA) was obtained with 30°C and 3 g L(-1) of sodium bicarbonate. The peak of VFA was in 45 h (pH 5.9) with a predominance of acetic (63%) and butyric acid (22%), followed by propionic acid (12%). Decreases in amounts of cyanide (12.9%) and chemical oxygen demand (21.6%) were observed, in addition to the production of biogas (0.53 cm(3) h(-1)). The process was validated experimentally and 3400 g L(-1) of TVFA were obtained with a low relative standard deviation.

Lamb meat showed better results for color quality traits. Hoggets had more appealing results, given the less acidic taste of their meat. Maize grain provided superior meat quality in terms of instrumental traits. Sorghum grain provided softer meat with lower strange-aroma perception.

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The operation parameters used in solid-state fermentation (SSF) support the growth of filamentous fungi, which grow on solid substrates producing important metabolites such as proteases. The aim of this work is to obtain fungal proteases by SSF using the residues of a local brewery industry (barley bagasse and trub), that have high contents of proteins and soluble matter such as carbohydrates, vitamins, and mineral salts. The methodology includes the preparation of residues, the screening of microorganisms, evaluation of operational conditions for SSF using factorial design, purification and partial characterization of protease.The results indicate that A. niger sp. UPT-03 isolated from the residue shows higher yields in terms of enzyme production (0.36 U gdm -1 h -1 ). The purification with DEAE-cellulose resulted in protease recovery with 30-fold of purification with a specific activity of 550 U mg protein -1 . Higher proteolytic activity of purified enzyme was obtained at pH 5.5 and 55 ºC.

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