Evaluación de las proteínas hidrolizadas del lactosuero como fuente de nitrógeno en la fermentación láctica de la lactosa

It was evaluated a strategy for the use and valorization of whey proteins obtained from curd process from acid milk. It is proposed the stages of precipitation (thermal and acid denaturalization) and enzymatic hydrolysis, to be used as a nitrogen source in the fermentation of lactose for the production of lactic acid. pH of 10 and 60 °C were the best hydrolysis conditions. Hydrolysates with molecular sizes lower than 6.5 kDa were obtained at those conditions. Finally, the hydrolysates were used in the fermentation of lactose with Lactobacillus casei ATCC 393, in concentrations of 1 %w and 7 %w. Fermentations using a medium with 1 %w of yeast extract were also carried out as a reference. The microbial growth (2.1*109 y 1.9*109 CFU/cm3), the product/substrate yield (0.78 and 0.76 g/g) and productivity (0.41 y 0.30g/dm3.h) were similar for the yeast extract and hydrolysate mediums at 1 %w, while the hydrolysate at 7 %w showed certain inhibition in the medium which was reflected in the response variables mentioned above (9.5*108 UFC/cm3, 0.53 g/g and 0.18 g/dm3.h).