Cheese whey permeate as a precursor of lactose-free, galactose-rich bioproducts: an approach for optimization and application

Abstract

Abstract Under specific conditions, the fermentation of whey permeate (WP) by Brettanomyces claussenii can create bioproducts with high galactose concentrations and potential functionalities. The aims of this research are to optimize the fermentation of WP by B. claussenii using response surface methodology to maximize the production of ethanol and galactose, and to characterize various products obtained with this approach. For this purpose, five fermentation factors were studied to determine their impacts on ethanol and galactose: temperature (20 - 40°C), substrate concentration (5 - 15%TS), lactase enzyme/substrate ratio (0 - 40 IU/ g lactose), inoculation level (6 - 8 log cfu/mL), and time (6 - 30 days). Linear models, containing quadratic and interaction effects, were built for the optimization of both responses. Optimal levels were predicted for the maximum obtainment of ethanol and galactose simultaneously, which utilized the following parameters: 15%TS, 37 IU / g lactose, 28°C, 7.5 log cfu/mL, and 30 days, which together were predicted to produce 4.0%v/v ethanol and 51 g/L galactose in the final product. These parameters were then applied to 18-L fermentations, and the resulting fermentates were processed via distillation and freeze-drying. As a result, four product streams were obtained: a fermented product with 3.4%v/v ethanol and 56 g/L galactose; a 45%v/v ethanol distillate; a galactose-rich drink base (63 g/L); and a galactose-rich powder (55%w/w). These results demonstrate that it is possible to maximize the production of ethanol and galactose from the fermentation of WP and to design manufacturing processes based on these optimization models, to develop novel, potentially functional bioproducts from this stream.