Cheese Whey Permeate as a Precursor of Lactose-Free, Galactose-Rich Bioproducts: An Approach for Optimization and Application.

Under specific conditions of oxygen availability and lactose hydrolysis, Brettanomyces claussenii OYL-201 can convert glucose in dairy coproducts into ethanol, leaving the galactose almost untouched. This approach could be applied specifically to whey permeate (WP) to develop foods with low-glycemic loads and other potential health benefits. The aims of this research are to optimize the fermentation of WP by B. claussenii, 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 outputs 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 applied to 18-L fermentations, and the 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 WP and to develop novel, potentially functional bioproducts from this stream. [ABSTRACT FROM AUTHOR]