Influence of whey protein hydrolysate addition to whey permeate batch fermentations for producing lactic acid

Addition of whey protein hydrolysate (WPH) to whey permeate fermentations, by Lactobacillus helveticus, to produce lactic acid was investigated. Three to four percent (w/w) supplementation with WPH solution (10% w/w protein) was required to obtain high lactose conversion and lactic acid yield in a fermentation time of 30-40 h. At this percentage supplementation, the nitrogen content of the media was 0.06-0.09% w/w. The bacteria used around 0.02% w/w nitrogen during fermentation, thus there was an abundance of unused nitrogen remaining at the end of fermentation. At 3-4% supplementation, it was calculated that around 36-47% of whey protein concentrate produced from whey would be required to supplement the whey permeate fermentation in the form of the hydrolysate.