Influence of trypsin action in yoghurt milk on the release of caseinophosphopeptide-rich fractions and physical properties of the fermented products

The influence of trypsin action in yoghurt milk on the release of caseinophosphopeptide (CPP)-rich fractions was studied and the physical properties of the fermented products determined. Trypsin treatment of skim milk led to increased fermentation times and a substantially lowered production of l -lactic acid as well as to delayed and reduced proteolysis caused by peptidases of the starter cultures. The functional properties of the milk proteins were decreased and the sensory properties less pronounced in yoghurt from trypsin-treated milk, but were described as less bitter than samples from nontreated milk. The CPP sequences β-CN(1–25)-4P and α _s1 -CN(43–79)-7P were released during enzyme treatment.