Heating milk for 1 or 4 min does not influence the physico chemical properties of yogurts containing different casein:whey protein ratios in the conditions tested. How ever,
the yogurt physico chemical properties were influenced by
the casein:whey proteinratio. The impact of the casein:
whey protein ratio on the digest ibility of yogurt in vitro
and the availability of nitrogenous compounds was evaluated for the first time in this study. Yogurts containing different casein:whey protein ratios ( 4.5 : 1 , 2.8 : 1 and 1.5 : 1 )
exhibited different behaviors. The ratio 1.5 : 1 was more
hardly digested , possibly due to the presence of the β -lactog lobulin/κ -casein complex and denatu red whey protein
aggrega tes that formed after heat treatment. Both the aggregates and complexes are believed to have a larger size in the ratio 1.5:1, which would affect the activity of pepsin on
casein. It can be concluded that the digestion kinetics of
nitrogenous compo unds are infl uenced by the visco sity and
microst ructure of the food matrix and therefore could impact
their satiating and nutritional properties