Heating milk for 1 or 4 min d oes n ot infl uence the p hysico ch em ica l p ro pe rti e s of y og urt s c on ta inin g di fferen t ca sein:w hey prote in ratios in the condit ions tested. How ever,
the yogurt physicochem ical properties were infl uenced by
t h e c a s e i n : w h e y p r o t e i n r a t i o . T h e i m p a c t o f t h e c a s e i n :
whey prote in rati o on the d igest ibil ity o f yo gurt in vitr o
and the availabil ity of nitrogenou s compo unds was evaluated for the first time in this study. Yogurts containing differe n t c a s e i n : w h e y p r o t e i n r a t i o s ( 4 . 5 : 1 , 2 . 8 : 1 a n d 1 . 5 : 1 )
e x h i b i t e d d i ff e r e n t b e h a v i o r s . T h e r a t i o 1 . 5 : 1 w a s m o r e
h a r d l y d i g e s t e d , p o s s i b l y d u e t o t h e p r e s e n c e o f t h e β -
lactog lobulin/κ -casein complex and denatu red whey protein
aggrega tes that formed after heat treatmen t. Both the aggregates and complexes are beli eved to have a large r size in the
rati o 1.5:1, whi ch would affect the acti vity o f pepsi n on
casei n. It can be conclu ded that the diges tion kinet ics of
nitrogenous compo unds are infl uenced by the visco sity and
microst ructu re of the food matrix and therefore could impact
their satiati ng an d nutri tional proper ties