The aim of the research was to study the effect of heating (72ºC/15 s, 92ºC/60 s) water solutions of milk protein concentrate (pH 7.1), obtained by ultrafiltration, on the enzymatic phase during chymosin activity at 32ºC at pH 7.1, 6.6 and 6.0. It was found that heating at 72ºC limited the number of peptides released at pH 7.1 by 33.3 %, and heating at 92ºC - by 25.0 %. It was affected by differences in the access of the enzyme to glycosylated κleased at pH 7.1 by 33.3 %, and heating at 92ΊC - by 25.0 %. It was affected by differences in the access of the enzym number of released peptides by 13 %. The level of the temperature, however, influenced significant differences in RCT which was longer by 17.0 % and 34.0 % in the substrates heated to 72ΊC and 92ΊC. After reducing pH to 6.0, it was found that heating at 72ΊC and 92ΊC limited the number of released peptides by 11.2 %. However, significant (p=0.05) elongation of RCT (by 8 %) was observed only after heating at 92ΊC.