Partial substitution of sheep and goat milks of various fat contents by the respective sweet buttermilks: Effect of cream heat treatment

摘要

The potential of sweet sheep and goat buttermilks (BMs) to partially replace sheep and goat milks was investigated. The experimental factors were: the heat treatment of cream - 66 degrees C/30 min or pasteurized 85 degrees C/20 s - the fat content of milks, i.e., standardized- or full-, reduced-, low-fat, and the level of substitution, i.e., 5, 10, 15% BM. Milks, BMs and their mixtures were analyzed for composition, rennet clotting behavior - i.e., clotting time (RCT), curd firming rate (K20), curd firmness (A30) - and syneresis of the rennet-gels. The pasteurization-induced denaturation of whey proteins decreased significantly (P < 0.05) the syneresis of BM rennet-gels but it did not affect significantly the composition, the extended RCT and low A30 of BMs. The composition and behavior of milk/BM mixtures were not affected by the cream treatment. The increase of %BM level decreased significantly (P < 0.05) the A30 and syneresis although not in a dose-dependent manner. In conclusion, the BMs from sheep or goat dairy cream - safely handled due to cream pasteurization - could be used in the manufacture of reduced- or low-fat cheeses without pre-fractionation or concentration. These findings could be the first step for the development of novel circular dairy foods.