PREPARATION AND SOME PROPERTIES OF HEAT-TREATED WHEY-PROTEIN HYDROLYSATES

Changes in the tryptic whey protein isolate (WPI) hydrolysate heated a t 90 degrees C for 10 min were examined by gel permeation chromatograp hy, SDS-PAGE and electronmicroscopy. Turbidity of the heat-treated WPI hydrolysates increased in relation to the increase in degree of hydro lysis (DH). The heat-treated WPI hydrolysates with a DH between 3.08 a nd 6.00% were of a milk-white color without any precipitates. The patt erns of the heat-treated WPI hydrolysates on SDS-PAGE and the elution profiles obtained by gel filtration demonstrated preferential aggregat ion of beta-lactoglobulin in the tryptic WPI hydrolysates during heat treatment. On transmission electronmicroscopy the beta-lactoglobulin a ggregates were similar to casein micelles in size.