TEXTURAL PROPERTIES OF COLD-SET GELS INDUCED FROM HEAT-DENATURED WHEY-PROTEIN ISOLATES

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured a t 80 degrees C for 30 min. Size-exclusion HPLC showed that native WP f ormed soluble aggregates after heat-treatment. Additions of CaCl2 (10- 40 mM), NaCl (50-400 mM) or grucono-delta-lactone (GDL, 0.4-2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelati on of the denatured solution at 45 degrees C. Textural parameters, har dness, adhesiveness, and cohesiveness of the gels so formed changed ma rkedly with concentration of added salts or pH by added GDL. Maximum g el hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concen tration continuously increased gel hardness. Generally, GDL-induced ge ls were harder than salt-induced gels, and much harder than the protea se-induced gel.