EFFECTS OF N-ETHYLMALEIMIDE AND CACL2 ON COLD GELATION OF WHEY-PROTEIN ISOLATE

The combined effect of CaCl2 (10-120 mM) and N-ethylmaleimide [NEM] (0 -5 mM) on colour and textural properties of Ca2+-induced cold-set whey protein isolate (WPI) gels was investigated. Raising [CaCl2] resulted in increasing gel opacity and hardness while reducing cohesiveness. I n gels prepared by dialyzing against a 10 mM CaCl2 solution, increasin g [NEM] to 2 mM in resulted in a slight increase in opacity and hardne ss. At > 2 mM NEM, both parameters were reduced due to the lower degre e of sulfhydryl-disulfide interchange reaction. Gels prepared by dialy zing against greater than or equal to 30 mM CaCl2 showed an increase i n opacity and a decrease in hardness as [NEM] was raised from 0 to 5 m M.These changes were likely to be related to the degree of WPI polymer ization during the pre-heating stage, i.e. prior to calcium addition a nd gelation. (C) 1998 Canadian Institute of Food Science and Technolog y. Published by Elsevier Science Ltd. All rights reserved.