P. Hongsprabhas et S. Barbut, CA2-INDUCED COLD GELATION OF WHEY-PROTEIN ISOLATE - EFFECT OF 2-STAGEGELATION(), Food research international, 30(7), 1997, pp. 523-527
The combined effect of a secondary heat treatment and CaCl2 level (5-1
20 mmol dm(-3)) on Ca2+-induced cold gelation of whey protein isolate
(WPI) was investigated. Pre-heating was required to induce cold gelati
on. Prolonging pre-heating time (30 to 60 min at 80 degrees C) increas
ed gel clarity but had no effect on Young's modulus, shear stress and
strain at failure and water holding capacity (WHC). Re-heating the col
d-set gels at 80 degrees C for 30 min significantly (p less than or eq
ual to 0.05) increased gel opacity, Young's modulus, stress and strain
and decreased WHC. Scanning and transmission electron micrographs rev
ealed that re-heating resulted in an increase in pore size and lowered
the degree of protein strand connectivity. Overall, the second heatin
g step changed the gel's properties due to increasing aggregation of t
he calcium-induced cold-set gels. (C) 1998 Canadian Institute of Food
Science and Technology. Published by Elsevier Science Ltd. All rights
reserved.