Ca2+-induced gelation of whey protein isolate: Effects of pre-heating

The combined effect of pre-heating temperature (70 degrees-90 degrees C) and Ca2+ level (10-120 mM) on Ca2+-induced gelation of whey protein isolates at room temperature was investigated. High pre-heating temperature produced clearer gels than low temperature, and high [CaCl2] produced opaque gels. When protein suspensions were pre-heated to 70 degrees C (for 30 min), only the gel's clarity was affected by [CaCl2]. Fracture and water holding properties were affected by [CaCl2] only at pre-heat treatment greater than or equal to 80 degrees C. High gel strength (determined as fracture force and work required to break the gel) was obtained when protein suspensions were pre-heated at high temperature and dialysed against high [CaCl2]. High pre-heating temperature resulted in high water holding capacity and gel extensibility (after compression), whereas [CaCl2] only affected gel extensibility but not water holding capacity. Copyright (C) 1996 Published by Elsevier Science Ltd on behalf of the Canadian Institute of Food Science and Technology