Formation and physical properties of acid milk gels: a review

Acidified milk products like yoghurt are an important food product but there are relatively few reports on the mechanisms involved in gel formation and the effects of processing variables such as heat treatment and gelation temperature on the important physical properties (such as whey separation) of acid-induced gels. Most previous reviews have described the microbiology of the starter cultures and technologies used in yoghurt manufacture. Recent developments are reviewed including the use of techniques such as dynamic low amplitude oscillatory rheology to monitor the gel formation process; confocal scanning laser microscopy to examine gel microstructure; and various models for the aggregation of particle gels are discussed in terms of possible mechanisms involved in the formation of acid-induced milk gels. (C) 1998 Canadian Institute of Food Science and Technology. Published by Elsevier Science Ltd. All rights reserved.