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Milk gel Structure: II. Relation between firmness and ultrastructure of heat-induced skim-milk gels containing 40–60% total solids*

Published online by Cambridge University Press:  01 June 2009

Miloslav Kalab
Affiliation:
Food Research Institute, Research Branch, Agriculture Canada, Ottawa, Ontario, Canada
V. R. Harwalkar
Affiliation:
Food Research Institute, Research Branch, Agriculture Canada, Ottawa, Ontario, Canada

Summary

Milk gels varying widely in firmness were examined by both scanning and transmission electron microscopy, and a close correlation was found between their ultrastructure and firmness. In gels containing 40 and 50% total solids (14 and 17% protein respectively), casein micelles appeared as individual entities linked by some bridging material. At 60% total solids (20% protein), the micelles were fused and offered a considerably higher resistance to a penetrometer probe. Likewise some additives to gels, such as ammonium persulphate and CaCl2, caused the micelles to fuse. These chemicals appreciably increased firmness of such gels. In gels containing hexametaphosphate, a known inhibitor of gelation, most of the casein micelles were disintegrated; these gels were soft.

Type
Research Article
Copyright
Copyright © Proprietors of Journal of Dairy Research 1974

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