Microstructural changes in casein supramolecules during acidification of skim milk

Journal of Dairy Science
D J McMahonK M Larsen

Abstract

Pasteurized skim milk was acidified using different levels of glucono-delta-lactone at 10, 20, 30, and 40 degrees C to give slow, medium, and fast rates of acidification. Milk coagulation was monitored by measuring turbidity and curd firmness, and microstructural changes during acidification were observed on glutaraldehyde-fixed, agar-solidified milk samples using transmission electron microscopy. Rate of acidification had little influence on changes observed during acidification, except at 10 degrees C. At 40 degrees C, the casein supramolecules were spherical throughout acidification, whereas at lower temperatures they became progressively more ragged in appearance. All of the milks gelled at the same pH (pH 4.8), as measured by curd firmness, whereas increases in turbidity, assumed to be brought about by an increase in number of light-scattering particles, were observed to start at about pH 5.2 to 5.4. As the milk was acidified, aggregates of loosely entangled proteins were observed, presumably originating from proteins that had dissociated from the casein supramolecules. These aggregates were often as large as the casein supramolecules, particularly as the pH of the milk approached the isoelectric point of the caseins. Larg...Continue Reading

References

Jan 1, 1959·Advances in Protein Chemistry·W KAUZMANN
Oct 7, 2004·Colloids and Surfaces. B, Biointerfaces·Marcela Alexander, Douglas G Dalgleish
Apr 19, 2008·Journal of Dairy Science·D J McMahon, B S Oommen

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Citations

Sep 15, 2012·Journal of Perinatology : Official Journal of the California Perinatal Association·T EricksonG M Chan
Jul 23, 2014·Asian-Australasian Journal of Animal Sciences·T X YangQ Y Li
Jun 28, 2015·Journal of Human Lactation : Official Journal of International Lactation Consultant Association·Diana Escuder-ViecoCarmen Rosa Pallás-Alonso
Feb 6, 2018·Journal of Dairy Science·M YangW B Zhang
Jul 27, 2010·Journal of Dairy Science·D S Horne
Feb 6, 2019·Food Research International·Thais Caldas Paiva MoreiraRosiane Lopes da Cunha
Mar 6, 2021·Journal of Dairy Science·Linran Wang, Carmen I Moraru
Jun 6, 2013·Journal of Agricultural and Food Chemistry·Kang PanSeung Joon Baek
Apr 21, 2020·Journal of Chemical Education·Mark T JeffersonGlenn A Hurst

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