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Rennet-induced aggregation of homogenized milk: Impact of the presence of fat globules on the structure of casein gels

Rennet-induced aggregation of homogenized milk: Impact of the presence of fat globules on the... The present study investigated the renneting behaviour of casein micelles as influenced by the presence of fat globules. The gelation of skim milk, homogenized milk and homogenized milk with Tween 20 added was observed using diffusing wave spectroscopy and rheology. By adding Tween 20 to homogenized milk, it was possible to displace most of the milk protein from the oil/water interface and create a system with the same colloidal attributes as homogenized milk but with oil droplets with a very different interfacial composition, and relatively inert during rennet-induced aggregation. The primary phase of gelation was faster in homogenized milk compared to skim milk. Casein micelles were altered by the homogenization process which spreads them at the interface, making κ-casein more readily available. The addition of Tween 20 did not further affect the enzymatic activity on the micelles. However, the onset of gelation occurred earlier in homogenized milk with Tween 20 added, as the micelles aggregated at a lower level of proteolysis compared to homogenized milk. This work clearly showed that the gels formed in homogenized milk with and without Tween 20 have different physico-chemical properties, because of the different colloidal state of the filler particles. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Dairy Science & Technology Springer Journals

Rennet-induced aggregation of homogenized milk: Impact of the presence of fat globules on the structure of casein gels

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Publisher
Springer Journals
Copyright
Copyright © 2010 by Springer S+B Media B.V.
Subject
Chemistry; Food Science; Agriculture; Microbiology
ISSN
1958-5586
eISSN
1958-5594
DOI
10.1051/dst/2010023
Publisher site
See Article on Publisher Site

Abstract

The present study investigated the renneting behaviour of casein micelles as influenced by the presence of fat globules. The gelation of skim milk, homogenized milk and homogenized milk with Tween 20 added was observed using diffusing wave spectroscopy and rheology. By adding Tween 20 to homogenized milk, it was possible to displace most of the milk protein from the oil/water interface and create a system with the same colloidal attributes as homogenized milk but with oil droplets with a very different interfacial composition, and relatively inert during rennet-induced aggregation. The primary phase of gelation was faster in homogenized milk compared to skim milk. Casein micelles were altered by the homogenization process which spreads them at the interface, making κ-casein more readily available. The addition of Tween 20 did not further affect the enzymatic activity on the micelles. However, the onset of gelation occurred earlier in homogenized milk with Tween 20 added, as the micelles aggregated at a lower level of proteolysis compared to homogenized milk. This work clearly showed that the gels formed in homogenized milk with and without Tween 20 have different physico-chemical properties, because of the different colloidal state of the filler particles.

Journal

Dairy Science & TechnologySpringer Journals

Published: Jul 4, 2011

References