Plasmin Activity in UHT Milk: Relationship between Proteolysis, Age Gelation, and Bitterness
Author
Summary, in English
Plasmin, the major indigenous protease in milk, is linked to quality defects in dairy products. The specificity of plasmin on caseins has previously been studied using purified caseins and in the indigenous peptide profile of milk. We investigated the specificity and proteolytic pathway of plasmin in directly heated UHT milk (>150 degrees C for <0.2 s) during 14 weeks of storage at 20 degrees C in relation to age gelation and bitter peptides. Sixty-six peptides from alpha(s)- and beta-caseins could be attributed to plasmin activity during the storage period, of which 23 were potentially bitter. Plasmin exhibited the highest affinity for the hydrophilic regions in the caseins that most probably were exposed to the serum phase and the least affinity for hydrophobic or phosphorylated regions. The proteolytic pattern observed suggests that plasmin destabilizes the casein micelle by hydrolyzing casein casein and casein calcium phosphate interaction sites, which may subsequently cause age gelation in UHT milk
Department/s
- Department of Food Technology, Engineering and Nutrition
Publishing year
2014
Language
English
Pages
6852-6860
Publication/Series
Journal of Agricultural and Food Chemistry
Volume
62
Issue
28
Document type
Journal article
Publisher
The American Chemical Society (ACS)
Topic
- Agricultural Science, Forestry and Fisheries
Keywords
- age gelation
- bitterness
- casein
- plasmin
- proteolysis
- UHT milk
Status
Published
ISBN/ISSN/Other
- ISSN: 0021-8561