Effects of milk proteins and posttranslational modifications on noncoagulating milk from Swedish Red dairy cattle

K. Nilsson, L. Buhelt Johansen, D. J. de Koning, S. I. Duchemin, M. Stenholdt Hansen, H. Stålhammar, H. Lindmark-Månsson, M. Paulsson, W. F. Fikse, M. Glantz

Research output: Contribution to journalArticlepeer-review

Abstract

Milk that does not coagulate after rennet addition, also called noncoagulating (NC) milk, is unwanted in cheese production due to prolonged processing time. Amounts of whey and casein proteins, genetic variants, as well as posttranslational modifications (PTM) of proteins are all contributing factors in rennet-induced coagulation of milk. In this study, we conducted a wide-ranging investigation of milk proteins in milk samples from 616 Swedish Red dairy cattle using liquid chromatography-high resolution mass spectrometry. Relative concentration of proteins, genetic variants, and PTM were compared between NC milk and coagulating milk. The PTM investigated were phosphorylation of caseins and glycosylation of κ-casein. Several genetic variants and PTM were found, including rare phosphorylation variants of the αS-caseins. Genetic variants were found to effect the expressed amount of different proteins. Further, the effect of protein amounts and PTM on a binary NC milk trait was modeled using a generalized linear model. The model showed that NC milk significantly correlated with higher relative concentrations of α-lactalbumin and β-casein and lower relative concentrations of β-lactoglobulin and κ-casein. Regarding PTM of caseins, an effect on NC milk from a lower relative concentration of αS1-casein with 8 phosphate groups were found, even though an effect from total relative concentration of αS1-casein was not found. This study has provided insights into protein variants and PTM important for NC milk to improve this undesirable property.

Original languageEnglish
Pages (from-to)6858-6868
Number of pages11
JournalJournal of Dairy Science
Volume103
Issue number8
Early online date2020
DOIs
Publication statusPublished - 2020 Aug 1

Subject classification (UKÄ)

  • Food Engineering

Free keywords

  • genetic variants
  • milk coagulation
  • posttranslational modifications
  • protein profile

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