pH-dependent sedimentation and protein interactions in ultra-high-temperature-treated sheep skim milk

Simple item page
dc.citation.issue3
dc.citation.volume106
dc.contributor.authorPan Z
dc.contributor.authorYe A
dc.contributor.authorDave A
dc.contributor.authorFraser K
dc.contributor.authorSingh H
dc.coverage.spatialUnited States
dc.date.accessioned2024-05-07T23:16:05Z
dc.date.available2024-05-07T23:16:05Z
dc.date.issued2023-03
dc.description.abstractSheep milk is considered unstable to UHT processing, but the instability mechanism has not been investigated. This study assessed the effect of UHT treatment (140°C/5 s) and milk pH values from 6.6 to 7.0 on the physical properties of sheep skim milk (SSM), including heat coagulation time, particle size, sedimentation, ionic calcium level, and changes in protein composition. Significant amounts of sediment were found in UHT-treated SSM at the natural pH (∼6.6) and pH 7.0, whereas lower amounts of sediment were observed at pH values of 6.7 to 6.9. The proteins in the sediment were mainly κ-casein (CN)-depleted casein micelles with low levels of whey proteins regardless of the pH. Both the pH and the ionic calcium level of the SSM at all pH values decreased after UHT treatment. The dissociation levels of κ-, β-, and αS2-CN increased with increasing pH of the SSM before and after heating. The protein content, ionic calcium level, and dissociation level of κ-CN were higher in the SSM than values reported previously in cow skim milk. These differences may contribute to the high amounts of sediment in the UHT-treated SSM at natural pH (∼6.6). Significantly higher levels of κ-, β-, and αS2-CN were detected in the serum phase after heating the SSM at pH 7.0, suggesting that less κ-CN was attached to the casein micelles and that more internal structures of the casein micelles may have been exposed during heating. This could, in turn, have destabilized the casein micelles, resulting in the formation of protein aggregates and high amounts of sediment after UHT treatment of the SSM at pH 7.0.
dc.description.confidentialfalse
dc.edition.editionMarch 2023
dc.format.pagination1626-1637
dc.identifier.author-urlhttps://www.ncbi.nlm.nih.gov/pubmed/36543644
dc.identifier.citationPan Z, Ye A, Dave A, Fraser K, Singh H. (2023). pH-dependent sedimentation and protein interactions in ultra-high-temperature-treated sheep skim milk.. J Dairy Sci. 106. 3. (pp. 1626-1637).
dc.identifier.doi10.3168/jds.2022-22637
dc.identifier.eissn1525-3198
dc.identifier.elements-typejournal-article
dc.identifier.issn0022-0302
dc.identifier.piiS0022-0302(22)00742-1
dc.identifier.urihttps://mro.massey.ac.nz/handle/10179/69505
dc.languageeng
dc.publisherElsevier Inc and Fass Inc on behalf of the American Dairy Science Association
dc.publisher.urihttps://www.journalofdairyscience.org/article/S0022-0302(22)00742-1/fulltext
dc.relation.isPartOfJ Dairy Sci
dc.rights(c) The author/sen
dc.rights.licenseCC BY 4.0en
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/en
dc.subjectcasein micelle
dc.subjectionic calcium
dc.subjectparticle size
dc.subjectprotein composition
dc.subjectwhey protein
dc.subjectCattle
dc.subjectFemale
dc.subjectAnimals
dc.subjectSheep
dc.subjectMilk
dc.subjectMilk Proteins
dc.subjectCaseins
dc.subjectHot Temperature
dc.subjectMicelles
dc.subjectCalcium
dc.subjectTemperature
dc.subjectWhey Proteins
dc.subjectHydrogen-Ion Concentration
dc.titlepH-dependent sedimentation and protein interactions in ultra-high-temperature-treated sheep skim milk
dc.typeJournal article
pubs.elements-id458641
pubs.organisational-groupOther
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