Colloidal properties of protein complexes formed in β-casein concentrate solutions as influenced by heating and cooling in the presence of different solutes

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dc.contributor.authorCrowley, Shane V.
dc.contributor.authorKelly, Alan L.
dc.contributor.authorO'Mahony, James A.
dc.contributor.authorLucey, John A.
dc.contributor.funderFulbright Associationen
dc.contributor.funderFood Institutional Research Measureen
dc.contributor.funderDepartment of Agriculture, Food and the Marineen
dc.date.accessioned2018-12-20T16:00:32Z
dc.date.available2018-12-20T16:00:32Z
dc.date.issued2018-10-28
dc.date.updated2018-12-20T15:48:34Z
dc.description.abstractMonomeric bovine β-casein self-associates into micelles under appropriate conditions of protein concentration, serum composition and temperature. The present study investigated self-association characteristics of a β-casein concentrate (BCC) prepared from milk at pilot-scale using membrane filtration. The BCC had a casein:whey protein ratio of 77:23, with ∼95% of casein consisting of β-casein, and the remainder being mostly κ-CN. BCC was reconstituted to 1.2% protein (a typical level in infant formula) in various liquid media at pH 6.8 and incubated at different temperatures from 4 to 63 °C for 30 min. Self-association of β-casein on heating was thermo-reversible in deionised water, lactose (4, 6 or 8%) or calcium (9 mM) solutions. In most serum phases, BCC became highly opaque after incubation at 63 °C, but clarified rapidly during cooling to 25 °C. However, in simulated milk ultrafiltrate (SMUF), which has a high ionic strength and is supersaturated in calcium phosphate (CaP), BCC remained opaque during cooling to 25 °C, and retained residual turbidity after 15 h of holding at 4 °C; if SMUF was prepared without phosphate then turbidity development in BCC solutions was markedly reduced. The complexes responsible for this turbidity development were successfully dissociated with 50 mM trisodium citrate. Analysis of pH during heating and holding at 60 °C indicated that SMUF acidified continuously under the period of study, while acidification in BCC/SMUF mixtures terminated after a short period, indicating that the type of CaP formed on heating is altered in the presence of BCC. This study demonstrates that BCC ingredients exhibit pronounced temperature-dependant changes in colloidal properties that are strongly affected by the presence of minerals commonly found in nutritional product formulations.en
dc.description.sponsorshipFulbright Association (Fulbright Commission Scholarship)en
dc.description.statusPeer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationCrowley, S. V., Kelly, A. L., O’Mahony, J. A. and Lucey, J. A. (2019) 'Colloidal properties of protein complexes formed in β-casein concentrate solutions as influenced by heating and cooling in the presence of different solutes', Colloids and Surfaces B: Biointerfaces, 174, pp. 343-351. doi: 10.1016/j.colsurfb.2018.10.067en
dc.identifier.doi10.1016/j.colsurfb.2018.10.067
dc.identifier.endpage351en
dc.identifier.issn0927-7765
dc.identifier.journaltitleColloids and Surfaces B-Biointerfacesen
dc.identifier.startpage343en
dc.identifier.urihttps://hdl.handle.net/10468/7250
dc.identifier.volume174en
dc.language.isoenen
dc.publisherElsevieren
dc.relation.urihttp://www.sciencedirect.com/science/article/pii/S0927776518307665
dc.rights© 2018 Elsevier B. V. All rights reserved. This manuscript version is made available under the CC-BY-NC-ND 4.0 licenseen
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/en
dc.subjectCaseinen
dc.subjectMicelleen
dc.subjectCalcium phosphateen
dc.subjectSelf-associationen
dc.subjectTurbidityen
dc.subjectPrecipitationen
dc.subjectSedimentationen
dc.subjectProtein-mineral interactionsen
dc.titleColloidal properties of protein complexes formed in β-casein concentrate solutions as influenced by heating and cooling in the presence of different solutesen
dc.typeArticle (peer-reviewed)en
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