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dc.contributor.authorBoiani, Mattia
dc.contributor.authorMcLoughlin, Padraig
dc.contributor.authorAuty, Mark
dc.contributor.authorFitzgerald, Richard J.
dc.contributor.authorKelly, Philip M.
dc.date.accessioned2019-08-12T15:30:23Z
dc.date.available2019-08-12T15:30:23Z
dc.date.issued2017-07-06
dc.identifier.citationBoiani, M., McLoughlin, P., Auty, M. A. E., FitzGerald, R. J., & Kelly, P. M. (2017). Effects of depleting ionic strength on 31P nuclear magnetic resonance spectra of micellar casein during membrane separation and diafiltration of skim milk. Journal of Dairy Science, 100(9), 6949–6961. https://doi.org/10.3168/jds.2016-12351en_US
dc.identifier.urihttp://hdl.handle.net/11019/1720
dc.descriptionpeer-revieweden_US
dc.description.abstractMembrane separation processes used in the concentration and isolation of micellar casein-based milk proteins from skim milk rely on extensive permeation of its soluble serum constituents, especially lactose and minerals. Whereas extensive literature exists on how these processes influence the gross composition of milk proteins, we have little understanding of the effects of such ionic depletion on the core structural unit of micellar casein [i.e., the casein phosphate nanocluster (CPN)]. The 31P nuclear magnetic resonance (NMR) is an analytical technique that is capable of identifying soluble and organic forms of phosphate in milk. Thus, our objective was to investigate changes to the 31P NMR spectra of skim milk during microfiltration (MF) and diafiltration (DF) by tracking movements in different species of phosphate. In particular, we examined the peak at 1.11 ppm corresponding to inorganic phosphate in the serum, as well as the low-intensity broad signal between 1.5 and 3.0 ppm attributed to casein-associated phosphate in the retentate. The MF concentration and DF using water caused a shift in the relevant 31P NMR peak that could be minimized if orthophosphate was added to the DF water. However, this did not resolve the simultaneous change in retentate pH and increased solubilization of micellar casein protein. The addition of calcium in combination with orthophosphate prevented micellar casein solubilization and simultaneously contributed to preservation of the CPN structure, except for overcorrection of retentate pH in the acidic direction. A more complex DF solution, involving a combination of phosphate, calcium, and citrate, succeeded in both CPN and micellar casein structure preservation while maintaining retentate pH in the region of the original milk pH. The combination of 31P NMR as an analytical technique and experimental probe during MF/DF processes provided useful insights into changes occurring to CPN while retaining the micellar state of casein.en_US
dc.language.isoenen_US
dc.publisherElsevieren_US
dc.relation.ispartofseriesJournal of Dairy Science;Vol. 100 (9)
dc.rightsAttribution-NonCommercial-ShareAlike 3.0 United States*
dc.rights.urihttp://creativecommons.org/licenses/by-nc-sa/3.0/us/*
dc.subjectphosphoproteinen_US
dc.subjectnuclear magnetic resonanceen_US
dc.subjectcaseinen_US
dc.subjectphosphate nanoclusteren_US
dc.subjectmicellar structureen_US
dc.titleEffects of depleting ionic strength on 31P nuclear magnetic resonance spectra of micellar casein during membrane separation and diafiltration of skim milken_US
dc.typeArticleen_US
dc.embargo.terms2018-07-06en_US
dc.identifier.doihttps:/dx.doi.org/10.3168/jds.2016-12351
dc.contributor.sponsorIrish Department of Agriculture Food Institution Research Measureen_US
dc.contributor.sponsorTeagasc Walsh Fellowship Programmeen_US
refterms.dateFOA2018-07-06T00:00:00Z


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