Physicochemical changes in a model protein bar during storage

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dc.contributor.authorLoveday, SM
dc.contributor.authorHindmarsh, Jason
dc.contributor.authorCreamer, Lawrence K
dc.contributor.authorSingh, Harjinder
dc.date.accessioned2009-12-09T02:54:03Z
dc.date.accessioned2016-03-06T22:25:53Z
dc.date.availableNO_RESTRICTIONen_US
dc.date.available2009-12-09T02:54:03Z
dc.date.available2016-03-06T22:25:53Z
dc.date.issued2009
dc.description.abstractHigh-protein snack bars (protein bars) contain high-quality protein, sugars and other low molecular weight polyhydroxy compounds (PHCs), high-energy confectionary fats, and a minimum of water (water activity ≤ 0.65). The consequence of the intimate mixing of these components in protein bars is that they can react together, creating sensory characteristics that are unacceptable to consumers. This study examined the changes occurring in a model protein bar during storage for 50 days at 20 °C. Over this time, fracture stress increased from 20.1 +/- 1.8 Pa to 201 +/- 75 Pa at a rate that decreased slightly over time. 1H nuclear magnetic resonance (NMR) showed that the molecular mobility of PHCs decreased dramatically over the first 5 days as the batter set into a solid bar. Over the first 17 hours after manufacturing, protein particles became more clustered, and soluble protein appeared to precipitate, as shown by confocal microscopy. Reactive lysine fell 38% in the first 10 days of storage and was approximately constant thereafter. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed little change in protein molecular weights. Following the initial ‘setting’ phase of 5-10 days, fracture stress continued to increase and the molecular mobility of PHCs decreased. Changes in PHC molecular mobility were consistent with glucose crystallisation. Chemical changes were minimal during this phase, which suggests that chemical reactions play little part in the hardening of protein bars and that changes in molecular mobility and changes in microstructure driven by moisture migration may be more important.en_US
dc.identifier.citationLoveday, S. M., Hindmarsh, J. P., Creamer, L. K., & Singh, H. (2009). Physicochemical changes in a model protein bar during storage. Food Research International, 42(7), 798-806.en_US
dc.identifier.elements-id30311
dc.identifier.harvestedMassey_Dark
dc.identifier.harvestedMassey_Dark
dc.identifier.issn0963-9969
dc.language.isoenen_US
dc.publisherElsevieren_US
dc.relation.isformatofhttp://dx.doi.org/10.1016/j.foodres.2009.03.002en_US
dc.subjectHigh-protein snack baren_US
dc.subjectMilk protein concentratesen_US
dc.subjectShelf lifeen_US
dc.subjectIntermediate-moisture foodsen_US
dc.subjectMaillard reactionsen_US
dc.subjectNuclear magnetic resonanceen_US
dc.subject.otherFields of Research::290000 Engineering and Technology::290100 Industrial Biotechnology and Food Sciences::290102 Food engineeringen_US
dc.titlePhysicochemical changes in a model protein bar during storageen_US
dc.typeJournal Articleen_US
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