title: Effect of sulphydryl reagents on the heat stability of whey protein isolate.
abstract: The effects of sulphydryl (-SH) reagents on protein aggregation reactions in heated whey protein isolate (WPI) and pure α-lactalbumin (α-La) were investigated. In contrast to its previously reported effect with pure β-Lg, dihydrolipoic acid (DHLA) markedly reduced the heat stability of WPI, especially the α-La component, which aggregated much more readily in the presence of DHLA than in WPI alone. Whilst pure α-La is quite stable to heat, it is much less stable in the presence of DHLA. An effect similar to DHLA was observed with reduced glutathione (GSH). N-ethylmaleimide (NEM), and to a lesser extent, dithio(bis)-p-nitrobenzoate (DTNB), improved the heat stability of WPI; these reagents had little effect on α-La.
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, Brisbane, QLD 4072, Australia. Electronic address: heni.wijayanti@uqconnect.edu.au.
authors.forename: Heni B
authors.initials: HB
authors.lastname: Wijayanti
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, Brisbane, QLD 4072, Australia. Electronic address: n.bansal@uq.edu.au.
authors.forename: Nidhi
authors.initials: N
authors.lastname: Bansal
authors.affiliation: Dairy Innovation Australia Limited, Werribee, VIC 3030, Australia. Electronic address: rsharma@dairyinnovation.com.au.
authors.forename: Ranjan
authors.initials: R
authors.lastname: Sharma
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, Brisbane, QLD 4072, Australia. Electronic address: h.deeth@uq.edu.au.
authors.forename: Hilton C
authors.initials: HC
authors.lastname: Deeth
mesh_terms: D002851:Chromatography, High Pressure Liquid; D006358:Hot Temperature; D007768:Lactalbumin / Q000737:chemistry; D008894:Milk Proteins / Q000737:chemistry*; D055550:Protein Stability; D013439:Sulfhydryl Reagents / Q000494:pharmacology*; D000067816:Whey Proteins
chemical_list: D008894:Milk Proteins; D013439:Sulfhydryl Reagents; D000067816:Whey Proteins; D007768:Lactalbumin
keywords: Aggregation; Dihydrolipoic acid; Heat stability; Sulphydryl reagents; Whey protein isolate; α-Lactalbumin; β-Lactoglobulin