Effect of sulphydryl reagents on the heat stability of whey protein isolate

Food Chem. 2014 Nov 15:163:129-35. doi: 10.1016/j.foodchem.2014.04.094. Epub 2014 May 4.

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.

Keywords: Aggregation; Dihydrolipoic acid; Heat stability; Sulphydryl reagents; Whey protein isolate; α-Lactalbumin; β-Lactoglobulin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromatography, High Pressure Liquid
  • Hot Temperature
  • Lactalbumin / chemistry
  • Milk Proteins / chemistry*
  • Protein Stability
  • Sulfhydryl Reagents / pharmacology*
  • Whey Proteins

Substances

  • Milk Proteins
  • Sulfhydryl Reagents
  • Whey Proteins
  • Lactalbumin