Effect of cysteine on lowering protein aggregation and subsequent hardening of whey protein isolate (WPI) protein bars in WPI/buffer model systems

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Whey protein isolate (WPI) bar hardening without and with cysteine (Cys) or N-ethylmaleimide (NEM) was investigated in model systems (WPI/buffer = 6:4, by weight, pH 6.8, aw ~ 0.97) in an accelerated shelf-life test (ASLT) at 45 °C over a period of up to 35 days. The formation of insoluble aggregates as determined by solubility and the structural rearrangement of WPI protein aggregates as observed by SEM were responsible for the WPI bars' hardening. As corroborated by electrophoresis analysis, both β-lactoglobulin (β-lg) and α-lactalbumin (α-la) were involved in the formation of aggregates via the thiol-disulfide interchange reaction and/or noncovalent interactions. The former force dominated the bar hardening at an earlier stage, whereas the latter force played a role for the long-term hardening. In comparison with the control bar without Cys, the thiol-disulfide interchange reaction was significantly reduced by Cys (WPI/Cys = 0.05), increased by Cys (WPI/Cys = 0.25), and inhibited by NEM (WPI/ NEM = 2). Therefore, bar hardening was significantly delayed by Cys (WPI/Cys = 0.05) and NEM but accelerated by Cys (WPI/Cys = 0.25).

Original languageEnglish (US)
Pages (from-to)7970-7979
Number of pages10
JournalJournal of agricultural and food chemistry
Volume58
Issue number13
DOIs
StatePublished - Jul 14 2010

Keywords

  • Cysteine
  • Hardness
  • Protein bar
  • Shelf life
  • Whey protein isolate

Fingerprint Dive into the research topics of 'Effect of cysteine on lowering protein aggregation and subsequent hardening of whey protein isolate (WPI) protein bars in WPI/buffer model systems'. Together they form a unique fingerprint.

Cite this