PH shifting alters solubility characteristics and thermal stability of soy protein isolate and its globulin fractions in different pH, salt concentration, and temperature conditions

Jiang Jiang, Youling L. Xiong, Jie Chen

Research output: Contribution to journalArticlepeer-review

216 Scopus citations

Abstract

Soy protein isolate (SPI), β-conglycinin (7S), and glycinin (11S) were subjected to pH-shifting treatments, that is, unfolding at pH 1.5 or 12.0 followed by refolding at pH 7.0, to induce molten globule structures. Treated samples were analyzed for protein solubility, thermal stability, and aggregation in 0, 0.1, and 0.6 M NaCl solutions at pH 2.0-8.0. The pH12 shifting resulted in drastic increases (up to 2.5-fold) in SPI solubility in the pH 6.0-7.0 range, especially at 0 M NaCl. The PH1.5 shifting had a generally lesser effect on solubility. 11S exhibited a solubility pattern similar to that of SPI, but the solubility of 7S was unaffected by pH shifting except at 0.6 M NaCl. The pH shifting, notably at pH 12.0, produced soluble, disulfide-linked polymers from 11S and reduced (P<0.05) its enthalpy but not its temperature of denaturation. Soy proteins structurally altered by pH shifting had a reduced sensitivity to thermal aggregation.

Original languageEnglish
Pages (from-to)8035-8042
Number of pages8
JournalJournal of Agricultural and Food Chemistry
Volume58
Issue number13
DOIs
StatePublished - Jul 14 2010

Keywords

  • Glycinin
  • PH shifting
  • Solubility
  • Soy protein isolate
  • β-conglycinin

ASJC Scopus subject areas

  • General Chemistry
  • General Agricultural and Biological Sciences

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