Influence of thiol metabolism of lactobacilli on egg white proteins in wheat sourdoughs

Jussi Loponen, Katja König, Jianping Wu, Michael G Gänzle

Research output: Contribution to journalArticleScientificpeer-review


In wheat sourdoughs, the degradation of gluten proteins is favored by acidification and reducing conditions. This study aimed to determine the proteolytic degradation of egg white proteins in wheat sourdoughs acidified with lactobacilli differing in their thiol metabolism. Ovotransferrin was the only major egg white protein that degraded during sourdough fermentations. An extensive degradation of ovotransferrin required a heterofermentative lactobacilli starter, Lactobacillus sanfranciscensis, with glutathione reductase activity. Ovotransferrin was more resistant to breakdown when sourdoughs were acidified with homofermentative lactobacilli or a mutant strain of L. sanfranciscensis lacking the glutathione reductase. Its susceptibility to proteolysis in L. sanfranciscensis sourdoughs is thus attributable to thiol accumulation by L. sanfranciscensis, which apparently altered the structure of ovotransferrin through a reduction of disulfide bonds. Proteolytic degradation of ovotransferrin was attributable to wheat aspartic proteinases. In addition to the susceptibility to proteolysis, other functional properties of egg proteins may be influenced by thiol-exchange reactions.
Original languageEnglish
JournalJournal of Agricultural and Food Chemistry
Issue number9
Pages (from-to)3357-3362
Number of pages6
Publication statusPublished - 2008
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 514 Sociology
  • 414 Agricultural biotechnology
  • 411 Agriculture and forestry

Cite this