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

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

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    Sammanfattning

    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.
    Originalspråkengelska
    TidskriftJournal of Agricultural and Food Chemistry
    Volym56
    Utgåva9
    Sidor (från-till)3357-3362
    Antal sidor6
    ISSN0021-8561
    DOI
    StatusPublicerad - 2008
    MoE-publikationstypA1 Tidskriftsartikel-refererad

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