Factors limiting the enzymatic hydrolysis of wheat gluten.

The enzymatic hydrolysis of wheat gluten for the production of seasonings using mixtures of endo- and exopeptidases results in yields typically below 40%. Possible limiting parameters, such as an increasing product inhibition, autopeptidolysis of the enzymes, and lack of cleavage sites, were studied using novel peptidases from Flammulina velutipes or the commercial Flavourzyme preparation. Seven intermittent electrodialysis steps (10 g/L gluten and 10 kaU/mL) for the in situ removal of amino acids minimized the product inhibition. During 16 h, hydrolysis progressed nearly linearly. Compared to the batch control, a 3-fold yield of amino acids released was obtained indicating that an integrated product removal alleviates the problem of product inhibition. Autopeptidolysis, as shown using sodium dodecyl sulfate polyacrylamide gel electrophoresis and enzyme activity assays, was suppressed with increasing concentrations of competing gluten substrate. Peptidases of F. velutipes showed product inhibition only, whereas a combined effect of product inhibition and lack of cleavage sites was observed for Flavourzyme.