[The microflora of sourdough. XVIII. The protein degrading capabilities of lactic acid bacteria in sourdough].

Acidification of the dough by the use of sourdough or acidifiers is necessary not only for good baking quality of rye flour but it is also very important for development of the typical sensory characteristics of rye bread. We confirmed that the lactic acid bacteria of sour dough are proteolytic. Proteolytic effects are observed in the increase of the amino acid content during fermentation. A marked increase was found in the content of leucine, alanine, valine, isoleucine, glutamic acid, glutamine, arginine, lysine, methionine, phenylalanine, tyrosine and serine. Lactobacillus plantarum showed a higher proteolytic activity than L. brevis ssp. lindneri or L. fructivorans.