Free D‐ and L‐Amino Acid Evolution During Sourdough Fermentation and Baking

Abstract

ABSTRACT The evolution of free D‐ and L‐amino acids in sourdoughs started with various lactic acid bacteria (LAB) and yeasts was studied. Lactobacillus brevis subsp. lindneri CB1 and Lactobacillus plantrum DC400 had high proteolytic activity. During sourdough fermentation, Saccharomyces cerevisiae 141 and Saccharomyces exiguus M14 sequentially utilized free amino acids produced by bacterial activity. Due to increased cell yeast autolysis, more S. exiguus M14 inocula caused more free amino acids which were partially utilized by LAB without causing hydrolysis of wheat flour protein. D‐alanine, D‐glutamic acid and traces of other D‐isomers were observed in sourdoughs fermented with L. brevis subsp. lindneri CB1 and S. cerevisiae 141. Free total D‐ and L‐amino acid content decreased by more than 44% after baking the sourdoughs. No abiotic generation of new D‐amino acid isomers was detected in the baked sourdoughs.