Abstract: Significant effects of freeze-dried Lactobacillus sanfranscensis (L.s.) sourdough starters on the aroma of common and whole fermented wheat doughs and breads were investigated using high performance liquid chromatography (HPLC) and solid phase micro-extraction/gas chromatography-mass spectrometry (SPME/GC-MS) analysis. Organic acids and total free amino acids contents in sourdough bread were higher than those in corresponding non-sourdough formulation. Volatile compounds concentrations were enhanced through lactic acid sourdough fermentation, with the increase of 11.31% and 14.98% from non-sourdough bread (NSHB) to L.s. sourdough bread (SSHB) and from non-sourdough whole wheat bread (NSWB) to L.s. sourdough whole wheat bread (SSWB), respectively. More free amino acids were detected in whole wheat fermented doughs, which endowed corresponding breads with more flavor. Total volatiles contents were raised by 22.54% and 26.58% from NSHB to NSWB and from SSAB to SSWB, respectively. Compounds positively correlated with bread aroma were 3-methyl-1-butanol, acetic acid, furfural, phenylethanol, 3-hydoxy-2-butanone, 3-methyl-butanoic acid, 3-methylbutanal and E-2-nonenal. The impacts of L.s. sourdough starters varied on different flours. SSAB contained more lactones whereas SSWB provided more 3-methyl-1-butanol and 3-hydoxy-2-butanone.

Key words: freeze-dried sourdough starter, Lactobacillus sanfranscensis, fermented dough, aroma, organic acid, free amino acid