Correlation between the key aroma compounds and gDNA copies of Bacillus during fermentation and maturation of natto

The aim of the study was to analyze the correlation between the key aroma compounds and gDNA copies of Bacillus natto during fermentation and maturation of natto. Solvent-assisted flavor evaporation (SAFE) techniques were employed to extract volatile organic compounds. Aroma compounds were separated and analyzed through gas chromatography-olfactometry-mass spectrometry (GC-MS/O) using DB-5 and DB-Wax capillary columns. Seventy-nine compounds were extracted and identified, including 17 ketones, 17 alcohols, 9 aldehydes, 6 acids, 7 esters, 8 pyrazines, 8 aromatics, and 7 others. Twenty-two compounds were identified as the key aroma compounds of natto by aroma extraction dilution analysis (AEDA). Pyrazines played a key role in the flavor of natto both during the fermentation and maturation. 2,5-Dimethylpyrazine, 2,3,5-trimethylpyrazine, 2,3,5,6-tetramethylpyrazine, and 2,3,5-methyl-6-ethylpyrazine contributed substantially to natto flavor. They presented significant positive and negative correlations with the gDNA copies of Bacillus natto during fermentation and maturation, respectively.