Impact of Different Raw Materials on Changes of Volatile Compounds during Moromi Fermentation

The composition and ratio of volatile compounds in soy sauce have a major impact on its organoleptic properties.Considering the important influence of long-term (3 months) moromi fermentation on the aroma formation of the soy sauces from different materials (soybean, Rice, Black Bean, Wheat, Wheat flour, and mungbean), the volatile compounds of 24 samples in total, taken from three different stages of moromi fermentation, were analyzed by solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS). The results showed a total of 77 volatile compounds, including acids (4), alcohols (14), phenols (6), aldehydes (12), esters (26), ketones (5), furan(one)s (5), and pyrazine (5), and the majority of the compounds were common. Among all samples, The highest amount of volatile compounds (5528.58 ± 1308 µg/L) was detected in the moromi made from the combination of soybean, black bean, and wheat flour on the first month of fermentation, and the sample that had the lowest amount of volatile compounds (63.25 ± 1.70 µg/L) was detected in the moromi sample from the combination of soybean and wheat flour on day 0. During the three months of moromi fermentation, the relative contents of acids, alcohols, phenols, aldehydes, esters, ketones, furan(one)s, and pyrazines changed gradually. Finally, the total presence of volatile compounds identified in the 24 samples increased from 0 days to one month and from month to month perfectly.