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 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 via solid phase microextraction coupled with gas chromatography–mass spectrometry (SPME–GC–MS). The results show a total of 77 volatile compounds, including acids (4), alcohols (14), phenols (6), aldehydes (12), esters (26), ketones (5), furan(one)s (5) and pyrazines (5), and the majority of the compounds were common. Among all samples, the highest number 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 number of volatile compounds (63.25 ± 1.70 µg/L) was detected in the moromi sample made 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 day 0 to 1 month and from month to month perfectly.

Lactic acid fermentation of vegetables could be a good alternative solution for extending their shelf-life and adding value. However, lactic acid bacteria (LAB) are diverse, with variable metabolic activities during fermentation, which leads to the production of different metabolites that can be important for consumer acceptance. The aim of this work was to study the impact of LAB metabolism on volatile organic compounds (VOCs) during cucumber fermentation. Among 161 LAB isolated from Cambodian fermented vegetables, five LAB species including Lactiplantibacillus plantarum, Lactiplantibacillus pentosus, Lactococcus lactis, Limosilactobacillus fermentum, and Pediococcus pentosaceus were selected to ferment mashed cucumbers by single inoculation for 24 h. VOCs were analyzed by using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. The results indicated that each LAB strain had an impact on the profile of these VOCs. For instance, aromatic compounds, likely coming from amino acid metabolism, were highly produced by both species of Lactiplantibacillus. However, these strains showed different behaviors regarding compounds derived from plant fatty acid metabolism. The concentration of aldehydes which was of 39.14 μg-4-nonanol-equivalent/kg in the plant, was increased to 66.03 μg/kg for L. plantarum, while L. pentosus produced the highest total semi-quantitative amount of saturated primary alcohol at 94.65 μg-4-nonanol-equivalent/kg. With 22 compounds, L. lactis generated more than twice as much different esters; while, with 21.80 and 18.24 μg-4-nonanol-equivalent/kg, respectively, L. fermentum and P. pentosaceus produced the highest level of acetic acid. As a heterofermentative LAB, L. fermentum might produce acetic acid via glucose metabolism, whereas P. pentosaceus, as homofermentative LAB, might synthesize acetic acid from other pathways. Our results showed that LAB present metabolic diversity with differences among species on mashed cucumbers as green vegetables.

This research evaluated a soy sauce produced from germinated soybeans with varying salt concentrations. Soybeans were germinated over 48 and 72 h, then homogenized with roasted wheat and 0.1% of Aspergillus oryzae, and kept three days for koji fermentation. They were then homogenized with 18% and 22% salt, and then fermented for 210 days at ambient temperature for moromi fermentation. Moreover, 5 × 10⁷ CFU/mL of Zygosaccharomyces rouxii was used. The quality of soy sauce made from germinated soybeans over 48 h resulted in the best conditions regarding the physicochemical characteristics and sensory evaluation analysis.