Analysis on the Difference of the Volatile Flavor Compounds of Northeast Farmhouse Soybean Paste with Different Salt Concentrations

This paper studied the influence of salt concentration on the volatile flavor compounds during the fermentation of Northeast farmhouse soybean paste. HS-SPME-GC-MS combined with electronic nose technology were used to analyze the changes of volatile flavor substances and flavor characteristics of soybean paste with different salt concentrations (8%, 10%, 12%) during the fermentation process (0, 30, 60 d). The differences between samples were statistically analyzed through PCA and cluster analysis. The results of HS-SPME-GC-MS showed that there were 2 flavors with OAV≥0.1 at 0 days of fermentation. At the time of 30 days, 8%, 10% and 12% salt concentration samples of flavor substances with OAV≥0.1 increased to 12, 8 and 8, respectively. At the time of 60 days, 8%, 10% and 12% salt concentration samples of the flavor substances with OAV≥0.1 increased to 19, 11 and 10, respectively. And the OAV values of most flavor substances decreased with the increase of salt concentration. This indicated that salt concentration affected the type and content of volatile flavor compounds. The results of the electronic nose showed that the increase in salt concentration would promote the production of organic sulfur compounds and inhibit the production of alkanes, alcohols and hydride compounds. With the extension of the fermentation time, the methyl, alcohol, aldehyde and ketone compounds in the soybean paste would gradually increase, while the ammonia, short-chain alkanes and organic sulfides would gradually decrease. The results of PCA and cluster analysis showed that the difference between samples with different salt concentrations fermented for 0 days was very small, and with the extension of the fermentation time, the difference between the soybean paste with different salt concentrations would become more and more significant. To sum up, the salt concentration has a significant effect on the volatile flavor components in the Northeast farmhouse soybean paste.