In conclusion, the present study revealed the class of volatiles and the constituents of each class that actually acted as aroma-active compounds for the aroma of soy sauces, as well as
the relationship of aroma profiles with the fermentation process. Forty-one aroma compounds were found in all the three types of soy sauces (HLFSS, LSFSS and KSS), of which 23 aroma-active
compounds were present at average concentrations higher than their corresponding odour thresholds. In particular, the aroma compounds resulted from amino acid degradation, such as 3-methyl-1-butanol, 3-methylbutanal, 2-methylbutanal, 3-(methylthio)-propanal and benzeneacetaldehyde, or from fermentation, such as ethanol and acids, as well as some esters like ethyl acetate and ethyl 2-methylpropanoate, and dimethyl trisulphide all significantly
contributed to the overall aroma of soy sauce. Furthermore, the difference in the overall aroma of those different types of soy sauce was more due to the quantity of these compounds rather
than their composition. Further work should be directed toward the interactions between aroma compounds and food matrix, as well as the effect of the physical characteristics of soy sauce on
aroma release, in order to elucidate the processing and ingredient effects on the flavour qualities of different soy sauces and provide valuable information for the soy sauce industry.