which is considered as the traditional Chinese-type soy sauce.Moreover, HLFSS has been taking an increasing proportion of the Chinese market because of its better consumer flavour acceptability
Thus, it is important to get insight into the key characteristic flavours in both kinds of soy sauce, so as to improve the flavour quality of soy sauce.Several studies on the volatile compositions of Chinese soy sauces have been reported, and results from these studies suggested that aroma profiles of HLFSS and LSFSS are quite different found that the dominant volatile compound groups of HLFSS were alcohols, esters, aldehydes and ketones. Sun et al.(2012) studied the volatiles in twelve samples of HLFSS using HS-SPME, and found that alcohols and acids were the main volatiles.On the other hand, the predominant volatile groups isolated in LSFSS were acids and alcohols, accounting for about 47% and 14% of the total area, respectively However,the chemical analysis and quantification of the flavour volatiles was not satisfactory in these studies.Gas chromatography-olfactometry (GC-O) has been applied to identify the aroma-active compounds in many foods 4-Hydroxy-5-ethyl-2-methyl-3(2H)-furanone (4-HEMF), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDF) and 3-(methylthio)propanal were detected as the most aroma-active compounds with a high flavour dilution (FD) factor in Japanese and Korean soy sauces