Original article Effect of koji fermentation on generation of volatile compounds in soy sauce production

Summary The generation of aroma compounds and the changes in sensory characteristics through the soy sauce kojifermentation were investigated to evaluate the crucial impact of the koji fermentation on soy sauce aroma.The sensory analysis showed a marked increase in ‘musty’ and ‘soy sauce-like’ odours, whereas the beanyattribute decreased significantly during koji fermentation. Aldehydes and alcohols were the major volatileclasses present in the koji samples. Gas chromatography–olfactometry was used to identify the aroma-active compounds in harvested koji, and the results showed that 1-octen-3-ol, 3-octanol, (E)-2-octenal,di-epi-a-cedrene, benzeneacetaldehyde and 3-(methylthio)-propanal exhibited the greatest aroma intensitiesin harvest koji. Moreover, relative contents of (E)-2-octenal, benzeneacetaldehyde, 3-(methylthio)-prop-anal and 2-phenylpropenal were found to be positively related to ‘musty’ and ‘soy sauce-like’ odours.Results from principal component analysis showed that the growth and sporulation of Aspergillus oryzaehad the important impacts on the volatile evolution.Keywords