Volatile components of the Chinese fermented soya bean curd as affected by the addition of ethanol in ageing solution

Two Chinese fermented soya bean curd products were prepared using Actinomucor taiwanensis and ageing in brine solution with or without ethanol. The volatile compounds in these Sufu products were identified and quantified by GC and CC-MS. A total of 61 volatile compounds were identified including 22 esters, 18 alcohols, 7 ketones, 3 aldehydes, 2 pyrazines, 2 phenols and 7 other compounds from the 75-day aged Sufu products. Of the 61 identified compounds, 55 compounds were found to exist simultaneously in the two Sufu products prepared. Quantitatively and qualitatively, less volatile components were found in Sufu ageing without ethanol than those ageing with ethanol. In general, as the ageing period extended, contents of nearly all the volatile fractions in Sufu, particularly ester and alcohol, increased. In addition, a significantly higher amount of ester was noted in Sufu aged with ethanol than in that aged without ethanol. (C) 1999 Society of Chemical Industry.