Abstract: Volatile flavor components in three different red fermented soybean curds were extracted by a simultaneous steam distillation extraction method and analyzed by gas chromatography-mass spectrometry. The content of amino nitrogen in pehtze and soup were determined by formaldehyde titration. Results showed that more flavor components in pehtze were detected than in soup, which included 18, 24 and 27 kinds of esters, 13, 11 and 15 kinds of aldehydes, 5, 7 and 6 kinds of alcohols, 3, 4 and 4 kinds of ketones and one furan were detected in pehtze from three kinds of sufu, respectively. Among these flavor components, esters were the major components, and long chain fatty acid esters were accounted for more than 90%. Methyl pyrazine, linoleic acid ethyl ester and other amphiphilic esters were more abundant in sufu juice. Amino nitrogen in sufu juice was more than in sufu pehtze, and amino nitrogen contents in three kinds of sufu revealed a significant difference.

Key words: pethze and soup of red fermented soybean curds, volatile flavor components, amino acid nitrogen, simultaneous steam distillation, gas chromatography-mass spectrometry (GC-MS)