NOVEL TARTARIC ACID ISOFLAVONE DERIVATIVES THAT PLAY KEY ROLES IN DIFFERENTIATING JAPANESE SOY SAUCES

Nonvolatile components in various brands of Japanese fermented soy sau ce were analyzed by gradient reversed phase HPLC. The resulting HPLC p rofiles were correctly assigned into their original brands by chemomet ric pattern recognition techniques, such as cluster analysis, linear d iscriminant analysis (LDA), linear discriminant analysis using genetic algorithm (GALDA), and SIMCA. Three key components found to significa ntly contribute to the differentiation were isolated by preparative HP LC and purified. Their FAB-MS, H-1- and C-13-NMR, and IR spectra sugge sted that their molecular weights were 386, 402, and 418, respectively , and that each contained isoflavone moieties. By applying HMBC spectr al analysis, these isoflavone derivatives were identified as conjugate d ethers of 2,3-dihydroxysuccinic acid (tartaric acid) with daidzein, genistein, and 8-hydroxygenistein. These new isoflavone derivatives ar e produced during the mash fermentation in the soy sauce manufacturing process.