Isomers and homologues of L-glutamic acid 5-n-butyl ester as promoters of sediment formation in raw soy sauce
1999
Tomita, M. (Tohoku Women's Junior Coll., Hirosaki, Aomori (Japan)) | Motomura, Y. | Kitahara, H. | Yoshiki, Y. | Okubo, K.
Soy sauce was found to contain promoters of sediment formation aI 60 degrees C (1, 2), one of which has previously been identified as L-glutamic acid 5-n-butyl ester (3). Isomers and homologues of L-glutamic acid 5-n-butyl ester (n-propyl, isopropyl, n-butyl, isobutyl, and see-butyl esters of L-glutamic acid) were synthesized using 80% (w/w) sulfuric acid as a catalyst and identified by 1H-NMR and the ninhydrin test. The yields of L-glutamic acid 5-n-propyl, isopropyl, n-butyl, isobutyl, and see-butyl esters from 10 g L-glutamic acid were 25, 101, 72, 130, and 134 mu-mol, respectively. For maximum sediment formation in 1 ml soy sauce, 1.2, 8.6, 22.0, 22.0, and 26.5 mu-mol/ml of n-butyl, n-Propyl, isobutyl, sec-butyl) and isopropyl esters were respectively required. Sediment-forming activity was not observed with L-glutamic acid and L-glutamic acid 5-methyl, ethyl and tert-butyl esters
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