Dimethyl sulfide as a source of the seaweed-like aroma in cooked soybeans and correlation with its precursor, S-methylmethionine (vitamin U).

Among the soybean germplasm in Japan, two varieties, Nishiyamahitashi 98-5 (NH) and Shinanokurakake (SICK), have an intense seaweed-like flavor after cooking. Gas liquid chromatography with mass spectrometry (GC-MS) indicated that a significant amount (11.5 +/- 3.46 mu g g(-1) for NH and 6.66 +/- 0.91 mu g g(-1) for SICK) of dimethyl sulfide (DMS) was formed after heat treatment. DMS is formed from S-methylmethionine (SMM, vitamin U). SMM was detected in all soybean varieties examined here, but its concentration in NH and SKK seeds was >100-fold higher than in the other varieties and ranged from 75 to 290 mu g g(-1). The SMM content and the ability to form DMS upon heat treatment correlated among them. The plumes and radicles contained SMM exclusively. This is the first report of soybean varieties containing SMM at a level equivalent to or higher than that in vegetables known to contain high levels of SMM, for example, turnip, cabbage, and celery.