• Food Science and Biotechnology
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• v.17 no.1
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• pp.172-175
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• 2008

Two new fermentation products were separated from cheonggukjang by high performance liquid chromatography (HPLC) and tentatively identified as succinyl daidzin and succinyl genistin by HPLC-mass spectrometry (MS). Both succinyl daidzin and succinyl genistin were detected in all 4 commercially available and one laboratory prepared cheonggukjang and 1 commercially available natto. However, these compounds were not detected in commercially available 4 home-made and 4 factory-produced doenjang. Peak areas of succinyl genistin were about 1.95-2.45 times higher than those of succinyl daidzin in cheonggukjang, which may be due to the higher concentration of genistin derivatives than daidzin derivatives in soybeans. This is the first report on the succinyl derivatives as isoflavone metabolites from cheonggukjang and these 2 isoflavone derivatives could be characteristic indicators for cheonggukjang.

• Korean Journal of Food Science and Technology
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• v.41 no.2
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• pp.141-145
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• 2009

Cheongyukjang, a Banga food, is a heavy soy-soup prepared by boiling cheonggukjang, sea foods, and meats. Soybeans roasted at 140$^{\circ}C$ for 21.0 min and 220$^{\circ}C$ for 6.0 min, respectively, were used for cheonggukjang preparation. Distributions of isoflavones in raw soybeans, roasted soybeans, cheonggukjang, and cheongyukjang were analyzed by high performance liquid chromatography. The total isoflavones in roasted soybeans, cheonggukjang and cheongyukjang were about 79-80, 56-65, and 47-50% of those in raw soybeans, respectively. Roasting caused significant increases in acetyl derivatives and ${\beta}$-glucoside isoflavones, and significant decreases in malonyl derivatives (p < 0.05). The major isoflavones in cheonggukjang and cheongyukjang were ${\beta}$-glucosides. Succinyl-${\beta}$-daidzin and succinyl-${\beta}$-genistin, which are recognized as new metabolites of isoflavones, were not detected in raw and roasted soybeans. Peak areas of succinyl-${\beta}$-genistin were higher than thse of succinyl-${\beta}$-daidzin, in both cheongyukjang and cheonggukjang.