Researching Umami from Soybean Paste

Doenjang is a fermented soybean paste, similar to miso, that provides protein, especially lysine, and umami flavor to traditional Korean foods. Studies also show it may have antimutagenic and anticancer activities. The commonly used Korean flavoring and condiment is fermented by Bacillus subtilis and lactic acid bacteria, as well as various molds. To investigate its flavor properties, Korean scientists examined doenjang water extract for component compounds that contribute to its taste.

Researchers at the Functional Food Technology Research Group, Korea Food Research Institute, Baekhyun-dong, Republic of Korea, found that a 1% solution produced the highest umami taste ratings in a taste profile test. The researchers replaced   9.4% of monosodium glutamate with 3% solution of doenjang water extract to test its role in the taste in a soup base, and found it masked the bitter taste of hydrolyzed animal protein when mixed in solution.

The doenjang water extract was fractionated, based on molecular weights, and the researchers found that the fraction with the highest peptide contents produced the strongest umami taste and that the acidic peptide fraction of that fraction elicited the strongest umami taste. The major bound-type amino acids in extract and the high-flavor peptide fractions were glutamic acid and aspartic acid. The scientists concluded that doenjang extracts umami taste characteristics were a result of the low-molecular-weight acidic peptides naturally produced during the fermentation of soybeans.