Extensive Analysis of Monosaccharide Diversity in Fermented Soybean Paste Using LC-MS/MS

Doenjang, a widely consumed fermented soybean paste in Korea, contains abundant carbohydrates. However, the composition of various monosaccharides present in fermented foods has not been thoroughly investigated. Thus, we used a rapid and accurate liquid chromatography-tandem mass spectrometry (LCMS/MS) method to simultaneously analyze monosaccharides in the soybean paste. The method exhibited excellent linearity, sensitivity, and accuracy as confirmed by spiking experiments. In the soybean paste, we identified 11 monosaccharides, with galactose, glucose, and arabinose being predominant, alongside galacturonic acid, N-acetylglucosamine, and glucuronic acid. Analyzing 8 modified and 9 traditional soybean paste samples from different regions, we found a significant correlation between manufacturing method and monosaccharide profiles, with traditional soybean paste exhibiting greater monosaccharide diversity. This method is adaptable for rapid and efficient analysis of monosaccharides in various fermented foods.