Jeonbuk National University Researchers Explore the Impact of Different Seasonings on the Flavor Perception of Doenjang Soup

Researchers examine how different seasonings shape kokumi perception in doenjang soup and influence consumer acceptance

JEONBUK-DO, South Korea, Dec. 15, 2025 /PRNewswire/ -- Doenjang is a traditional Korean fermented soybean paste made from meju—naturally fermented soybean blocks—mixed with salt and aged through long-term fermentation. Unlike Japanese miso, Korean doenjang does not use koji; its flavor develops entirely from the natural fermentation of meju. It is prepared via fermentation and aging with microbial cultures, which produce umami compounds that improve its palatability. While umami is a well-understood concept, kokumi—a term used to describe attributes like mouthfulness, richness, and flavor continuity—is surrounded by divergent views. Some perceive kokumi as a sensory amplification of flavor, whereas others define it by the presence of specific compounds such as glutathione and γ-glutamyl peptides. These kokumi-active compounds exist in various fermented foods, including doenjang.

In a recent study, researchers from the Department of Food Science and Human Nutrition and the K-Food Research Center at Jeonbuk National University, Republic of Korea, led by Professor Mina K. Kim, the Director of the K-Food Research Center at Jeonbuk National University, examined how monosodium glutamate (MSG) and nucleotide-based seasonings influence kokumi perception in doenjang soup and affect consumer acceptance. Their findings were made available online on 5 May 2025 and have been published recently in Volume 131 of the journal Food Quality and Preference on 1 October 2025.

The researchers applied a consumer-centered approach using 113 untrained panelists, who completed liking assessments and Check-All-That-Apply questions after testing doenjang soup samples containing different seasonings a follow - none, 1% MSG, 1% disodium 5′-inosinate, 1% disodium 5′-guanylate, and 1% disodium 5′-ribonucleotide.

They found that even within the same category of seasonings, MSG, an amino acid–based seasoning, and nucleotide-based seasonings influence doenjang soup in different ways. While MSG boosts both umami and kokumi, nucleotide-based seasonings mainly increase umami alone, showing that these two types of flavor enhancers work differently even in the same food system. "Our results show that umami is a major sensory driver of kokumi perception—shaping how consumers experience depth, richness, and lingering flavor in doenjang soup. These insights offer a clear, evidence-based direction for formulating more impactful seasoning systems and advancing premium doenjang-based product development," remarks Prof. Kim.

Beyond traditional Korean doenjang, this research offers broader insights into how kokumi can be enhanced in many kokumi-rich foods found around the world, such as aged cheeses, long-simmered broths, miso, soy sauce, parmesan, and even certain seafood-based dishes. Since kokumi contributes to body, richness, and lingering taste, these findings can also be applied to improving the flavor quality of soup-based products and savory beverages. In addition, by strengthening kokumi while maintaining umami balance, this study provides a useful strategy for developing products with reduced-sodium without sacrificing their taste.

"Our research can help develop fermented foods that retain the complex flavors of traditional doenjang while meeting modern consumer expectations. By showing how umami and kokumi interact in consumer evaluations, our findings support flavor-standardization efforts and the creation of healthier, more satisfying fermented products. As kokumi research progresses, we expect the industry to adopt more precise, evidence-based approaches to enhancing flavor depth and persistence," concludes Prof. Kim.

Reference
Title of original paper: Umami and kokumi: The role of MSG and nucleotide-based seasonings in Doenjang soup
Journal: Food Quality and Preference
DOI: 10.1016/j.foodqual.2025.105579

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