Soybean paste holds a significant position as a condiment in many Asian Culinary heritages, including Chinese, Japanese, and Korean cuisines, and it has also gained popularity worldwide (Deng et al., 2022; Kim et al., 2023; Yu et al., 2023; Zhang et al., 2021b). The production of soybean pastes involves in soaking and cooking soybeans, and then fermenting soybeans with ingredients like wheat flour (Yu et al., 2023; Zhang et al., 2021b). The whole fermentation procedure is crucial for flavor characteristics of the soybean paste. It features a savory, umami flavor with slightly sweet aroma. Soybean paste is usually used as seasoning in soups, stews, sauces, and marinade for meats and vegetables. Notably, soybean paste is a valuable source of protein, fiber, and essential minerals as well, making it a nutritious addition in the diet (Tian et al., 2022a; Yue et al., 2021). Soybean pastes have been an indispensable ingredient in traditional and modern cooking.

The microbiota of soybean pastes hold an essential position in shaping thier safety and quality properties (Ren et al., 2021; Yao et al., 2022; Yue et al., 2021). Their preservative characteristics are important for prolonging shelf life, maintaining product quality, and ensuring food safety through preventing spoilage. Flavor and sensory has been reported (Xie et al., 2019; Zhang et al., 2021b), there is still a scarcity of studies regarding comprehensive relationship between microbiota and preservative properties of soybean pastes, particularly when categorizing soybean pastes as HP or ES ones (Ren et al., 2024).

In our preliminary investigations, some soybean pastes remained well-preserved for extended periods, but others deteriorated rapidly, even the similar fermentation materials, techniques, and storage conditions were employed (Ren et al., 2024). The disparity in these outcomes could be attributed to the distinguish microbiota and metabolites within these soybean pastes (Ren et al., 2024). Therefore, comparing metatranscriptomics and volatile profiles of HP and ES soybean pastes from China were focused, metatranscriptome sequencing, qRT-PCR verification, HS-GC-IMS research, and FTIR were employed. A thorough investigation were conducted to explore more on the microbial gene functions, metabolic properties, volatile metabolites, and the microorganisms significantly influencing the quality of soybean pastes. Furthermore, the microorganisms contributing to preservative properties of soybean pastes were determined. This research intends to give valuable perspectives on the active microbial composition, functional genes and pathways, and volatile metabolites with the preservation and spoilage of soybean paste. Moreover, the results could give references for future quality control measures, biopreservative development strategies, and enhancing the health benefits of soybean pastes.