The Flavor and Health Secrets of Propionic Acid in Fermented Foods
2025-11-18
Propionic acid is ubiquitous in various fermented foods, but its content varies significantly depending on factors such as food type, raw materials, fermentation process, and conditions.
01. Propionic acid content in vinegar
Vinegar is typically made from grains such as wheat, millet, and sorghum through microbial fermentation. Its flavor is mainly formed by aroma substances such as esters, aldehydes, ketones, and heterocyclic compounds, while acid compounds such as propionic acid play an important role in the harmony of vinegar flavor.
Studies have found that the range of propionic acid content in brewed vinegar (0-0.28 g/L) is wider than that in prepared vinegar (0-0.14 g/L), which may be related to the complex microbial community metabolism during the brewing process. Additionally, changes in conditions such as fermentation time, pH, and oxygen can significantly affect the content of propionic acid in vinegar. Research shows that the content of propionic acid increases over time in the early stage of fermentation and then decreases in the later stage and during aging.
02. Propionic acid content in soy sauce
Soy sauce is a traditional seasoning made from soybeans, wheat, and other ingredients through the fermentation of Aspergillus oryze, yeast, and other microorganisms. The types and contents of organic acids in soy sauce directly affect its flavor and quality. Studies show that the average content of propionic acid in soy sauce is approximately 0.89 μg/L. An appropriate amount of propionic acid can enhance the flavor complexity of soy sauce, but excessive content can lead to excessive sourness and affect product quality. Therefore, monitoring the changes in the content of organic acids such as propionic acid during soy sauce production can serve as an important quality control indicator.
03. Propionic acid content in fish seasonings
Fish seasonings include fish sauce, fish paste, and shrimp paste, which are specialty seasonings made from low-value fish or seafood by-products through salt preservation, autolysis, and microbial decomposition and fermentation. The main aroma components of these products include ammonia flavor, cheese flavor, and meat flavor. The cheese flavor mainly comes from low-molecular-weight organic acids such as propionic acid and butyric acid, which are produced during the later stages of fermentation. Studies have found that the content of propionic acid varies in different fish seasonings: 19.1 mg/L in fish sauce, 16.0 mg/L in fish paste, and 20.7 mg/L in pickled shrimp paste, reflecting the influence of different fermentation substrates and processes on the accumulation of propionic acid.
04. Content of propionic acid in sauce-based seasonings
Sauce-based seasonings are semi-solid condiments made from grains through microbial fermentation. Research has shown that the average content of propionic acid in soybean sauce is 0.004 mg/kg, and that in noodle sauce is 0.0037 mg/kg. The contents are similar and relatively low. It is worth noting that during the fermentation process of sauce-based products, the content of propionic acid shows an increasing trend. Taking mold-type soybean pickles as an example, the content of propionic acid in raw soybeans is 32.14 mg/kg. It gradually increases after 2 days of fermentation and reaches 37.14 mg/kg after 215 days of fermentation, indicating that microbial metabolism is the main pathway for the accumulation of propionic acid.
05. Content of propionic acid in fermented dairy products
The content of propionic acid in fermented dairy products varies depending on the product type. The average content of propionic acid in semi-hard cheese is 18.78 mg/kg, and that in soft cheese is 6.80 mg/kg. Propionic acid and other volatile acid compounds are important flavor substances in fermented dairy products, contributing to the light, medium, and strong flavor characteristics, with a more significant contribution to the strong flavor characteristic. The high content of propionic acid in Swiss cheese is a key contributor to its characteristic flavor. In addition, the lipase produced by microorganisms during traditional fermented dairy product manufacturing can promote the release of free fatty acids, further influencing the formation of propionic acid and other flavor substances.
06. Content of propionic acid in other fermented foods
Apart from the above foods, propionic acid has also been detected in fermented foods such as pickled radishes, bread, and fruit wine. The propionic acid in these foods mainly comes from microbial metabolism and lipid oxidation processes. It is worth noting that as the freshness of the food decreases, the content of short-chain fatty acids usually increases, which may be related to the enhanced microbial activity.
01.Flavor regulation effect
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