Fermentation is a process in which food is pre-digested by bacteria or fungi to create a product that may be tastier in some ways, or have other culinary or medicinal value lacking in the original food. Fermented foods are often good sources of healthy probiotic bacteria that contribute to the bacteria in the intestinal tract, the balance of which may be offset by various factors such as antibiotic use, poor diet or stress. A variety of health benefits have been attributed to the probiotic bacteria in fermented foods.
Koumiss
A traditional beverage of Central Asia made from fermented mare's milk, known as koumiss, contains an extensive array of beneficial bacteria, according to a Chinese study, published in the May 2010 "Journal of Dairy Science." Lactic acid-fermenting bacteria -- useful for their contribution to the population of healthy intestinal bacteria -- were the predominant species present and included Lactobacillus acidophilus, Lactobacillus helveticus, Lactobacillus fermentum, Lactobacillus kefiranofaciens, Lactobacillus paracasei, Lactobacillus kitasatonis and Lactobacillus kefiri. The study was the first of its kind to be performed on koumiss and the researchers plan to use their results to aid in the industrial production of koumiss.
Conjugated Linoleic Acid
Lactic acid-fermenting bacteria with high levels of conjugated linoleic acid-producing activity were the subject of a Chinese study on sauerkraut, published in the May-July 2009 "Journal of Food Science." Conjugated linoleic acid is a fatty acid with powerful anti-cancer properties. In the study, 15 such strains of lactic acid bacteria were identified from the sauerkraut tested, with the highest conjugated linoleic acid production coming from a species called Lactobacillus plantarum, which had an efficiency rate of 26 percent conversion of linoleic acid into conugated linoleic acid.
Fermented Fish
A Korean fermented fish product made from anchovy and shrimp, known as jeotgal, is a particularly good source of probiotic bacteria, according to a South Korean study published in the February 2011 "Food Microbiology" journal. The researchers identified a total of 104 species from two samples of joetgal. Bacillus bacteria were the most populous type in one of the samples, a variety of which have probiotic benefits.
Cancer
Fermented soy products increase risk for stomach cancer, according to a Japanese study published in the January 2011 "Cancer Science" journal. While many fermented foods and soy products are known for their ability to decrease risk for various forms of cancer, the study found an odds ratio of 1.22 to 1 associated with fermented soy and an odds ratio of 0.64 to 1 for nonfermented soy, high levels of nitrates and salt in fermented soy products may be the causative factor in the increased risk.
References
- Pub Med: Identification of the bacterial biodiversity in koumiss by denaturing gradient gel electrophoresis and species-specific polymerase chain reaction
- Pub Med: Identification of lactic acid bacterial strains with high conjugated linoleic acid-producing ability from natural sauerkraut fermentations
- Pub Med: Dietzia alimentaria sp. nov., isolated from a traditional Korean food
- Pub Med: Analysis of the cultivable bacterial community in jeotgal, a Korean salted and fermented seafood, and identification of its dominant bacteria
- Pub Med: Fermented and non-fermented soy food consumption and gastric cancer in Japanese and Korean populations: a meta-analysis of observational studies
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