Biochemical, microbiological, and nutritional aspects of kimchi (Korean fermented vegetable products).

Kimchi is a traditional, fermented Korean food that is prepared through a series of processes, including pretreatment of oriental cabbage (or radish), brining, blending with various spices and other ingredients, and fermentation. The characteristics of kimchi differ depending on the kimchi varieties, raw materials used, process, fermentation, and preservation methods. However, kimchi has typical biochemical, nutritional, and organoleptic properties and health-related functions. Kimchi fermentation is initiated by various microorganisms originally present in the raw materials, but the fermentation is gradually dominated by lactic acid bacteria. Numerous physicochemical and biological factors influence the fermentation, growth, and sequential appearance of principal microorganisms involved in the fermentation. Complex biochemical changes occur depending on the environmental conditions before, during, and after fermentation. The most important characteristics are the compositional changes of sugars and vitamins (especially ascorbic acid), formation and accumulation of organic acids, and texture degradation and softening. Nutritionally, kimchi is an important source of vitamins, minerals, dietary fiber, and other nutrients. This review covers in some detail the biochemical, microbiological, and nutritional characteristics of kimchi.