Unique combination of rice and lactobacilli
─ the health food material cultured from Japan's staple food ─

Japan has traditional foods such as Izushi (sushi of a shellfish called Igai) and Funazushi (sushi made from crucian and rice), which are types of Narezushi (matured fish and rice). They are the original form of sushi, having unique tastes and are made by fermenting rice with lactobacilli. Certainly rice and lactobacilli make a good combination, but it is a considerable achievement to have established technology for producing the viscous polysaccharide kefiran using rice as the main ingredient, employing a lactobacillus (L. kefiranofaciens) that is usually fed with milk. As one of those involved in the classification and nomenclature of the lactobacilli who knows how difficult it is to culture them in volume,

I am pleased that this has become possible and that it will be applied in food production. At the same time, there is something romantic about the fact that the lactobacilli that are alive in the traditional food (kefir) of the Caucasus, a region famous for the longevity of its people, have produced a new food in Japan from rice, a new food that will be useful in maintaining the health of people throughout the world. I expect that Rice Kefiran will come into wide use as a food for preventing lifestyle-related diseases.

・ ・ Tomotari Mitsuoka Professor Emeritus of the University of Tokyo, Doctor of Agriculture

The fermented milk kefir contains components that directly act on the metabolic system (biogenics) and components that indirectly boost the vital functions of the organs by promoting enteric bacteria (prebiotics). The biogenic components are commonly viscous polysaccharide, kefiran, and L (+)-lactic acid. The prebiotic components are the bacterial compound of lactic bacteria and an antibiotic substance that is a type of bacteriocin produced by lactobacillus.

The food function of kefir is very interesting. It is reported to improve the intestinal environment, improve hepatic function, prevent arteriosclerosis, immunopotentiation, and so on.

There are however a few problems preventing its widespread use in Japan, namely, 1) alcohol is contained in kefir, 2) carbon dioxide is generated for storage, and 3) it does not suit Japanese taste. We pushed ahead with the development of Rice Kefiran in the belief that a kefir-derived novel food ingredient is produced with the improved palatability and enhanced functionality, it would become more widespread in Japan and all around the world.

It is known that L. kefiranofaciens, which forms kefir grain, plays a significant role in the expression of the functionality of kefir. The lactobacillus L. kefiranofaciens was isolated from kefir grain and denominated by a Japanese researcher (professor Tomotari Mitsuoka).

Viscous polysaccharide, kefiran, is the main substance utilized for kefir to properly act in healthy drinks, and this substance is produced by L. kefiranofaciens. Furthermore, this bacterium is homolactic fermented bacterium, so it does not produce alcohol nor generate carbon dioxide.

We therefore thought that lactic fermentation using the isolated L. kefiranofaciens cells would make up for kefir's shortcomings and enhance the functionality. Although the large-scale culture of this bacterium had proved troublesome, it poses some problems when used as lactobacillus and we had met with no success.

We received a subsidy from the Ministry of Agriculture, Forestry and Fisheries of Japan and established a technique to produce Rice Kefiran stably, a vegetable food ingredient with a higher content of kefiran, by a unique culture method using rice as the source of nutrient.