This invention relates to a method for producing foods and drinks containing bifidobacteria.
Bifidobacterium predominates in intestinal bacterial flora of suckling infants, and is being watched with keen interest since it has an influence on the health of breast-fed infants.
There are many reports on the study of the physiological significance of this bacteria, clarifying (1) the inhibitory effect on putrefaction by putrefactive bacteria, (2) the inhibitory effect on production of toxic amines, (3) the digestive effect on human milk casein by the action of phosphoprotein phosphatase, and (4) the effect of suppressing the growth of pathogenic bacteria by lowering intestinal pH following production of organic acids such as lactic acid, acetic acid, and formic acid.
However, this Bifidobacterium favourable to infants is present in a very small amount in the intestines of bottle-fed infants, which is considered to be one of the causes for their susceptibility to intestinal diseases, greater than that of breast-fed infants.
Aimed at approximating the intestinal flora of bottle-fed infants to that of breast-fed infants, an attempt has been made to produce Bifidobacterium-containing powdered milk for infants and to modify powdered milk for infants in such a manner as to be similar to a mother's milk.
However, due to the problems as mentioned below, it has been difficult to practice an industrial cultivation of Bifidobacterium in a medium consisting of milk only.
That is, as compared with dairy lactic acid bacteria which are widely used in processing milk, Bifidobacterium has the following problems:
(1) An industrial mass cultivation is difficult since Bifidobacterium requires strict anaerobic conditions for growth, and accordingly entails a large equipment cost and requires high level cultivation techniques;
(2) The nutritional requirement for the cultivation is complicated and fastidious and therefore the bacteria do not substantially propagate on a pure cow's milk medium containing no growth promoting substance such as yeast extract, peptone and the like; and
(3) Acetic acid, the main metabolic product of Bifidobacterium, is highly stimulative, and therefore generally impairs the taste and flavour of foods and drinks containing the same.
We have found that bifidobacteria having the above mentioned properties can be prosperously propagated under the same aerobic culture conditions as in the cultivation of dairy lactic acid bacteria in a medium containing as the main component a pasty or milky product of .alpha.-starch-transformed non-glutinous or glutionous rices, polished, whole, non-polished or powdered thereof, and further containing sugars fermentable by Bifidobacterium, such as glucose, lactose, fructose, galactose and the like (the sugar may vary depending on the species of Bifidobacterium used), and that the cultivated product has a good flavour since the fermentation product, acetic acid, well matches with the flavour of cooked rice.