Method and buffered bulk starter media for propagation of useful bacteria

Abstract

The invention comprises a novel starter medium for the commercial propagation of acid producing bacteria, such as those used in food fermentation processes. The compositions are unique in that they contain a highly effective buffering ingredient which is a sodium, potassium, or ammonium salt or double salt of a linear aliphatic dibasic acid having from three to seven carbon atoms. The salts are present in an amount sufficient to maintain the growth medium at pH levels of about 5.0 or above during the time in which the bacteria are multiplying in the culture medium. Disodium or diammonium succinate, glutarate, or adipate are materials which have been found to be particularly effective. These may be used in combination with nutrients such as whey, whey permeate, nonfat dried milk, yeast extract, and diammonium phosphate. The addition of trace quantities of certain metals promotes the growth and activity of the acid producing bacteria. Small quantities of ferrous, manganous, or manganese ions are particularly useful. A combination of iron and manganese with the other ingredients in the media produced results better than either of these materials standing by itself. In a commercial test, the cheese produced using an inoculant based on one of the present formulations was of excellent quality. Most of the formulations containing the bibasic acid salts appear to be highly resistant to bacteriophage infection.