Abstract: A bacteria-containing composition for use in making cottage cheese is prepared containing a strain of Streptococcus diacetilactis that produces substantial amounts of diacetyl in a milk culture, a strain of diacetyl deficient mutant Streptococcus diacetilactis that produces essentially no diacetyl in a milk culture and a suitable carrier for maintaining viability of the Streptococcus diacetilactis. By the use of the two types of Streptococcus diacetilactis, a manufacturer of cottage cheese can optimize both the cell count to achieve the desired inhibition of spoilage bacteria and flavor production to achieve the desired flavor in the finished product.

Abstract: Cottage cheese is prepared containing a blend of normal and mutant strains of Streptococcus diacetilactis. The mutant strain is similar to the normal strain except that it produces little or no acetaldehyde and diacetyl. By varying the ratio of the strains in the blend, the cottage cheese can be made with the maximum possible shelf life obtainable from Streptococcus diacetilactis and yet have virtually any amount of flavor that may be desired, from very mild to strong.

Abstract: A process is disclosed for rapidly and economically growing the bacterial species Lactobacillus sanfrancisco.

Abstract: Flavor and shelf life of cottage cheese are improved by adding to cottage cheese or a creaming mixture for creaming cottage cheese a concentrated cell preparation of Streptococcus diacetilactis to provide a concentration of cells in the cottage cheese of from 1.0 .times. 10.sup.6 cells per gram to 2.0 .times. 10.sup.8 cells per gram of cottage cheese. The concentrated cell preparation can be a freeze dried culture, frozen concentrated cells or freeze dried concentrated cells.