Numerous fermented milk products containing probiotic lactobacilli have recently been commercialized in Japan. Certain probiotic lactobacilli grow slowly in milk. Therefore, some products are produced by co-culture with ordinary yogurt starter bacteria after the addition of sufficient amounts of separately propagated viable probiotic cells. Only a limited culture media for the test purpose of lactobacilli are commercially available (for example MRS broth), but the media for large-scale propagation of viable cells which are able to be used as food additive are not available. The manufacture of a low -priced and preferred novel medium for lactobacilli was, therefore, attempted using cheese whey powder as a starting material. Heat labile proteins in cheese whey were removed by pre-heating, then the whey solution was complemented with casein-protease hydrolyzate, glucose, yeast extract of food additive grade, Tween 80 and minerals. The growth test was mainly performed using human originated Lactobacillus acidophilus strains. The growth of several lactobacilli in the finally attained medium (WIM broth) composed of 7% deproteinized cheese whey, 1% glucose, 0.3% yeast extract, 0.1% Tween 80 and minerals, was comparable to MRS broth. The modified WIM broth which Tween 80 was replaced with decaglycerol-monooleate and composed of only food additive grade minerals was also a prominent medium for large-scale propagation of viable cells for the purpose of adding into several food products.
The fluorescent filter method with “Bioplorer” (Bioplorer method), the official direct microscopic count method (Breed Method), the measurement count with “BactoScan” (BactoScan method) and the viable cell count by standard plate count method (SPC) were comparatively examined each other for the total bacterial counts (TBC) in raw milk. The coefficient of variation of Bioplorer method was better than that of Breed method. The TBC of Bioplorer method correlated well with that of Breed method. Whereas the correlations between TBC of Bioplorer method and that of BactoScan method and/or SPC were low, and the correlations between TBC of Breed method and that of BactoScan method and/or SPC were similarly low. Consequently, it was recognized that Bioplorer method was qualified for the microbes enumeration method in raw milk instead of the official direct microscopic count method (Breed method).