Abstract: First, prepared is a whey degradation medium to which a protease, yeast extract, and the like are added. Further, polyoxyethylene sorbitan monooleate or propylene glycol monooleate is added to the whey degradation medium. The whey degradation medium is inoculated with bacteriocin-producing lactic acid bacterium and the lactic acid bacterium is cultured while the whey degradation medium is maintained at pH of 4 to 5. After the completion of the culture, the whey degradation medium (culture solution) is centrifuged to thereby separate therefrom a concentrated cell suspension containing the lactic acid bacterium in a concentrated form. The concentrated cell suspension has very low antibacterial activity (several tens AU or less). Then, by adding the concentrated cell suspension to a yogurt mix and fermenting the same, it is possible to produce yogurt containing the bacteriocin-producing lactic acid bacterium without any delay in the fermentation.

Abstract: A method for culturing lactic acid bacteria includes (a) adding a proteolytic enzyme to an aqueous whey solution containing whey and water to thereby prepare a culture solution containing whey degraded by the proteolytic enzyme; (b) inoculating the culture solution with Lactobacillus gasseri which is a bacteriocin-producing lactic acid bacteria; and (c) maintaining the culture solution inoculated with the bacteriocin-producing lactic acid bacteria at a pH of not lower than 5.2 and not higher than 5.8 to provide cultured lactic acid bacteria. After the completion of culturing, the culture solution is centrifuged to separate a concentrated cell suspension containing the lactic acid bacterium in a concentrated form. The concentrated cell suspension has extremely high antibacterial activity, several tens of thousands AU, and is usable as a food preservative. Yogurt is produced by fermenting a yogurt mix to which 0.01% to 0.1% by weight of the concentrated cell suspension is added.

Abstract: First, prepared is a whey degradation medium to which a protease, yeast extract, and the like are added. Further, polyoxyethylene sorbitan monooleate or propylene glycol monooleate is added to the whey degradation medium. The whey degradation medium is inoculated with bacteriocin-producing lactic acid bacterium and the lactic acid bacterium is cultured while the whey degradation medium is maintained at pH of 4 to 5. After the completion of the culture, the whey degradation medium (culture solution) is centrifuged to thereby separate therefrom a concentrated cell suspension containing the lactic acid bacterium in a concentrated form. The concentrated cell suspension has very low antibacterial activity (several tens AU or less). Then, by adding the concentrated cell suspension to a yogurt mix and fermenting the same, it is possible to produce yogurt containing the bacteriocin-producing lactic acid bacterium without any delay in the fermentation.