Abstract: Strains of L. helveticus which form exclusively L(+) lactic acid in milk, particularly deposited strains CNCM I-1154, CNCM I-1155 and CNCM I-1156. The strains are employed to prepare an acidified milk product.

Abstract: A dehydrated acidified milk product is made by preparing an aqueous composition containing milk protein and having a dry matter content of from 10% to 40% by weight. The aqueous composition is inoculated with a strain of L. helveticus which exclusively forms lactic acid L(+) and a strain of S. thermophilus and fermented to obtain a fermented composition having a pH of from 4 to 5. The fermented composition is dried to obtain the dehydrated acidified product.

Abstract: Process for the continuous preparation of a fermented milk in which (1) a milk fermented by lactic acid bacteria is prepared in a first device, the fermented milk being subjected to stirring and pH conditions such that syneresis of the milk does not occur, the pH being regulated by the continuous addition of unfermented milk to the first device and continuously drawing off fermented milk from the first device; (2) in a second, post-acidification device, the fermented milk drawn off from the first device is cooled to a temperature of less than 15.degree. C. so as to subject the fermented milk to a post-acidification, the residence time of the fermented milk in the second device being adjusted so that at the outlet of the latter, the pH of the fermented milk is less than pH 4.7; and (3) a fermented milk having a pH of less than pH 4.7 is continuously drawn off from the second device.