Caractérisation technologique de souches pures de bactéries propioniques : test en minifabrication de fromages à pâte cuite

Abstract

Eighteen strains of Propionibacterium freudenreichii and one strain of P thoenii were tested for their ability to produce volatile fatty acids and gas in small scale Swiss-type cheese. Micro-filtrated milk and standardized propionic strains were used. Sixty-six mini-cheeses were made according to a standardized classical emmental cheesemaking process. During the hot room ripening, weekly determination of cheese volume and bimonthly analysis of volatile fatty acids and lactate contents permitted to distinguish five groups of strains. Propionate content and change in cheese volume were the most discriminant parameters. Four groups of strains showed different technological properties, where propionic fermentation seemed to be achieved after 14 to 28 days. Differences appeared in latent period, fermentation velocity and synchronism of gas and propionate productions. The strains of the last group were unsuitable for Swiss-type cheese technology. Some of them did not grow in the cheeses, some grew very slowly and others produced volatile fatty acids but not CO2 on a great scale. Weekly determinations of volatile fatty acids and lactate contents permitted a better characterization of the more precocious strains. As a general rule, the technological properties also reflected differences in growth and metabolic activities. © 1995 Elsevier/INRA.