Cinétique d’une coagulation lactique d’un lait fromager par deux souches lactiques acidifiantes : Lactococcus lactis subsp diacetylactis et Lactobacillus acidophilus

Abstract

The present study focused on the technological aptitudes of two lactic strains, one mesophilic (Lactococcus) and the other thermophilic (Lactobacillus). The strains were revived and phenotypically re-characterized by determining morphological and physiological characteristics. The technological profile involved monitoring their acidifying power, through acidification kinetics and the hydrogen potential developed, as well as their proteolytic activity, a comparative study of the lactic coagulation kinetics of the 02 strains, and a determination of cheese yield in culture alone and in combination. The Lactobacillus strain presumed to be Lactobacillus acidophilus performed best, with a high acidifying power (acidity of 98 °D and a pH of 3.98), compared with the Lactococcus strain presumed to be Lactococcus lactis subsp. 5 lactis biovar diacetylactis, with an acidity of 56 °D and a pH of 5.38, which reached the same level. The activity of these strains reveals good cheese-making technological aptitudes. Lactobacillus is a good lactic leavening agent for milk fermentation and lactic coagulation. Lactococcus, with its low acidification kinetics, reveals a highly interesting aromatic profile that can be adapted to either fresh or ripened cheese technology. The mixed culture reveals a good cheese yield with a combination that can be used to produce either lactic or mixed cheese curds.