Survival of Bifidobacterium strains in organic fermented milk is improved as a result of membrane fatty acid composition

Survival of three Bifidobacterium strains in organic and conventional fermented milks in relation to their membrane fatty acid composition was studied during chilled storage. Survival of Bifidobacterium lactis BB12 and BL04 over 21 days at 4 °C was improved in organic fermented milks, whereas these parameters were less effective for Bifidobacterium infantis ATCC15697. These different behaviours were linked to acidification activity, oxidoreduction potential and relative fatty acid composition, which differed among the strains and the types of milk used. The higher relative unsaturated fatty acid content in organic products, including trans-vaccenic, conjugated linoleic and α-linolenic acids, resulted in an increase in the linoleic and α-linolenic acid content in the cell membranes of B. lactis BB12 and BL04. The study showed that the membrane fatty acid composition, which depended on the strain and on the milk fatty acid composition, affected the survival of bifidobacteria during chilled storage in fermented milk products.