Survival of bifidobacteria during refrigerated storage in the presence of acid and hydrogen peroxide

Abstract

26 Bifidobacteria (survival during refrigerated storage) Survival of 9 strains of bifidobacteria (Bifidobacterium bifidum 1900 and 1901, B. longum 1941 and 20097, B. infantis 1912, B. adolescentis 1920, B. breve 1930, B. pseudolongum 20099 and B. thermophilum 20210) during 6 weeks storage at 4°C in the presence of acid and acid and hydrogen peroxide was studied. Cultures grown in sterile nonfat dry milk for 18 h at 37°C were adjusted to pH 4.3, 4.1, 3.9 and 3.7 with 4N lactic acid, and hydrogen peroxide was added to another set of cultures adjusted to pH 3.7 to 4.3 to achieve a final concentration of 10O μg/ml. After the pH and hydrogen peroxide adjustments, the cultures were stored at 4°C for 6 weeks, and samples were taken at 6 d intervals to determine the viable counts of bifidobacteria. The survival of B. bifidum 1900 and 1901, B. adolescentis 1920, B. breve 1930, B. longum 20097 and B. thermophilum 20210 was adversely affected in presence of acid, and the viability of these strains was even more affected in presence of acid and hydrogen peroxide, indicating a synergistic inhibition of bifidobacteria by acid and hydrogen peroxide. However, B. infantis 1912, B. longum 1941 and B. pseudolongum 20099 survived well in presence of acid and acid and hydrogen peroxide, suggesting that these strains can be used as dietary adjuncts in fermented dairy foods.