Effect of Inulin and Lactulose on Survival of Lactobacillus

The effect of supplementation of lactulose and inulin as prebiotics on the growth of L. acidophilus LA-5 and B. bifidum BB-02 in Acidophilus-Bifidus (AB) yoghurt and some quality parameters of the resulting products were studied. Yoghurts produced from milks with added inulin at levels of 0.5 % and 1.0%, or with lactulose at levels of 0.25 % and 2.5 % were compared with classical yoghurt and AB yoghurt (without added prebiotics). The results showed that inulin and lactulose did not affect the growth of yoghurt starter bacteria, but stimulated the growth of B. bifidum BB-02 to a great extent. Lactulose was found to be more effective on the growth of both probiotic strains than inulin. Inulin did not stimulate the growth of L. acidophilus LA-5. The cell counts of B. bifidum BB-02 and L. acidophilus LA-5 were dependent upon concentrations of lactulose and inulin used. No significant (p0.05) difference between the samples were observed with regard to the pH and lactic acid values. However, lactulose or inulin added samples had lower acetaldehyde and tyrosine contents than the untreated samples. Key Words: yoghurt, probiotics, prebiotics, Lactobacillus acidophilus, Bifidobacterium bifidu