MVSc

An experiment was conducted to study the beneficial effect of incorporating L. acidophilus in dahi and yogurt as a dietary adjunct. An attempt was also made to find out the bile tolerance of L. acidophilus and other lactic acid bacteria.

An exhaustive review of literature has been presented on the issues of lactose intolerance and hypercholesteremia and the beneficial effects of lactic acid bacteria in alleviating these drawbacks, with a special emphasis on bile tolerance and intestinal colonization.

The methods of analysis of some important components of dahi and yogurt have been detailed.

Treatment dahi was prepared by inoculation with L. acidophilus in addition to normal dahi cultures. This was compared with control dahi prepared with normal dahi cultures alone.

Treatment yogurt was prepared with inoculating L. acidophilus along with normal yogurt cultures. This was compared with control yogurt prepared using normal yogurt cultures. The samples were then analyses for various parameters.

There was an increase in the B-galactosidase specific activity of treatment dahi when compared to the control dahi. But in the case of yogurt, the treatment yogurt was having a low B-galactosidase specific activity when compared to the control yogurt.

Control dahi showed inhibition against E. aerogenous, M. falvous, E. coli and S. aureus. It did not showed any inhibition against B. cereus. Treatment dahi exerted a significantly high inhibiton zone against all the test organisms in comparison to control dahi. Control yogurt inhibited only E. aerogenous and E. coli.Treatment yogurt exerted a signi ficantly high antibacterial activity against all the organisms tested. Of, all the lactic acid bacteria tested for their ability to grow in the presence of 0.3 per cent of Oxgall, only L. acidophilus grew satisfactorily. L. delbrueckii ssp bulgaricus showed a poor growth, where as S. Salivarius ssp thermophilus Lac. Lactis and Lac. lactis ssp diacetylactis failed to grow in the presence of Oxgall.

Both the dahi and yogurt treatments showed higher hypocholesteremia when compared to their respective controls. The total serum cholesterol level, serum triglyceride, LDL-Cholesterol and cardiac risk factor of the treatment groups were significantly lower than the respective controls. The HDL-Cholesterol was high in both the treatments when compared to the respective controls.

The growth rate of treatment dahi group was low when compared to the control dahi group. But the treatment yogurt group showed a higher growth rate as compared to the rats fed on control yogurt.

From above study the following conclusions are made.

1. The incorporation of L. acidophilus in dahi, increases its bB-galactocidase specific activity. However, in yogurt it resulted in a decreased B-galactosidase specific activity when compared to normal yogurt.

2. In both dahi and yogurt, the incorporation of L. acidophilus resulted in an elevated antibacterial activity against E. aerogenous, M. falvous , E. coli, S. aureus and B. cereus.

3. L. acidophilus was able to grow satisfactorily in the presence of Oxgall. While the other lactic acid bacteria tested either showed a poor growth or no growth at all in the presence of Oxgall.

4. Rats fed with dahi and yogurt incorporated with L. acidophilus showed a lower serum total cholesterol, serum triglyceride, and LDL-cholesterol levels, when compared to the control groups.

5. The HDL-Cholesterol level was high in both the treatment dahi and treatment yogurt fed rat groups.

6. The treatment dahi and treatment yogurt fed rats showed a significant decrease in the cardiac risk factor when compared to their respective controls.

7. The treatment dahi showed a lower growth rate, and treatment yogurt showed a high growth rate when compared to their controls.