71A-35 |
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S. A. IBRAHIM, Food Science and Nutrition Program, North Carolina A&T State Univ., Dept. of Human Environment and Family Sciences, 171-B Carver Hall, Greensboro, NC 27411-1064 Many reports have shown the health benefits associated with regular consumption of dairy food products containing bifidobacteria. Dairy products have been the preferred medium to reintroduce viable populations of bifidobacteria into the GI tract of both children and adults. Bifidobacteria must remain viable in large numbers in the carrier food to be used with confidence as a dietary adjunct; however, the survival of these cultures during refrigerated storage has been a challenge to the dairy industry. The objectives of this study were to investigate whether the resistance of bifidobacteria to cold storage could be improved by natural selection and to test the cold-resistant strain for galactoside activity and autoaggregation behavior. Twenty-nine bifidobacteria cultures propagated in TPY broth were used in this study. These strains were transferred dairy into fresh TPY broth and incubated at 37 °C as initial growth temperature. The natural selection procedure was based on the daily transfer of these cultures into fresh TPY and by lowering the growth temperature two degrees every week. The growth was monitored by measuring the optical density at 610nm. Results indicated that all strains were able to grow at lower temperatures and achieve high cell density. However, only 10 strains were able to survive growth temperature below 20 °C and maintain high cell density (O.D. > 0.90). Five strains were able to survive temperatures below 15 °C and had high cell density (O.D. > 0.80). However, two strains were able to grow at 7 °C and reached high cell density (O.D. >0.80). The galactosidase of these strains were similar to wild strains and showed the ability to autoaggregate in TPY. These results suggest that cold-resistant bifidobacteria can be improved by natural selection to produce viable cells of probiotic cultures to be used in dairy products.
Session 71A, Dairy Foods: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |