Effect of lipid source on probiotic bacteria and conjugated linoleic acid formation in milk model systems
2004
Xu, S. | Boylston, T.D. | Glatz, B.A.
The objective of this research was to study the effects of probiotic bacteria, lipid source, and fermentation time on the CLA content of a milk model system. The evaluation of 11 probiotic bacteria showed that they were able to produce CLA from linoleic acid in a model system containing hydrolyzed soy oil (1%) emulsified in milk, but not in model systems of unhydrolyzed oil (1%) emulsified in milk or 1% fat milk. Propionibacterium freudenreichii subsp. shermanii 56, P. freudenreichii subsp. shermanii 51, and P. freudenreichii subsp. freudenreichii 23 demonstrated the greatest increase in CLA content. Propionibacterium freudenreichii subsp. shermanii 51, produced the highest cis-9,trans-11 CLA content and also produced the greatest increase in trans-10,cis-12 CLA content as fermentation time was increased from 24 to 48 h. The fermentation of probiotic bacteria for 24 h was often most effective in increasing the CLA content. Viable counts of probiotic bacteria increased significantly from 0 to 24 h. These results demonstrated that the content of CLA during fermentation was primarily dependent on the strain of probiotic bacteria and the lipid source in the milk model system. This research suggests an efficient approach to produce CLA-enriched cultured dairy products.
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