Effect of lipid source on probiotic bacteria and conjugated linoleic acid formation in milk model systems

Abstract

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 soy 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.

Dairy Propionibacteria: Less Conventional Probiotics to Improve the Human and Animal Health

“…By varying the source of LA for conjugation and the fermentation conditions it has been observed that P. freudenreichii convert free LA to mainly extracellular CLA with a high efficiency (50-90%), being the optimal conditions that favor the accumulation of CLA also determined [97,101]. Besides, it has been observed that CLA formation and growth of dairy propionibacteria in fermented milks were enhanced in the presence of yogurt microorganisms whereas organoleptic attributes obtained with yogurt starter cultures were not affected by co-cultures with the propionibacteria [100].…”

Influence of processing on the fatty acid composition and the content of conjugated linoleic acid in organic and conventional dairy products - a review

“…Xu et al [83] investigated 11 probiotic bacteria for the ability to form CLA. Three of them were propionibacteria.…”

Conjugated Linoleic and Linolenic Acid Production by Bacteria: Development of Functional Foods

“…Moreover, CLA production in B. bifidum cultured in skim milk, using as substrate hydrolyzed soy oil was reported by Xu et al [65], where authors detected CLA production after 24-48 h only as c9,t11 isomer, and traces of the t10,c12 form.…”

“…CLA production in a fat milk model supplemented with hydrolyzed soy oil for 24 to 48 h was demonstrated in two P. freudenreichii ssp shermanii and P. freudenreichii ssp freudenreichii [65]. Higher levels of CLA were determined in skim milk than MRS broth.…”

“…Propionibacteria represents another important group of bacteria where the capacity of LA isomerization in vitro was demonstrated, being relevant since it could be included in fermented products as cheeses. So, P. freudenrehichii was able to produce CLA mainly as c9,t11 form according to different studies [58,65,[70][71] although other author reported eight different isomers of CLA produced by enzyme extract in this bacteria [72].…”