Functional and technological use of lactobacilli as producers of butyric acid in fermented milk

Introduction Butyric acid (BA) may exert significant beneficial effects on human health. Recent studies highlighted that in people with type 1 diabetes, some intestinal bacteria, responsible for BA production, are absent. For the potential use of one or more bacterial strains as probiotics in the food industry, the objective of the investigation was to evaluate the ability of the lactic acid bacteria strains (LABs) to produce BA. Method UHT skimmed and whole milk were commercial products. The lyophilized cultures identified with the progressive numbers from 1 to 8 (Lactobacillus asini ssp. Butyricus (1-3), Lactobacillus plantarum (4-6), Lactobacillus sp. 7-8) were revitalized by individual inoculation. The inoculum was made at 2% in UHT skimmed and whole milk. After 24 h at 30°C, fermented milks were distillate and submitted to the determination of BA using gas chromatography coupled with mass spectrometry (GC/MS) in SIM mode. Results / Discussion / Conclusion Butyric acid was produced by the LABs in amount not higher than 0.8 and 15 ppm respectively in skimmed and whole fermented milk samples. When tributyrin was added in skimmed milk, at the concentration of 5g/L, an average quantity of 85ppm butyric acid was produced. The strains were able to release tenfold higher levels of butyric acid than in milk, confirming that the lipase activity of some Lb. plantarum strains is highest on tributyrin. This allows us to conclude that BA in milk inoculated with the eight LAB strains originated from lipolytic hydrolysis of triacylglycerols and not from fermentation of sugar.