Optimal culture conditions for producing conjugated linoleic acid in skim-milk by co-culture of different Lactobacillus strains

Abstract

The ability of different Lactobacillus strains to produce conjugated linoleic acid (CLA) was determined. Three species - Lactobacillus plantarum (Lp), Lactobacillus acidophilus (La) and Streptococcus thermophilus (St) - were co-cultured in a medium containing skim-milk supplemented with hydrolyzed safflower oil. This study was aimed at future applications in dairy products. The optimal operation parameters were established by response surface methodology. More CLA was produced by co-culture than by single strain culture. The CLA produced by co-culture of La and Lp (La-Lp) was more than that produced by La and St (La-St). Maximum CLA production of 316.52 μg/mL was obtained with La-Lp co-culture using a substrate concentration of 5.0 %, inoculum size of 5.0 %, an initial medium pH of 6.4 and a temperature of 36.4 C for 48 h. To our knowledge, this is the first report in the literature of the use of co-cultures of La-St and La-Lp to produce CLA. © 2012 Springer-Verlag and the University of Milan.