Variables affecting conjugated linoleic acid production process in probiotic yogurt by the Taguchi Method

Conjugated linoleic acid (CLA) is an unique fatty acid naturally found in milk fat. Beneficial properties of CLA include its antioxidant‚ anti-carcinogenic‚ immune-system regulation‚ anti-hypertensive‚ cholesterol-reducing, and anti-diabetic effects. On the other hand, probiotic yoghurt also has many health-promoting properties and is highly accepted and consumed by the people. The aim of this study was to determine effect of different processing variables on the CLA content of probiotic yoghurt. The effect of the following variables, at 2 levels, on the CLA content of probioltic yogurt prepared with L. acidophilus, B. lactis, and traditional yoghurt starters was determined: the amount of non-fat dry milk added to the whole milk, the amount and the time of adding safflower oil‚ and the time and temperature of incubation. The highest CLA content was obtained as a result of adding non-fat dry milk (2%) and safflower oil addition when at pH value of 6.0‚ at an incubation temperature of 37˚C and termination of incubation at pH value of 4.8. On the basis of the findings, it can be concluded that at the optimized conditions the CLA content in the probiotic yoghurt increased by 32.2% from an average of 7.07 mg/g in the non-treated (control) yoghurt to 9.23 mg/g fat in the probiotic yoghurt containing safflower oil.