The changes in concentrations of fatty acids in X2 and Y2 during cold storage are presented in Table 5. In both Y2 and X2 samples, the major fatty acids were myristic (C14:0), palmitic (C16:0), stearic (C18:0), and oleic (C18:1) acids. The ratio of total saturated fatty acids to total unsaturated fatty acids was calculated to be 58:42. Also, the effect of the SCT on the proportions of saturated and unsaturated fatty acids was not significantly important (p > .05). Yadav, Jain, and Sinha (2007) analyzed the control and probiotic dahi and reported the ratio of 65:35 and 55:45, respectively. The increase in unsaturated fatty acids of the buffalo milk yogurt samples might be mainly due to the increase in the amount of oleic acid (18:1) during fermentation. It was also easily noted that 20 days of cold storage did not significantly (p > .05) change the ratio of saturated fatty acids to unsaturated fatty acids. In general, the amounts of fatty acids in X2 and Y2 did not follow a regular trend during cold storage. Similar results were reported by Güler (2007), while Yadav et al. (2007) observed an increase in the amounts of fatty acids throughout the storage. Yadav et al. (2007) indicated that butyric acid was formed principally by lipolytic activity of lactic acid bacteria, and the lactobacilli having probiotic activity can produce conjugated linoleic acid (CLA) in milk during fermentation by lipolysis of natural milk fat. Alternatively, distinct changes in the butyric acid and linoleic acid contents of X2 and Y2 were not observed in this study, which can be attributed to the pH levels of the both Y2 and X2 samples. Kim and Liu (2002) also indicated that pH below 4.6 has more effect on CLA synthesis than SCT. Only, the decrease in linoleic acid content of X2 and Y2 samples was observed after 20 days of cold storage and it might be explained that the starter cultures used in this study utilized the linoleic acid as a substrate for CLA synthesis as stated by Yadav et al. (2007). Beshkova et al. (1998) stated that the hydrolytic activity of S. thermophilus toward milk fat is low, and the most important precursors of volatile fatty acids were amino acids. They also indicated that formation of volatile fatty acids (C2–C10) was more active in mixed cultures than that of in pure ones. However, SCT did not significantly affect the amounts of volatile fatty acids in this study (p > .05).