Detection of Vegetable Oil and Animal Depot Fat Adulteration in Anhydrous Milk Fat (Ghee) using Fatty Acid Composition

Abstract

Two type of adulterants i.e. soybean oil (SO) and buffalo depot fat (BDF) along with pure cow and buffalo milk fats, collected and prepared after every two months of interval for a complete one year, were analyzed for their fatty acid composition using gas liquid chromatography. Both the adulterants were added individually at 5, 10 and 15 percent levels (v/v) as well as in their combinations at 5+5 (10), 10+10 (20) and 15+15 (30) percent levels (v/v) in both types of milk fat separately. It was observed that soybean oil consisted of high amount (51.86 percent) of linoleic (C 18:2 ) acid, while buffalo depot fat possessed high content (49.17 percent) of oleic (C18:1) acid. Milk fats from both the species of cow and buffalo were found containing more of myristic (C 14:0 ), palmitic (C 16:0 ), stearic (C 18:0 ) and oleic (C 18:1 ) acids. The results revealed that the SO was detected even at 5 percent level using linoleic (C18:2) acid as marker, while BDF was detectable at 5 percent level using oleic (C 18:1 ) acid as the base. When the ratios of some fatty acids (C14:0/C16:0, C14:0/C18:1, C14:0/C18:2, C16:0/C18:1, C16:0/C18:2 and C18:0/ C 18:2 ) were calculated for detecting adulteration, it was noticed that two fatty acid ratios (C 14:0 /C 18:1 and C 14:0 /C 18:2 ) were found more useful in detecting adulteration in maximum number (78 percent) of samples. Whereas, on the basis of the ratios of sum of C 4:0 to C 14:1 / sum of C 15:0 to C 20:0 fatty acids and vice-versa, addition of both the adulterants at all the levels (added individually as well as in their combinations) in both the milk fats was easily detected.