Reversed phase liquid chromatographic determination of triacylglycerol composition in sesame oils and the chemometric detection of adulteration

Abstract

Triacylglycerol (TG) composition of authentic and adulterated sesame oils with perilla was studied by using reversed phase liquid chromatography. Triacylglycerols were separated according to equivalent carbon number. 1,2-Dilinoleoyl-3-oleoyl- rac-glycerol (LLO) was the most predominant in sesame oils, and its concentration was 7.690–14.097% (w/w). The other abundant components were 1,2-dioleoyl-3-linoleoyl- rac-glycerol (OOL) and trioleoylglycerol (OOO), but trilinoleoylglycerol (LLL) and 1,2-dioleoyl-3-stearoyl- rac-glycerol (OOS) were minor. The remarkable differences between sesame and perilla oils are the amounts of LLO and trilinolenoylglycerol (LnLnLn). LnLnLn/LLO ratio for authentic sesame oils were less than 0.029. LnLnLn/LLO ratio looks promising as a detection index for adulterated sesame oils mixed with more than 5% perilla oil. Authentic and adulterated sesame oils with perilla were differentiated by applying principal component analysis and discriminant analysis to liquid chromatographic data sets. The minimum detectable limit for adulterated sesame oils was estimated to about 5% in mixing ratio. Chemometric technique provides a valuable tool to detect adulteration of oil.