APPLICATION OF FOURIER-TRANSFORM INFRARED-SPECTROSCOPY IN QUANTITATION OF TRIERUCIN IN HIGH-ERUCIC-ACID RAPESEED OILS

Development of varieties of high-erucic-acid (HEAR) rapeseed with high levels of erucic acid (C22:1) would be valuable for use in oleochemic al feedstocks. As an aid to this breeding effort, a rapid method to de tect trierucin (C22:1 triacylglycerol), an indicator that erucic acid is being incorporated in all three positions of the triacylglycerol, w ould be useful. Fingerprint (1850-600 cm(-1)) Fourier transform infrar ed (FT-IR) spectra of HEAR oil extracted from Brassica napus L. cc Mer cury, trierucin, and varying amounts of trierucin spiked in this oil w ere recorded. The regions of 1790-1690 cm(-1) and 1485-990 cm(-1) were subjected to a partial least-squares (PLS) procedure to obtain a cali bration equation [R-2 = 0.992 and root-mean-squared deviation (RMSD) = 2.78]. The established calibration was then tested on the spectra of mixtures of another HEAR oil from B. napus cv. Turret and trierucin. T he predicted values differ from the actual values with an RMSD of 1.6% . The calibration was also tested on high-erucic-acid oils from crambe (Crambe abyssinica) and nasturtium (Tropaeolum majus L.) seeds. For c rambe, the value found (0.48) was close to that reported in the litera ture, while the value of 75% for nasturtium oil was close to the value for total triacylglycerols with erucic acid in the 2-position as repo rted in the literature. FT-IR spectra of triolein (C18: 1 triacylglyce rol), trieicosenoin (C20:1 triacylglycerol), and trinervonin (C24:1 tr iacylglycerol) compared with the FT-IR spectrum of trierucin revealed the uniqueness of IR spectrum of trierucin that forms the basis of PLS analysis of trierucin in HEAR oils.