ESTIMATING THE FATTY-ACID COMPOSITION OF THE OIL IN INTACT-SEED RAPESEED (BRASSICA-NAPUS L.) BY NEAR-INFRARED REFLECTANCE SPECTROSCOPY

The objective of this work was to evaluate the potential of near-infra red reflectance spectroscopy (NIRS) as a rapid method to estimate the fatty acid composition of the oil in intact-seed samples of rapeseed. A total of 549 samples (3 g intact seed) from selected mutant and bree ding lines were scanned by NIRS, and 220 of them were selected and sca nned again by using two different adapters, which reduced the sample s ize to 300 and 60 mg, respectively. Selected samples were analysed by gas liquid chromatography and calibration equations for individual fat ty acids were developed. Calibrations for oleic, linoleic, linolenic, and erucic acid were highly accurate, with values of r(2) in cross val idation from 0.95 to 0.98 (samples of 3 g), from 0.93 to 0.97 (300 mg) , and from 0.84 to 0.96 (60 mg). Calibrations for palmitic and stearic acid were less accurate, with values of r(2) in cross validation alwa ys lower than 0.8, probably because of the narrow range available for these fatty acids. The accuracy of the calibration equations for eicos enoic acid was very low (r(2) = 0.69 in 3 g samples), although improve d equations were developed (r(2) from 0.78 to 0.91) when the relations hip between erucic and eicosenoic acid was taken into account. We conc lude that NIRS is a powerful technique to estimate the fatty acid comp osition of the oil in rapeseed, provided that samples covering a wide range of fatty acid levels are available, with the advantage that such estimation is possible with few additional costs when NIRS is used fo r the determination of other seed quality traits.