Identification of rancidity markers in roasted sunflower seeds produced from raw materials stored for different periods of time

Roasted sunflower seeds contain high levels of unsaturated fatty acids, which are susceptible to oxidative rancidity when they are stored under inappropriate conditions. This lipid oxidation affects the quality of roasted sunflower seeds. Rancidity components (mainly including 11 aldehydes, 1 alcohol, 2 ketones, 1 acid and 1 furan) were identified in roasted sunflower seeds using HS-GC-MS-O (headspace-gas chromatography-mass spectrometry-olfactometry). Sunflower seeds harvested within the last year and those stored for one or two years were used to produce roasted sunflower seeds. The roasted sunflower seeds were stored at room temperature for 160 days and analyzed by HS-GC-MS-O. In roasted sunflower seeds, 16 rancidity compounds showed similar increasing trends with age of raw material, while the levels of the pyrazine compounds did not change during storage. Nonanal, hexanoic acid, 2,4-nonadienal, and heptanal were determined to be responsible for the off-flavor of the rancid products, and could be used to discriminate between final products made fresh and stored raw materials.