Commercial Cold Pressed Flaxseed Oils Quality and Oxidative Stability at the Beginning and the End of Their Shelf Life

The aim of the study was to determine quality and oxidative stability of selected cold pressed flaxseed oils, fresh (after producing, the beginning of shelf life) and stored at refrigerator temperature (after three months, the end of declared shelf life). The fresh oils were characterized by organoleptic assessment, fatty acids composition and bioactive compounds content (sterols, tocols, squalene, carotenoids, and phenols). For the fresh and stored oils oxidative stability in the Rancimat test, and the hydrolytic and oxidation degrees using standard methods were determined. It was found that fresh flaxseed oils were differentiated in fatty acid composition and content of bioactive compounds. Shares of saturated fatty acids, and content of squalene and phenolic compounds were most variable in the oils. At the end of shelf life flaxseed oils were characterized by 9-26% shorter induction time in compare to the initial state, and increased content of hydrolysis (acid value by 18-40%) and oxidation products (peroxide value by 16-37%, anisidine value by 13-41%, diene content by 10-21%, triene content by 23-42%) was detected.