PROC-015: Effect of Oil Extraction Method on Oil Quality and Oxidative Stability

The increase in consumer interest in oils with high health-promoting values, observed in recent years, has contributed to the development of the market for these products. Increasingly, less traditional technologies are used to produce such healthpromoting oils. On the Polish market, apart from cold-pressed oils, oils extracted with supercritical carbon dioxide are increasingly common. The aim of this study was to compare the quality and oxidative stability of oils from three batches of flax seeds obtained by cold pressing and supercritical extraction with carbon dioxide. In the research part of the study, the most important indicators of oils quality were determined (fatty acid composition, acid value, peroxide value, anisidine value, Totox index, content of conjugated dienes and trienes, content of carotenoids and chlorophylls). The oxidative stability of the oils was investigated using the stable DPPH radical and the determination of oxidation induction times using the Rancimat test. Based on the obtained results, it was found that the fatty acid composition of cold-pressed linseed oils did not differ statistically from the oils extracted with supercritical carbon dioxide from the same batch of seeds. All oils analysed met the Codex Alimentarius requirements for acid (4 mg KOH/g) and peroxide (15 mEq O2/kg) value of cold-pressed oils. Coldpressed linseed oils were characterized by a lower acid value than their extracted counterparts. However, the method of extracting linseed oil had no influence on the value of its peroxide value, anisidine value and TOTOX index, and thus on the degree of oxidative changes. This was confirmed by the analysis of the content of conjugated dienes and trienes. The method of extraction of linseed oil did not affect the antioxidant activity tested with the DPPH radical. Analysis of the oxidative stability of flaxseed oils showed higher stability of oils obtained by pressing than by extraction. The pressed linseed oils tested had longer oxidation induction times than their extracted counterparts.