Quality Characteristics of Iranian Extra Virgin Flaxseed Oil and the Effect of the Refining Stages before Deodorization on its Physicochemical Properties

Abstract

Flaxseed oil is known as a functional oil because of the high content of α-linolenic acid; therefore, the aim of this research was to investigate some physicochemical properties of Iranian extra virgin flaxseed oil (EVFO) and the impact of the refining stages before deodorization on these properties. Fatty acid composition, peroxide and anisidine values, free fatty acids, Crystallization point, chlorophyll content, β-carotene content, and color were analyzed. The Iranian flaxseed oils had about 39-40% omega-3 fatty acids and a low ratio of omega-6 to omega-3 and equal to 0.44-0.47, which can be combined with oils rich in omega-6 to reach a favorite omega-6 to omega-3 ratio. In addition, the results showed that when EVFO was refined, the crystallization thermograms changed significantly. The presence of phospholipid compounds in EVFO made its onset, crystallization, endset points higher than the RFO. The amount of β-carotene and chlorophyll content of refined flaxseed oil (RFO) were 6 and 22.33 times lower than its EVFO. Also, RFO had significantly (p<0.05) more L*, less tendency to yellow color, and tendency to a green color as compared to its EVFO. The results showed that flaxseed oil fatty acid content, free fatty acids, peroxide, Anisdine values, crystallization temperature, chlorophyll and β-carotene content and the color were significantly affected by the refining stages. So it is recommended that flaxseed oil not to be refined, but be used in a short time period. Also, it should be consumed in blending with omega-6 oils (in order to maintain omega-6 to omega-3 ratio).