Enzyme-aided cold pressing of flaxseed (Linum usitatissimum L.): Enhancement in yield, quality and phenolics of the oil

Abstract

The effect of different enzyme preparations (Viscozyme L, Kemzyme, and Feedzyme) on the yield and physicochemical and antioxidant properties of cold pressed flaxseed oil were assessed. The oil yield (35.2-38.0%) from enzyme-treated cold pressed flaxseeds (ETCPF), although lower than Soxhlet extracted oil (SEO) yield, was considerably higher when compared with the control (32.5%) while the contents of protein, fiber, and ash were unaffected by the enzymatic treatment. Most of the physicochemical parameters such as refractive index, density, iodine number, free fatty acid contents, saponification value, color and fatty acid profile did not vary significantly among the ETCPF oil, SEO and the control. Interestingly, the oxidation status in terms of peroxide value, para-anisidine value, conjugated dienes and triens and induction period (Rancimat method) as well as the sensory score of the ETCPF oil were superior compared with the control. An appreciably higher amount of tocopherols (350-400 mg kg-1) was determined in the ETCPF oil, compared to the control (270 mg kg-1), showing an increase of 22.8-32.5% in the recovery of total tocopherols. Moreover, ETCPF oil exhibited greater antioxidant activity as well as total phenolics and individual phenolic acid content. This study advocates the exploration of enzyme-assisted cold pressing as a viable alternative to conventional cold-pressing for improving not only the extraction yield but also the functional food quality of flaxseed-like high-value oils.