Effect on Antioxidant Activity and Composition of Linseed Oil (Linum Usitatissimum L.) Using Different Methods of Oil Extraction

Abstract

(Linum usitatissimum), also known as flaxseed, the cultivated linseed belongs to the family Linaceae. Linseed due to sufficient levels of fat, protein and sugars can supply 530 calories/100 g. In this view, and it’s higher levels of alpha linolenic acid, and essential fatty acid. For experimental purpose, two varieties of linseed were taken namely ‘neelum’ and ‘gaurav’. The oil extraction process of linseed was carried out with three methods viz; screw press, soxhlet extraction and microwave assisted extraction at varying levels. Microwave assisted extraction gave the best yield of oil as 40.90 % for neelum and 43.10 % for gaurav in 50 mins of time which is consuming lesser energy and time.At varying temperature of 80, 90,100, 110 and 120º C oil is extracted through screw pess in which the 80º C was found to be best by giving the yield of 33.11 % for neelum variety and 36.11 % for gaurav variety. Soxhlet extracted oil yield was considered more than microwave assisted and screw press as it gave 42.12 % for neelum and 43.32 % for gaurav when extracted with n-hexane at 7.5 hrs of time duration. Antioxidant activity analysis through FRAP was performed in which, microwave assisted extraction exhibited greater antioxidant activity of 0.829 μg/ml followed by 0.629 and 0.463 μg/ml through screw press and soxhlet extraction respectively for neelum variety. Similarly antioxidant activity was much more 1.047 μg/ml followed by 0.807 and 0.631 μg/ml through screw press and soxhlet extraction respectively for gaurav variety. Most of physiochemical parameters such as refractive index, specific gravity, iodine number, free fatty acids, saponification value and color did not vary much among the screw press, soxhlet extarction and microwave assisted extraction. Peroxide value and acid value were found to be lesser as 1.06 meq/kg and 0.68 mg/KOH in neelum variety and peroxide value as 1.05 meq/kg and acid value is 0.72 mg/KOH through microwave assisted extraction which is comparitively lesser than traditional methods and do affect the shelf life of oil. Lipid oxidation is the most important quality parameter decreasing economic value of linseed oil during storage to avoid that oil is stored in PET bottles. Oxidation resulting with an undesirable rancid taste makes linseed unacceptable for the consumer. Antioxidant compounds in food provide some protection against oxidation. This study advocates exploration of microwave assisted extraction as a variable alternative to conventional methods of extraction for improving not only extraction yield but also the functional food quality of linseed like high-value oils.