EVALUATION OF SELECTED HERB EXTRACTS ON PHYSICOCHEMICAL PROPERTIES AND OXIDATIVE STABILITY OF FLAXSEED OIL

Abstract Flaxseed or linseed which is a member of the Linaceae family is an important oil seed crop in the world. The oxidative stability of flaxseed oil is the result of a delicate balance between the activities of anti and prooxidants. During storage, an imbalance between the presence of reactive oxidants and the antioxidant defence mechanism can cause oxidation. This study was conducted with the objective of evaluation of leaf extract of Kesse ( Lippia adoensis var. adoensis), Rosemary (Rosmarinus officinalis L.) and Coriander (Coriandrum sativum L.), on oxidative stability. Total phenolic content (TPC) and Total flavonoid content (TFC) of extracts were determined by Folin–Ciocalteu and aluminum chloride method, respectively. 1, 1-diphenyl-2-picrylhydrazyl (DPPH) scavenging, Ferric reducing power (FRP), total antioxidant activities (TAA) and ferrous chelating ion (FCI) were taken as parameters for the evaluation of antioxidant activities. After the flaxseed oil produced from the flaxseed, it was treated with Kesse, Rosemary and Coriander extracts at 0.2 %, compared with 0.2 % butylated hydroxyltoluene and control flaxseed oil. Flaxseed oil incorporated with dietary herbal extracts and control flaxseed oil samples were kept in the oven at 65°C for a period of storage days (for five days). Physicochemical changes occurring during storage period of flaxseed oil were analyzed every 24 hours for 5 days. It was found that Kesse contained the highest TPC (48.16 ± 0.66 milligram of Gallic acid equivalent per gram of dried extract) and TFC (83.12 ± 8.18 milligram of catechin equivalent per gram of dried extract). The strongest activity of DPPH (IC50 = 64.02 ± 2.76 μg/mL), chelating ion activity (IC50 = 224.68 ± 2.04 µg/mL) exhibited by the Kesse extracts. The acidity of flaxseed oil incorporated with herbal extracts were range from (0.28 ± 0.13 to 11.95 ± 0.26 milligram of KOH/gram); free fatty acid varies from (0.56 ± 0.25 to 23.75 ± 0.52 %); peroxide values were range from (2.85 ± 0.21 to 55.00 ± 0.13 milliequivalents peroxide/kg oil through period of storage days. Control flaxseed oil showed highest lipid oxidation amount during period of storage days. The lowest lipid oxidation was found in flaxseed oil incorporated with Kesse extracts. The results of physicochemical and antioxidant evaluation showed that, flaxseed oil incorporated with Kesse extracts showed strongest physicochemical and antioxidant activity than the rest of flaxseed oil incorporated with Rosemary and Coriander extracts. In conclusion, flaxseed oil incorporated with Kesse extract improved physicochemical an d quality of flaxseed oil 12 during a storage days has been comparable efficiency with 0.2 % butylated hydroxyltoluene.