INCORPORATION OF SWEET PEPPER EXTRACTS TO IMPROVE THERMAL STABILITY OF VEGETABLE OIL MIXTURES

Abstract

Sweet pepper is known not only for taste, aroma and flavor, but also for antioxidant effects and properties. Sweet pepper contains phenolic substances such as phenolic acids, flavonoids, phenolic diterpenes and volatile oils. Phenolic compounds in these vegetable materials are closely associated with their antioxidant activity and also play an important role in stabilizing lipid peroxidation. Efficacy of sweet pepper extracts in stabilizing sunflower and grape seeds oils in thermal oxidation conditions has been studied. Extracts were prepared in water/ethanol and oil solutions, total polyphenol content (TPC) was in the range of 25.3-59.4 mg/ml for extracts on the basis of oil and in the range of 50.01-267.2 mg/ml for extracts on the basis of EtOH/H₂O and antioxidant activity range in the extracts was 20-74,29%. Being highest in TPC and antioxidant potential of sweet pepper extracts were added to vegetable oil mixtures. Obtained samples of oils with extracts were heated at 160⁰C. The oxidation of the oil samples was evaluated by means of free fatty acids content, peroxide and p-anisidine value. The results of UV/Vis spectroscopy confirm stabilization effect on thermal oxidation of the tested oils. This study demonstrates that natural vegetable extract such as sweet peppers can effectively inhibit the lipid oxidation of sunflower and grape seeds oil mixture in thermal oxidation conditions.