Cork oak (Quercus suber L.) leaf extracts potential use as natural antioxidants in cooked meat

Abstract

Different extracts (water, ethanol, water: ethanol (1:1 v/v), and water: ethanol (3:7 v/v)) were obtained from cork oak leaf and their antioxidant activities, antioxidant compounds (phenolics, flavonoids, condensed tannins, and tocopherols) and individual phenolic compounds were determined. The potential use of the obtained extracts to control oxidation and discolouration in a cooked meat model was investigated. Water: ethanol extracts presented a greater antioxidant activity, as well as a greater number of antioxidant compounds. Cork oak leaf extracts (COLEs) were applied (2 % v/w) in cooked chicken models, and their ability to prevent lipid oxidation and colour changes were evaluated during 5 and 10 days of storage, respectively, at 4 °C. In comparison with the control group, all tested COLEs effectively prevented lipid oxidation in the models reducing thiobarbituric acid reactive substances and the ability to control oxidation was equivalent to butylated hydroxytoluene (0.1 % ethanol) added at 2 % (v/w). Cork oak leaf extracts significantly modified instrumental colour coordinates L*a*b* producing significant total colour changes compared with the control group.