Antioxidative Potential of Apple Peel Extracts And its Effect on the Stabilization of Corn oil ~ Chemistry Hub

Monday, May 18, 2015

Antioxidative Potential of Apple Peel Extracts And its Effect on the Stabilization of Corn oil

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Abstract

The antioxidant activity of three apple varieties (White Apple, Black Apple and Golden Apple) indigenous to Pakistan was evaluated. The order of antioxidant activity was evaluated by measurement of total phenolic content, reducing power and metal chelating ability. All the three varieties showed appreciable amount of total phenolic content, reducing power and chelating activity. Golden Apple showed highest amount of total phenolic content (4.43mg/g) followed by White Apple (4.37mg/g) followed by Black Apple (4.35mg/g). For the chelating activity, the same order is followed i.e. Golden Apple (114.9mg/g) > White Apple (105.4mg/g) > Black Apple 103.0mg/g). Again reducing power follows the same order i.e. Golden Apple > White apple > Black Apple. All the varieties exhibited appreciable antioxidant potential and significant differences were observed among the varieties in different systems of antioxidant activity evaluation.

Apple peel extract, as natural antioxidant was evaluated during a 28 days storage of refined corn oil at 25˚C and 55˚ C. Free fatty acid (FFA), peroxide values (POVs) and iodine values (IVs) were used as a criterion to assess the antioxidant activity of apple peel extract. Different organic solvents including acetone, ethyl acetate, methanol and ethanol were used to prepare the extracts of apple peels. Methanol produced the maximum yield of apple peel extract followed by ethanol. Ethyl acetate produced better yield than acetone. Different ratios of ethanol and methanol were also used to prepare the extract of apple peels but the maximum yield was given by commercial methanol followed by commercial ethanol. After 28 days of storage at 25 and 55˚C, corn oil containing 1600 and 2400ppm of ethanolic apple peel extract showed lower values of FFA (0.620 % at 25˚C and 0.679 % at 55˚), POV (24.7meq/kg at 25˚C and 48.34meq/kgat 55˚C) and higher values of IV (55.175 at 25˚C and 95.175 at 55˚C) than the control samples. Corn oil containing 200ppm BHA and BHT showed values of FFA, POV and IV comparable to those obtained by a concentration of 2400ppm of apple peel extract. These results illustrate that apple peel extract, at various concentrations exhibited a strong antioxidant activity which was almost equal to synthetic antioxidants BHA and BHT. Therefore apple peel extract in oils, fats and other food products can safely be used as natural antioxidant to suppress lipid peroxidatio.