Isolation of Shahmirzadi Husk Walnut Extract Using Microwave Assisted Extraction (MAE) and Evaluation of its Antioxidant Activity

Doubts about the safety and health hazard concerned with the use of synthetic antioxidants have led to a growing demand for the application of natural antioxidants. In this study the antioxidant activities of water and alcoholic extracts of shahmirzadi variety of green husk of walnut based on reducing power, total antioxidant activity and DPPH scavenging activity were evaluated. The effects of extracts on inhibition of oxidation chain reactions of soyabean oil was examined by measuring peroxide and thiobarbitoric acid values as means to evaluate the antioxidant activities. Phenolic compounds were extracted with methanol (80%), ethanol (50%) and water and the total phenolic content was measured by Folin-Ciocalteu method. The results showed that the highest total phenolic compounds were present in the methanolic extract using microwave. The results also indicated that the extracts were able to retard the oxidation and the antioxidant activity was concentration dependent and the sample with the concentration of 1000ppm extract inhibited the oxidation of soyabean oil. Walnut husk might be regarded as a potential source of natural antioxidants but further investigation might be recommended for its possible application in food and related industries.