بهینهسازي عصارههاي اتانولی پوست سبز گردو استخراج شده به روش ماکروویو و بررسی خواص آنتیاکسیدانی آنها .

The Oxidation of oils and fats causes the reduction of their nutritional value and sensory properties. Today, a new approach to the use of natural antioxidants such as essential oils and plant extracts has been developed and used as a desired alternative antioxidants than chemical antioxidants in foods. In this study, ethanolic extracts of walnut green peel (0, 50 and 100% concentrations), different microwave powers (90, 450 and 900 watts) and different extraction time (1, 8 and 15 minutes) were extracted. In order to determine the optimum extract for adding to the oil, the total amount of phenolic compounds and the antioxidant activity of the extracts were measured by Reducing Power assay, scavenging of DPPH radical and total antioxidant capacity. Data analysis showed that optimized extracts were ethanol 53% (extraction time 6 minutes, microwave power 700 watts). Then, different concentrations of optimized extracts (200, 600 and 1000 ppm) were added to soybean oil and were kept in 65°C for the 16 days. The oxidative stability of all treatments was done by evaluation of peroxide value, TBA value, p-anisidin index, totox index and total amount of polar compounds in 0th, 8th and 16th Days of storage and compared with a treatment containing 200 ppm of BHT. The results indicated that different concentrations of optimized ethanolic extracts were effective in oxidation reduction in all treatments (p<0.05). 1000 ppm concentration of ethanolic extract was more effective than BHT and had no adverse effect on color, smell and taste of oil. Thus, the extracts of green walnut peel can be used as natural and effective antioxidant to reduce the oxidation rate of soybean oil. [ABSTRACT FROM AUTHOR]