Antioxidant effect of microencapsulated sodium selenite in soybean oil during one year storage

Encapsulated sodium-selenite at different concentration (100, 300, 500, 700 and 900 mg/20cc) with Arabic-gum (25%, 26%, 27%, 28%, 29%) and analogous Farsi gum (5%, 4%, 3%, 2%, 1%) as wall materials by solvent evaporation method was studied. Ethanol in different purity as solvent was used (80%, 84%, 88%, 92%, 96%). The optimization of microcapsules based on the highest encapsulation-efficiency and smallest microcapsules-size with usage of RSM analyze were surveyed. Based on mentioned parameters 2 optimum conditions were chosen. The first-one was a condition where the samples produced with 107mg sodium-selenite in 20cc sprayed solution, 29% and 1% Arabic-gum and Farsi-gum respectively. The ethanol-purity was 96%. In this condition the encapsulation efficiency was 99.71% whereas the microcapsules-size was 30/46µm. The second-condition was followed by 307mg sodium-selenite in 20cc sprayed solution, 29% and 1% Arabic-gum and Farsi-gum with ethanol-purity of 96%. The result of 97.73% encapsulation efficiency and the size of 47.46µm obtained. Finally 490ppm capsules of the first condition and 176ppm capsules of second condition (equal to 8.6ppm sodium-selenite salt), synthesized BHA (200ppm) and sodium-selenite salt (8/6ppm) were added to a free anti-oxidant soybean oil and were kept at 55°C at 0, 23 and 46 days which was equal with 20°C at 0, 180, 360 days. In this condition peroxide-value, acidity, Thiobarbituric-acid, Anisidine-value, Totox-value and antioxidant-activity of free antioxidant soybean oil with SPSS software were evaluated. The results achieved by RSM analyze showed that sodium-selenite concentration with encapsulation efficiency had reverse relation whereas it was direct relation with microcapsules-size. Also Arabic-gum concentration and ethanol-purity had direct relation with encapsulation-efficiency and the reverse one with microcapsules-size. The result of SPSS analyze showed that with presence of the encapsulated sodium-selenite antioxidant and synthesized BHA antioxidant in soybean oil, peroxide-value, acidity, Thiobarbituric acid, Anisidine-value, Totox-value decreased whereas antioxidant activity of soybean oil increased.