EFFECT OF HEATING PROCESS ON THE STABILITY OF SOYBEAN AND SUNFLOWER OIL MIXTURE TREATED WITH SOME DIFFERENT NATURAL ANTIOXIDANTS.

Soybean oil is the most popular types of edible oils in Egypt. It is characterized by rapidly due to oxidation and rancidity processes. This study has been conducted to study the various transactions mixing and heating on the stability of soybean oil. And has been mixing soybean oil to sunflower oil by ratio (1: 1) and has been conducting the process of primary heating at 50^ₒC for 3 hours and then was treated with natural antioxidants extracted from waste of fruits and grains factories for example mango peels, apple pomace and wheat bran with concentrations (200, 400 and 600 ppm) and TBHQ as synthetic antioxidants with concentration (200 ppm).
        Results for the identification and separation of phenolic compounds of the antioxidants using HPLC being as follows: chlorogenic, salicylic, vannillic, benzoic and ellagic acids were the predominant obtained phenolics compounds. also the results obtained from total  phenolic compounds as gallic acid  being (14.53: 144.13 mg / g) and 2,2 diphenyl1-picrylhydrazyl(DPPH) results showed that mango peel extract gave the highest antioxidant activity(96.59%) compared to other extracts.
        Treated oil were  thermally heated  at 65^ₒC for 96 hours and some chemical properties (acid number, peroxide value and TBA value) were evaluated , our results showed an observed increase  in acid value of  untreated oil samples  compared with treated samples with different  antioxidants extracts , whereas high gradual increase in  the constants of oxidation and rancidity (peroxide and TBA values). Peroxide and TBA values were reached a maximum values which peroxide values being 22.57 ml.eqv./Kg oil for untreated oil sample and 12.96ml.eqv./Kg oil for treated oil sample with mango peels extract, while TBA values being 2.330 mg malonaldhyde/Kg oil for untreated oil sample compared with and 0.700  mg malonaldhyde/Kg oil in oil samples treated mango peel extract after 96 hours of heating.
       From then evident from the previous results that the additions of mango peel extract concentration of 600 ppm led to the improvement of the qualities of soybean oil mixture and thermally laboratories (chemical and natural) and delay rancidity and oxidation processes.