Abstract:
This study was conducted to compare between quality of oil produced from Pumpkin and sunflower seeds and the effect of frying on physicochemical characteristics of oils. Samples of pumpkin and sunflower seeds were collected from Bahri market and the extraction of oils by mechanical presses was in Um durman market .All the steps of refining were carried out at laboratory in college of agricultural studies Sudan University, seeds were subjected to proximate analyses of seeds and for oils physicochemical analyses before and after frying process. The oils were reused for frying three days consecutively .After each frying process, oil was taken daily after cooling for analyses. The oil content33%, moisture5.17, protein29.50, crude fiber19.07, and ash 4.59 for pumpkin seeds and oil content 37%, moistures 4.04%,protein 26.12%,crud fiber 19.07% and ash 4.69% for sunflower seeds, respectively. The values obtained for physical properties of pumpkin seeds oil were for density 0.94, viscosity 38 , refractive index,1.47 and for yellow, color 71, red color 8.10 . Physical properties of sunflower seeds oil were for density 0.89, viscosity 31.50, refractive index 1.47 ,yellow color 51,red color 2.50 ,respectively .The chemical properties of pumpkin seeds oil include acid value 0.27 , peroxide value 2.30 and Saponification number, 240.50 .Chemical properties of sunflower seeds oil acid value 0.24, peroxide value 2.25 and saponification number 189.90,respectively .The fatty acid composition were determined as Palmitic acid17.51, linoleic acid 17.77, Linolenic acid 49.31,oleic acid 7.95 and other acids 7.46% for pumpkin seeds oil . And Palmitic acid 11.10, linoleic acid 32.32, Linolenic acid 46.33, oleic acid 6.18 and other acids 4.07% for sunflower seeds oil, respectively. The density did not increase for both oils (0.95-0.95 in pumpkin and 0.88-0.89 in sunflower), and viscosity increased from 42 to 44 in pumpkin oil and 35 to 40 in sunflower oil. Also refractive index for both oils did not increase .The yellow color increased from 70 to 73, red color from 9 to 10.10 in pumpkin oil and yellow color 47 to 51, red color from 4.30 to 6.20 in sunflower oil .The changes in chemical properties of both oils were the acid value for both oils did not increase (0.27-0.34 in pumpkin oil and 0.24-0.34 in sunflower oil)and peroxide value is unstable during frying but it is acceptable because it is within the acceptable range (not more than 10 m.Eq/kg), and saponification number increased from 229.75 to 236.30 in pumpkin oil and 179.50 to 236.40 in sunflower oil .
