Characterization and Stability Studies of Egusi Melon Seed Oil (Citrullus colocynthis L.)

Abstract

The physical value of oil depends upon its chemical composition, even today these values play a vital role while using different oil for industrial products and also, despite the vast nutritional and medicinal significance of egusi melon, there are little details on the shell life and stability of its oil over time. Therefore, the influence of time and temperature on melon seed oil was investigated at temperatures of 0oC and 30oC at different weeks to ascertain its physicochemical value and storage stability. For week zero, at 0oC and ambient temperature (30oC), the result revealed iodine value 124.09, Acid value 3.64 mgNaOH/g, Free Fatty Acid value 1.84 mgNaOH/g, Saponification 217.35 mgKOH/g, Peroxide value 1.25 mg/g oil, pH 5.89 and thiobarbituric acid value 0.1383 respectively. In the 5th week, at 30oC, the result revealed iodine value 91.1543, acid value 12.8921 mgNaOH/g, free fatty acid value 6.4988 mgNaOH/g, Saponification 346.42 mgKOH/g, Peroxide value 9.5mg/g oil, pH 3.2 and thiobarbituric acid value 0.413 respectively. Also at 0oC in the 5th week, the results were observed as follow: Iodine value 102.53, Acid value 7.96 mgNaOH/g, Free Fatty Acid value 4.01 mgNaOH/g, saponification 287.51 mgKOH/g, Peroxide value 6.1 mg/g oil, pH 5.05, and thiobarbituric acid value 0.2658 respectively. Refrigeration (0oC) of oil reduced the rate of most of the oxidative deterioration that produces rancidity. These values are within recommended range for edible oils. These results indicate that egusi melon oil could be a good source of table oil. The statistical results show that there was a significant difference between the melon seed oil stored at 0oC and 30oC (P < 0.001).