Some Chemical Properties of Watermelon Seeds and the Effect of Roasting Process on the Oxidation of Watermelon Seed Oil

Abstract

Turkey is among the world‘s leading countries in terms of production and consumption of dried fruits and nuts and several dried fruit and nut products are used as snack foods in Turkey. Watermeloon seed is one of these snack foods. In this study, some chemical compounds of watermelon seeds, consumed as a snack, supplied from Mardin, Diyarbakır and Batman were determined. In addition, the effects of different roasting temperatures (140, 160 and 180°C) during 60 min on the oxidative stability of watermelon oil were investigated in watermelon seeds obtained from Batman. It was determined that the content of dry matter, ash, oil, protein, total tocopherol and total phenolics of watermelon seeds varied between 95.39 and 95.58%, 3.10 and 3.38%, 51.65 and 52.75%, 32.76 and 34.87%, 360.12 and 393.16 mg/kg, 427.75 and 478.80 mg GAeq./kg oil-free, respectively. The fatty acid composition of watermelon seeds showed that it is an important source of linoleic acid (60.74%) which is an essential fatty acid and also contained a high amount of oleic acid (20.48%). It was concluded that the roasting process did not affect the fatty acid composition of watermelon seeds, and the peroxide values slightly varied between 1.57-3.0 meq O2/kg oil. On the contrary, the effect of roasting temperature on the peroxide values of the samples was found statistically significant. While the values of K232 ranged from 2.54 to 4.01 during roasting, K268 values of the samples roasted changed from 4.99 to 5.04. K232 and K268 values of sample roasted at 180°C were statistically different from those roasted at 140°C and 160°C. As a result of the study, it was determined that watermelon seeds contained significant amounts of linoleic acid, the essential fatty acid, and that the roasting process to in the oil oxidation parameters.