Effect of cooking and extraction method on oleaginous cucurbit seed oils quality

Abstract

In sub-Saharan Africa, Lagenaria siceraria seeds are cooked before consumption. Cooking seed may alter their chemical composition, leading to changes in their health benefits. Thus, this study aimed at determining the effect of cooking of L. siceraria seeds on their edible oil quality. Heat treatments were performed as roasted (100 and 125 °C) and boiled (10, 35, 60 and 90 min). Then oils were extracted with petroleum ether solvent and hot-water flotation process. Peroxide and acid index, and fatty acids composition were evaluated. With the hot-water flotation process, roasting and boiling had no significant effect on acid index and fatty acids composition. However, peroxide values varied from 1.1 to 2.9 meqO2 kg-1 oil. The highest peroxides values were revealed at 90 and 60 min, respectively, in seeds roasted at 100 and 125 °C. With solvent extraction, roasting and boiling affected only peroxide values and fatty acids composition. The highest peroxide values were reached after 10 min of ebullition of roasted seeds, both at 100 and 125°C. Saturated and polyunsaturated fatty acid contents increased after 10 min of boiling of seeds roasted at 100 and 125°C; then decreased to reach the initial content. But, the monounsaturated fatty acids content decreased after 10 min of boiling, and then increased to reach the initial content. The highest values of peroxides and polyunsaturated fatty acids contents were observed with solvent extraction compared to hot-water flotation method. Cooking of L. siceraria seeds does not alter the quality of their oil; solvent extraction makes their oil highly unstable.

Key words: Fatty acids, Lagenaria siceraria, quality indexes