Quality Assessment of Seed Oil from Selected Cactus Pear Cultivars (Opuntia ficus-indicaandOpuntia robusta)

Abstract

Seven South African cactus pear varieties of Opuntia ficus indica and O. robusta were evaluated for seed oil content, fatty acid composition and oil quality. Oil quality parameters included refractive index, iodine value, peroxide value, free fatty acid content, p-anisidine value and oxidative stability index. Cultivars had oil contents ranging between 5.65% and 8.09%. Fatty acid unsaturation varied between 55.98% and 67.62% while fatty acid saturation varied between 16.59% and 20.71%. Iodine values of oil samples ranged between 110.68 and 126.24 g iodine absorbed by 100 g of oil. Peroxide values ranged between 9.50 and 33.67 meq O2/kg. The p-anisidine values ranged between 0.02 and 3.73 mmol/kg. These oils demonstrated a relatively low oxidative stability index ranging between 2.16 and 4.15 h. Oxidative stability showed significant correlations with the oil content, oleic acid, stearic acid and monounsaturated fatty acid contents. Physiochemical properties such as the peroxide value and the p-anisidine value were also significantly correlated with the oxidative stability index. Practical Applications Cactus pear fruit seeds are considered as waste products and are discarded during processing of the fruit. Previous research has reported on the fatty acid content and composition of this edible oil which comprises of mostly unsaturated fatty acids. This oil is comparable to other seed oils such as rape seed and grape seed oil. The further investigation into the quality properties of cactus pear seed oil reported in this study will lead to better understanding and ultimately better utilization of this multipurpose crop. Cactus pear seed oil can be used not only in the food industry but also in the pharmaceutical and cosmetic industries and can be used to reduce waste products delivered during processing. Best oil producing cactus pear species and cultivars are identified and will benefit producers of cactus pears for the oil industry.