QUALITY ASSESSMENT OF SEED OIL FROM SELECTED CACTUS PEAR CULTIVARS (OPUNTIA FICUS-INDICA AND OPUNTIA ROBUSTA)

摘要

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.