Quality changes of Moringa oleífera, variety Mbololo of Kenya, seed oil during frying.

Abstract

The frying performance of Moringa oleífera variety Mbololo of Kenya seed oil (produced by cold pressure, extraction with n-hexane and a mixture of chloroform-methanol) was studied especially as regards repeated frying operations. The oils were used for intermittent frying of potato slices and cod filets at a temperature of 175 ± 5°C for 5 consecutive days. Under such conditions thermal and oxidative decomposition of the oils takes place. The chemical changes occurring in the oils were evaluated. Free fatty acid content, peroxide value, specific extinction at 232 nm, polar compounds, colour and viscosity of the oils all increased, whereas the iodine values, smoke points, polyunsaturated fatty acid content, induction period and tocopherol concentration decreased. The effect of the oils on the organoleptic quality of these fried foods was also determined. The analytical and sensory data showed that the lowest deterioration occurred in cold pressure produced oil and the highest in n-hexane extracted oil.