ABSTRACT

The effect of storage on the oxidative stability of palm oil samples collected from NIFOR Benin and produced from Elaeis guineensis and Elaeis oefera was investigated. Five oil quality parameters namely: non-esterified fatty acid content (NEFA), peroxide value (PV), Anisidine value (AV), carotene as well as moisture content were estimated. The Malaysian palm oil board (MPOB) test analyses methods were adopted. The evaluation was carried out for 12 weeks after extracting crude palm oil from the palm species using the screw press method. Oil was stored at 4°c, 25°c, 40°c, 50°c, and 60°c using variable Gallenkamp oven and freezer. The parameters evaluated showed that storage at different temperatures and time duration affected the oxidative stability of the palm oil samples in general. The result indicated that storing the oil at 25°c is an optimum storage temperature for the different palm oil samples. Elevated temperatures of storage oxidized the oil samples. At 0-week mean values of all the parameters measured for Eiaeis oleifera were higher than the mean values for Elaeis guineensis. At 6th week of storage, mean NEFA value (2 5.90± 0.00 % palmitic acid) for Elaeis olefera was significantly higher (p<0.05) than mean value (13.60±..0.06% palmitic acid) for Elaeis guineensis at 40°c at 12th week of storage, mean NEFA value (26.30 ± 0.12% palmitic acid for Elaeis OIefera was significantly higher P<0.05) than mean value (13.80± 0.19% palmitic acid) for Elaeis guineensis at 40°c. At week of storage, mean peroxide value (12.90 ±.0.05 Meq 02/kg oil) for Elaeis oleijera at 50°c was significantly higher (P<0.05) than the mGan peroxide value (6.20±0.25 Meq 02/kg oil) for Elaieis guineensis at 50°c. At 1 week, mean peroxide values for Eiaeis Ole?fera and Elaeis guineensis were 13.50 ± 0.00 and 6.50 ± 0.20 respectively at 50°c. Mean anisidine value (1.07 ± 0.01 Meq 02/kg oil) for E. Ole jfera at 40°c was significantly higher (P<0.05) than mean anisidine value (0.58 ± 0.1 Meq 02 1kg oil) for Eiaeis guineensis at 40°c in the 6t1i week. In the 12th week, the values were 1.12 ± 0.01 and 0.29 ± 0.02 Meq 02 /kg oil for Elaeis o1efera and Elaeis guineensis respectively at 40°c. Mean anisidine values at 60°c for Elaeis Oiefera and Eiaeisguineensis were 1.15 ± 0.01 and 0.10 ± 0.01 Meq 02 /kg oil respectively. Mean Carotene content for Elaeis olefera (800.80 ± 59.20 mg /kg) at 25°c in the 6th week was signIficantly higher (P<0.05) than the value for Elaeis guineensis (483.90 ± 0.00 mg 1kg) at the same temperature. Similar trend was observed in the 12th week Mean moisture content for Elaeis olefera were • significantly higher <0.05) than mean moisture content for Elaeis guineensis across the storage tçmperatures. Generally, our results indicated that Elaeis guineensis oil sample is more stable to oxidative degradation than Elaeis Olefera.