Extraction of Palm Kernel Oil in Cameroon: Effects of Kernels Drying on the Oil Quality

摘要

The kernels of the Elaeis guinensis palm fruits grow in the littoral region of Cameroon were collected, analysed and the composition of oil extracted were investigated. The effect of time and drying temperature (in sun and in electric ovens) of palm kernel on the quality of palm kernel oil obtained were studied. The lipid content of the kernels was 52.76%. The major fatty acids in kernel oil were about 54.51% lauric acid, 15.49% myristic acid and 9.53% oleic acid. Palm kernel oil was about 88.58% saturated and 11.37% unsaturated. Hexane extracted oil from the collected kernels give 9.58% as oleic acid, 3.59 as peroxide value. The research of optimal conditions during sun drying of different kernels sizes at different times showed that oil extracted from flours have much free fatty acids after 10 days drying as compared to other samples dried in the same conditions. In addition, the peroxide number of this oil sample from flours is very high (127.45 meq kg-1). Finally, for oil with acceptable qualities, kernels destined for extraction have to be dried in the whole state and deprived from flour smash during 6 days. In electrical air dryer, the regression model have shown that it is suitable to dry at <120°C for >100 min, so as to have perfect dehydration without loss of fats. Less acidic oils (percent oleic acid ≤1.5) are obtained when working at temperature >60°C for >100 min. High peroxide value (>30 meq) are obtained from drying kernel at very high temperature (>120°C) or from drying kernel for <300 min. While, acceptable value, propose by Codex Alimentarius (IP<10 meq kg-1) are obtained from drying kernels between 60-100°C for >300 min. Finally, in an electrical air dryer, kernels have to be dried between 60 and 100°C during 300-400 min to limit the fat losses and to obtain oil with poor free fatty acids and less oxidized.