In the oil palm (Elaeis guineensis Jacq.), an active endogenous lipase is responsible for the massive release of free fatty acids (FFA) in the mesocarp of fruits at maturity. This can lead to the production of oils with unacceptable acid values. We have investigated the lipase activities in 39 genotypes of oil palm presently used in breeding programs. While most E. guineensis genotypes exhibited high lipase activity values, four of them with negligible activities were identified. We analyzed in situ lipolysis in the mesocarp upon severe wounding of fruits. The FFA content of high-lipase fruits ranged from 17 to 55%, while all low-lipase fruits contained less than 7.5% FFA. The analysis of oil from fallen overripe fruits indicated that all lowlipase genotypes contained less than 1.2% FFA (oil acidity ,5% FFA, FAO-WHO international norms), while all but one high-lipase genotypes had FFA contents much higher than the acceptable standards. Because the identified low-lipase lines are of high agronomical value and at least one of them is an elite genotype, it will soon be possible to provide farmers with new low-lipase oil palm lines allowing significant savings on labor costs, without any need for further breeding.
In the frame of African artisanal small-scale extraction of palm oil, the effects of post-harvest storage time and freezing of palm fruits on the extraction yield and quality of crude palm oil (CPO) were studied at laboratory scale using a process mimicking artisanal extraction. The extraction yield and free fatty acid (FFA) content of CPO increased with the length of fruit storage time at room temperature and freezing. FFA, total fatty acid and triacylglycerol profiles indicated a lack of specificity of the lipases at work. During post-harvest storage, the carotenoid content of CPO decreased slightly, tocopherols and tocotrienols (tocols) remained steady, while lipid oxidation remained at a very low level. For frozen fruits, carotene and tocol contents decreased sharply as a function of storage time, thought remaining quite high, but decreasing amounts of secondary oxidation products were detected. The FFA content and lipid oxidation level were highly correlated, indicating a pro-oxidant effect of FFAs. To conclude, three days of storage prior to artisanal extraction seemed the best trade-off between extraction yield and CPO quality. Combined storage at room temperature and freezing of palm fruits led to a large range of FFA contents in CPO. Optimization of the FFA contents of artisanal CPOs in line with local consumer’s demand calls for an assessment of their functional properties and sensory perception of foods formulated with CPOs.
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