Yield Potential and Oil Quality of Pappea capensis Eckl. & Zeyh. (Jacket Plum Tree) for Biodiesel Production

Pappea capensis Eckl. & Zeyh. is a member of the Sapindaceae family and widely distributed throughout Southern Africa. This tree is considered drought and frost tolerant, with its edible fruit being of economical importance. The seed contains a high concentration of oil that shows great potential to be used as a bio-diesel. No information is available on the phenology of the tree, seed yields or the quality of the oil. In this study it was found that the trees are andromonoecious, starting with male flowers and switching to the production of female flowers. Flowers and fruit are borne on shoot terminals mostly on the canopy surface. The seed, embedded in an aril, is contained in a capsule. A frame counting technique was applied to determine fruit and seed yield per tree. An average of 21.85 kg of seed was obtained from trees with an average canopy surface area of 20 m². The seed contains about 73.5% oil which conformed to the 14.81 litres of oil we obtained from 21.85 kg seed. From these results extrapolations were made, showing that yields of 3018 kg of seed (1996.41 litre oil) from 200 trees per hectare should be possible.

The oil was extracted with a press and samples were analysed by the company ‘BioServices’ in Randburg, South Africa, according to the American Oil Chemist Society standards and it was found suitable for the use in bio-fuel production as a B5-blend.

This is a first study attempting to estimate the fruit/seed/oil yield of Pappea capensis trees. There is a strong correlation between yield obtained from frame counting and manual harvesting. Figures where obtained from wild population trees, therefore higher yields can be expected from grafted and cultivated trees.

Keywords: biodiesel, seed yield, oil