Physical, morphological and chemical characteristics, oil recovery and fatty acid composition of Balanites aegyptiaca Del. kernels

Abstract

Balanites aegyptiaca Del. kernels were chemically, physically and morphologically characterized. Crude oil (49.0%) and crude protein (32.4%) were the two major constituents of the kernels. Phytic acid content was relatively high compared to other legumes. In contrast, antitryptic activities of the kernel flours were very low. Sapogenin contents of the full fat, defatted and testa flours were 1.5, 2.7 and 3.0%, respectively. The hardness of the kernel was found to be about 10.4 x 10(5) N/m(2), which was somewhat high. The morphological structure of the kernel using a scanning electron microscope revealed that the protein matrix was embedded in a lake of oil droplets. Oil recovery, as a function of pressing time, pressure, temperature and particle size was investigated. With increasing temperature up to 70 degreesC at 400 bar, for 120 min, an oil recovery of 79.4% was obtained. Using an expeller at 115 degreesC, about 85% of the kernel oil was recovered. The reduction of particle size had a negative effect on oil recovery under the same conditions. The fatty acid composition was not affected by the pressing temperature up to 115 degreesC. The total amount of the unsaturated fatty acids was found to be up to 74.8% (50 degreesC) and 75.1% (115 degreesC) of the total fatty acids content.