Yield and Physicochemical Properties of Marula (Sclerocarya birrea) Seed Oils among Nine International Provenances Tested in Malawi

Abstract

Sclerocarya birrea (Marula) is an indigenous fruit tree that is revered for its numerous socioeconomic contributions to human livelihood. Among others, the species is an important source of seed oil that is utilized in various domestic and industrial applications. This study was carried out to assess the yield and physicochemical properties of seed oils among nine international provenances of Sclerocarya birrea (subspecies caffra and birrea) planted in Malawi. Seed oils were obtained using the Soxhlet extraction method while quality parameters were determined using procedures described by the Malawi Bureau of Standards. Oil yield was highest (52.2%) in subspecies birrea (Missira provenance; Mali). Oil moisture content, free fatty acids, acid value, and peroxide value ranged from 0.06 to 076%, 1.96 to 4.07%, 3.91 to 8.13 mg·KOH/g, and 1.84 to 5.15 meq·KOH/g, respectively. Variations in oil yield and physicochemical properties could be attributed to genetic differences and the origin of genotypes. The selection of Sclerocarya birrea for oil production and use should be based on both provenance and subspecies levels. Further studies should study the heritability of the oil content and its physicochemical properties before conclusive decisions on the use of seed for propagation are carried out.