Temperature Effects on Granular Morphology and Oil Properties of Chrysophyllum albidum (African Star Apple) Cotyledon: A Response Surface Approach

Abstract

This research was designed to study temperature effects on granular morphology of Chrysophyllum albidum (African star apple) cotyledon and constituents of its oil using response surface methodology. The independent variables were roasting temperature (120oC - 200oC) and roasting duration (10 - 40 min). Granular morphology, oil yield, free fatty acids, specific gravity and chemical compositions were responses. The particle surface of the samples showed an inter-twined tiny tissue that is compact and smooth. Temperature variations were reflected in the cell morphology, indicating that roasting at increasing temperatures significantly affects the cellular structure of Chrysophyllum albidum cotyledons. The percentage oil yield ranged between 11.76 and 14.16 %. Maximum oil yield recorded was 14.16% and achieved at 192.43oC and 30min duration. Percentage content of free fatty acid in Chrysophyllum albidum cotyledon oil ranged from 1.26 to 2.25%. Heat treatment significantly influence free fatty acids contents. The highest specific gravity was achieved at temperature and duration of 192.43oC and 30min respectively, while the lowest specific gravity value was achieved at temperature and duration of 107oC and 30min. Eighteen (18) compounds were identified. The dominating compound was 9, 12-Octadecadienoic acid (Z, Z) with percentage weight of 28.08 ± 2.8 while the least was Tetracontane having percentage weight of 0.69 ± 0.068. Total percentages of unsaturated fatty acids in the compound were 73.56%. These findings suggest that Chrysophyllum albidum cotyledons have the potential to serve as a viable source of edible oil.