Characterization of oils and defatted residues of terminalia catappa L. seed kernels of two varieties

Abstract

The seed kernel of Terminalia catappa Linn (T. catappa) is an underutilized plant food with promising potential. This study investigated the physicochemical properties, fatty acid composition, thermal behavior, and Fourier transform infrared (FTIR) spectral characteristics of oils extracted from kernels of yellow and purple cultivars of T. catappa and proximate compositions of their defatted residues. The oils extracted through a cold press micro-expeller, differed in color, with yellow oil being lighter than purple oil. Both cultivars demonstrated high iodine values and lower saponification values. Thermal profiles displayed major exothermic and endothermic peaks associated with the crystallization and melting of triacylglycerols (TAGs). Both oils were rich in unsaturated fatty acids (USFAs), particularly oleic and linoleic acids, with palmitic acid being the predominant saturated fatty acid (SFA). FTIR spectra indicated the presence of functional groups such as methyl, methylene and esters representing the complex composition of the oils. Proximate composition analysis revealed that whole kernels were high in fat, while defatted residues were richer in protein and minerals. These findings suggest that T. catappa kernels from both cultivars were good sources of plant oils with potential for high-fat products, and defatted residues could be used in protein-rich supplements, offering diverse industrial applications.