Under-utilised palm kernels: Amino acids, fatty acids and mineral elements composition of Dypsis lutescens and Saribus rotundifolius palm kernels

Abstract

Dypsis lutescens and Saribus rotundifolius are exotic palm species widely grown in Nigeria as ornamentals but reported to be edible for both animals and humans in some climes. In this study, the palm kernels of D. lutescens and S. rotundifolius were analysed for amino acids, fatty acids, and mineral elements using standard procedures. Glutamic acid (12.51 and 13.08 g/100 g), aspartic acid (8.90 and 8.24 g/100 g), arginine (6.81 and 5.28 g/100 g), and leucine (6.81 and 6.34 g/100 g) were the predominant amino acids in the kernels of D. lutescens and S. rotundifolius, respectively. The percentage yields of the kernel oils were 2.01 and 0.86 % w/w for D. lutescens and S. rotundifolius, respectively. Gas chromatography (GC) facilitated the identification of 13 fatty acids, which mainly comprised oleic acid (35.53 and 55.26%), linoleic acid (46.24 and 24.42 %), and palmitic acid (11.31 and 16.05 %) in D. lutescens and S. rotundifolius, respectively. The GC analysis also revealed that the fixed oils of D. lutescens and S. rotundifolius kernels were highly unsaturated (82.68 % and 80.12 %, respectively). Both kernels also contained calcium (Ca), copper (Cu), iron (Fe), zinc (Zn), magnesium (Mg), manganese (Mn), sodium (Na), and potassium (K). Dypsis lutescens kernels primarily contained sodium (21.5 mg/kg) and potassium (45.0 mg/kg), while S. rotundifolius kernels contained a notable amount of sodium (20.0 mg/kg), magnesium (40.8 mg/kg), and potassium (43.3 mg/kg). A significant amount of magnesium (40.8 mg/kg) was detected in kernels of S. rotundifolius compared with the kernels of D. lutescens (4.07 mg/kg) this is a 10-fold difference. The results show that the kernels of D. lutescens and S. rotundifolius have notable concentrations of amino acids, fatty acids, and mineral elements. These unexploited palm kernels could be processed for animal feed, as a fibre-rich blend, or for other industrial applications. Therefore, further studies on their toxicity profile and nutritional bioavailability are warranted.