Comparative Evaluation of Amino Acid Composition and Volatile Organic Compounds of Selected Nigerian Cucurbit Seeds

Abstract

Amino acid composition and volatile organic compounds (VOCS) of five Nigerian cucurbits namely: Luffa aegyptiaca (Mill.), Citrullus lanatus (Thunb. Matsum), Cucurbita maxima (Duchesne, ex Lam), Cucumis metuliferus (E.Mey. ex Naudin) and Momordica balsamina (L.) were investigated using Amino acid Analyzer and Gas Chromatography-Mass Spectrometry (GC-MS). The proportion of essential amino acids ranged from 22.75- 30.23 g/100 g protein with the highest content in M. balsamina with 30.23 g/100 g protein and the least in C. lanatus with 22.75 g/100 g protein. High content of leucine was found in C. maxima and M. balsamina with 7.04 and 6.11 g /100 g protein respectively. The GC-MS analysis revealed the presence of thirty-one compounds, the most abundant classes of organic compounds in L. aegyptiaca comprised of esters with 65.17% and Fatty Acids (FA) had 32.62% while hydrocarbons amounted to 29%. In C. lanatus, seven compounds were identified dominated by FA and hydrocarbons with 91.5 and 7.25% respectively. In C. maxima, ten compounds were identified dominated by FA (52.24%) and hydrocarbons (43.46%). In C. metuliferus, FA had 30.74% while aromatic compounds and alcohol had 9.18 and 0.68%, respectively. Among the five seeds studied, the most abundant compounds identified were linoleic acid methyl ester in L. aegyptiaca with 63.72%. Cis-cis linoleic acid is most abundant in M. balsamina (62.03%) totaling the fatty acid portion to 86.41%. These results suggest the potential of the seeds as a source of amino acids and fatty acids that could be useful in food and feed fortification strategies. The unique VOCS could be useful as biomarkers for delimitation of the studied species.