Fatty Acid and Amino Acid Compositions of the Edible and Inedible varieties of Air Potato Yam (Dioscorea bulbifera).
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Abstract
The fatty acid and amino acid compositions of the edible and inedible varieties of Dioscorea bulbifera were investigated. The results revealed the presence of only two fatty acids; oleic (5.82%) and linoleic (94.18%) in the edible variety and three fatty acids; palmitoleic (54.00%), oleic (37.47%) and linolenic (8.52%) in the inedible variety. The edible variety lacked linolenic acid while the inedible variety lacked linoleic acid. The edible yam variety had a total amino acid composition of 68.82g/100g. This value is slightly lower than the value of 76.65g/100g for the inedible variety. The inedible variety had higher values of all the amino acids than the edible variety. Both varieties had aspartic and glutamic acids as the predominant amino acids and methionine as the most deficient amino acid. The edible yam variety had a total essential amino acid value of 31.27g/100g protein while the inedible variety had a total essential amino acid value of 34.82g/100g protein. These values represent 45.44% and 45.43% respectively of the essential amino acid compositions. However, the inedible variety had higher values of all the essential amino acids than the edible variety. The branched chain amino acids; valine, leucine and isoleucine made up 13.66g/100g (19.85%) protein of the edible variety and 15.03g/100g (19.61%) protein of the inedible variety. The sulphur-containing amino acids; methionine and cystine made up 1.61g/100g (2.34%) protein of the edible variety and 1.91g/100g (2.49%) protein of the inedible variety. The inedible variety had higher values of threonine and valine than their respective FAO/WHO/UNU reference standards. The edible variety had lower values. Both the edible and inedible varieties had higher values of leucine, isoleucine and phenylalanine+tyrosine than their respective FAO/WHO/UNU reference standard values.
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