Proximate Composition and Amino Acid Profile of Raw and Cooked Black Variety of Tiger nut (Cyperus esculentus L.) Grown in Northeast Nigeria

Abstract

Tiger nut (Cyperus esculentus L.) is an underutilized tuber of family Cyperaceae which produces rhizomes from the base of the tuber that is somewhat spherical. The three varieties of yellow, brown and black tiger nut are grown in Nigeria. Proximate and amino acid compositions of raw and cooked black variety of Cyperus esculentus were investigated using standard analytical techniques. The respective proximate composition values (%) for the raw and cooked samples were: Moisture (3.73 and 4.66), ash (2.57 and 3.38), crude fat (8.94 and 9.92), crude protein (12.09 and 9.25), crude fibre (7.02 and 4.52), and carbohydrate (65.66 and 69.29). The calculated fatty acids and metabolizable energy for the raw and cooked samples were 7.15 and 7.94%; 1652.53 and 1702.22 kJ/100g, respectively. The values of metabolizable energy in this study showed that both samples have energy concentrations more favourable than cereals. The amino acid profile revealed that raw and cooked samples of Cyperus esculentus contained nutritionally useful quantities of most of the essential amino acids with total essential amino acid (TEAA) (with His) were 45.69 and 48.25%, respectively. The value of predicted protein efficiency ratio (P–PER) for the raw tuber was 2.77, the value is higher than the reported P–PER values of some legumes in the literature. However, essential amino acid supplementation may be required in Ile, Leu, TSAA and Val when comparing the EAA in this report with the recommended FAO/WHO provisional pattern. The limiting EAAs in the raw and cooked Cyperus esculentus tuber were Leu and TSAA, respectively.

Keywords: Proximate, amino acids, tigernut