Nutritive Value of Nigerian Tigernut (Cyperus Esculentus L.)

Abstract

The proximate, mineral, vitamin and amino acids composition of tigernut (Cyperus esculentus) flour were determined using standard analytical techniques. The physicochemical characteristics of the oil were also investigated. The proximate composition of the raw tubers was, crude protein (8.07±0.37%), crude fat (24.3±0.58%), crude fiber (24.0±1.58%), ash (1.80±0.10%) and carbohydrate (30.0%), while that of the roasted tubers was, crude protein (6.80±0.89%), crude fat (25.2±0.10%), crude fiber (23.3±0.58%), ash (1.78±0.10%), and carbohydrate (31.7%). The minerals (mg/100g) of the raw tubers included sodium (34.13±1.53), calcium (100.0±2.65), iron (4.12±0.10), zinc (3.98±0.31), potassium (486.0±59.9), magnesium (94.4±1.28), copper (0.92±0.05), manganese (0.26±0.01) and phosphorus (219.0±10.0). The roasted tubers on the other hand contained (mg/100g) sodium (34.1±1.44), calcium (99.9±2.86), iron (4.11±0.26), zinc (3.96±0.50), magnesium (96.0±0.68), copper (0.88±0.15), manganese (0.30±0.02) and phosphorus (217.0±12.1). The vitamins (mg/100g) in the raw tubers included vitamin A (0.21±0.01), vitamin C (7.30±0.97), vitamin D (0.42±0.02) and vitamin A (0.21±0.01), while the roasted tuber contained vitamin A (0.20±0.01), vitamin C (4.59±0.09), vitamin D (0.41±0.01) and vitamin E (0.57±0.10). Amino acid analysis revealed that tigernut flour contained nutritionally important essential amino acids though in small quantities. The first and second limiting amino acids were leucine (0.07) and lysine (0.08). The result of the physicochemical properties of the tigernut tuber oil showed the color to be golden brown, refractive index (1.464), specific gravity (0.965), acid value (0.81±0.03 mgKOH/g), saponification value (210.15±1.67 mgKOH/g), iodine value (89.33±1.46 mgIodine/g), peroxide value (1.01±0.01 MeqO_2/kg), free fatty acids (0.41 mg/g), ester value (209.34 mgKOH/g). These values indicated that the tuber oil is edible, non-drying and suitable for soap making.

Keywords: Tigernut, Cyperus esculentus, nutritive composition, physicochemical characteristics