Nutritive Value of Nigerian Tigernut (Cyperus Esculentus L.)

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 MeqO2/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 characteristic

Phytochemical Composition and the Effects of Aqueous Extract of Tigernut Tuber on the Haematology and Serum Biochemistry of Albino Rats

The phytochemical composition of the tigernut tuber was determined and the effects of its aqueous extract on haematological and biochemical parameters were determined in rats administered different concentrations of the extract. The presence of alkaloids, cyanogenic glycosides, resins, tannins, sterols, and saponins were observed in the raw tuber, however only alkaloids, sterols and resins were observed in the roasted tuber. Analysis of the antinutrient composition yielded oxalates (0.25±0.65 g/100g), phytate (1.97±0.81 mg/100 g), saponins (0.88±0.02 g/100 g), tannins (9.50±0.46 mg/100 g) and cyanogenic glycosides (1.80±0.69 mg/100g). Roasting numerically decreased the levels of the anti-nutritive factors analysed. At the end of the treatment period, the mean weights of the animals increased. The blood glucose level decreased significantly in concentration dependent manner (p<0.05), while serum albumin level increased significantly in a concentration dependent manner (p<0.05) in the groups administered the different concentrations of the extract. There was no significant effect (p>0.05) on serum cholesterol and protein and on total and differential white blood cell, red blood cell, haemoglobin, packed cell volume, and erythrocyte sedimentation rate. The results therefore indicate the absence of undesirable effect in the use of the tigernut tuber even in the raw form at least at the administered concentration and for the duration of feeding. These findings are of nutritional, health and industrial relevance since the tuber is currently being used as food in many homes in Nigeria.     &nbsp

The Role of Rubber Seed Lipoxygenase in the Quality Restoration of Stored Lesser Yam

Partially purified rubber seed lipoxygenase was used to bleach lesser yam tubers (Dioscorea esculenta) that were browned by storing the cut yam tubers at room temperature. There was increase in the bleaching of polyphenols extracted from the browned yam tubers as the enzyme concentration and time of the incubation of the enzyme were increased. Moreover, there was increase in the bleaching of the browned yam tubers as the enzyme concentration was increased. The browned yam tubers were completely bleached to their original yellow colour at the enzyme concentration of 15 unit /ml. Key Words: Rubber seed, lipoxygenase, lesser yam Bio-Research Vol.2(2) 2004: 15-1

Lecithin extraction and characterization from melon seeds obtained from Nigeria

Melon seed oils from different agricultural zones of Nigeria were sampled. Oils were extracted using soxhlet extraction techniques, characterized and lecithin extracted using standard biochemical methods. The percentage oil yield was higher when n-hexane solvent system was used than when  chloroform/methanol solvent system was used. Physico-chemical characteristics of the oils indicated that they were all yellow coloured, and had varied viscosity and specific gravities. The percentage yield of lecithin extract was low in all the melon samples when compared to soya bean