No abstract

Potato (Solanum tuberosum) is a popular staple food in South Africa, whereas cocoyam (Colocasia esculenta) remains unpopular and not well known outside KwaZulu-Natal Province, where it is cultivated mainly for subsistence. A comparative study of the nutritional compositions of commercially available tubers of both crops in South Africa was carried out. The results showed that the tubers of the two crops were high in carbohydrate and energy but low in lipid contents. Although potato was significantly higher in moisture and ash than the tubers of cocoyam, carbohydrate, caloric and crude protein contents were not significantly different (P < 0.05) in both tubers. Whereas boiling improved the availability of crude protein, fiber and lipid contents for both species, boiling reduced the ash contents in the tubers of both crops. Manganese levels were not detectable, whereas iron contents were appreciably high, but magnesium and copper contents were in the average range in both tubers. Whereas cooking reduced iron level in potato (11.20-9.95 mg/100 g DM), a significant increase in iron was observed for cocoyam . Cooking significantly lowered magnesium, potassium and copper contents in both crops. Oxalates and phytate contents were significantly higher in cocoyam when compared with potato. Cooking remarkably reduced the anti-nutrient contents of both tubers.3 Corresponding

Colocasia esculenta (L.) Schott (cocoyam) is cultivated mainly for its edible tubers. The effect of cooking the tubers on the proximate composition of seven accessions (UFCe1-UFCe7) of the crop growing in South Africa was investigated. When compared with the uncooked, the ash and crude fibre contents of the accessions significantly decreased after cooking. The moisture content, crude protein, crude lipid, carbohydrate and caloric contents increased with cooking in all the accessions, except UFCe1 and UFCe5 where the crude lipid content reduced. The results indicate that cooking enhanced the carbohydrate, energy and protein contents of the tubers. They further showed that the tubers could be used for allergic infants, old people and invalids since the fibre contents were still appreciably high despite the slight reduction after cooking the tubers.

The liver and kidney functional indices of weanling albino rats (Rattus norvegicus) maintained on different accessions (offspring of a variety planted/collected at a specific location and time but differing in certain morphological characteristics) of cooked Colocasia esculenta (cocoyam)-based diets (UFCe1-UFCe7) for 28 days were investigated. All the accessions of C. esculenta-based diets did not significantly (P > .05) alter the serum levels of albumin, globulin, inorganic phosphorus, calcium, magnesium, and uric acid of the animals.The total protein and total bilirubin levels decreased only in the UFCe3- and UFCe4-fed animals, respectively. Whereas UFCe1 and UFCe2 significantly decreased the conjugated bilirubin levels, UFCe3 and UFCe6 increased it. While all the accessions of C. esculenta-based diet decreased the serum alkaline phosphatase activity, γ-glutamyl transferase activity was increased. UFCe1 and UFCe5 increased the serum alanine aminotransferase activity, whereas UFCe4 decreased the activity of the enzyme. Again, UFCe3 and UFCe1 increased the serum creatinine and aspartate aminotransferase activity of the animals. Furthermore, the computed blood urea nitrogen:creatinine ratio was higher in animals maintained on UFCe1-, UFCe3-, UFCe4-, and UFCe5-based diets. Whereas UFCe6 and UFCe7 increased the level of sodium in the serum of the animals, UFCe4 and UFCe5 decreased the chloride level. The serum urea level was decreased by UFCe1, UFCe3, UFCe4, and UFCe5, whereas the potassium level increased in the UFCe4-, UFCe6-, and UFCe7-fed animals. Overall, the results revealed that all the accessions of C. esculenta produced selective effects on the hepatic and renal functional indices of the weanling rats. The highest alterations were produced by UFCe4, whereas the least was from UFCe2. These alterations may have consequential effects on the normal functioning of the liver and kidney of the animals. UFCe2 exhibited the least toxicity risk among the accessions of C. esculenta growing in the KwaZulu-Natal Province of South Africa.

No abstract