Antinutrient and micronutrient contents in leaves of Telfairia occidentalis Hook.f.: The effects of cooking and sun drying

Abstract

Levels of some antinutrients, namely, cyanide, nitrate, and oxalate and some micronutrients including vitamin C,

βâ€Âcarotene (provitamin A) and some mineral elements (Fe, Mg, Cu, Zn, Ca Na and K) were determined in fresh and processed samples of Telfairia occidentalis Hook.f. as a step towards establishing processing techniques that would reduce or eliminate unacceptable levels of antinutrients and the associated health problems. The processing methods used were cooking (5 and 10 min boiling) and sun drying. There was significant (p< 0.05) reduction in the levels of these phytotoxins. The cyanide levels in the variously processed samples were: fresh sample (170.83mg/kg), 5 min decoction (36.98mg/kg), 10 min decoction (44.87mg/kg), leaves boiled for 5 min (49.88mg/kg), and leaves boiled for 10 minutes (34.68mg/kg), and sundried leaves (94.74mg/kg). Vitamin C content was significantly (p< 0.05) reduced, the levels being 192.28mg/100g, 1.51mg/100g, 2.16mg/100g, 53.70mg/100g, 35.60mg/100g and 13.15mg/100g in fresh sample, 5 min decoction, 10 min decoction, leaves boiled for 5 min, leaves boiled for 10 min, and sundried sample respectively. βâ€Âcarotene content was elevated in the cooked vegetable, while its content decreased in sundried samples. However, cooking beyond 5 min led to significant (p < 0.05) reduction in β†carotene levels in the vegetable. Sun drying had no significant effect on Fe, Cu, Mg, Na and K in the vegetable. Cooking however, led to decreases in the levels of these minerals. It is concluded that moderate cooking and sun drying reduced the levels of the studied antinutrients in T. occidentalis without adversely compromising the micronutrient contents.