Effects Of Different Processing Methods On The Nutritional Anni) Anti-Nutritional Composition Of Three Different Cultivars Of Dioscorea Bulbifera.

ABSTRACT

Dioscorea bulbfera (aerial yam) popularly called 'edu' by igbo speaking people of Nigeria was evaluated in this study for their nutritional and anti -nutritional qualities. Three different cultivars of Dioscorea bulbfera (yellow, green and red) were evaluated by giving them four different treatments (the control was the raw un-treated sample (no treatment), boiling, soaking and roasting). The study reveals the proximate composition, mineral composition, vitamins and anti-nutritional properties of the yam, treatments like soaking, boiling and roasting and their effect on changes in the nutritional composition were also quantified. The study reveals that each treatments had a different effect on each cultivar, some nutritional composition increased while some reduced depending on the treatment given. Mostly, the toxic principles reduced after boiling. Generally, the yams have high nutritional content and the greatest nutritional content can be gotten with the adequate treatment for each cultivars. The proximate composition are as follow; Moisture (8.29%, 7.17,% 7.72%), Crude protein,(7.28%, 9,63%, 6.83%), Ash,(2.52%, 3.78%, 3.98%), Ether extract(4.16%, 0.36%, 2.21%), Crude flber(2.16%, 1.64%, 1.88%), and carbohydrate (76.41%, 77.13%, 77.40%) for yellow green and red cultivars respectively. The red cultivar had the highest vitamin A content (700.89mg/bOg) which is significantly higher than the vitamin A content of the green and yellow cultivars (443.91mg/bog and 137.24mg/bOg respectively). The yellow cultivar had the highest vitamin C content (0.26mg/lOOg), followed by the green cultivar 0.13mg/bOg and the red cultivar had the least vitamin C content (0.O4mg/g). The mineral content evaluated were manganese, potassium, sodium and iron. The yellow cultivar had the highest potassium content (667.53mg/bOg), the red variety had the highest manganese and sodium content (loomg/lOog and 2403mg/bOg). Boiling, soaking and roasting significantly reduced the anti-nutritional content of the three cultivars. Boiling reduced the oxalate content more than roasting and soaking 0.22 to 0.11mg/l0Og,0.19 to 0.1mg/bOg and 0.18 to 0.008mg/bOg for the green red and yellow cultivars respectively. The saponin content of the red cultivar was greatly reduced by boiling from5.46 to 1.20mg/bOg. Amongst all the treatments given, boiling had the highest significant reduction on the anti-nutritional composition of the three cultivars.