Effect of Drying Methods on the Nutritional Composition of Some Selected Yam Varieties Cultivated in Umudike, Abia State, Nigeria
Abstract
Yams are widely grown and consumed in various forms; these tropical food crops are abundant at a particular period. Since these food crops are highly perishable after harvest, drying is a common practice for preserving them. White yam (Dioscorea rotundata) and water yam (Dioscorea alata) were collected from (National Root Crops Research Institute Umudike) yam barn. The study investigated the effect of sun-drying and oven-drying methods on the nutritional composition of water yam and white yam varieties. Oven-drying was done at 60°C for 72 hrs, while sun drying was for 3 days, until a constant weight was obtained. The functional properties, proximate composition, mineral contents and pH were determined to investigate the effect of dry methods on the nutritional value of the yam flour. It was observed that all parameter examined were affected by the dry methods as they varied in composition with two different processed samples (sun and oven dried). The result showed that the proximate composition for samples sun dried were 5.01%, 3.45%, 1.93%, 0.65% and 85.63%, while samples oven dried were 6.46%, 1.23%, 2.26%, 1.60%, 0.77% and 87.35% respectively. Bulk density, water absorption capacity, oil absorption capacity, swelling power and gelation temperate for samples sun dried were 0.66%, 3.54%, 2.73%, 4.22% and 70.58b% respectively. The results of the experiment shows that sun dried yam flour retained the highest value in protein, ash, fiber, CHO and bulk density, and also in minerals (Ca, Mg and P), compared to oven dried method except moisture content which had a higher value than samples sun dried. Therefore, sun dried yam flour had the highest value, thereby retaining the best nutritional composition of the samples.
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