Influence of Blanching on the Mechanical Properties of Solar Dried Aerial Yam and Water Yam

Abstract

This work focuses on the influence of hot water blanching on the mechanical properties of solar dried aerial yam and water yam. This was done by solar drying some blanched and unblanched water yam and aerial yam at the same condition. The shear stress, hardness, modulus of elasticity, compressive strength, deformation at break, bio-yield, rupture energy, gumminess of the blanched water yam (BWY), unblanched water yam (UWY), blanched aerial yam (UAY) and blanched aerial yam (BAY) were determined using standard methods. The results show that blanching increased the shear strength of water yam from 3.094 to 3.536 N/mm2 and from 4.739 to 4.86 N/mm2 for aerial yam. Blanching decreased the hardness, rupture energy, modulus of elasticity and compressive strength of water yam and aerial yam. Bio-yield force increased on blanching from 262.5 to 304.5 N for water yam and decreased from443.5 to 231.5 N for aerial yam. The deformation at break increased for water yam on blanching but decreased for aerial yam on blanching. Gumminess also showed increase in value for both yams on blanching. The research result provides a theoretical basis and generated data for design of dryers and the material processing and handling.