SIZE AND SHAPE CHARACTERISATION OF TACCA INVOLUCRATA TUBERS

Abstract

Physical properties of crops are useful for proper design of processing machines and handling equipment. This study was designed to determine selected size and shape characteristics of tacca tubers using standard procedures. The physical characteristics determined include geometrical attributes, gravimetric properties and shape indicators. Length, width, thickness, Arithmetic Mean Diameter, Geometric Mean Diameter and Equivalent Mean Diameter of tacca tubers ranged from 34.81-114.24, 20.05-94.58, 22.48-87.81, 29.72-97.92, 28.82-97.36 and 29.51-97.38 mm, respectively. Projected areas along the three mutually-perpendicular axes ranged from 6.03-80.35, 5.89-61.48 and 8.40-82.79 cm2 respectively. Surface area and criterion area ranged from 26.10-297.88 and 6.77-74.87 cm2 respectively. Mass, volume and density ranged from 14.80-566.40 g, 13.00-460.00 cm3 and 915.15-2,625.00 kg/m3 respectively. Shape characteristics namely sphericity, aspect ratio, shape index, eccentricity and elongation ratio ranged from 60.32-99.03%, 0.52-0.99, 1.01-2.47, 0.11-0.85 and 1.01-1.91 respectively. Volume of the assumed ellipsoid shape was closer to the actual volume, indicating that tacca tubers are closer to being ellipsoidal in shape. The study has provided information that could serve as a guide in the design of systems for sorting, processing and handling tacca tubers.