Determination of selected physical properties of some varieties of onions in Nigeria

Abstract

Polar and equatorial diameters, thicknesses, arithmetic mean diameters, frontal surface, cross sectional and total surface areas,  sphericities, shape indexes, roundnesses, true and bulk densities, porosities and rolling angles on two surfaces of five varieties of  popularly cultivated onions in Nigeria were determined. Analysis of variance (ANOVA) at 1 and 5% level of significance and least  significant difference at 5% level probability were used to compare the data. The equatorial diameter, polar diameter and thickness for  Light Red onion were the largest among the varieties evaluated and gotten as 6.53 ± 0.94, 5.12 ± 0.59 and 2.53 ±0.24 cm respectively. The  ari thmetic and geometric mean diameters of White onion were 4.36 ± 0.42 and 4.0 ± 0.34 cm respectively; those of Red Creole were 4.42  ± 0.40 and 4.11 ± 0.33 cm and those o f Dark Red onions are 4.48 ± 0.48 and 4.18 ± 0.38 cm accordingly. Brow n onion had the least frontal,  cross-sectional and total surface areas of 17.74 ± 3.43, 12.52 ±2.28 and 27.60 ± 3.99 cm² respectively. All the varieties evaluated  were oval with shape index range of 1.65 ± 0.21 to 1.87 ± 0.21. The solid densities wer e obtained as 0.94 ± 0.04, 0.91 ± 0.0, 1.07 ± 0.08, 0.95  ± 0.04 and 0.95 ± 0.06 for Red Creole, Brown, Dark Red, White and Light Red varieties of Nigerian onions respectively. Rolling angles of the varieties ranged from 25 ± 2˚ to 29 ± 1˚ and 30.7 ± 1.5˚ to 33.7 ± 2.1˚ on galvanized steel and plywoo d surfaces respectively. The ANOVA  showed that the thicknesses, total surface areas, solid densities, and rolling angles on galvanized sheet and plywood were not significant  for the varieties while all other evaluated parameters were highly significant.