Abstract
We investigated the characteristics of onion bulbs in relation to workability and productivity of peel processing. In this study, we peeled onions by cutting off the top and bottom of the bulb and then peeling away the outer skin. Peeled and unpeeled bulb weights were strongly correlated, but the working times for peeling onions did not relate to any specific traits. It is considered that heavy bulbs improve workability in peel processing of onion and that a greater yield of product could be achieved within a given time by using heavy bulbs. However, model analysis of the peel processing yield of onion using a formula for a spheroid showed that, peel processing yield correlated only with bulb height; therefore, the productivity of peeling onions are improved by using bulbs with a greater height. Prediction equations of peel processing yield are derived from model analysis using the formula for a spheroid. Estimates based on prediction equations for an independent two-year study using several varieties have fit well with the experimental data and we concluded that the prediction equations obtained can be used to evaluate the peel processing yield of onion cultivars. We can evaluate the peel processing yield of onion varieties without actually peeling them, which allows efficient selection and breeding of onion varieties for the processing of peeled onions.
