Drying time and post-harvest quality of onion bulbs submitted to artificial curing

Tempo de secagem e qualidade pós-colheita de bulbos de cebola submetidos à cura artificial

ABSTRACT

After harvest, onion bulbs are submitted to curing, whose objective is to provide loss of moisture in leaves and drying of outer layers (peel) of bulbs, reaching attractive external coloration and reduction in the intensity of rottenness. The objective of this study was to use an air treatment unit (ATU) - known as heat pump - as an alternative drying method, and to evaluate drying time and preservation of the chemical and physical characteristics. The experiment was carried out in a complete random design with ten replicates and three treatments, which were the following: T_1- (control) natural curing in shed; (2) T_2- (aeration with air artificially heated by propane burning); and (3) T_3- (aeration with artificially dehydrated and heated air using ATU). Curing completion time, relative water content (RWC) of the skin and inner layers, pulp color and skin coloring, total titratable acidity (TTA), total soluble solids (TSS), visual index of dormancy breaking (VID), and fresh weight loss (FWL) were evaluated in this study. No significant difference (p < 0.05) were found for TTA, TSS, VID, FWL, and pulp color among treatments. It can be concluded that T₃ promoted a faster curing (12 hours) of bulbs, which provided bulbs with drier skin and intense yellow color.

Key words:
Allium cepa; chemical and physical characteristics; drying methods; heated air