Modified atmosphere in preserving the quality of 'Thompson Seedless' grapes and reducing Aspergillus rot

There is a demand in Submédio São Francisco, a semiarid grape producing region in Brazil, for sustainable measures to control postharvest diseases, since the current model of coating boxes with high density polyethylene, associated with sodium metabisulfite, has not been effective in controlling fungi occurring in this region. The aim of this study was to evaluate the control of Aspergillus rot in 'Thompson Seedless' grapes by modifying the atmosphere, using polyamide bags to cover the grape boxes. Polyamide (PA) bags were compared with high density polyethylene (HDPE) bags, commonly used in this region, combined or not with sodium metabisulfite (SO2). Fruits from a commercial area, after being selected and disinfested, were wounded with an entomological pin and inoculated with a suspension of Aspergillus niger at a concentration of 10(6) conidia mL-1 and then kept in a wet chamber for 24 hours. After that, grape boxes were placed in specific bags according to the treatment and stored at temperature of 2º C and relative humidity of 75% for 40 days. From the 12th day of storage, the incidence of the disease and the physico-chemical variables: mass loss, total soluble solids (TSS), pH, titrable acidity (TA), ratio (TSS / TA); peroxidase (POD) and measurement of the concentrations of CO2 and O2 were weekly evaluated until the 40th day. The experimental design was completely randomized in split plot with five replicates. The covering of grape boxes with polyamide bags, even without the use of sodium metabisulfite, showed to be a viable alternative for maintaining the postharvest quality of grapes 'Thompson Seddless', as well as for reducing rot caused by A. niger. The enzyme peroxidase may have acted in the process of maintaining fruit quality, contributing to a reduction in the level of the disease in grapes.

postharvest disease; alternative control; polyamide