Association of SO-Generating Pads before Packaging and during Cold Storage to Extend the Conservation of 'Italia' Table Grapes.

The SO-generating pads contain different concentrations of sodium metabisulfite, which absorbs water from the grapes' transpiration, releasing SO gas, and there are slow-(SlowSO) and dual (DualSO)-releasing pads (fast release in the first 48 h and slow for up to 60 days). The ultra-fast SO-generating pad (FieldSO) releases the SO quickly for up to 6 h, and it was designed to be used soon after the harvest and until the grapes' packaging. The goal was to study the effect of FieldSO associated with SlowSO and DualSO pads on gray mold incidence and physicochemical and appearance characteristics of 'Italia' table grapes. Grapes were harvested from a commercial vineyard in Parana, Brazil, in 2020 and 2021, and packaged in cardboard boxes, and the treatments were as follows: control (without SO-generating pads); FieldSO + SlowSO; and FieldSO + DualSO. After 30, 45, 60, 75, and 90 days of cold storage (1 ± 1 °C), the grapes were assessed for gray mold incidence, mass loss, shattered berries, stem browning, and filamentous fungi on the surface. The use of FieldSO associated with SO-generating pads is effective in controlling gray mold on 'Italia' table grapes, especially the treatment FieldSO + DualSO, which provides the lowest incidence of the disease up to 90 days of cold storage, while the combination with SlowSO results in intermediate efficacy. Treatments combining these SO-generating pads extend the postharvest shelf life of 'Italia' grapes, with few shattered berries, low mass loss and freshness of the rachis without impairing the bunch's appearance.