Uvasys SO2 Sheet Dual Release Blue 4.5kg 460x350

Uvasys is the pioneer & industry leading brand of laminated plastic SO2 generating sheets throughout countries that produce, export or store Table Grapes.

Uvasys Blue is based on the original true dual release SO2 generating sheet, protecting grapes from postharvest fungal decay, particularly Botrytis Cinerea (grey mould), during storage and transport.

Uvasys Blue was specifically developed for cultivars that show a sensitivity to Sulphur burn. By lowering the concentration of SO2 released during the first stage, thin skinned cultivars such as Magenta seedless, Ralli & Flame can be safely packed.

How does it work?

• Uvasys Blue consists of a sequence of laminated plastic membranes, each bonded by a wax layer containing precise concentrations, and particle sizes, of Sodium Metabisulfite: Na2S2O5
• The top and middle plastic membranes, sandwiches the Slow Release layer
• The middle and bottom membranes sandwiches the Fast Release layer
• At 70% relative humidity an autocatalytic reaction is initiated, whereby the sheet starts releasing a time, and concentration-varying stream of SO2
• The Fast Release sterilizes the surface of the table grapes, by releasing a large enough dose of sulphur dioxide over a 24 to 48 hour period to kill and eliminate any actively growing Botrytis cinerea fungal spores
• The Slow Release layer remains active for up to 120 days, emitting a low, continual dose of sulphur dioxide gas, concentrated enough to inhibit any superficial latent or inherent Botrytis cinerea spores from growing, but also low enough to ensure sulfite residues within the table grapes remain safely below the legal limit of 10 ppm
• Infection which occurred at flowering could still develop but will be contained to the affected berry
• The quantity of SO2 emitted is critical to the efficacy of the product as an excessive release of SO2 can cause bleaching while insufficient release may not prevent the development of Botrytis
• SO2 not only protects against fungal growths but also helps in maintaining a greener stem colour
  

Instructions

• Use the Uvasys sheet recommended for the corresponding carton size; refer to the below options table.
  
• Line the carton with a perforated (ventilated) liner bag. The optimum ventilation type and size will depend on your unique combination of: Production area; Cooling systems; Post-harvest handling times; Pack type (loose, punnets, carry bag, etc.)
• Fold open the liner bag once correctly positioned inside the carton. Please note: Uvasys needs a minimum of 75% Relative Humidity to activate and using a liner bag will also limit moisture loss.
• Place grapes inside the liner bag. Punnets (heat sealed or open top), clamshells, Zip-lock bags, polycote bags, carry bags or loose packed grapes may be used.
• NB: When using open top punnets please ensure a minimum of 10 mm headroom. If this is not achievable, please use tissue paper (25g or higher) beneath the Uvasys sheet or make use of side-ventilated punnets.
• Place the Uvasys sheet on top of the grapes, with the printed (shiny) side facing away from the grapes. (We recommend not to cut or modify the sheet)
• Use a MAM on top of the Uvasys sheet if you are expecting excessive condensation.
• Fold the plastic liner, back, over the content of the carton, close and cool to storage temperature (-0.5 ℃) as soon as possible.