A: SO₂ is a typical food-grade antimicrobial agent. During fruit storage, it exerts strong fungicidal and growth-inhibitory effects on fungi, effectively reducing postharvest decay and softening in berries such as grapes and blueberries caused by Botrytis cinerea, Penicillium spp., Alternaria spp., and Fusarium spp.
A: The pad should be applied in the packing room after the pre-cooling. It is important to control the temperature difference between the pre-cooled blueberries and the packing room environment. Excessive temperature differences can cause condensation during packing, which increases the risk of mold infection and SO₂ injury.
A: Whether to use absorbent paper depends on the packaging format. When an case liner is used, it is recommended to include absorbent paper. The absorbent paper helps regulate humidity inside the bag, preventing excessive condensation that can lead to decay and SO₂ injury. When the FreshShield SO₂ pad is placed outside the PET clamshell and the entire pallet is wrapped with a tray cover, absorbent paper is not required.
A: The dual-release SO₂ Pad features a two-stage release profile: a fast-release layer (completing release within 24–48 hours) and a slow-release layer (providing effective release for up to 30 days). The fast-release pad has only a single fast-release stage.
A: Store FreshShield SO₂ pads in their original sealed bag and carton. Keep the storage temperature below 25°C, relative humidity below 70% RH, ensure a dry environment, and avoid direct sunlight.
A: Unused FreshShield SO₂ pads should be promptly returned to the sealed bag, and the zip seal should be tightly closed to prevent ambient moisture from activating the pad, which would cause the product to lose effectiveness.
A: Yes. SO₂ is approved as a food additive for postharvest use on grapes and blueberries. In China, products are compliant for domestic sale as long as the Maximum Residue Limit (MRL) remains within 50 ppm. For most export markets, compliance is achieved when the MRL is kept within 10 or 9 ppm.