Effect on `Cardinal' Grapes of Position of Sulfur Dioxide Generators and Retention of Gas and Water Vapor in Unvented Containers

Abstract

`Cardinal' grapes stored 10 weeks in unvented containers had significantly less decay and significantly more bleaching when packed with top and bottom sulfur dioxide generators than with only a top generator. Increasing the NaHSO₃ dose by adding side generators did not reduce decay further, but did increase bleaching of the fruit. Decay was less and bleaching greater with an unvented polyethylenecoated curtain than with a dry-waxed curtain. Stem drying rates were significantly lower in unvented than in the vented control containers. After 10 weeks of storage an unvented packaging system with top and bottom sulfur dioxide generators, either in a wooden lug with a water-vapor-barrier liner or in a curtain-coated corrugated container, showed a balance of decay control and bleaching injury equal to, or better than, that of the vented control. Needed for decay protection to four months, yet with bleaching within acceptable limits, are generators which release sulfur dioxide at a more constant rate than those now available.