Evaluation of sulfur dioxide-generating pads and modified atmosphere packaging for control of postharvest diseases in blueberries

Authors: Saito, Seiya; Xiao, Chang-Lin

Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2016
Publication Date: 11/26/2017
Citation: Saito, S., Xiao, C. 2017. Evaluation of sulfur dioxide-generating pads and modified atmosphere packaging for control of postharvest diseases in blueberries. Acta Horticulturae. 1180:123-128. https://doi.org/10.17660/ActaHortic.2017.1180.17.
DOI: https://doi.org/10.17660/ActaHortic.2017.1180.17

Interpretive Summary: Postharvest fruit rots are a limiting factor of storage and shelf life of blueberries. Gray mold caused by the fungus Botrytis cinerea is one of the most important postharvest diseases in blueberries grown in California. In this study, we evaluated the effectiveness of sulfur dioxide (SO2)-generating pads (designated as Dual or Slow release pads) alone or in combination with modified atmosphere packaging (MAP) for control of gray mold and other diseases. Freshly harvested fruit were placed in clamshells in cardboard boxes, the treatments were applied, and the fruit were then stored at 1°C for 5 weeks. We found that on the fruit treated with the Dual pad, no gray mold was observed on the inoculated fruit, thus no spread of gray mold. Although gray mold developed on the inoculated fruit treated with Slow pad or MAP bag alone, gray mold spread was significantly reduced compared to the control. Incidence of decayed fruit was significantly reduced with either Dual or Slow pad, especially in combination with MAP bag, compared to the control. However, more than 20% of blueberries treated with Dual pad exhibited bleaching due to SO2 injuries, and fruit became significantly softer than those treated with Slow pad or control. Our results suggested that the combination of Slow pad and MAP bag is a promising method for control of fruit decay while maintaining blueberry fruit quality during storage.

Technical Abstract: Postharvest diseases are a limiting factor of storage and shelf life of blueberries. Gray mold caused by Botrytis cinerea is one of the most important postharvest diseases in blueberries grown in California. In this study, we evaluated the effects of sulfur dioxide (SO2)-generating pads (designated as Dual or Slow release pads) alone or in combination with modified atmosphere packaging (MAP) on gray mold and other diseases and fruit quality. Freshly harvested fruit were placed in clamshells in cardboard boxes. In each box, 6 clamshells in which one single fruit pre-inoculated with B. cinerea was placed in the center of the clamshell were used to evaluate the treatment effects on the fruit-to-fruit spread of gray mold, and the remaining 6 clamshells without pre-inoculated berries were used to examine natural infection. All clamshells together in each box were then wrapped with either a regular liner or MAP bag. There were three replicates for each pad and bag combination. Fruit were stored at 1°C for 5 weeks. On the fruit treated with the Dual pad, no gray mold was observed on the inoculated fruit, thus no spread of gray mold. Although gray mold developed on the inoculated fruit treated with Slow pad or MAP bag alone, gray mold spread was significantly reduced compared to the control. Incidence of decayed fruit was significantly reduced with either Dual or Slow pad, especially in combination with MAP bag, compared to the control. However, more than 20% of blueberries treated with Dual pad exhibited bleaching due to SO2 injuries, and fruit became significantly softer than those treated with Slow pad or control. Our results suggested that the combination of Slow pad and MAP bag is a promising method for control of fruit decay while maintaining blueberry fruit quality during storage.