Effect of gaseous chlorine dioxide (ClO2) with different concentrations and numbers of treatments on controlling berry decay and rachis browning of table grape

Chlorine dioxide (ClO2) gas was used to control berry decay and rachis browning of table grape due to its antimicrobial and anti-browning properties. It was proposed that if ClO2 gas is fully absorbed by the fruit, the maximum total ClO2 dose can be calculated based on the maximum allowable residual concentration. To avoid possible bleaching effects on grape peel from high concentrations of ClO2, the total amount of ClO2 gas needs to be injected into the packages in many small doses at specific time intervals over the course of the 90-day storage period. Spoilage microorganism counts, decay rate, electrolyte leakage, rachis browning and residual ClO2 in berry were investigated. The results showed that ClO2 treatment could significantly reduce berry decay and rachis browning (p ≤ .05) compared to the control. Grape treated with 1.0 mg L−1 ClO2 6 times at 15-day intervals maintained better fruit quality without any risks from the residual ClO2. Practical applications The present research found that ClO2 treatment is useful for improving the microbial safety of grapes and reducing berry decay and rachis browning during storage, and low doses of ClO2 spread over many treatment can yield better results.