Postharvest treatment of tomato fruit with chlorine dioxide gas: dose affects fruit quality

Michael Mahovic, Jerry A. Bartz, Adrian D. Berry, Steven A. Sargent


Chlorine dioxide (ClO2) gas shows potential as a postharvest sanitizing treatment for fresh market tomatoes. Previous tests with ClO2 applied at 1 to 2 mg kg-1 of tomato resulted in a significant reduction in recoverable bacterial populations and in the incidence of soft rot in inoculated wounds. However, treatment with 88 or 99 mg kg-1 produced bleached and sunken wounds and stem scars, whereas effects of these high treatments on the ripening or other quality factors were not recorded. Here, standard round tomatoes from three commercial harvest/handling steps (field pack of light reds, green fruit post ethylene gas treatment, and green fruit prior to the dump tank at the packinghouse) were exposed to a standard or 10 standard dose of ClO2 gas for 2 hours and were then ripened at 20C for up to 6 days to evaluate the effects of an overdose on fruit quality. By the conclusion of the 20-mg treatments, each of the stem scars appeared slightly whiter than those on the untreated controls or those treated with 2-mg. Within 24-h of storage after treatment, the bleached appearance became more evident and had progressed into the pigmented tissues beyond the corky ring around the stem scar. By contrast, stem scars on the 2-mg fruit appeared similar to those on the control fruit. Green fruit not treated with ethylene and then exposed to ClO2 at 20 mg kg-1 had an accelerated onset of ripening; all other fruit ripened similar to controls. However, the stem scars of fruit from any harvest method treated with 20 mg kg-1 ClO2 (only) were observed to have whitened immediately following treatment and, by day 6, 28% to 61% of these developed visible fungal growth. By contrast, no other detrimental changes in fruit quality could be attributed to either dose of ClO2.


Lycopersicon esculentum; decay control; phytotoxicity; sanitation

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283