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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Citrus and Other Subtropical Products Research » Research » Publications at this Location » Publication #327870

Research Project: Quality, Shelf-life and Health Benefits for Fresh, Fresh-cut and Processed Products for Citrus and Other Tropical/Subtropical-grown Fruits and Vegetables

Location: Citrus and Other Subtropical Products Research

Title: The effect of controlled-release ClO2 on the preservation of grapefruit

item SUN, XIUXIU - University Of Florida
item Baldwin, Elizabeth - Liz
item Ference, Christopher
item NARCISO, JAN - Retired ARS Employee
item Plotto, Anne
item Bai, Jinhe
item RITENOUR, MARK - University Of Florida
item HARRISON, KEN - Curoxin, Llc
item GANGEMI, DAVE - Curoxin, Llc

Submitted to: Florida State Horticultural Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/8/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The effect of controlled-release ClO2 gas on the safety and quality of grapefruit was studied. Three different tests were run: 1) isolated peel tissue with microorganism inoculation in a chamber system; 2) individual fruit with microorganism inoculation in a chamber; and 3) boxed fruit under commercial conditions. For the peel tissue test, a freshly isolated healthy peel section (1 cm × 1 cm), inoculated with 20 µL of either Escherichia coli (6.28 logs) or Penicillium digitatum (6.16 logs), or a Xanthomonas citri naturally inoculated peel section (with citrus canker lesions), was incubated in a chamber containing a dose equivalent to 10, 50 or 100 mg/L of pure ClO2 as an antimicrobial agent. After 24 h, microbial growth was reduced significantly, and the lowest dosage of 10 mg/L reduced the population of E. coli, P. digitatum and X. citri by 5.83, 5.87, and 3.30 logs, respectively. The highest dosage caused tissue bleaching (phytotoxicity). The effects were confirmed on intact fruit at even lower doses. For the simulated commercial experiment, fruit were harvested in late October, passed through a commercial packing line, and packed in 4/5th-bushel boxes. ClO2 packets were attached to the top lids with the following 5 treatments: fast-release, slow-release, slow/fast-release combination (each containing 14.5 mg of pure ClO2), double dose fast-release (containing 29 mg of ClO2), and control. The highest concentrations in the headspace of the boxes at 10°C were 0.8, 0.2, 0.5, and 1.5 ppm in fast-release, slow-release, slow/fast-release combination and double dose fast-release treatments, respectively, which were reached in the initial two days. The concentrations decreased to 0.19, 0.02, 0.11, and 0.42 ppm, respectively, by day 10, and decreased to barely detectable levels after 28 days in all dosages. After 6 weeks of storage at 10°C (to simulate storage and transportation) + 1 week of storage at 20°C (to simulate retail market), the antimicrobial activity following treatment with ClO2 was analyzed. The slow-release treatment at standard dose exhibited the best antimicrobial activity, reducing total aerobic bacteria count (TBC) and yeasts/molds count (YMC) by 0.95 and 0.94 log CFU/g, respectively. Fruit were evaluated for visual quality, peel disorders (browning), stem-end rot, and sensory quality. The slow-release treatment at single dose exhibited the best visual, sensory, and overall quality.