Progress 10/01/05 to 09/30/06
Outputs
Chlorine dioxide gas can be applied to tomato fruit at a dose based on the weight of fruit treated. Effective doses dissipate within the treatment chamber by the end of 2 or 24 h depending on the treatment. As such, the chamber does not require purging to remove unreacted gas. The cardboard carton used for tomato fruit is a chlorine dioxide sink. Treatments of tomatoes in such cartons show reduced efficacy.
Impacts
Chlorine dioxide gas can be used on packaged fruit but either the cardboard container or the way the gas is delivered will need to be changed because too much gas is lost to reaction with the cardboard surfaces.
Publications
- Mahovic, M.J., J.A. Bartz and K.R. Schneider. 2006. Chapter 5: Controlling biotic factors that cause postharvest losses of fresh market tomatoes. In: Janick, J (ed.). Horticultural Reviews. Vol. 33. pp. XX-XX, John Wiley & Sons, Inc., NY (in press)
- Bartz, J. A., Mahovic, M. J., and Tenney, J. 2006. Chlorine dioxide gas controls postharvest pathogens of tomato by mass transfer from a source to the fruit Phytopathology 96:S9.
- Felkey, K., Archer, D. L., Bartz, J. A., Goodrich, R. M. Goodrich, and Schneider, K. R. 2006. Chlorine disinfection of tomato surface wounds contaminated with Salmonella. HortTech. 16: 253-256.
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Progress 10/01/04 to 09/30/05
Outputs
Chlorine dioxide gas generated from either a mixture of dry ingredients or by off-gassing from a solution was used to inactivate soft rot bacteria in wounds on tomato fruit. At a ratio of approximately 2.0 mg chlorine dioxide to 1 kg of tomato fruit, soft rot was prevented or greatly reduced at 6 x 1 sq cm wounds on green tomato fruit. Tomato box material reacts with chlorine dioxide and, is a irreversable sink. Free moisture absorbs chlorine dioxide but is a reversible sink since the gas comes back out of the solution as the headspace concentrations decrease. Water channels in the surface of tomato fruit enable water soluble dyes or bacterial suspensions to readily internalize.
Impacts
Chlorine dioxide gas has potential to eliminate gram negative bacteria from fresh wounds on tomato fruit. Processes that lead to water congestion of openings in a tomato fruit surface enable ready internalization of particular matter including bacteria.
Publications
- Bartz, J.A. and J.W. Scott. 2005. Water infiltration and postharvest problems in tomato fruit. Florida Tomato Institute Proceedings pp. 20-23. (Gilreath and W.M. Stall, eds.) PRO 522. University of Florida/IFAS Extension and Citrus & Vegetable Magazine. Bartz, J. A., Mahovic, M., and Tenney, J. 2005. Chlorine dioxide as a postharvest sanitizer: Reversible in irreversible sinks. (Abstr) Phytopathology 95:S7.
- Mahovic, M., Bartz, J. A., and Schneider, K. 2005. Some factors affecting infiltration of water into tomato fruit. (Abstr.) Phytopathology 95:S64.
- Bartz, J. A. 2006. Internalization and infiltration. pp. 75-94. In: Microbiology of Fruits and Vegetables. G. M Sapers, J. R. Gorny, and A. E. Yousef, (eds). CRC Taylor and Francis LLC, Boca Raton, FL
- Nunes, M. C. N., Morais, A.M.M.B., Brecht, J. K., Sargent, S. A., and Bartz, J. A. 2005. Prompt cooling reduces the incidence and severity of decay caused by Botrytis cinerea and Rhizopus stolonifer in strawberry. HortTechnology 15:153-156.
- Yuk, H.-G., Bartz, J. A., and Schneider, K. R. 2005. The Effectiveness of Individual or Combined Sanitizer Treatments for Inactivating Salmonella spp. on Smooth Surface, Stem Scar, and Wounds of Tomatoes. J. Food Sci. 70:M409-M414.
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Progress 10/01/99 to 09/30/05
Outputs
OUTPUTS: Chlorine dioxide gas generated from either a mixture of dry ingredients or by off-gassing from an aqueous solution was used to inactivate soft rot bacteria in wounds on tomato fruit. At a ratio of approximately 2.0 mg chlorine dioxide to 1 kg of tomato fruit, soft rot was prevented or greatly reduced at 6 x 1 sq cm wounds on green tomato fruit. Tomato box material reacts with chlorine dioxide and, is a irreversable sink. Free moisture absorbs chlorine dioxide but is a reversible sink since the gas comes back out of the solution as the headspace concentrations decrease. Water channels in the surface of tomato fruit enable water soluble dyes or bacterial suspensions to readily internalize. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Target audience includes the producers and packers of tomatoes as well as the marketing chain for fresh market tomatoes. The impact of this reseach reduces both decay and food safety hazards in fresh tomato products. Additionally, the methods devised can be applied against other fresh fruits and vegetables. PROJECT MODIFICATIONS: At the onset of this project, we were unware of the technology for producing low amounts of chlorine dioxide on a continuous basis. Once this technique was introduced, the project changed focus from mostly investigation of various liquid sanitizers and if they were a viable alternative to chlorine, to an investigation of chlorine dioxide gas.
Impacts
Chlorine dioxide gas has potential to eliminate gram negative bacteria from fresh wounds on tomato fruit. The gas is strictly an oxidizer and does not chlorinate compounds in reactions. As a consequence, it is not as corrosive as chlorine and does not produce hazardous disinfection by products such as halomethanes. The dry material technology is a much safer way to produce the gas since potentially explosive concentrations cannot be produced. Treatment involves an incremental damage to exposed microbes. This avoids large head-space concentrations that could be hazardous to workers. Processes that lead to water congestion of openings in a tomato fruit surface enable ready internalization of particular matter including bacteria. Moreover, wet conditions during harvest enable decay development by pathogens that aren't particularly aggressive on mature green fruit, the favored stage of ripeness for most harvests. Also, wet tomatoes would be prone to internalize various hazardous microorganisms including those that cause human illness.
Publications
- Lukasik, J., Bradley, M. L., Scott, T. M., Dea, M., Koo, A., Hsu, W-Y., Bartz, J. A., and Farrah, S. R. 2003. Reduction of Poliovirus 1, Bacteriophages, Salmonella montevideo, and Escherichia coli O157:H7 on strawberries by physical and disinfectant washes. J. Food Protection 66:188-193.
- Nunes, M. C., Morais, A., Brecht, J. K., Sargent, S. A. & Bartz, J. A. 2005. Prompt cooling reduces incidence and severity of decay caused by Botrytis cinerea and Rhizopus stolonifer in strawberry. HortTechnology. 15:153-156.
- Bartz, J. A., Mahovic, M. J. & Tenney, J. 2005. Chlorine dioxide as a postharvest sanitizer: reversible and irreversible sinks. (abstr) Phytopathology. 95:S7:7-7.
- Mahovic, M. J., Bartz, J. A. & Schneider, K. R. 2005. Some factors affecting infiltration of water into tomato fruit. (abstr) Phytopathology. 95:S64:64-64.
- Mahovic, M. J., Bartz, J. A., and Schneider, K. R. 2006. Controlling biotic factors that cause postharvest losses of fresh market tomatoes. pp. 351-392. In: Jancik, J. (ed.) Horticultural Reviews. Vol. 33. John Wiley and Sons, Inc. NY.
- Nunes, M. C., Brecht, J. K., Morais, A., Sargent, S. A. & Bartz, J. A. 2006. "Interaction of strawberry fruit ripeness, postharvest temperature, and controlled atmosphere on Botrytis fruit rot development. HortScience. Submitted.
- Scott, J. W., Olson, S. M., Bryan, H. H., Bartz, J. A., Maynard, D. N. & Stoffella, P. J. 2006. Solar Fire' Hybrid Tomato; Fla. 7776 Tomato Breeding Line. HortScience. 41/6:1504-1505.
- Yuk, H. -., Bartz, J. A. & Schneider, K. R. 2006. "The effectiveness of sanitizer treatments in eliminating Salmonella spp. on smooth surface, stem scar, and wound of bell pepper, cucumber, and strawberry." J.of Fd. Sci. 71:95-99.
- Bartz, J. A., Mahovic, M. J., and Tenney, J. 2006. Chlorine dioxide gas controls postharvest pathogens of tomato by mass transfer from a source to the fruit. (abstr) Phytopathology 96:S9.
- Bartz, J. A. 2006. Internalization and infiltration. pp. 75-94. In: Microbiology of Fruits and Vegetables. Eds. G. M. Sapers, J. R. Gorny and A. E. Yousef. CRC, Taylor and Francis. Boca Raton, FL.
- Ergun, M., Huber, D. J. & Bartz, J. A. 2006. Suppression of ethylene sensitivity prolongs shelf life and quality of fresh-cut ripe papaya fruit. J. American Soc. Hort. Sci. 131:97-103.
- Ergun, M., Huber, D. J. & Bartz, J. A. 2006. "Extended Shelf Life and Quality of Fresh-Cut Papaya (Carica papaya) Derived from Ripe Fruit Treated with the Ethylene Antagonist 1-Methylcyclopropene." Journal of the American Society for Horticultural Science. 131:97-103.
- Felkey, K., Archer, D. L., Bartz, J. A., Goodrich, R. M. & Schneider, K. R. 2006. Chlorine disinfection of tomato surface wounds contaminated with Salmonella spp.. HortTechnology. 16-2:253-256.
- Mahovic, M., Bartz, J. A., Berry, A. D., and Sargent, S. A. 2006. Postharvest treatment of tomato fruit with chlorine dioxide gas affects fruit quality. Proc. Fla. State, Hort. Soc. 119: 340-342.
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Progress 10/01/02 to 10/01/03
Outputs
The inability of the chlorine to disinfect wounds occurs because microorganisms including spores of fungi and cells of bacteria rapidly enter intercellular spaces in the fruit. Water congestion (cell sap) at the wound surface enables this penetration. Cells embedded in the plant's intercellular spaces are protected. When chlorinated water is applied to such wounds, the suspended pathogens are displaced further into the tissues. Cells of the soft rot pathogen, Erwinia carotovora subsp. carotovora are completely inactivated (>5 log reduction) by 100 ppm chlorine at pH 7.0 and 24 C when placed on the unbroken skin of the fruit at log 6 cfu . If placed on wounds created by shaving the cuticle, a portion of the cells survive and cause bacterial soft rot if the chlorine treatment is delayed by 5 to 10 sec. If the cells and chlorine are simultaneously placed on the wounds, however, bacterial soft rot does not occur and viable soft rot bacteria cannot be detected.
Impacts
In preparing fresh cut fruits and vegetables, a sanitizer that reacts at least as rapidly as chlorinated water must be present at the time of cutting to prevent microorganism from access to the wounds.
Publications
- Bartz, J. A., Mahovic, M.,Hermle, C. M. and Concelmo, D. 2003. Internalization of microorganisms into tomato fruit through water congested tissues. (Abstr.) book of abstracts 8th Congress, International Congress of Plant Pathology, Christchurch, NZ.
- Mahovic, M. J., Bartz, J. A., and Tenney, J. 2003. Use of dry chlorine dioxide gas in the treatment of tomato fruit for bacterial soft rot. (Abstr.) Phytopathology 93:S56.
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Progress 10/01/01 to 10/01/02
Outputs
Chlorine dioxide solutions were too unstable for effective use on fungal spore suspensions in a scale model flume. Offgassing occurred within 2 min and not enough active ingredient remained in the water. Rhizopus stolonifer was less sensitive than Geotrichum candidum although soft rot bacteria were readily inactivated.
Impacts
Really stable solutions of antimicrobials are needed for effective sanitation in produce washers. When the active ingredient offgasses during the washing, control does not occur.
Publications
- No publications reported this period
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Progress 10/01/00 to 10/01/01
Outputs
Suspensions of Penicillium digitatum containing log 6.0 conidia/ml contained significant chlorine demand (based on a reduction of free chlorine during a 2 min exposure as measured with a DPD test kit). Suspensions containing log 4.0 or 5.0 conidia/ml were more sensitive to chlorine that were those containing log 6.0 even accounting for a larger number. These spore suspensions were quite insensitive to acidified sodium chlorite, a potential alternative to chlorine for packinghouse water treatment. Concentrations of acidified sodium chlorite (pH 2.5) up to 1200 ppm failed to protect wounded oranges from becoming inoculated (= 100% decay within 1 week in storage) in a scale model flume (fruit were added to the flume before the spores), whereas 200 ppm chlorine at pH 7.0 allowed just 10% decay.
Impacts
Acidified sodium chlorite has potential as a disinfectant of the surface of fresh fruits (prior to processing) when bacteria but not fungal spores are involved. Spores of Penicillium spp appear especially resistant to surface treatments.
Publications
- No publications reported this period
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Progress 10/01/99 to 09/30/00
Outputs
Three postharvest decay fungi, Geotrichum candidum, Rhizopus stolonifer, and Penicillium digitatum, were killed more readily by solutions of sodium chlorite that had been activated 60 as compared with 1 min before application. Significant differences existed even between the 15 and 1 min solutions. How effective aged solutions would be for sanitizing fruit or vegetable surfaces prior to light processing is unclear.
Impacts
Fruits and vegetables intended for lightly processed products need to be free of human pathogens and spoilage agents before they are cut. An effective surface disinfectant would reduce the risk that such microbes would be put into wounds during processing.
Publications
- No publications reported this period
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