Progress 01/01/09 to 09/30/13
Outputs
Target Audience: Florida tomato growers, packers, industry consultants, tomato handlers (repackers), and associated suppliers (sources of materials used by growers, packers and the market chain). Changes/Problems: Due to Salmonella hazards and market disruptions when Salmonella contamination was alleged to have occurred in Florida produced tomatoes, a significant effort was devoted during the last two years to examining the dynamics of this contamination. What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest? Advances in sanitation and food safety have been regularly presented at Food Safety Conference for Packinghouses, that is held just prior to the Florida Tomato Institute. Additionally, abstracts and posters were presented at the Annual Meeting of the American Phytopathological Society. These posters demonstrated a model system for evaluating proliferation of Salmonella in tomato fruit as well as use of chlorine dioxide gas to sanitize tomato fruit (see earlier progress reports). What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Ability to sanitize raw tomatoes with chlorine dioxide gas was limited by the reaction of the gas with the tomato box material. Use of ozone in the storage atmosphere restricts surfacedevelopment of decay pathogens andlimit sporulation of fungal pathogens, but has littleeffect ontissue maceration/necrosis. Salmonella proliferation in tomato tissues (surface pericarp) is increased if storage temperatures are higher than ideal (35o C versus20o C), if fruit are red ripe as compared with mature green, or congested with water if green but not red. Cells of the bacterium migrate from surface wounds deeper into tissues but do not cause discernable tissue necrosis. Extremely hazardous populations >Log10 9.0 cfu/gm tissue weight can develop within 3 to 5 days of inoculation if fruit are warm. Age of wounds at the time of inoculation (0 to 24 h old) had no effect on prolilferation. Presence of surfactant in a suspension of cells did not markedly enhance proliferation. Proliferation was similar if cells were suspended in phosphate buffered saline as compare with suspended in deionized water. However,tomato tissues absorbed less water when salt solutions were applied, suggesting thatwater movement into fruit tissues was at least partially caused byosmotic forces. Tissue sections absorbing> ca. 5% water by weight, usually became swollen anddeveloped cracks incuticular tissues.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Bartz, J. A., Marvasi, M. and Teplitski, M. 2014. Salmonella and tomatoes, (in) THE PRODUCE CONTAMINATION PROBLEM: CAUSES AND SOLUTIONS, SECOND EDITION (eds.) Karl R. Matthews, Gerald Sapers, and Charles P. Gerba. Academic Press, Elsevier Inc., Burlington, MA.
Massimiliano, M., Hochmuth, G. J. II, George, A.S., Giurcano, M. C., Bartz, J. A.,
Bartz, J. A., Spiceland, D., Teplitski, M. and Hochmuth, G. J. 2013. Factors affecting proliferation of Salmonella enterica in tomato tissues. (abstr). Phytopathology APS 23P.
Bartz, J. A., Sargent, S. A., and Scott, J. W. 2004. Weather fronts and postharvest decays and safety of field-grown tomatoes. Proc. International Soc. Hort. Sci. (in press).
Marvasi M, Hochmuth GJ, Giurcanu MC, George AS, Noel JT, et al. (2013) Factors That Affect Proliferation of Salmonella in Tomatoes Post-Harvest: The Roles of Seasonal Effects, Irrigation Regime, Crop and Pathogen Genotype. PLoS ONE 8(12): e80871. doi:10.1371/journal.pone.0080871
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Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: Further tests on irrigation regime at the time of harvest failed to reveal changes in susceptibility of tomato fruit to sour rot or bacterial soft rot or proliferation of Salmonella Typhimurium in fruit tissues. However, proliferation of Salmonella was enhanced when green fruit tissues where water congested in the laboratory as compared with no change or a slight reduction when fruit were red. Water uptake by pericarp tissues was greater when sections were exposed to deionized water as compared with a phosphate buffered saline solution. Thus, more water inflow occurs with higher water potential. Surfactants were variable in their effect on water uptake, certain ones increasing and others decreasing uptake as compared with deionized water. Proliferation of Salmonella at wound sites was not affected by washing wounds with deionized water prior to inoculation. Moreover, clear evidence of bacterial migration in tomato tissues was observed. Thus, nutrition supporting proliferation appears to be that available in cell walls lining intercellular spaces. This suggests that if systemic contamination of tomato plants by Salmonella occurs, then any bacteria transported by xylem fluids into intercellular spaces have a high potential for proliferation. Fortunately, most fluids transported into tomato fruit move in phloem tissues. Rapid movement of water into wounds on fruit surfaces indicates that harvesting of wet fruit is hazardous, both in terms of postharvest decay and undesirable contamination. This type of contamination cannot be eliminated by sanitizers such as chlorinated water. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Target audience was the tomato industry, particularly in Florida as information provided enabled them to have fewer decay problems and to help them reduce food safety hazards. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Tomato growers have been informed of hazards concerning "wet harvests" (harvesting fruit when crop is wet with rainfall, dew or guttation) as well as harvests of water congested fruit. If market or crop conditions mandate "wet harvests," then special precautions must be taken to avoid decay or wholesomeness problems. "Wet harvests" can be caused by weather events in addition to rainfall. An extension publication (EDIS) detailing such events along with probable photos of affected fruit has been published.
Publications
- Bartz, J. A., Sargent, S. A., and Scott, J. W. 2012. Postharvest quality and decay incidence among tomato fruit as affected by weather and cultural practices. IFAS document PP294, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. http://edis.ifas.ufl.edu
- Ritenour, M. A. and Bartz, J. A. 2012. Maintaining tomato fruit health after harvest. pp. 159-172. (in) R. M. Davis, K. Pernezny and J. C. Broome (eds) Tomato Health Management. Plant Health Management Series. APS Press. St. Paul, Mn.
- Bartz, J. A., Mahovic, M., Spiceland, D., and Teplitski, M. 2012. Detached leaf assay adapted to tomato pericarp sections for modeling contamination of tomato fruit by Salmonella Typhimurium. (abstr.) Phytopathology 102:S4.9
- Bartz, J. A. 2012. Postharvest: 5 Fruiting Foes. Page 24. American Vegetable Grower. Meister Media Worldwide.
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Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: Tomato fruit that are congested with water are more likely to be bruised during harvest and more likely to develop postharvest decays. Excessive water transport into fruit is associated with white/yellow speckles located in the pericarp as well as cracks in the pericarp surface. According to the literature, speckles are accumulations of calcium oxalate crystals. Most accumulations are irregularly shaped lumps in idoblast cells. However, raphid crystals may develop near seeds in locular cavities. A combination of speckles and cuticle cracking was observed in photographs of decaying fruit that had been sampled from harvests over a several year period. In certain cases, lesions developed at cuticle cracks suggesting fruit were wet for a prolonged period of time. These harvests occurred at times of the year when field temperatures ranged from very cool to warm. However, a characteristic of each period was an imbalance of foliar transpiration versus water uptake by roots. Events such as heavy rainfall occuring after a period of drought, change in air temperature due to frontal passage, or perhaps, even over-irrigation following a reduction in transpiration could be responsible for excessive water being forced into maturing fruit. A low level of ozone (0.1 ppm) in the atmosphere over stored tomatoes prevented the outgrowth and sporulation of Botrytis cinerea, Rhizopus stolonifer, and Geotrichum candidum from inoculated wounds. The effect was strongest where fruit were stored under cool temperatures. Wound expansion was not inhibited, whereas sporulation of Alternaria alternata was only slightly inhibited. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Information about a correlation between speckles on fruit surfaces, cuticle cracking and decay-prone fruit will be submitted to an audience of tomato growers and packers in Florida. Currently, we are working on a third draft of the information and hope to have it out soon. A final version will be published as an EDIS document and will be available online. A presentation: "Packinghouse sanitation - Do wet tomatoes affect the efficacy of your sanitation program?" was given at state-wide Florida tomato packinghouse workshop in Naples, Florida during early September. PROJECT MODIFICATIONS: Due to the impact of tissue water congestion on the susceptibility of green tomatoes to sour rot, other hazards are being evaluated. Funding for an examination of the effect of tomato fruit water congestion on proliferation of Salmonella typhimurium was received. Preliminary observations are that proliferation increases with tissue water congestion in green tomatoes but decreases if the fruit are ripe. Irrigation level (low, medium, high) used to produce field grown tomatoes had no effect on proliferation. However, there was no evidence that an imbalance between root water uptake and canopy transpiration was acheived. External water rapidly enters fresh wounds on fruit with an up to 8% increase in tissue weight within 15 min after pericarp sections are floated on water. This rapid movement of water into intercellular spaces of fruit tissues potentially internalizes bacteria. As such, sanitiation procedures cannot protect the fruit.
Impacts
A clear correlation between postharvest decays and excessive water movement into fruit, a condition that cannot be corrected by fruit sanitation practices, indicates growers and packers must take special precautions when certain weather events occur. Irrigation must be linked to plant needs and not be simply applied at the same time and same amount day-to-day. Harvests should be limited after rainfall-temperature reduction-fog events until fruit no longer bruise easily. Two occasional practices should be banned. Fruit should never be harvested from wet plants and freshy harvested fruit should not be exposed to uncontrolled water, whether from rainfall or condensation.
Publications
- Teplitski, M., Warriner, K., Bartz, J. and Schneider, K. R. 2011. Untangling metabolic and communication networks: interactions of enterics with phytobacteria. Trends in Microbiology 19:121-127.
- Gu G, Hu J, Cevallos-Cevallos JM, Richardson SM, Bartz JA, et al. (2011) Internal Colonization of Salmonella enterica Serovar Typhimurium in Tomato Plants. PLoS ONE 6(11): e27340. doi:10.1371/journal.pone.0027340
- Bartz, J. A., Elkahky, M., and Spiceland, D. 2011. Effect of immersion depth, dwell time and fruit-water temperature differences on water uptake by flumed tomatoes. (abstr) Phytopathology S:768-P (poster APS, IPPC joint meeting, Honolulu, Hawaii).
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: Temperature difference between fruit and dump tank/flume water is not a major cause of infiltration/internalization of bacteria in tomato fruit. When warm fruit are dumped into cooler water, the temperature change in the fruit is gradual. Thus, if the fruit dwell time is limited to 2 min, or better yet, 30 sec, cooling-induced water penetration is minimal. Depth of immersion such as the stacking of fruit or overfilling of the flume is another matter. Tomato fruit stacked to a depth of 28 inches in the dumptank are exposed to 1 psi water pressure on their surfaces. This is approximately a 20-fold greater pressure imbalance than experienced by a fruit that cooled 9 degrees F. Note also, that the only water pressure over an exposed stem scar is the depth of water held in place by the fruit shoulders, whereas the pressure imbalance on stacked fruit is the sum of the hydrostatic pressure (depth of immersion) and the vacuum created by any temperature change. Pinhole wounds on tomato fruit absorb dye solutions, which diffuse beneath and beside the wound. Dwell-time and wound age affect the amount of dye entering the wound. There was no evidence fruit-dye temperature differences (up to 36 degrees F difference) affected dye penetration, particularly with short (30 sec) dwell times. Chlorine dioxide was found to be incompatible (was completely reduced to chloride) with a proprietary wash-aid. Thus, fruit sprayed prior to harvest with similar products may not be adequately sanitized if chlorine dioxide is used as a chlorine alternative. Chlorine from sodium hypochlorite, aqueous solution of chlorine dioxide and peroxyacetic acid were compatible with two fungicides (propiconazole and fludioxynil) which are being tested for control of several fungal decay pathogens of tomatoes. Mixing the sanitizers with the fungicides for a hour prior to sensitivity tests did not lead to a reduction in the activity of the fungicides against the target fungi. PARTICIPANTS: PARTICIPANTS: This work is being done in collaboration with Drs. Keith Schneider of the U of Florida Department of Food Science and Human Nutrition, S. A. Sargent, J. K. Brecht and M. Ritenour of the Horticultural Sciences Department. Support is being provided by the Florida Tomato Committee, by in-kind support from ThermoKing Inc. (airo-care EMS Unit), AquaPulse Systems (chlorine dioxide generator), ICA-TriNova LLC (dry reactant chlorine dioxide generator), Biosafe Systems, LLC (Sanidate 12.0) and Syngenta Inc. (fungicides Mentor and Scholar). TARGET AUDIENCES: Presented progress reports and updates to the Florida Tomato Growers at the Florida Packinghouse institute, Naples, Fl. Analysis of water temperature issues was presented at that time. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
If packinghouse managers limit the amount of time (< 2 min) tomatoes are floating in water, differences in initial temperature between the fruit and the water have minimal influence on water uptake by the fruit. By contrast, allowing fruit to stack or build up in dumptanks or flumes directly influences water uptake by openings in the fruit surfaces (wounds or the stem scar). Thus, the water need not be heated above fruit temperature, whereas limiting the depth of immersion is essential to preventing water induced internalization of microorganisms. Two prospective fungicides providing excellent control of sour rot, Rhizopus rot, gray mold and black molds can be applied as a recoverable drench or immersion bath which would include a sanitizer that would keep the treatment site as well as downstream packing line equipment sanitary.
Publications
- Bartz, J. A., Sargent, S. A., and Mahovic, M. 2010. Identifying and controlling post harvest tomato disease in Florida. IFAS document HS866, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. http://edis.ifas.ufl.edu
- Ritenour, M. A. and Bartz, J. A. 2010. Postharvest handling, processing and storage. In M. Davis and K. Pernezny (eds) Tomato Health Management, APS Press.
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: Application of chlorine dioxide gas within a carton of tomatoes did not lead to an acceptable level of control of bacterial soft rot in the wound inoculated tomatoes. The cardboard exhibited a high level of irreversible absorption of chlorine dioxide most likely by reacting with the gas (high chlorine dioxide demand). Chlorine dioxide off-gassed from an aqueous solution reacted incrementally with potassium iodide solutions (sinks) in a polycarbonate chamber. After 30 min, 45% of the initial dose was detected as chlorite ion in the sink, whereas 35% of the initial dose was still in the source. Movement from source to sink is continuous, which precludes the development of large headspace concentrations and the need for a tight chamber seal. The addition of pieces of tomato box material to the chamber greatly reduced capture of the off-gassed chlorine dioxide. PARTICIPANTS: This work is being done in collaboration with Drs. Keith Schneider of the U of Florida Department of Food Science and Human Nutrition, and S. A. Sargent and J. K. Brecht of the Horticultural Sciences Department. Support is being provided by the Florida Tomato Committee as noted in a previous field and by in-kind support from ThermoKing Inc. (airo-care EMS Unit), AquaPulse Systems (chlorine dioxide generator), and ICA-TriNova LLC (dry reactant chlorine dioxide generator). TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
This is a new project. Support funds are being provided by the Florida Tomato Committee. Work is continuing on ways to treat tomato fruit with a surface sanitizing gas after the fruit have been packed.
Publications
- Mahovic, M., Bartz, J. A., Schneider, K. R., and Tenney, J. D. 2009. Chorine dioxide gas from an aqueous solution: reduction of Salmonella in wounds on tomato fruit and movement to sinks in a treatment chamber. J. Food Protection 72: 952-958.
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