Progress 09/01/23 to 08/31/24

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?Throughout this effort, accurately controlled amounts of chlorine dioxide (CD) will be generated using a MiniDox M system provided by ClorDiSys. Exposures of CDIs to CD will occur in specially designed exposure chambers which are capable of maintaining various environmental paramaters (temperature, relative humidity, CD concentration) for specified periods of time to achieve target doses of CD. Replicates of CDI prototypes will be exposed to the cantaloupe and tomato target dose cycles in a 2 ft3 chamber (Morphix Technologies) and an 800 ft3 room (ClorDiSys Solutions) under identical conditions. Digital photographs of each run will be taken at 0, 5, 10, 15 min and full color development (which may occur before or after the 15 min point) to characterize the performance of the CDI sensor in these two exposure spaces. This data will then be used to determine any negative or positive bias in sensor performance as a function of exposure space volume. Continued shelf-life testing of CDIs in packaging will be carried out under heat dose cycles to achieve accelerated aging according to Arrhenius considerations. Third party tests will be conducted to correlate CDI color change with microbial kill rates on inoculated tomatoes and cantaloupe exposed to targeted doses of ClO2 . This testing will be performed by an ISO/IEC certified microbiological laboratory, with support from ClorDiSys for ClO2 treatment. Microorganisms to be tested include Listeria monocytogenes (ATCC 19111), Salmonella typhimurium cultures (ATCC 14028) and of freshly harvested Geotrichum candidum spores (ATCC 34614) representing two foodborne illness pathogens and one produce spoilage pathogen. The overall aim of this objective is to evaluate and understand how the CDIs perform under the varied real use conditions and to iterate the CDI design as necessary to meet field-use requirements. Recognizing that real-world conditions are rarely perfect in the agriculture industry, test conditions used in the test plan are based on industry feedback, and allow for reasonable process variation. As further industry feedback is received, it is possible that the test plans may be modified to ensure that the CDIs meet real-world application requirements. It is also expected that the testing will uncover shortfalls in CDI performance, which will be addressed through an iterative process under which modified CDI prototypes are designed, produced and tested.

Impacts
What was accomplished under these goals? This project is focused on the development and demonstration of a chemical dose indicator (CDI) targeting relevant CD doses for tomatoes and cantaloupe. The CDI will provide a simple visual indicator that produce has received an effective dose of CD dose to kill microbes on the produce, and proof of this treatment throughout the produce supply chain. A colorimetric CDI for CD is proposed to ensure that fruits and vegetables have been exposed to an efficacious dose of CD to achieve 3 - 6 log10 reduction (sanitization-disinfection) of microbial threats. Produce treated with CD and verified with the CDI resists spoilage for significantly longer times during storage and shipping periods and is essentially free of human pathogens and safe for human consumption. More of this CD-treated produce will reach the consumer, including those in remote areas, leading to significant reduction in field-to-table losses and enhanced food safety and accessibility to vulnerable populations. Work performed in this reporting period toward Objective 1: Work was carried out to further improve the CDI design and manufacturing method. These improvements have resulted in CDIs targeting tomato and cantaloupe doses with increased accuracy and precision of dose indication. Improved CDIs are unaffected by exposure to simulated peak Florida UV irradiation and temperature conditions, making them robust for anticipated field condtions associated with produce manufacture. Additionally, CDIs exhibit good performance when exposed to simulated field environmental conditions (25-35 oC, 30-90 %RH) prior to CD exposure. Linearity of dose indication studies show that the improved CDIs indicate relevant CD dose accurately across a wide range of concentration x exposure time (dose), ensuring that user error associated with CD generation and timing of the treatment is mitigated.

Publications

Progress 09/01/22 to 08/31/23

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?Throughout this effort, accurately controlled amounts of chlorine dioxide (CD) will be generated using a MiniDox M system provided by ClorDiSys. Exposures of CDIs to CD will occur in specially designed exposure chambers which are capable of maintaining various environmental paramaters (temperature, relative humidity, CD concentration) for specified periods of time to achieve target doses of CD. Replicates of CDI prototypes will be exposed to the cantaloupe and tomato target dose cycles in a 2 ft3 chamber (Morphix Technologies) and an 800 ft3 room (ClorDiSys Solutions) under identical conditions. Digital photographs of each run will be taken at 0, 5, 10, 15 min and full color development (which may occur before or after the 15 min point) to characterize the performance of the CDI sensor in these two exposure spaces. This data will then be used to determine any negative or positive bias in sensor performance as a function of exposure space volume. Shelf-life of CDIs in packaging will be carried out under heat dose cycles to achieve accelerated aging according to Arrhenius considerations. Third party tests will be conducted to correlate CDI color change with microbial kill rates on inoculated tomatoes and cantaloupe exposed to targeted doses of ClO2 . This testing will be performed by an ISO/IEC certified microbiological laboratory, with support from ClorDiSys for ClO2 treatment. Microorganisms to be tested include Listeria monocytogenes (ATCC 19111), Salmonella typhimurium cultures (ATCC 14028) and of freshly harvested Geotrichum candidum spores (ATCC 34614) representing two foodborne illness pathogens and one produce spoilage pathogen. The overall aim of this objective is to evaluate and understand how the CDIs perform under the varied real use conditions and to iterate the CDI design as necessary to meet field-use requirements. Recognizing that real-world conditions are rarely perfect in the agriculture industry, test conditions used in the test plan are based on industry feedback, and allow for reasonable process variation. As further industry feedback is received, it is possible that the test plans may be modified to ensure that the CDIs meet real-world application requirements. It is also expected that the testing will uncover shortfalls in CDI performance, which will be addressed through an iterative process under which modified CDI prototypes are designed, produced and tested.

Impacts
What was accomplished under these goals? This project is focused on the development and demonstration of a chemical dose indicator (CDI) targeting relevant CD doses for tomatoes and cantaloupe. The CDI will provide a simple visual indicator that produce has received an effective dose of CD dose to kill microbes on the produce, and proof of this treatment throughout the produce supply chain. A colorimetric CDI for CD is proposed to ensure that fruits and vegetables have been exposed to an efficacious dose of CD to achieve 3 - 6 log10 reduction (sanitization-disinfection) of microbial threats. Produce treated with CD and verified with the CDI resists spoilage for significantly longer times during storage and shipping periods and is essentially free of human pathogens and safe for human consumption. More of this CD-treated produce will reach the consumer, including those in remote areas, leading to significant reduction in field-to-table losses and enhanced food safety and accessibility to vulnerable populations. Work performed in this reporting period toward Objective 1: Performance was carried out to improve the CDI design and manufacturing method. These improvements have resulted in CDIs targetingtomato and cantaloupe doses with increased accuracy and precision of dose indication. Additionally, the improvements have addressed ultraviolet light-induced discoloration seen on previous CDI prototypes. Improved CDIs are unaffected by exposure to simulated peak Florida UV irradiation and temperature conditions, making them robust for anticipated field condtions associated with produce manufacture.

Publications

Progress 09/01/21 to 08/31/22

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Microbial contamination of produce leads to foodborne illness and food spoilage, representing a costly and deadly problem for the food industry. Disinfecting produce with the correct dose of chlorine dioxide (CD) gas dramatically reduces microbial contamination in produce, thereby significantly reducing foodborne illness and spoilage. There are currently no field-practical tests to confirm that CD exposure has been sufficient to achieve the needed microbial kill rate on produce. This project is focused on the development and demonstration of a chemical dose indicator (CDI) targeting relevant CD doses for tomatoes and cantaloupe. The CDI willprovide a simple visual indicator that produce has received an effective dose of CD dose to kill microbes on the produce, and proof of this treatment throughout the produce supply chain. A colorimetric CDI for CD is proposed to ensure that fruits and vegetables have been exposed to an efficacious dose of CD to achieve 3 - 6 log10 reduction (sanitization-disinfection) of microbial threats. Produce treated with CD and verified with the CDI resists spoilage for significantly longer times during storage and shipping periods and is essentially free of human pathogens and safe for human consumption. More of this CD-treatedproduce will reach the consumer, including those in remote areas, leading to significant reduction in field-to-table losses and enhanced food safety and accessibility to vulnerable populations. Work performed in this reporting period toward Objective 1: Performance was carried out to study the linearity of response of the CDI to CD exposure dose. In this context, dose is defined as exposure to a specified concentration of CD over a specified time period (i.e. dose = concentration x time). This important study was designed toprovide an understanding of the tolerance of the CDI to user error. CD exposures for produce in the field may not be as exacting as high-fidelity laboratory testing. Some users will likely generate CD with a high-fidelity system (e.g. ClorDiSys Minidox), while others may use less sophisticated generation systems (e.g. powders) and may be less discriminating on the exact duration of the CD exposure. The goal is to have the CDI indicate a true representation of the cumulative dose of CD while accounting for user error in terms of exposure time and actual CD concentration. The results of this study indicate that the CDI response to CD dose is highly linear over a range of CD concentrations and exposure times. These favorable results attest to the robustness of the CDI design with respect to user error and variations in methods ofCD generation. Thus, users of this technology can make mistakes in performing disinfection of produce in the field and the CDI will still indicate a true representation of the CD dose achieved during treatment. The CDI provides a visual tool to verify that produce has been treated with an effective dose of CD known to eradicate dangerousmicrobial contamination.

Publications