Source: EASTERN REGIONAL RES CENTER submitted to
NOVEL APPROACH FOR DECONTAMINATING FRESH AND FRESH-CUT PRODUCE UTILIZING CHLORINE DIOXIDE GAS PACKAGING SYSTEM
Sponsoring Institution
Agricultural Research Service/USDA
Project Status
NEW
Funding Source
Reporting Frequency
Annual
Accession No.
0414653
Grant No.
(N/A)
Project No.
1935-41420-018-02R
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Sep 1, 2008
Project End Date
Aug 31, 2011
Grant Year
(N/A)
Project Director
ANNOUS B A
Recipient Organization
EASTERN REGIONAL RES CENTER
(N/A)
WYNDMOOR,PA 19118
Performing Department
(N/A)
Non Technical Summary
(N/A)
Animal Health Component
(N/A)
Research Effort Categories
Basic
10%
Applied
40%
Developmental
50%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
50114991100100%
Goals / Objectives
The overall goals of the project are to establish the degree of efficacy of chlorine dioxide (ClO2) gaseous application in disinfecting fresh leafy greens and cherry tomatoes, to establish the point of dose-dependent injury to fresh quality and shelf-life so that such injury can be avoided, to evaluate the integration of post-harvest strategies of product sanitizing and exposure to an antimicrobial through packaging to assure the microbial safety of fresh produce, and to further improve, extend and transfer treatment application methods to end-users so that adoption of a commercially feasible process becomes possible.
Project Methods
1. Identify ClO2 gas treatment conditions that can inactivate human pathogens on fresh-cut leafy vegetables and cherry tomatoes without causing treatment-induced quality defects. 2. To determine a specific package design that ensures and maximizes effective gases distribution inside the package even in hard to reach areas. 3. Determine the efficacy of the packaging system in inactivating foodborne pathogens and prolonging the shelf life of lettuce, spinach and cherry tomatoes. 4. Evaluate a pilot scale treatment, using ERRC BSL-2 pilot processing facility, to demonstrate technical and economical feasibility.

Progress 10/01/12 to 09/30/13

Outputs
Progress Report Objectives (from AD-416): The overall goals of the project are to establish the degree of efficacy of chlorine dioxide (ClO2) gaseous application in disinfecting fresh leafy greens and cherry tomatoes, to establish the point of dose- dependent injury to fresh quality and shelf-life so that such injury can be avoided, to evaluate the integration of post-harvest strategies of product sanitizing and exposure to an antimicrobial through packaging to assure the microbial safety of fresh produce, and to further improve, extend and transfer treatment application methods to end-users so that adoption of a commercially feasible process becomes possible. Approach (from AD-416): 1. Identify ClO2 gas treatment conditions that can inactivate human pathogens on fresh-cut leafy vegetables and cherry tomatoes without causing treatment-induced quality defects. 2. To determine a specific package design that ensures and maximizes effective gases distribution inside the package even in hard to reach areas. 3. Determine the efficacy of the packaging system in inactivating foodborne pathogens and prolonging the shelf life of lettuce, spinach and cherry tomatoes. 4. Evaluate a pilot scale treatment, using ERRC BSL-2 pilot processing facility, to demonstrate technical and economical feasibility. Optimization of pilot scale ClO2 gas treatment of green and ripened tomatoes was conducted in a 12 cubic foot chamber. Tomatoes were inoculated to an average of 4.5 log CFU/g with Salmonella Montevideo, and stored at 12.5C for 24 h prior to treatment. Gaseous ClO2 treatments consisted of up exposure to up to 0.8 mg/l for up to 6 h. Treated and non- treated tomatoes were then stored at 12.5 or 21C for up to 14 days. Optimized ClO2 gas treatments using 0.4 mg/l ClO2 for 4 h exposure has resulted in reductions of 4.5 log CFU/g following up to 14 days of storage. This 0.4 mg/l ClO2 for 4 h treatment helped increase the shelf life of this commodity by reducing the natural spoilage microorganism populations on the surface. Also, this treatment has no adverse effects on the texture and color qualities other than bleached stem scar. This data suggest the feasibility of this process for enhancing the safety and shelf life of this commodity.

Impacts
(N/A)

Publications


    Progress 10/01/11 to 09/30/12

    Outputs
    Progress Report Objectives (from AD-416): The overall goals of the project are to establish the degree of efficacy of chlorine dioxide (ClO2) gaseous application in disinfecting fresh leafy greens and cherry tomatoes, to establish the point of dose- dependent injury to fresh quality and shelf-life so that such injury can be avoided, to evaluate the integration of post-harvest strategies of product sanitizing and exposure to an antimicrobial through packaging to assure the microbial safety of fresh produce, and to further improve, extend and transfer treatment application methods to end-users so that adoption of a commercially feasible process becomes possible. Approach (from AD-416): 1. Identify ClO2 gas treatment conditions that can inactivate human pathogens on fresh-cut leafy vegetables and cherry tomatoes without causing treatment-induced quality defects. 2. To determine a specific package design that ensures and maximizes effective gases distribution inside the package even in hard to reach areas. 3. Determine the efficacy of the packaging system in inactivating foodborne pathogens and prolonging the shelf life of lettuce, spinach and cherry tomatoes. 4. Evaluate a pilot scale treatment, using ERRC BSL-2 pilot processing facility, to demonstrate technical and economical feasibility. The impact of package design on antimicrobial efficacy of chlorine dioxide (ClO2) gas for fresh-cut lettuce was carried out. Commercially available bags were modified to create gas reservoirs (GR) allowing gas release from one side of the bag, from both sides, or in the center (1-GR, 2-GR, or mid-GR, respectively). ClO2 was generated in the GR gas at either 4 or 8 mg ClO2 per kg lettuce per day. Escherichia coli O157:H7- inoculated fresh-cut lettuce was packed in the bags and stored at 4 C for up to 7 d. Increasing ClO2 gas dose resulted in greater log10 CFU/g reductions of E coli O157:H7. Significantly greater (p < 0.05) log10 CFU/g reductions of E coli O157:H7 were observed in lettuce samples taken from locations adjacent to the GR. The performance of 2-GR bags indicated that the same degree of antimicrobial effect could be achieved with the lower ClO2 dose. Pilot scale ClO2 gas treatment of whole green tomatoes was conducted at the ERRC � BL-2 pilot plant facility.

    Impacts
    (N/A)

    Publications


      Progress 10/01/10 to 09/30/11

      Outputs
      Progress Report Objectives (from AD-416) The overall goals of the project are to establish the degree of efficacy of chlorine dioxide (ClO2) gaseous application in disinfecting fresh leafy greens and cherry tomatoes, to establish the point of dose- dependent injury to fresh quality and shelf-life so that such injury can be avoided, to evaluate the integration of post-harvest strategies of product sanitizing and exposure to an antimicrobial through packaging to assure the microbial safety of fresh produce, and to further improve, extend and transfer treatment application methods to end-users so that adoption of a commercially feasible process becomes possible. Approach (from AD-416) 1. Identify ClO2 gas treatment conditions that can inactivate human pathogens on fresh-cut leafy vegetables and cherry tomatoes without causing treatment-induced quality defects. 2. To determine a specific package design that ensures and maximizes effective gases distribution inside the package even in hard to reach areas. 3. Determine the efficacy of the packaging system in inactivating foodborne pathogens and prolonging the shelf life of lettuce, spinach and cherry tomatoes. 4. Evaluate a pilot scale treatment, using ERRC BSL-2 pilot processing facility, to demonstrate technical and economical feasibility. Chlorine dioxide gas (ClO2) is a strong oxidizing agent and an effective surface disinfectant. Its disinfecting capacity has been recognized since the early 1900s, and was used initially to treat water, as it causes less organoleptic problems than chlorine. Due to its bacteriocide effects, Cl02 gas is gaining significant interest in the food and pharmaceutical industries. In 2001, the FDA approved the incorporation of ClO2 within food packaging materials to be used for uncooked meats, such as poultry and seafood. If the package is going to be considered as a strategy for the application of Cl02 gas, the impact of package design on antimicrobial efficacy of Cl02 gas for fresh produce needs to be determined. Commercially available bags were modified to create gas reservoirs (GR) allowing gas release from one side of the bag, from both sides, or in the center (1-GR, 2-GR, or mid-GR, respectively). Cl02 was generated in the GR gas at either 4 or 8 mg ClO2 per kg lettuce per day. Fresh-cut lettuce, artificially inoculated with the human pathogen Escherichia coli O157:H7 was packed in the bags and stored at 4 deg C for up to 7 d. Increasing ClO2 gas dose resulted in greater reductions of E. coli O157:H7. Significantly greater reductions in E coli O157:H7 populations were observed in lettuce samples taken from locations adjacent to the GR. The performance of 2-GR bags indicated that the same degree of antimicrobial effect could be achieved with the lower Cl02 dose. Chlorine dioxide (ClO2) is gaining interest in the food industries due to its antimicrobial effects. One of the most promising applications of Cl02 is to be utilized in vapor-phase decontamination either as fumigation gas in the production line or as antimicrobial gas in a food packaging systems. When Cl02 gas is absorbed into the produce, it might react with organic matters, such as plant cells and pigments, and with microorganisms resided on the surface. The reactions typically generate chlorite (Cl02-) as a major byproduct, along with numerous compounds in trace amount. In this study, the absorption behavior of Cl02 gas by Romaine lettuce and cherry tomatoes, as well as processing factors that could affect this behavior, is being investigated by exposing commodities to 3.0 and 6.0 mg/L of Cl02 for 15-90 min, and then determined residual Cl02 and Cl02- in the samples using amperometric titration. For lettuce sample, Cl02-absorption increased as ClO2 concentration and/or exposure time increased. The study also showed that shredding, which introduced cut or bruises, to lettuce leaf increased Cl02-absorption by 100 times, while washing, which added moisture to the sample around 7% wt/wt, did not significantly affect the absorption behavior of shredded lettuce. Further study indicated that allowing enough time after Cl02 exposure, residual Cl02 and Cl02- will reduce to an undetectable amount. Absorption study of cherry tomatoes is being carried out. The study on both commodities will also include influences of temperature, especially at lower temperature (4 deg C), and correlation between antimicrobial efficacy of ClO2 and its absorption.

      Impacts
      (N/A)

      Publications


        Progress 10/01/09 to 09/30/10

        Outputs
        Progress Report Objectives (from AD-416) The overall goals of the project are to establish the degree of efficacy of chlorine dioxide (ClO2) gaseous application in disinfecting fresh leafy greens and cherry tomatoes, to establish the point of dose- dependent injury to fresh quality and shelf-life so that such injury can be avoided, to evaluate the integration of post-harvest strategies of product sanitizing and exposure to an antimicrobial through packaging to assure the microbial safety of fresh produce, and to further improve, extend and transfer treatment application methods to end-users so that adoption of a commercially feasible process becomes possible. Approach (from AD-416) 1. Identify ClO2 gas treatment conditions that can inactivate human pathogens on fresh-cut leafy vegetables and cherry tomatoes without causing treatment-induced quality defects. 2. To determine a specific package design that ensures and maximizes effective gases distribution inside the package even in hard to reach areas. 3. Determine the efficacy of the packaging system in inactivating foodborne pathogens and prolonging the shelf life of lettuce, spinach and cherry tomatoes. 4. Evaluate a pilot scale treatment, using ERRC BSL-2 pilot processing facility, to demonstrate technical and economical feasibility. Efficacy of antimicrobial agents in inactivating pathogenic microorganisms on fresh and fresh-cut produce surfaces in limited by the accessibility of such agents to the produce surfaces where the microorganisms are residing. Other factors contribute to this problem include biofilm formation by the microorganisms which allows the bacterial cells living within the biofilm to tolerate the harsh environment as well as the antimicrobial agents. Chlorine dioxide (ClO2) gas is able to reach such inaccessible sites on the produce surfaces and to penetrate the biofilm protective layer which gives it a superior efficacy in inactivating bacterial cells. To study the antimicrobial effects of ClO2 on a biofilm, the surfaces of Romaine lettuce were inoculated with Escherichia coli O157:H7 and then were treated with 0.2 mg/L ClO2 for 15 min. The treatment reduced the pathogen population by up to 1.5 logs. Scanning electron microscope pictures taken from both the untreated and ClO2-treated lettuce surfaces showed the noticeable reduction and damages to the biofilm structure following ClO2 treatment. The addition of ClO2 gas to the headspace of food packaging systems could improve the microbial safety and extend the shelf-life of perishable food products. This study considered different flexible package internal designs in which each design released ClO2 in different ways. Also, this study evaluated the impact of packaging design on the inactivation efficiency of ClO2 on shredded Romaine lettuce inoculated with E. coli O157:H7. Samples were taken from different area of the bags, and the results showed that the samples taken from the area next to the releasing spots had significantly higher CFU log reductions (up to 1.5 logs) as compared to those more distant from the releasing ports (up to 0. 5 log). The study also indicated that increasing the number of releasing ports per bag and decreasing the amount of ClO2 resulted in a comparable average log reduction to the bag with lower numbers of releasing ports and higher ClO2 concentrations. These important findings are being used to re-design the flexible packaging system that will include ClO2 for improving safety and extend shelf-life of leafy green products. The inadequacy of washing processes to inactivate microorganisms on tomatoes is attributed to biofilm formation and inaccessibility of microbial attachment sites to washing systems. The objective was to develop ClO2 gas treatment capable of inactivating human pathogens attached to inaccessible sites within biofilm on the tomatoes. Tomatoes were inoculated with Salmonella Poona and were treated with ClO2 for 6 h in a closed chamber. This treatment reduced S. Poona populations by more than 4.5 log CFU/gm, extended the shelf life of the tomatoes by reducing the spoilage microorganisms, and did not seem to have adverse effects on the quality of this commodity. This treatment was able to inactivate S. Poona cells attached to inaccessible sites and extend the shelf life of tomatoes without any apparent adverse effects on quality. Progress is monitored through meetings, site visits, conference calls, e- mail exchanges and exchanges of data.

        Impacts
        (N/A)

        Publications


          Progress 10/01/08 to 09/30/09

          Outputs
          Progress Report Objectives (from AD-416) The overall goals of the project are to establish the degree of efficacy of chlorine dioxide (ClO2) gaseous application in disinfecting fresh leafy greens and cherry tomatoes, to establish the point of dose- dependent injury to fresh quality and shelf-life so that such injury can be avoided, to evaluate the integration of post-harvest strategies of product sanitizing and exposure to an antimicrobial through packaging to assure the microbial safety of fresh produce, and to further improve, extend and transfer treatment application methods to end-users so that adoption of a commercially feasible process becomes possible. Approach (from AD-416) 1. Identify ClO2 gas treatment conditions that can inactivate human pathogens on fresh-cut leafy vegetables and cherry tomatoes without causing treatment-induced quality defects. 2. To determine a specific package design that ensures and maximizes effective gases distribution inside the package even in hard to reach areas. 3. Determine the efficacy of the packaging system in inactivating foodborne pathogens and prolonging the shelf life of lettuce, spinach and cherry tomatoes. 4. Evaluate a pilot scale treatment, using ERRC BSL-2 pilot processing facility, to demonstrate technical and economical feasibility. Significant Activities that Support Special Target Populations In the first part of our study we determined permeability, diffusion, and solubility coefficients of gaseous chlorine dioxide (ClO2) through the following packaging material: biaxial-oriented polypropylene (BOPP); polyethylene terephthalate (PET); poly lactic acid (PLA); multilayer structure of ethylene vinyl acetate (EVA) and ethylene vinyl alcohol (EVOH) [EVA/EVOH/EVA]; polyethylene (PE); polyvinyl chloride (PVC); polystyrene (PS); nylon. However, strong oxidizing agents such as ClO2 can cause oxidative degradation of these packing materials. The effects of ClO2 on properties, and performance of selected polymeric packaging materials were assessed by their IR spectrum, physical, mechanical, barrier, and color properties. The samples were exposed to 3,600 ppm ClO2 at 23 C for up to14 days. The IR spectra of the exposed samples indicated many changes in their chemical characteristics, such as the formation of polar groups in polyolefins, the changes in functional groups, the main chain scission degradation, as well as, the possible chlorination in several sample types. The exposed PEs samples showed a decrease in tensile properties. Decreases in barrier to moisture, oxygen and/or carbon dioxide were observed in PVC, PET and multilayer EVA/EVOH/EVA. On the other hand, significant increase in barrier to O2 was observed in the exposed nylon, which could be the result of the molecular reordering in the exposed sample, as implied through the increase in the crystallinity of the material. A continuous system for measuring the mass transfer of ClO2 through different packaging material was developed utilizing electrochemical sensor as a detector. Permeability, diffusion, and solubility coefficients of 3600 ppm ClO2 were determined through the following packaging material: biaxial oriented polypropylene (BOPP); polyethylene terephthalate (PET); poly lactic acid (PLA); multilayer structure of ethylene vinyl acetate (EVA) and ethylene vinyl alcohol (EVOH) [EVA/EVOH/EVA]; polyethylene (PE); polyvinyl chloride (PVC); polystyrene (PS); and nylon. Permeability values ranged from below 0.07 x 10-17 kg ClO2.m.m-2.s-1.Pa-1 for EVA/EVOH/EVA to 4.83 x 10-16 kg ClO2.m.m-2.s-1.Pa- 1 for PE. Results indicated that BOPP, PET, PLA, nylon, and EVA/EVOH/EVA had better barrier properties for gaseous ClO2 as compared to PE, PVC, and PS. The activation energy of permeation for PET and PLA, were determined to be 56.25 � 5.02 and 82.49 � 7.02 kJ/mol, respectively. The activation energy for PET are significantly lower than those for PLA indicating that the permeation of ClO2 trough the latter is less temperature dependent, which is considered beneficial when the packaging system is occasionally subjected to temperature abuses during transportation, or on shelf. Progress is monitored through meetings, site visits, conference calls, e- mail exchanges and exchanges of data via electronic and surface mail.

          Impacts
          (N/A)

          Publications