CHLORINE DIOXIDE RELEASING PACKAGING SYSTEMS TO IMPROVE MICROBIAL SAFETY OF FRESH-CUT PRODUCE

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: TERMINATED
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1001983
• Project No.: NJ10165
• Project Start Date: Dec 6, 2013
• Project End Date: Nov 30, 2018

Project Director
Yam, KI.

Recipient Organization
RUTGERS, THE STATE UNIVERSITY OF NEW JERSEY
3 RUTGERS PLZA
NEW BRUNSWICK,NJ 08901-8559

Performing Department
Food Science

Non Technical Summary
Chlorine dioxide (ClO2) is traditionally applied in the washing of fresh produce in order to remove dirt and inactivate microorganisms on the surface. This washing process has been found to be effective for lettuce, cabbage, green bell pepper, baby carrot, apple, tomato, mungbean sprout, and blueberry. However, the washing process has two disadvantages: (1) due to high surface tension of water, ClO2 in the aqueous phase cannot access the hard-to-reach areas such as pores and crevices on fresh produce where microbes are usually attached, and (2) once the washing process is completed, ClO2 is no longer available to combat the surviving microbes. Recently, these limitations have motivated scientists to explore the use of ClO2 gas treatment to complement the washing process. ClO2 gas can penetrate the areas inaccessible by washing. In fact, the use of ClO2 gas treatment has shown to be effective in microbial inactivation for a number of fresh produce products including lettuce, cabbage, green bell pepper, baby carrot, apple, tomato, blueberry, and so on. A possible but not preferable approach to apply the gas treatment is to gas flush the package with ClO2. Due to the unstable and explosive nature of ClO2, transportation and storage of this gas should be avoided. Hence this approach requires that ClO2 be generated onsite upon demand in the food manufacturing plant. Installing a ClO2 generator is either not feasible or too expensive for many fresh produce companies. A better approach is to develop an innovative ClO2 releasing packaging system to release ClO2 in a slow and controlled manner to provide the most benefit. Therefore, the objective of this project is to develop a packaging system that can generate and release chlorine dioxide in a controlled manner to improve the quality and microbial safety of fresh-cut produce. This package system may be used alone, or in combination with other technologies such as modified atmosphere packaging and controlled release packaging, to provide the most cost effective solution for the particular application.

Animal Health Component

0%

Research Effort Categories

Basic

50%

Applied

40%

Developmental

10%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
712	5010	2020	100%

Knowledge Area
712 - Protect Food from Contamination by Pathogenic Microorganisms, Parasites, and Naturally Occurring Toxins;

Subject Of Investigation
5010 - Food;

Field Of Science
2020 - Engineering;

Keywords

chloride dioxide

fresh produce

quality

dafety

food packaging

Goals / Objectives
The objective of this project is to develop a packaging system that can generate and release chlorine dioxide in a controlled manner to improve the quality and microbial safety of fresh-cut produce. These package systems may be used alone, or in combination with other technologies such as modified atmosphere packaging and controlled release packaging, to provide the most cost effective solution for the particular application.

Project Methods
1. Experimental efforts to develop the chloride dioxide releasing packaging system Define Effective ClO2 Concentrations on Microbial Inhibition. Existing data from the literature on the effects of ClO2 concentration on microbial inhibition in fresh produce will be collected and organized. More data will then be obtained by conducting experiments at Rutgers and the USDA Eastern Regional Research Center (ERRC). The specificfood products to be included will be determined shortly after the project is initiaited, in consultation with ERRC and our industry partners. Design and Manufacture ClO2 Releasing Packaging System. We will work with Specialty Extrusion Inc., a company who will produce films for the construction of our ClO2 releasing packaging system. Several packaging polymers will be used to produce the films. Evaluate ClO2 Release Kinetics of Packaging System. Automated iodometric titrator is used to quantify the concentration of gaseous chlorine dioxide released over time. Iodometric titration analysis is based on the oxidation of iodide ion by chlorine dioxide to produce iodine, which is continuously monitored and quantitated spectrophotometrically at 360 nm. This method has a precision of better than 1 percent (relative standard deviation of multiple injections). Microbial Study to Evaluate Effectiveness of Packaging System. Target microorganisms of concern depending on food commodities (fresh fruits, cut lettuce, leafy greens and vegetables) are mainly Escherishia coli O157:H7 and Salmonella enterica serotypes. The procedure used to test the effectiveness of gaseous ClO2 on microbial inactivation consists of the following steps: bacterial strains selection and inoculum development, inoculation of fresh produce, treatment with gaseous chlorine dioxide, microbiological analyses. For pathogens, antibiotic-resistant strains of microorganisms (from USDA ERRC culture collection and recent outbreaks) will be inoculated in broth. The inoculated samples will be incubated at 4, 8, 12, 15, 20, 25, and 30 C. After incubation, the samples will be plated onto selective media containing appropriate level and type of antibiotics to recover and enumerate the bacteria. The growth curve will be used as control for evaluating antimicrobials. Sensory Analysis. Sensory analysis will be conducted using expert panels and focus groups with the assistance of our industry partners. Three categories of tests (effective testing, affective testing and perception testing) will be conducted at different stages of research. Methods for experimental design and results interpretation will be adopted from literature with necessary modification. Color, Texture, Titrable Acidity Measurements. Since ClO2 may cause browning and bleaching in fresh produce such as lettuce and apple, quality and sensory attributes will be evaluated to determine the appropriate concentration of chlorine dioxide to avoid such quality damage. Color will be determined by color difference meter based on Hunter color scale. Firmness of fruit and vegetable slices will be determined by measuring force required for a 6-mm probe to penetrate the fruit or vegetable tissues for 10 mm using a TA-XT2i Texture Analyzer products, the maximum force and the yield strength of the samples will be determined using Texture Expert software. Soluble solid content will be measured using a digital refractometer. Titratable acidity will be measured by titrating a 10 ml aliquot of juice (extracted from fruits) to pH 8.1 with 0.1 N KOH with an autotitrator. Measurement of Film Properties. The tensile properties of the films will be measured. 2. Efforts to deliver science-based knowledge The results of this work will be published in peer-reviewed journalsand presented in conference. The knowledge will also be incorporated into the packaging courses taught by theproject director. 3. Evaluation The project will receive feedback from the reviewers of the journals.

Progress 12/06/13 to 11/30/18

Outputs
Target Audience:During this reporting period, the target audiences are researchers from universities and the food industry. The efforts included the publication of two peer-reviewed journal articles, presentations at two international conferences, and discssions with a company to further develop this technology for commercization. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project has provided the opportunity of training two graduate students who received their Ph.D. degrees working for this project. How have the results been disseminated to communities of interest?These results has been disseminated through peer-reviewed journal articles, presentations in major conferences, webinars, and workshops. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? While the market of ready-to-eat fresh produce products is rapidly growing in recent years, there is a critical need to develop better intervention technology to improve food safety since these products contain items that are highly susceptible to microbial risks, as documented by the recent foodborne outbreaks in Romaine lettuce, sliced apple, cantaloupes, spinach, etc. Postharvest loss of fresh produce is also a major problem, estimated to range from 10 to 30% in the United States. The goal of this project was accomplished by demonstrating the feasibility of developing two innovative packaging systems in the forms of sachet and package label to generate and release ClO2 to improve the microbial safety and reduce loss of fresh produce. Details about the principle, manufacture, and effectiveness of these systems are described in the papers listed in the publications section of this report. We are collaborating with MirTech Inc. to further develop these packaging systems for commercial applications.

Publications

• Type: Journal Articles Status: Published Year Published: 2018 Citation: Zhou, S., Hu, C., Zhao, G., Jin, T., Sheen, S., Han, L., . . . Yam, K. L. (2018). Novel generation systems of gaseous chlorine dioxide for Salmonella inactivation on fresh tomato. Food Control, 92, 479-487.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Zhou, S., Hu, C., Zhao, G., Liu, L., Sheen, S., & Yam, K. L. (2018). A novel gaseous chlorine dioxide generating method utilizing carbon dioxide and moisture respired from tomato for Salmonella inactivation. Food Control, 89, 54-61.

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:The target audience are (1) researchers and food technologists working for the fresh-cut produce industry or the packaging industry, and (2) faculty and graduate students with research interest in food packaging and shelf life extension. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provided training for two graduate students whose earned their Ph.D. degrees by conducting dissertation research in this area. How have the results been disseminated to communities of interest?The results of this research have been presented in two international conferences in food science and packaging. What do you plan to do during the next reporting period to accomplish the goals?To disseminate the findings of this project, we are preparing two additional papers for submission to high impact journals.

Impacts
What was accomplished under these goals? While the market of ready-to-eat fresh produce products is rapidly growing in recent years, there is a critical need to develop better intervention technology to improve food safety since these products contain items that are highly susceptible to microbial risks, as documented by the recent foodborne outbreaks in Romaine lettuce, sliced apple, cantaloupes, spinach, and many others. Postharvest loss of fresh produce is also a major problem, estimated to range from 10 to 30% in the United States. In the last report, we described our development of an innovative sachet to generate chlorine dioxide (ClO2) to improve food safety and reduce postharvest loss of fresh produce. During the past year, we have demonstrated the technical feasibility of developing an innovative package label to generate ClO2 to inhibit microbial growth of fresh produce in individual food packages. Although both the sachet and the label generate ClO2, their manufacture and activation principles are quite different. The manufacture of the label involves extruding packaging plastics (such as ethylene vinyl acetate copolymer) to incorporate citric acid. The activation of the label involves (1) spraying the surface with sodium chlorite, (2) heat pressing the label to facilitate physical contact between citric acid and sodium chlorite, and (3) trigging the generation and release of ClO2 by moisture emanating from fresh foods. The release of ClO2 from the label has been demonstrated to be effective in inhibiting against Salmonella growth. More details about the manufacture and activation principle of the label are described in the paper listed in the Publications section of this report. The sachet and the label developed in this project complement each other by providing the industry the ability to improve food safety and reduce postharvest loss of fresh produce products for a wider range of applications.

Publications

• Type: Journal Articles Status: Published Year Published: 2017 Citation: Saade, C., B. A. Annous, A. J. Gualtieri, K. M. Schaich, L. Liu and K. L. Yam (2017). "System feasibility: Designing a chlorine dioxide self-generating package label to improve fresh produce safety part I: Extrusion approach." Innovative Food Science & Emerging Technologies 43(Supplement C): 102-111.

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:The target audience are (1) researchers and food technologists working for the fresh-cut produce industry or the packaging industry, and (2) graduate students with research interest in food packaging and shelf life extension. 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?The results are being disseminated through presentations at major conferences. What do you plan to do during the next reporting period to accomplish the goals?We will fine tune this packaging system to optimize the conditions for the controlled release of ClO2 to inhibit the microbial growth of fresh produce products. We are alsopreparing manuscripts to report this workin peer-reviewed journals.

Impacts
What was accomplished under these goals? We developed a novel packaging system to generate chlorine dioxide (ClO2) to improve the microbial safety of fresh produce. The implementation of this packaging system placing a fresh produce such as tomato into a ClO2 generating package imbedded with sodium chlorite (NaClO2). The carbon dioxide (CO2) and moisture from the respiration of the fresh produce react with each other to provide carbonic acid (H2CO3), which in turn reacts with NaClO2 to generate ClO2. Using fresh tomatoes as the food model, we obtained experimental evidence to support the validity of this hypothesis. Our results show that this packaging system can completely inhibit against 102 CFU Salmonella spp. on TSA agar within 48 hours under 22 ºC. To optimize this packaging system, we further conducted experiments to study the effects of NaClO2 content (0.05, 0.1 and 0.2 g), CO2 content (7.5 and 15%), RH content (45 and 90%), temperature (10, 22 and 35 ºC) and environmental conditions (dark and light) in the release profile of ClO2 and the inhibition effects against 105 CFU Salmonella spp. on TSA agar within 48 hours are systematically investigated. The basic chemistry mechanism including the relationship between pH and ClO2 generation profile as well as the microbiology mechanism including the D value and the Z value are also studied. Based on the results, appropriate amounts of NaClO2 were embedded into three forms of delivery systems: sachet, gum arabic paste, and electrospun fiber. These delivery systems were tested using fresh tomatoes inoculated with 105 CFU Salmonella spp. on their surfaces. All of them were able to greatly improve microbial inhibition under practical conditions compared to the control, without significantly affecting the sensory attributes of the tomatoes. The sachet can be placed inside the package; the gum arabic paste and electrospun fiber can be applied as a coating on the package.

Publications

Progress 10/01/14 to 09/30/15

Outputs
Target Audience:The target audience are (1) researchers and food technologists working for the fresh-cut produce industry or the packaging industry, and (2) graduate students with research interest in food packaging and shelf life extension. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project provided professional training for Carol Saade who graduated with a Ph.D. degree this year. Carol also had the opportunity to collaborate with Dr. Bassam Annous from the USDA Eastern Regional Research Center in this project. She is now working for Kelloggs. How have the results been disseminated to communities of interest?The results are being disseminated through presentations at major conferences and peer-reviewed journals. What do you plan to do during the next reporting period to accomplish the goals?We plan to optimize the conditions for the controlled release of chloride dioxide to inhibit the microbial growth for another fresh produce product. We will also polish the drafts of the two manuscripts for publication submission.

Impacts
What was accomplished under these goals? The drafts of two papers have been prepared for submission for publication. The first paper is titled "System Feasibility: Designing a Chlorine Dioxide Self-Releasing Package Label to Improve Fresh Produce Safety Part I: Extrusion Approach," and the second paper is titled "System Feasibility: Designing a Chlorine Dioxide Self-Releasing Package Label to Improve Fresh Produce Safety Part II: Solution Coating Approach." These papers summarize the accomplishment under the goals above.

Publications

Progress 12/06/13 to 09/30/14

Outputs
Target Audience: The target audience are (1) researchers and food technologists working for the fresh-cut produce industry or the packaging industry, and (2) graduate students with research interest in food packaging and shelf life extension. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? The project provided trainng for twograduate students in producing packaging films andanalytical methodologies at Rutgers and the USDA Eastern Regional Research Center. How have the results been disseminated to communities of interest? We are preparing papers to be submitted to peer reviewed journals. What do you plan to do during the next reporting period to accomplish the goals? We plan to optimize the process variables to bettter control the release kinetics of chloride. This will allow us tomatch the microbial kinetics associated with the fresh produce. Besides fresh tomatoes, we will also evaluate the effectiveness of the system for other fruits and vegetables.

Impacts
What was accomplished under these goals? During this reporting period, we collaborated with the researchers at the USDA Eastern Regional Research Center todemonstrate the feasibility of incorporating a salt into a packaging film in such a manner that, whenfreshtomatoes were packaged inside the film, the carbon dioxide and moisture generated by the tomatoes could trigger the release of chloride dioxide to inhibit microbial growth in the tomatos without adversely affecting the sensory quality.

Publications