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There will be two sets of objectives and methods for each approach. They cannot be combined because the research involving antimicrobial films for RTE meat require direct contact and migration from the antimicrobial packaging material while the fresh produce, due to their high surface are, require a volatile antimicrobial system using a naturally derived agent or chemically generated system. <P>Antimicrobial Packaging for RTE Meats using Nisin 1. To determine the polymer or copolymer material that is ideal for extrusion of antimicrobial agents such as nisin for ready-to-eat deli meat. 2. To measure the antimicrobial performance of nisin in the incorporated material. 3. To characterize nisin's properties, once incorporated in the film. 4. To measure the effects of nisin on the physical and mechanical properties of film. 5. To complete a challenge study using the film packaging on a food matrices. 6. To ascertain long-term outcomes of the research Outcomes or Projected Impacts. The nisin film will be produced using commercial techniques in order to extend shelf-life and provide a secondary measure of safety from gram positive organisms in RTE deli meat, which have a zero tolerance for L. monocytogenes. The film will be a retail vacuum skin packaging so it will be in direct contact with the food to cause the maximum amount of inhibition by the nisin migrating into the food packaging and onto the food surface. The film will be manufactured with current equipment already in-use by food packaging companies. Research on antimicrobial of fresh produce is expected to result in a significant reduction of Escherichia coli O157:H7 and Salmonella Typhimurium (at least 2-3 log) with minimal sensory impairment, including little to no color change of the product, and little to no odor detected, and no residue remaining on the leaf. Currently, chlorine dioxide gas in conjunction with MAP is not used in the produce industry.
Non-Technical Summary:<br/>
Foodborne illness is a major concern in the United States as it affects approximately 1 in 6 people, according to the Centers for Disease Control (CDC). These estimated 48 million cases occur each year in the United States include 128,000 hospitalizations and 3,000 related deaths. According to the USDA Economic Research Service (USDA-ERS), outbreaks associated with foodborne illness cost over $6.9 billion per year in lost wages, recalls, and lawsuits (CFI, 2010). Compounding issues with foodborne outbreaks is that many consumers, due to hectic lifestyles, demand foods that are ready-to-eat or "RTE" (such as delicatessen products, including meats and cheeses), minimally processed (such as fruits and vegetables), and "take out" foods. Microorganisms associated with outbreaks include: Listeria monocytogenes and E. coli O157:H7. These bacteria have been involved in several recalls of raw vegetables, cheeses, milk, deli meats, fresh cut lettuce, alfalfa sprouts, cantaloupe and spinach, to name a few. Nisin is a antibacterial substance which has been approved for use in 57 countries around the world and has been affirmed as generally recognized as safe (GRAS) in the United States. In fresh produce a volatile antimicrobial agent could be effective for surrounding the produce. There are no commercially available antimicrobial packaging materials, but research over the years has shown that it can be effective on a laboratory scale. With the addition of this antimicrobial into food packaging materials, these high-risk foods can be better protected against potential contamination. Industry is better protected against negative economic impact, and consumers, no matter their demographic situation, are safer when consuming such products. In addition to addressing foodborne pathogens of concern in prepared foods, antimicrobial packaging can also decrease spoilage bacteria, thereby extending shelf life. Shelf life extention has two benefits. One benefit is improved food quality by providing a fresher product that can withstand a longer distribution cycle and longer storage in the home.
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Approach:<br/>
Objective 1. Using a cast extruder, the polymers/copolymers EVA, Surlyn. LLDPE & LDPE will be placed in the extruder hopper and pumped individually through the extruder at constant residence time. Objective 2. Nisin will be measured and evenly mixed with the resin from the polymer chosen from Objective 1. Both the resin and the nisin will be extruded at the temperature/residence time determined above. Samples from the beginning, during the middle and at the end of the run will be collected. In order to determine if the nisin survives the extrusion temperature and is able to release from the polymer, the plate overlay assay will be conducted. Objective 3 Nisin will be exposed to wavelengths produced by UV light to determine if the protein is excited and will emit blue light, causing naturally occurring fluorescence. This will be completed by using current fluorescence microscopy techniques and by using a UV microscope. Objective 4 A seal curve will be performed. Using a Hunter colorimeter, the color of the polymer will be evaluated to determine if there is a significant difference from the control. Permeation of H2O and O2 will be evaluated. Objective 5 The RTE deli meat will be inoculated with L. monocytogenes by mixing gently by hand for 1 min, left undisturbed for 5to10 min, deli meat will be removed aseptically, and placed under the biological safety hood to air dry on sterile trays for 10 min. Deli meat will be inoculated with L. monocytogenes Remaining deli meats will be vacuum skin packaged using both the nisin extruded film, the control film (not containing nisin) and stored at 4C or 22C (to measure temperature-abuse conditions). L. monocytogenes will be enriched, enumerated, and confirmed. The amount of inhibition will be determined and compared to the control. Antimicrobial Packaging of Fresh Produce - leafy greens will be selected as an example of the methods to be used. Objective 1 Chlorine dioxide gas sachets will be tested in various locations within the package to determine the best location for completed exposure of chlorine dioxide gas on the leafy greens. In addition varying concentrations for chlorine dioxide gas will be used (low, medium and high) for each location. Objective 2 The pathogens will be prepared as described above. The parallel experiments will be conducted for Escherichia coli O157: Fresh leafy green leaves will be cut into 2.5 cm by 2.5 cm pieces, washed to remove endogenous microflora in total chlorine solution (NaOCl) adjusted to pH 6.5 with HCl, and centrifuged for 2.5 min to remove excess water. Objective 3 The parallel experiments will be conducted for Escherichia coli O157:H7 and Salmonella Typhimurium each inoculated in separate bagged leafy greens. Objective 5-Sensory Analysis for odor caused by chlorine dioxide gas or AIT. The first step will be to design a survey to screen for sensory panelists who are typically consumers of bagged salad. The The panelists will only be looking visually at the product and smelling the product to determine if the odor from the chlorine dioxide or AIT is undesirable or if there is a color change.
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Progress:<br/>
2012/01 TO 2012/12<br/>
OUTPUTS: Preliminary work has been completed on two projects, both involving nisin for inhibition of Listeria monocytogenes in deli meats and cheese. The third project is in the experimental design stages but meetings have been held with a supplier of chlorine dioxide which have been helpful in identification of a supplier for tomatoes. Work will be presented at the following scientific meetings: International Association for Packaging Research Institutes, May 2013. Institute of Food Technologists Annual Meeting, June 2013. International Association for Food Protection, July 2013.
<br/>PARTICIPANTS: The following students are supported and working on these projects: Angela Richard, Ph.D. candidate. Michele Perna, Ph.D. candidate Chris Gottilla, M.S. candidate.
<br/>TARGET AUDIENCES: Not relevant to this project.
<br/>PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
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IMPACT: There are three major projects in progress. One involves coating methylcellulose based nisin material onto lidding material for vacuum skin packaging. To this point the coating material has been reformulated from a batch process to allow for continuous coating. The coating has been characterized using viscosity, pH, haze and coating thickness. Antimicrobial effectiveness of this coating against Listeria monocytogenes is underway. The second project involves the use of calcium salts to allow controlled release of nisin from coated parchment paper as an interleaf between vacuum skin packaged deli meat. The coated paper has proven to be an effective antimicrobial against Listeria monocytogenes but more formulation for controlled release is continuing. Work shows calcium salts are effective for slow release but the exact ratio to allow sustained release is under development. The third project involves use of chlorine dioxide for shelf life extension of fresh tomatoes. A supplier for chlorine dioxide sachets has been instrumental for assistance in experimental design and contacts for tomato suppliers. Work on this project is in the experimental design and supply acquisition stages.