Date of Award

8-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Packaging Science

Committee Member

Kay Cooksey, Ph.D., Committee Co-Chair

Committee Member

Duncan Darby, Ph.D., Committee Co-Chair

Committee Member

Charles Tonkin, Ph.D.

Abstract

With an increase in demand for fresh, ready-to-eat meats, the use of antimicrobial food packaging could help reduce food waste by delaying and decreasing growth of spoilage bacteria, thereby extending the shelf-life and enhancing food quality and safety. Nisaplin® is a commercially available antimicrobial peptide that is approved by the FDA and is designated GRAS as a food additive. This additive has the potential to be commercially added into antimicrobial packaging applications, specifically, ready-to-eat meat packaging. This study was conducted to determine if a coating containing Nisaplin® could be commercially applied to a polymer film substrate using large scale production equipment while still maintaining antimicrobial efficacy. A flexographic printing press was used to apply a liquid coating containing Nisaplin® to a PET/LLDPE laminate, a non-forming web film substrate. pH and viscosity testing of the liquid coatings was conducted prior to applying the coating. Heat seal tests were conducted to determine if the coated film could be commercially converted into a package. Basis weight tests were conducted to determine the weight of the coating applied, and for determining the total cost of the converted package. Tests were also conducted using a colorimeter to determine if the liquid coatings caused a change in the overall appearance and clarity of the coated films. Antimicrobial efficacy and tests to determine inhibition of aerobic bacteria, coliform bacteria, and staph growth were performed. Preservative and additive free sliced turkey deli meat was inserted into the treated and untreated converted pouches over an 11- day trial period. Inhibition testing was conducted on dry coated films to determine the maximum length of time in days that Nisaplin® proved effective in the inhibition of aerobic bacteria growth. Control films did not contain Nisaplin®. Uncoated films containing no coating were used as a second control set of pouches. The pH of the antimicrobial coating was found to be 7.27 with a viscosity of 19.53 when tested with a #3 Zahn cup. Peel-able seals for all three tested films (nisin coated, coating only, and uncoated film) were achieved at 300°, with seal properties for the treatment containing Nisaplin® showing an increase in strength as temperature increased. Coated films without Nisaplin® also achieved inhibition against the growth of aerobic bacteria with statistical difference between the coating with Nisaplin® and the two control groups (the coating without Nisaplin® and the uncoated film) on Day 5 (2-log reduction) and Day 9 (1-log reduction), 45 days after the coating was applied to the film. No statistical difference was found in the inhibition of coliform colony growth between the two coatings (with and without Nisaplin®) throughout the sample periods. Thus, the application of the coating, as well as converting and efficacy of the antimicrobial coating process suggest that it is possible to commercially produce an effective antimicrobial coating contain Nisaplin®. The work showed that the antimicrobial coating containing Nisaplin® reduced the overall aerobic microbial population of the refrigerated ready-to-eat turkey deli-meat. Further work needs to be conducted to validate shelf-life extension and improved safety of ready-to-eat food products.

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