Progress 10/01/11 to 09/30/13
Target Audience: The main target audience for this project is the US food industry, which could benefit directly from the results of this research. The scientific community, particularly microbiologists and food scientists, will benefit from the generated knowledge regarding the development of antimicrobial coatings. Changes/Problems:
What opportunities for training and professional development has the project provided? One graduate student was trained with partial funding from the project. The project was also instrumental in the professional development of one postdoctoral associate. How have the results been disseminated to communities of interest? The results of this project have been communicated at a conference, and will also be included in a research publication which is currently under preparation. We plan to also talk about the successful developments of this project (i.e. the nisin coating) in all future talks to industry and academia that will focus on antimicrobial strategies for food applications. What do you plan to do during the next reporting period to accomplish the goals?
What was accomplished under these goals?
1) Development of antimicrobial coatings and films. Experiments have been conducted to obtain chitosan coatings and films of uniform thickness and desirable properties. Commercial-grade chitosans with different levels of acetylation was used to prepare solutions, which were than cast on selected substrates (stainless steel and high density polyethylene). Films will be peeled from the plates after drying at ambient temperature in a laminar flow hood for about 48 h. and then subjected to specific physical property determinations. The best coating results were achieved using a 1% solution Chitosan with EDTA and lactic acid. Nonetheless, significant challenges were encountered in obtaining films that were uniform and thin enough for the targeted applications, and thus we decided not to pursue further this direction of research. 2) Use of nisin coating as antimicrobial for direct food applications. We have successfully obtained antilisterial effects of nisin coatings (applied as a dip) when applied to food surfaces (both meat products and cheese). To increase effectiveness, the application of nisin was tested in combination with another antimicrobial strategy – Pulsed Light treatment. For instance, nisin alone (applied as a 2.5% nisin solution) on cheddar cheese inoculated with L. innocua resulted in 2 log reduction. When nisin was applied in combination with PL, total inactivation was greater by about 1-log than with just \ low PL doses (1 and 3 pulses). 3) Adding an antimicrobial silver coating onto anodized food contact surfaces with nanoscale topography. Our group has worked on investigating the antimicrobial effects of anodized food contact surfaces with nanoscale topography, as part of a different project. In the current project, we investigated the possibility of adding an antimicrobial silver coating onto the anodized surfaces that are able to minimize bacteria attachment. Using the available technology for depositing the silver, we encountered significant challenges with the uniform distribution of the silver coating. While we still consider that this strategy could be successful, we were not able to demonstrate these effects due to limited manufacturing capabilities at the moment, and hope to revisit this in the future, is we get access to different silver application methods. Overall, the application of a nisin coating directly on the surface of foods was most successful. This strategy could be used in food safety applications in the food industry.
Conference Papers and Presentations
L. Hsu, B. Miller and C. I. Moraru. 2013. The effectiveness of hurdle strategies consisting of Pulsed Light treatment and antimicrobials on the inactivation of pathogenic bacteria on cheese. Book of Abstracts of the Annual Meeting of ADSA, Indianapolis, IN, July 2013
Progress 10/01/11 to 09/30/12
OUTPUTS: In the first year of the project, efforts have been focused primarily on the development of the actual coatings and films, which is the most challenging component of the work. Chitosan was used as the biopolymer of choice for the incorporation of antimicrobials, since chitosan has been shown before to maintain a high antimicrobial activity of antimicrobials. A considerable amount of time was spent trying to develop very thin films of uniform thickness, as this will be key for the successful application of this coating on substrates with a controlled surface topography. Progress has been made, and we will continue to improve upon the results obtained in the first year in terms of the coating quality and performance. PARTICIPANTS: 1) Project Director: Dr. Carmen I. Moraru - project supervision and management, will coordination of the experimental design, main responsibility for activities related to microbial attachment and biofilm formation and evaluation. She also coordinates the data analysis and formulation of the final conclusions. 2) Co-PD: Dr. Randy Worobo - Assistance with the Microbiology research and interpretation of the microbiological data. His lab will assist with the research involving antimicrobial coating. 3) Lillian Hsu- Postdoctoral Associate, Department of Food Science, Cornell University. Responsible for conducting the microbiological testing, the attachment and biofilm formation studies. 4) Dr. Esther Sendra Nedal - Visiting Scientist, Spain - assisted with the development of chitosan coatings. TARGET AUDIENCES: The main target audience for this project is the US food industry, which is expected to benefit directly from this research. We expect that the scientific community, particularly microbiologists and food scientists will benefit from the generated knowledge regarding the development of antimicrobial coatings. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
The goal of this project is to develop generally recognized as safe (GRAS) antimicrobial coatings that can be applied directly to foods or foods contact surfaces. This will provide solutions for minimizing pathogen contamination of foods, thus reducing the incidence of foodborne illness. As a main research activity for this phase of the project, we worked on developing encapsulation systems for the selected antimicrobials. Specifically, chitosan was selected as the encapsulating material and experiments have been conducted to obtain chitosan coatings and films of uniform thickness and desirable properties. Commercial-grade chitosans with different levels of acetylation was used to prepare solutions, which were than cast on selected substrates (stainless steel and high density polyethylene). Films will be peeled from the plates after drying at ambient temperature in a laminar flow hood for about 48 h. and then subjected to specific physical property determinations. A considerable amount of time was spent on optimizing the composition of the cast solution, i.e. the use of additives including glycerol, sodium acetate, ammonium acetate, EDTA, acetic acid and lactic acid. The use of sodium acetate yielded sticky coatings, while films buffered with ammonium acetate were not as sticky. Coatings derived from chitosan solubilized with acetic acid had better strength than those obtained with acetate. The best coating results were achieved using a 1% solution Chitosan with EDTA and lactic acid. The addition of glycerol addition did not result in any significant improvement of the coating properties. Experiments will be further fine-tuned to obtain the best possible coatings and film before the incorporation of antimicrobials.
- No publications reported this period