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A novel packaging system for meat safety and shelf-life extension

Final Report Summary - MEATPACK (A novel packaging system for meat safety and shelf-life extension)

Executive Summary:
The ability to manufacture high-quality and safe products consistently is the basis for success in the highly competitive food industry. Despite strict safety and hygiene standards, meat and poultry products can be vehicles for cases of foodborne illness. This highlights the need for effective decontamination to ensure consumer protection and confidence in meat.
Additionally, meat processors are constantly striving to lengthen product shelf-life. Consumer aversion to irradiation and chemical preservatives have opened up a technological gap where innovation is required for the development of novel food preservation systems.
A European consortium of 9 members counting small and medium enterprises of the meat industry, as well as research centres, have participated in the MEATPACK project, whose aim is to develop a novel non-thermal plasma* process to reduce microbial load in packed meats, thereby ensuring meat safety without compromising nutritional or quality aspects. The proposed MEATPACK system is expected to extend product shelf-life without the use of chemical sanitisers or heat treatment; it will be non-invasive; it will leave zero residues and it will not adversely affect product quality. A critical advantage of this technology in the in-package treatment, which is desired by the food industry as this approach mitigates the risk of recontamination and may increase shelf-life.
During the first year of the proposed project, a laboratory test-rig was used to study the critical plasma control parameters and packaging design that maximise the antimicrobial effect and quality retention. During the second year, an in-pack plasma system was built to pre-competitive prototype level and subsequently validated in a controlled environment and in the industry for meat pathogen reduction and shelf-life extension.
As microbial spoilage and subsequent quality deterioration of meat cause significant losses for the meat industry, MEATPACK, a technology simultaneously addressing pathogen reduction, control of spoilage microflora and quality retention (thereby extending shelf-life) will provide a competitive advantage for the European meat industry.
* “non-thermal plasma” (hereafter NTP) and “atmospheric cold plasma“ (hereafter ACP) will be used interchangeably throughout this document.

Project Context and Objectives:
The overall objective of the project was to develop an atmospheric plasma-based pre-competitive MEATPACK prototype, in order to reduce microbial load in packed meats and extend their shelf-lives without compromising nutritional or quality aspects.
In order to achieve the above, the technical and operational objectives that needed to be fulfilled are provided below.
1. To implement an industry-driven approach to define the specifications of the MEATPACK system.
2. To build a lab-scale ACP system that will enable DIT to investigate and optimise the conditions of operation and to help facilitate scale-up.
3. To establish a study protocol for validating the test rig in WP2 as well as the pre-competitive prototype from WP4 in relation to the quality and safety of the treated meat samples.
4. To study the critical control parameters (CCPs) governing antimicrobial efficacy at laboratory scale for a range of key pathogenic and spoilage microorganisms for meat.
5. To optimise meat packaging and to study the effect of modified atmosphere packaging (MAP) conditions of in-package plasma as a function of anti-microbial efficacy and quality retention.
6. To characterise the physical plasma discharge produced under the variable control parameters and to correlate plasma discharge characteristics with anti-microbial efficacy and community profiling towards optimising the application further (WP2, partial objective, achieved).
7. To design and build a precompetitive MEATPACK system for the in-pack decontamination of meat cuts taking into account the inputs from WP2 and WP3.
8. To perform comprehensive tests with samples of meat that have been decontaminated with MEATPACK pre-competitive prototype, in order to analyse and validate the performance of the treatment.
9. To install and run trials with the MEATPACK pre-competitive prototype in commercial meat packing facilities in order verify its ability to effectively treat meats.
10. To carefully outline scaling-up guidelines and development work for full production.
11. To facilitate the uptake of the MEATPACK results by the participating SMEs as well as a wider audience by carrying out a comprehensive series of knowledge transfer and training activities.

Project Results:
The project started by reviewing the technical needs of the participating SMEs. Meat types and cuts of interest were selected: raw pork loin muscle, sliced (of particular interest to partner DAZA), raw lamb chop, sliced (of particular interest to partner ICM) and cooked turkey, sliced (of particular interest to partner STEPHENS). Four pathogenic microorganisms (two gram positive: Staphylococcus aureus and Listeria monocytogenes; two gram negative: Escherichia coli and Campylobacter jejuni) which occur as common contaminants of the aforementioned meat types and one spoilage microorganism (Brochothrix thermosphacta) of particular concern to extended shelf-life MAP meat products were selected for the investigations. A plastic tray of approx. 200 x 150 mm with plastic lidding film was selected as a model functional unit for the project. Commonly-used modified atmosphere packaging (MAP) conditions for the selected meats were agreed, namely high N2 (ca. 70% N2 and 30% CO2) for cooked turkey and high O2 (ca. 70-75% O2 and 30-25% CO2) for raw meats. Meat storage conditions, as well as current and target shelf-lives for the study were agreed.
A semi-structured questionnaire was prepared to serve as a basis for direct in-depth consultations with industry representatives, made via on-site visits or phone interviews, whereby the RTDs gained in-depth understanding of the technological needs of the SMEs, as well as perceptions in terms of product safety and quality. As an addition to the consultations, comprehensive literature, patent and legislation reviews were carried out, in order to update the state-of-the-art in terms of food surface decontamination using plasma, and to identify relevant patents and legislation that had to be considered to ensure the MEATPACK technology and treated products can reach the market. As a result of the information gathered, the overall system specifications of the MEATPACK system were defined, based on consideration of the characteristics of the products and packages that are to be treated, the general requirements of a dielectric barrier discharge plasma unit and the regulations governing the high voltage machinery. The MEATPACK specifications are intended to enable building a machine that is effective and reliable in decontaminating food surfaces, operated within the meat processing and packing line, used by an operator without specialist training and at a price that is economically beneficial to an SME. The overall and individual component specifications will be key to the design of the pre-industrial prototype.
The technical work started with the modification of plasma test-rig at DIT120, by the installation of a by-pass protector in order to address the need for high plasma reproducibility and avoid arcing. After setting up the laboratory system, key extrinsic parameters (voltage level, inducer gas, post-treatment storage conditions) were optimised for the MEATPACK applications. The selected challenge microorganisms were subjected to plasma treatments in liquid meat model media under variable conditions. Following the demonstration of the efficacy of the system against challenge microorganisms in liquid media, a comprehensive evaluation of antimicrobial efficacy was carried out on the selected meat cuts over different periods of time, depending on their current shelf-life. Overall, plasma treatment showed a reduction of both challenge and background microflora, however the efficiency of the inactivation decreased with increasing complexity of the media/food matrix.
The plasma discharge was characterised inside sealed packages under the two different MAP selected, in order to correlate the active species generated with the antimicrobial efficacy shown. Findings suggest that that ozone stays active in the package for 100s of seconds after the plasma discharge, which could shorten the treatment times, and that the most active species are generated at the top of the package, close to the high voltage electrode. However, a drop in intensity was observed when meat was inside the package, which was correlated to a decrease in the volume due to the presence of the meat piece. The analysis of the OH intensity can be correlated with changes in the humidity inside the package. OH intensity in the packages with meat showed a change of 10% in the humidity from the medium to the upper position within the package.
Simultaneously to the plasma discharge characterisation, a microbial community profiling study was carried in order to determine the potential differences in the inactivation efficacies between different microbial species present in the meat products across product storage time, as well as differences between treated and non-treated samples. This technique can detect the changes of bacteria present on a product based on isolation of bacterial DNA, since some microorganisms present in the meat might not be culturable. The community profiles obtained from treated samples reflected those of the respective control samples, no predominant species with particular resistance towards plasma treatment were detected.
Cytotoxity and mutagenicity studies were also conducted to ensure additional consumer food safety. For this purpose mammalian cells lines were used to study the potential adverse effects on cell viability/growth or changes to the genetic composition after plasma discharge.
Furthermore, a wide range of food packaging materials was collected for selection as suitable for plasma treatment. PET+PE trays provided by partner HPL were selected as the most suitable for plasma treatment, since the measurements in sheets with these materials presented the lowest oxygen transmission rate values. Lidding films from the end-user SME partners were included in the study and showed the highest barrier properties and colour stability after plasma treatment, and were therefore selected for the rest of the study.
A shelf-life life study as a function of MAP blends was carried out in order to correlate the plasma discharge and generation of reactive species with antimicrobial efficacy and meat quality. Plasma diagnostics of O2/CO2 chemistry showed that plasma species were active in the middle of the food package while in N2/CO2 species are active in a much wider area in the middle of the package. High ozone concentrations were detected in lamb and pork trays but gas composition inside the package was back to the applied modified atmosphere after 24 h post-treatment storage. On the other hand, the absence of carbon monoxide was confirmed, as undetectable levels were found. The results from background microflora studies suggested that plasma treatment could potentially extend the shelf-life of MAP meat products with regards to acceptable levels of microbial content. Meat quality studies showed that surface colour of lamb meat was affected by plasma treatment at the beginning of the study whereas the visual appearance of pork loin and sliced turkey products were less affected by plasma.
The influence of plasma treatment in the stability of MAP (i.e. high-oxygen and high-nitrogen concentration packages) was also evaluated through the study of changes in surface properties (i.e. hydrophylicity of films) and barrier properties (i.e. oxygen permeability and migration of plastic components to the food environment). In general, film surfaces became more hydrophilic after plasma treatment, which could lead to vapour condensation at the inner face immediately after treatment, however no water condensation was observed after the first storage day during the shelf-life study. Oxygen permeability of films was slightly improved, while the migration study in food simulants showed the compliance of all the plasma treated materials with the current EU legislation, which overall confirmed that bulk properties of the packaging materials are not affected by changes observed at surface level. The changes in the gases composition inside the packages over the shelf-life study were also monitored in order to predict the gas dynamics within the packages and adapt the quality assurance process in the previous and further steps accordingly. As a result, a mathematical model explaining the oxygen behaviour inside the packages was developed for each type of meat from experimental data obtained during the shelf-life study. Sliced turkey packages followed the logistic model while lamb chop and pork loin packages both fitted in the exponential model, with oxygen content decreasing gradually over the shelf-life.
Based on the system specifications collected, as well as knowledge acquired through previous work, prototype ideation and hardware design work started. The general design concept entailed a compact, batch mode, pre-competitive MEATPACK prototype to be loaded manually. To comply with normal production practice during the tests carried out in the SMEs facilities, it was decided for the prototype to be a stand-alone device, meaning it would offer the possibility to be installed without affecting the normal production lines. Nevertheless, the design accounted for future integration of an upgraded version of the prototype into the production lines.
The MEATPACK prototype uses DBD plasma technology as an alternative, batch, in-pack decontamination system for meat. Dielectric-barrier discharge (DBD) is the electrical discharge between two electrodes separated by an insulating dielectric barrier. The system comprises both treatment and control modules, which are intended to be placed far enough from each other to provide a safe manipulation for the prototype operator. The package of meat to be treated is to be located between the two electrodes that have been mention above; in this case, the dielectric barrier of the bottom electrode is used as the surface to hold the sample, which is accessible by opening the treatment chamber. By closing again the treatment chamber lid the top electrode gets in contact with the meat tray; both top and bottom electrodes are connected to a high voltage transformer. When the transformer is powered on by means of the generator control a dielectric barrier plasma discharge takes place in the gap between the two electrodes. This high voltage process ionises the gas contained within the food package, resulting in the generation of significant amounts of reactive species that have a bactericidal effect on the product.
In the meantime, a study protocol for validating the NTP technology was developed. In all, three protocols were devised (1) a protocol for laboratory validation on food safety for WP2, (2) a protocol for pilot plant validation on food safety, shelf life, sensory profiling and nutritional evaluation for WP5 and (3) a protocol for industrial validation on shelf life. All the protocols specify the type of trials (meat, treatment and storage), which will be performed with NTP treated meat, and the laboratory analysis (analysis, number of samples and repetitions) that will be conducted.
The MEATPACK prototype was used to study the lethal effect of cold plasma treatment on a cocktail of Salmonella, Campylobacter, VT Escherichia coli and Listeria monocytogenes on the surfaces of MA-packed pork and lamb steaks and the inactivation of a cocktail of Escherichia coli, Campylobacter, Listeria monocytogenes and Staphylococcus aureus on cooked sliced MA-packed turkey. The meat surfaces were inoculated with the pathogens just before MA-packaging and CAP treatment and the number of pathogens were measured 24 hours after treatment and at the end of shelf life in treated an un-treated samples as a control. The results show a lower reduction of pathogens than found on plastic surfaces, blueberry surfaces, cabbage and peppercorn due to the high water content in meat, which might reduce the antimicrobial effect of plasma. To complete the study, the effect of cold plasma treatment on the microbial shelf life was validated on fresh pork, fresh lamb steaks and sliced processed turkey. In particular, microbial and sensory evaluation was followed during the storage, as well as nutritional evolution of the meat by measuring the content of secondary oxidation products (TBARS) 1 day and 7 days after packaging and the relevant vitamins.
Finally, the MEATPACK prototype was installed directly at the end user facilities where changes were implemented to improve the efficiency of the system. In particular, the trial took place at Stephens Fresh Foods Ltd (UK) and Embutidos DAZA (Spain). The validation of the system was focused on the safety aspect of the meat products and thus mainly microbiological analysis were performed on fresh meat products, in particular for sliced turkey (with an 80% of meat in its composition) at STEPHENS and pork at DAZA. Two different packaging formats were employed during validation trials at STEPHENS (trays with a modified atmosphere and bags) whereas treatment at different times were tested in the case of DAZA for trays with pork.
Validation test with trays at STHEPHENS agreed with those described by DMRI during pilot plant trials. However, positive outcomes were achieved with cooked turkey bags with air inside after a 1 minute treatment using a lower gap and a thinner dielectric sheet; obtaining reductions in microbial content of nearly 1 log. Whereas, validation results in DAZA showed reduction of more of 1 log in Psychrophiles within 1 minute treatment
After validation at industrial and pilot scale facilities, inputs from partners were collected and a number of recommendations for further research work and developments were done.

Potential Impact:
The MEATPACK project has developed a novel non-thermal plasma process to reduce microbial load in packed meats, thereby extending shelf-life without compromising nutritional or quality aspects.
The end-users of the technology will be able to differentiate their products and gain competitive advantage through the MEATPACK benefits:
• Non-thermal treatment - no heat is generated inside the package, thereby no degradation to the meat.
• Non-invasive treatment that leaves zero residues.
• Efficient to run - very low energy is required.
• No risk of recontamination - packed meats are treated at the end of the processing stage, thereby preventing any recontamination.
• Compatible with several packaging formats, including MAP
By having access to a technology such as MEATPACK, meat processors will be equipped to provide meat products that deliver on safety, quality and nutrition throughout extended distribution networks. The development of a novel non-thermal meat preservation method represents a significant scientific advance for the meat industry. METATPACK will benefit both the European meat industry and European consumers, through increased confidence in these products, together with a positive impact on the competitiveness of European companies along its supply chain.

In terms of Dissemination, a dissemination strategy has been in place to ensure that non-confidential MEATPACK information is disseminated as widely as possible among industrial stakeholders, academic community and general public. A project website ( was created and used to inform the public and interested parties on the basics of the technology, latest news and the progress of the project insofar as it can be disseminated without threatening the proper protection of the developed IP. Project poster and leaflet (annexed to the report) were prepared, printed and distributed in events. MEATPACK project was presented to the industrial stakeholders (food processors, food traders, food safety monitoring companies and monitoring equipment suppliers) through tradeshows and exhibitions, magazines and professional newsletters, as well as through oral presentations and scientific posters to the scientific community. Overall, 35 dissemination activities have been carried out throughout 24 months and 2 scientific publications are under preparation.
In addition, training activities were performed throughout project in order to ensure a profitable knowledge transfer from the RTDs to the technical and managerial staff of the industrial partners of the Consortium.

In terms of exploitation, the aspects of the foreground and their novelty have been presented and discussed during the project meetings based on the results of the RTD work. With increased demand for high quality, convenient, innovative, regular and safe meat products with natural flavor and taste and an extended shelf-life, the development of alternative technologies called non-thermal technologies, where atmospheric plasma is framed is promising, nevertheless at the final stage of the project, the SMEs´ understanding is that further development is required to bring the MEATPACK to a saleable state.

List of Websites:
Dr Edurne Gaston Estanga