==== Front Braz J MicrobiolBraz. J. MicrobiolBrazilian Journal of Microbiology1517-83821678-4405Elsevier S1517-8382(16)30998-410.1016/j.bjm.2017.09.009Food MicrobiologySurvival of Salmonella spp. in minced meat packaged under vacuum and modified atmosphere Djordjević Jasna jasnalonce@gmail.coma⁎Bošković Marija aStarčević Marija aIvanović Jelena aKarabasil Nedjeljko aDimitrijević Mirjana aLazić Ivana Branković bBaltić Milan Ž. aa University of Belgrade, Faculty of Veterinary Medicine, Department of Food Hygiene and Technology of Animal Origin, Belgrade, Serbiab Institute of Meat Hygiene and Technology, Belgrade, Serbia⁎ Corresponding author at: Faculty of Veterinary Medicine, University of Belgrade, Bulevar oslobodjenja 18, 11000 Belgrade, Serbia. jasnalonce@gmail.com12 2 2018 Jul-Sep 2018 12 2 2018 49 3 607 613 8 11 2016 23 9 2017 © 2018 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda.2018Sociedade Brasileira de MicrobiologiaThis is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).The effect of different modified atmosphere packaging regimes on the behavior of Salmonella spp. on minced meat was studied. Minced meat was experimentally contaminated with a Salmonella spp. cocktail (S. Enteritidis, S. Typhimurium, S. Infantis and S. Arizonae), packaged under vacuum or modified atmosphere with initial headspaces containing 20%O2/50%CO2/30%N2 and 20%O2/30%CO2/50%N2) and stored at 3 ± 1 °C for 12 days. Samples were analyzed for Salmonella spp., viable and lactic acid bacteria count every third day. Salmonella spp. counts decreased during storage in all packaging types, with reductions of about 1.5 log CFU/g. A significant difference (p < 0.01) was noted between Salmonella spp. counts in meat packaged in vacuum and modified atmospheres, although there was no significant difference in Salmonella spp. count between meat packaged in 50%CO2, and meat packaged in 30%CO2. At the end of the study, there were significant differences (p < 0.01; p < 0.05) in total viable and lactic acid bacterial counts between meat packaged in vacuum and modified atmosphere, and the lowest counts were noted in meat packaged in modified atmosphere with 50%CO2. Keywords Minced meatModified atmosphere packagingVacuumSalmonellapHAssociate Editor: Luis Augusto Nero ==== Body Introduction Pork and beef minced meat are widely consumed in Europe.1 In Serbia as well as in other Balkan and some Mediterranean countries, minced meat is an inseparable part of traditional dishes (e.g. moussaka, sarma), and meat products (e.g. sausages, ćevapčići, hamburger). The mincing process disrupts the meat cellular structure, releasing tissue fluids and making the minced meat a highly nutritious medium supporting bacterial growth; mincing also allows migration of surface bacteria throughout the product.2 Therefore, it presents a highly perishable product that need to be wrapped or packaged and chilled immediately to an internal temperature of not more than 2 °C or frozen to -18 °C during storage and transport (Regulation (EC) 853/2004).3 Despite measures to control foodborne pathogens from farm to fork the burden of diseases caused by foodborne pathogens remains important health and economic issue.4, 5, 6, 7, 8 Some of these pathogens, such as Salmonella spp., continue to cause major human public health and economic problems in both developed and developing countries.9 Salmonella spp. are the second most often reported bacteria causing food-borne disease in humans, following Campylobacter spp.10, 11 Meat can be contaminated with Salmonella during the slaughter, dressing and deboning processes, or during processing, transport, storage and household use, as a result of cross-contamination.12, 13 S. Enteritidis and S. Typhimurium are the most frequently reported serotypes causing human salmonellosis in both the EU and the United States, while the incidence of S. Infantis is increasing.14, 15, 16, 17, 18 This highlights the need for improved prevention and control of Salmonella spp. in food. The food industry has developed numerous preservation techniques in order to prevent and control Salmonella and other food-borne pathogens and spoilage microorganisms in fresh meat products, making the meat safer for consumption and extending its shelf life. Vacuum packaging (VP) and modified atmosphere packaging (MAP) are the most commonly used packaging methods for meat and meat products. MAP is considered to be an effective technique for raw meat preservation.19, 20, 21, 22, 23 These methods are based on removal of the surrounding atmosphere (VP) or flushing it out and replacing it with a gas mixture (MAP) before sealing in gas barrier materials.20, 21, 22, 23 Gases most often used in MAP are carbon dioxide, which inhibits bacterial growth, oxygen, which prevents anaerobic growth and retains meat color, and nitrogen, which avoids oxidation of fats and pack collapse. Depending on the type of food or effect desired, these gases can be used separately or in combination in various concentrations.19, 21 Considering the prevalence of Salmonella in minced meat and the frequency of its consumption via many traditional products and, taking into account that packaging of meat is the most common method of food preservation, there is a need to explore the effect of packaging methods on Salmonella spp. survival, especially in mixed minced meat (pork and beef). Therefore, the aim of this study was to compare the effects of vacuum and two initial headspace-modified atmosphere conditions (20%O2/50%CO2/30%N2 and 20%O2/30%CO2/50%N2) on the survival of Salmonella spp., total viable bacteria and lactic acid bacteria in minced meat stored at 3 ± 1 °C. Materials and methods Pork and beef muscles from leg of different carcasses used in the study were provided 48 h post-slaughter by a local slaughterhouse (Pećinci-Subotište, Serbia). Connective tissues and visible fat were trimmed after which the pieces of meat were minced separately in a sterile grinder (4 mm perforation diameter in the meat grinder plate), mixed in a 50:50 ratio of pork:beef and transported under refrigeration to the laboratory within an hour. Four serovars of S. enterica (S. Enteritidis ATCC 13076, S. Typhimurium ATCC 14028, S. Arizonae ATCC 13314 and S. Infantis ATCC 51741) (www.atcc.org) were used in this study. The serovars were stored in Brain Heart Infusion (BHI; Merck, Germany) with 20% glycerol at −80 °C until needed. One ml of each frozen Salmonella serovar was added to 10 ml of BHI (Merck, Germany), incubated at 37 °C for 24 h, then were streaked on Xylose Lysine Tergitol-4 Agar (XLT4) (Merck, Germany) to verify their characteristics. In order to get a second subculture isolated, black colonies were picked from the XLT4 plates and inoculated into BHI tubes (1 colony per tube) and further incubated for another 24 h at 37 °C. After incubation, the cultures were centrifuged at 5000 × g (Eppendorf, Hamburg, Germany) for 10 min and suitable dilutions were prepared in BHI. A Salmonella cocktail was prepared by combining equal portions of standardized cell suspensions to yield approximately 8 log CFU/ml of each serovar in the mixture. Salmonella counts were determined by serial dilution and subsequent enumeration on XLT4. This Salmonella cocktail (40 ml of the cocktail) was used to inoculate 9 kg of minced meat in the sterile mixer in the experimental laboratory of the Faculty of Veterinary Medicine, University of Belgrade. According to legal requirement for the absence of Salmonella in 25 g of raw meat, meat used in the present study was not naturally contaminated with Salmonella. Minced meat was divided in portions of 100 g, and packaged in three different conditions: VP, modified atmosphere package 1 (MAP1, containing 20%O2/50%CO2/30%N2) and modified atmosphere package 2 (MAP2, containing 20%O2/30%CO2/50%N2). MAP treatments were conducted considering ratio of 1:3 (v/w) between the volume of gas and weight of the minced meat (G/P ratio). A Variovac packaging machine (Variovac Primus, Zarrentin, Germany) was used for VP and MAP. Minced meat was packaged in a OPA/EVOH/PE foil (oriented polyamide/ethylene vinyl alcohol/polyethylene Dynopack, POLIMOON, Kristiansand, Norway), with low gas permeability (O2 – 3.2 cm3/m2/day at 23 °C, N2 – 1 cm3/m2/day at 23 °C, CO2 – 14 cm3/m2/day at 23 °C, water vapor – 15 g/m2/day at 38 °C). All minced meat samples weighed 100 ± 5 g and were refrigerated at 3 ± 1 °C. Minced meat was analyzed for Salmonella spp., total viable count (TVC-mesophiles, 30 °C), and lactic acid bacteria (LAB) count immediately and on days 3, 6, 9 and 12 of storage. For bacterial enumeration, approximately 10 g of meat were weighed aseptically after package opening, transferred into sterile Stomacher bags and 90 ml of Buffered Peptone Water (BPW) (Merck, Germany) was added to each sample. Meat samples were homogenized in a Stomacher blender (Stomacher 400 Circulator, Seward, UK) for 2 min. Serial decimal dilutions were prepared in buffered peptone water (Merck, Germany) and 1 ml or 0.1 ml of appropriately diluted homogenized meat was inoculated directly on the surface of XLT4 (Merck, Germany) for Salmonella spp. enumeration24 and incubated for 24 h at 37 °C, Plate Count Agar (PCA; Merck, Germany) for TVC-mesophiles enumeration according to ISO 4833:2003,25 and incubated at 30 °C for 72 h and MRS Agar (Merck, Germany) for LAB enumeration according to ISO 15214:1998,26 and incubated at 30 °C for 72 h. After incubation, plates were examined visually for typical colonies and morphological characteristics associated with each growth medium, the number of colonies was counted and results were recorded as colony forming units per g (CFU/g). Suspect colonies of Salmonella spp. were tested using API 20e (BioMerieux Italia-Bagno a Ripoli, Florence), while suspect colonies of lactic acid bacteria were stained by Gram and catalase test was done. The meat pH was measured after 10 min at room temperature using a hand-held pH meter, Testo 205 (Testo AG, Lenzkirch, Germany), equipped with a penetrating glass electrode. Measurement of headspace gas composition in the minced meat packaging was conducted using the gas composition tester, Oxybaby (WITT Gasetechnik GmbH & Co. KG, Witten, Germany). The measurement range of the instrument is 0–100% by volume (vol) for oxygen (O2) and carbon dioxide (CO2). The nitrogen content is calculated as the difference from 100% after the measured values of oxygen and carbon dioxide are deducted. The accuracy of the device is 0.1% for oxygen and carbon dioxide. Statistical analysis The study was conducted in a completely randomized design, six repetitions were carried out for each treatment and the treatments were arranged in a 3 × 5 factorial design (3 treatments, 5 sampling days). Numbers of bacteria (CFU/g) were transformed into logarithms (log) before statistical analysis. Statistical analyses of the results were conducted using the software GraphPad Prism version 6.00 for Windows (GraphPad Software, San Diego, CA, USA, www.graphpad.com). The results were expressed as mean ± standard error of the mean and are reported in tables. The effects of different treatments during the storage period were appraised by one-factor analysis of variance- ANOVA and Tukey's multiple comparison test (p < 0.05). Results Microbiological status of the minced meat The initial Salmonella spp. count in the inoculated minced meat was 8.8 ± 0.04 log CFU/g (Table 1). The Salmonella spp. count decreased until the day 6 in all groups, with significantly higher (p < 0.05) counts in VP than in MAP1 minced meat. A significant reduction of Salmonella spp. count was found on day 6 (average reduction of 1.9 log CFU/g). From day 9, slightly increasing Salmonella spp. counts were observed in all packaging types, except in packages with 50% CO2 where it decrease again from day 9 to day 12. Number of Salmonella spp. in VP meat was significantly higher (p < 0.05) than in both MAP meat on day 12 (Table 1). Significant difference (p < 0.05) also was noted between two MAP packaging, with lower count in MAP with 50% CO2.Table 1 Change in Salmonella spp. count, LAB count and TVC (log CFU/g) in packaged minced meat samples during storage at 3 ± 1 °C (mean ± SEM). Table 1Parameter Day of storage 0 3 6 9 12 F df p  Salmonella spp. count  VP 8.8Aa ± 0.04 8.3Aa ± 0.01 6.9Ab ± 0.00 7.1Ab ± 0.01 7.4Ac ± 0.08 212.0 4 <0.0001  MAP1 8.8Aa ± 0.04 8.0Ab ± 0.02 6.7Bc ± 0.01 7.1Ad ± 0.00 6.9Be ± 0.01 569.6 4 <0.0001  MAP2 8.8Aa ± 0.04 8.0Ab ± 0.02 6.8ABc ± 0.02 7.1Ad ± 0.00 7.2Cd ± 0.02 344.6 4 <0.0001  F – 3.003 6.558 0.3535 57.68  df – 2 2 2 2  p – 0.0800 0.0090 0.7079 <0.0001 LAB count  VP 3.1Aa ± 0.02 3.9Ab ± 0.01 4.0Abc ± 0.02 4.4Ac ± 0.09 5.0Ad ± 0.09 50.86 4 <0.0001  MAP1 3.1Aa ± 0.02 4.0Abd ± 0.05 3.7Bc ± 0.04 3.9Bb ± 0.03 4.0Bd ± 0.03 556.4 4 <0.0001  MAP2 3.1Aa ± 0.02 3.6Bb ± 0.03 3.9Cc ± 0.02 4.1ABd ± 0.05 4.9Ac ± 0.03 514.9 4 <0.0001  F – 25.45 155.9 4.529 66.67  df – 2 2 2 2  p  – <0.0001 <0.0001 0.0289 <0.0001 TVC  VP 7.0Aa ± 0.02 8.1Ab ± 0.01 7.9Ab ± 0.04 9.2Ac ± 0.03 9.5Ac ± 0.08 73.77 4 <0.0001  MAP1 7.0Aa ± 0.02 7.7Abc ± 0.07 7.2Ba ± 0.00 7.3Bab ± 0.00 7.9Bc ± 0.01 12.24 4 <0.0001  MAP2 7.0Aa ± 0.02 7.8Aab ± 0.00 8.8Cbc ± 0.02 8.2ABbc ± 0.03 9.1Ac ± 0.02 8.973 4 0.0001  F – 2.364 118.9 11.65 9.907  df – 2 2 2 2  p  – 0.1281 <0.0001 0.0009 0.0018 Different lowercase lettera–e within lines indicate significant difference p < 0.05 between different days of same treatment; different uppercase letterA–C within column, within same bacterial group, indicate significant difference p < 0.05 between treatments of the same day. The LAB count in minced meat increased during storage in all packaging types (Table 1). On day 12, the maximum detected LAB count was in VP meat, while the lowest LAB count was in MAP1, i.e. in meat packaged with modified atmosphere with a higher concentration of carbon dioxide. Significant differences (p < 0.05) were detected between the LAB count in VP meat and MAP1, as well as between MAP1 and MAP2. The maximum detected TVC was in the VP on day 12. The lowest TVC at the end of experiment was recorded in the MAP1, and it was significantly lower (p < 0.05) than it other groups. Headspace gas The headspace gas data for the two MAP types are shown in Table 2.Table 2 Concentrations of CO2, O2 and N2 in headspace gas of packaged minced meat samples during storage at 3 ± 1 °C (%). Table 2Parameter Day of storage 0 3 6 9 12 F df p  MAP1  O2 20.0a ± 0.0 15.5b ± 0.2 12.0c ± 0.4 8.5d ± 0.2 7.4e ± 0.2 417.5 4 <0.0001  CO2 50.0a ± 0.0 40.2b ± 0.2 42.1c ± 0.5 44.1d ± 0.7 53.5e ± 0.4 156.7 4 <0.0001  N2 30.0a ± 0.0 44.3b ± 0.3 45.7bc ± 0.4 47.3c ± 0.8 39.1d ± 0.5 190.2 4 <0.0001 MAP2  O2 20.0a ± 0.0 19.4a ± 0.6 14.5b ± 0.3 10.8c ± 0.4 10.5c ± 0.5 120.3 4 <0.0001  CO2 30.0a ± 0.0 19.1b ± 0.5 22.4c ± 0.3 25.9d ± 0.6 26.0d ± 0.5 79.91 4 <0.0001  N2 50.0a ± 0.0 61.4b ± 1.0 63.1b ± 0.3 63.3b ± 0.7 63.5b ± 0.7 77.16 4 <0.0001 Different lowercase lettera–e within lines indicate significant difference p < 0.05 between different days of the same headspace gas. Meat pH In all meat sampled, the pH was 5.7 at the beginning of the study and then increased during storage (Table 3). A significant difference (p < 0.05) in pH was observed between VP and MAP1 on day 9.Table 3 Change of pH in packaged minced meat samples during storage at 3 ± 1 °C (mean ± SEM). Table 3Group of sample Day of storage 0 3 6 9 12 F df p VP MAP1 MAP2 5.7Aa ± 0.004 5.8Ab ± 0.003 5.8Abc ± 0.003 5.9Acd ± 0.003 5.9Ad ± 0.009 28.18 4 <0.0001 5.7Aa ± 0.004 5.8Aab ± 0.002 5.8Abc ± 0.008 5.8Bcd ± 0.006 5.9Bd ± 0.006 13.04 4 <0.0001 5.7Aa ± 0.004 5.8Aab ± 0.005 5.8Abc ± 0.009 5.9Bc ± 0.005 5.9ABc ± 0.009 15.46 4 <0.0001 F – 1.98 2.58 7.51 3.99 df – 2 2 2 2 p  – 0.1728 0.1091 0.0055 0.0409 Different lowercase lettera–d within lines indicate significant difference p < 0.05 between different days of same treatment; different uppercase letterA–B within column, within same bacterial group, indicate significant difference p < 0.05 between treatments of the same day. Discussion The decrease of Salmonella spp. count until day 6 in the MAP packaging in the present study partly can be attributed to the inhibitory action of carbon dioxide, especially in the MAP1 with high CO2 content (50%), which was more effective than VP in the reducing Salmonella count (Table 1). Gram-negative bacteria, including Salmonella are highly sensitive to CO2 because its interact with membrane lipids, causing changes in ion membrane transport, penetrates the membrane and causes cytoplasmic acidification, disordered synthesis of specific enzymes, reduces cell metabolism extended the lag phase of microbial growth and reduced the growth rate during the logarithmic phase.22, 27, 28, 29, 30 More sensitive Gram-negative Salmonella compare to LAB, Gram-positive bacteria, as is the case in the present study, can be explained due to the denser cell wall and higher peptidoglycan content of Gram-positive bacteria compared to Gram-negative bacteria.31, 32 Carbon dioxide is highly soluble in high moisture and fatty foods such as meat.30 In addition to the level of solubility of carbon dioxide an important factor affecting bacterial growth is storage temperature of the packaged meat. Storage temperatures below 5 °C, as in the current study where meat samples were stored at 3 ± 1 °C, increase the solubility of carbon dioxide, whose antimicrobial activity increases, but also increase the sensitivity of bacterial cells to the effects of carbon dioxide.27, 30, 33, 34 In the present study, the CO2 concentration was 50% (MAP1) and 30% (MAP2) at the beginning of the experiment. Decrease of CO2 during first tree days of storage is attributed to its absorption in meat and was fallowed by its increase until the end of the storage period. Increase of CO2 was caused by bacterial activity. Similar results were reported by Goulas.35 The decrease of O2 concentration observed in both MAP can be attributed to the growth of aerobic bacteria and microbial respiration, which utilize O2 and produce CO2 that contributes to spoilage. Competitive microbiota, as well as the initial concentration of bacterial cells, has an influence on the growth of Salmonella spp. Although Salmonella spp. are able to grow and compete with other microorganisms,36 these bacteria are described in the literature as a relatively weak competitor.30, 37, 38, 39, 40 Because of these reason it is supposed that this group of bacteria are inhibited in MAP in the present study until day 6 (Table 1) by LAB, dominant bacteria in packaged meat stored at refrigeration temperatures (below 10 °C).41, 42, 43, 44, 45 LAB are an integral part of the natural microbiota of meat.46 During present study, the LAB increase in the minced meat during 12 days at 3 ± 1 °C was greater than increases of the other bacterial groups studied, which could be due to the better adaptation of LAB to these conditions. During refrigeration of packaged raw meat, the mostly used method in order to extend shelf life, there is a pronounced growth of psychrotrophic and strictly or facultative anaerobic microbes like LAB.46 Although were expected increased number of LAB under high concentrations of CO2, LAB counts were higher in VP (Table 1), which is in agreement with the results of Li et al.,40 who reported higher LAB counts for raw pork packaged under vacuum than in MAP (40%O2/40%CO2/20%N2). In the present study the LAB count reached around 5 log CFU/g (Table 1), which was less than the usual limit of acceptability at levels 6 log CFU/g.45, 47, 48, 49 Increasing LAB counts, as the dominant microorganisms in packaged meat stored at refrigeration temperatures were reported by Pexara et al.,50 Santos et al.,51 Martinez et al.,52 and Ruiz-Capillas and Jimenez-Colmenero.53 Based on the results of present study which showed that CO2 is effective against high Salmonella count (8 log CFU/g), it is supposed that will be effective against lower levels of naturally-occurring Salmonella as well. TVC is a parameter which also determines meat shelf-life. The initial microbial load is one of the most important parameters determining the shelf life of meat.39 The biggest proportions of the initial microbiota on fresh meat are mesophilic and psychrotrophic bacteria, and this latter group of bacteria is mainly responsible for meat spoilage. For these reasons TVC is used as an important microbiological quantitative indicator of production process hygiene, and for safety evaluation, as well as a spoilage indicator of raw meat.2, 54, 55 Based on numerous investigations, a TVC value of 107 CFU/g in meat is considered as a critical value for assessment of spoilage.56, 57, 58, 59 The number of microorganisms including bacteria depends on the intrinsic and extrinsic factors including pH, meat surface morphology, O2 availability, temperature and the presence and development of other bacteria.60 Changes in these factors and bacterial competition could influence the changes in the TVC in the present study. At the end of experiment, lower TVC was present in meat samples packaged with modified atmosphere, especially MAP with 50% CO2. Results from the present study showed lower values of TVC in meat packaged in the higher concentration of carbon dioxide, which can be attributed to antibacterial effect of modified atmosphere, especially carbon dioxide are consistent with the results of other authors.27, 61 Many factors can affect the pH of packaged meat, but it is considered that a major factor responsible for its decline is the LAB population.62 Microorganisms’ growth as well as chemical reactions occurring during proteolytic processes throughout storage cause increases in meat pH (Table 3). These processes create alkali compounds (ammonia, trimethylamine, dimethylamine) responsible for pH increases.63 The increasing pH in all meat packaging regimes can be explained due to the high concentration of bacteria, resulting in production of alkali compounds. Furthermore, the pH increases could also be due to proteolysis, causing the production of free amino acids and leading to the formation of NH3 and amines.64 The results obtained in the present study are consistent with those obtained by Milijašević,65 Bozec et al.,66 and Cachaldora et al.45 while in the results obtained by Schirmer and Langsrud44 and Babić et al.,67 meat pH remained consistent during the storage period. Conclusions All types of packaging used in present study decreased the Salmonella spp. count during first days of storage. This pathogen was best inhibited by MAP containing higher CO2 concentration (50%), followed by MAP with 30% CO2 and VP. Furthermore, MAP with a higher CO2 level exhibited greater antibacterial activity against TVC and LAB. Conflicts of interest The authors declare no conflicts of interest. Acknowledgments This paper was supported by the Ministry of Education, Science and Technological Development, Republic of Serbia, through the funding of the project Selected biological hazards to the safety/quality of food of animal origin and the control measures from farm to consumer (No. 31034). ==== Refs References 1 Koppel R. Eugster A. Ruf J. Rentsch J. Quantification of meat proportions by measuring DNA contents in raw and boiled sausages using matrix-adapted calibrators and multiplex real-time PCR J AOAC Int 95 2 2012 494 499 22649937 2 Motjaremi Y. Moy G. Todd E. Encyclopedia of Food Safety vol. 1 2014 Academic Press Elsevier San Diego, CA, USA 3 Efsa Biohaz Panel (EFSA Panel on Biological Hazards) Scientific Opinion on the public health risks related to the maintenance of the cold chain during storage and transport of meat. Part 2 (minced meat from all species) EFSA J 12 7 2014 3783 4 Bacon R.T. Sofos J.N. Characteristics of biological hazards in foods Schmidt H.R. Rodrick G. Food Safety Handbook 2003 Willey Interscience, John Wiley & Sons, Inc. Hoboken, New Jersey 712 1641 5 Sofos J.N. Challenges to meat safety in the 21st century Meat Sci 78 2008 3 13 22062090 6 Newell D.G. Koopmans M. Verhoef L. Food-borne diseases. The challenges of 20 years ago still persist while new ones continue to emerge Int J Food Microbiol 139 2010 3 15 7 Linscott A.J. Food-borne illnesses Clin Microbiol Newsl 33 2011 41 45 8 Bošković M. Baltić ŽM Ivanović J. Use of essential oils in order to prevent foodborne illnesses caused by pathogens in meat Tehnol Mesa 54 1 2013 14 20 9 EFSA Journal The community summary report on trends and sources of zoonoses. Zoonotic agents and food-borne outbreaks in the european union in 2008 EFSA J 8 1 2010 1496 10 Carrasco E. Morales-Rueda A. García-Gimeno R.M. Cross-contamination and recontamination by Salmonella in foods: a review Food Res Int 45 2 2012 545 556 11 Boskovic M. Zdravkovic N. Ivanovic J. Inhibitory effect of thyme and oregano essential oils and some essential oil components on Salmonella Senftenberg and Salmonella Give Meat Technol 57 1 2016 67 71 12 Miya S. Takahashi H. Hashimoto M. Development of a controlling method for Escherichia coli O157: H7 and Salmonella spp. in fresh market beef by using polylysine and modified atmosphere packaging Food Control 37 2014 62 67 13 Sofos J.N. Meat and meat products Motarjemi Y. Lelieveld H. Food Safety Management: A Practical Guide for the Food Industry 2014 Elsevier 119 162 14 Vugia D.J. Samuel M. Farley M.M. Marcus R. Shiferaw B. Shallow S. Invasive Salmonella infections in the United States FoodNet, 1996–1999: incidence, serotype distribution, and outcome Clin Infect Dis 38 2004 149 156 14679463 15 Centers for Disease Control (CDC) Multistate outbreak of Salmonella Typhimurium infections associated with eating ground beef—United States, 2004 MMWR Morb Mortal Wkly Rep 50 2006 180 182 16 Cheung P.Y. Kam K.M. Salmonella in food surveillance: PCR, immunoassays, and other rapid detection and quantification methods Food Res Int 45 2 2012 802 808 17 Mukhopadhyay S. Ramaswamy R. Application of emerging technologies to control Salmonella in foods: a review Food Res Int 45 2 2012 666 677 18 Chironna M. Tafuri S. Gallone M.S. Outbreak of Salmonella Infantis gastroenteritis among people who had eaten at a hash house in southern Italy Public Health 2014 19 Narasimha R.D. Sachindra N.M. Modified atmosphere and vacuum packaging of meat and poultry products Food Rev Int 18 4 2002 263 293 20 Skandamis P.N. Nychas G.J.E. Preservation of fresh meat with active and modified atmosphere packaging conditions Int J Food Microbiol 79 1 2002 35 45 12382683 21 Chouliara E. Karatapanis A. Savvaidis I.N. Kontominas M.G. Combined effect of oregano essential oil and modified atmosphere packaging on shelf-life extension of fresh chicken breast meat, stored at 4 °C Food Microbiol 24 6 2007 607 617 17418312 22 McMillin K.W. Where is MAP going? A review and future potential of modified atmosphere packaging for meat Meat Sci 80 1 2008 43 65 22063169 23 Zhou G.H. Xu X.L. Liu Y. Preservation technologies for fresh meat—a review Meat Sci 86 1 2010 119 128 20605688 24 Pathania A. McKee S.R. Bilgili S.F. Singh M. 2010 inhibition of nalidixic acid-resistant Salmonella on marinated chicken skin J Food Protect 73 11 2010 2072 2078 25 ISO 4833:2003 – Microbiology of food and animal feeding stuffs – Horizontal method for the enumeration of microorganisms – Colony-count technique at 30 degrees C. 26 ISO 15214:1998 – Microbiology of food and animal feeding stuffs – Horizontal method for the enumeration of mesophilic lactic acid bacteria – Colony-count technique at 30 degrees C. 27 Martinez L. Djenane D. Cilla I. Beltran J.A. Roncales P. Effect of different concentrations of carbon dioxide and low concentration of carbon monoxide on the shelf-life of fresh pork sausages packaged in modified atmosphere Meat Sci 71 3 2005 563 570 22060934 28 Sanjeev K. Ramesh M.N. Low oxygen and inert gas processing of foods Crit Rev Food Sci Nutr 46 5 2006 423 451 16891213 29 Cornforth D. Hunt M. The American Meat Science Association Low-oxygen packaging of fresh meat with carbon monoxide. Meat quality, microbiology and safety White Paper Ser 2 2008 30 Cooksey K. Modified atmosphere packaging of meat poultry and fish Han H. Jung Innovations in Food Packaging 2nd ed. 2014 Elsevier 475 493 31 Goulas A.E. Kontominas M.G. Combined effect of light salting, modified atmosphere packaging and oregano essential oil on the shelf-life of sea bream (Sparus aurata ): biochemical and sensory attributes Food Chem 100 2007 287 296 32 Hsouna A.B. Trigui M. Mansour R.B. Jarraya R.M. Damak M. Jaoua S. Chemical composition, cytotoxicity effect and antimicrobial activity of Ceratonia siliqua essential oil with preservative effects against Listeria inoculated in minced beef meat Int J Food Microbiol 148 2011 66 72 21601302 33 Devlieghere F. Debevere J. Van Impe J. Concentration of carbon dioxide in the water-phase as a parameter to model the effect of a modified atmosphere on microorganisms Int J Food Microbiol 43 1998 105 113 9761344 34 Mullan W.M.A. Science and Technology of Modified Atmosphere Packaging 2002 http://www.dairyscience.info/index.php/packaging-/117-modified-atmosphere-packaging.html 35 Goulas A.E. 2008 Combined effect of chill storage and modified atmosphere packaging on mussels (Mytilus galloprovincialis ) preservation Packag Technol Sci 21 2008 247 255 36 Mackey B.M. Kerridge A.L. The effect of incubation temperature and inoculum size on growth of Salmonellae in minced beef Int J Food Microbiol 6 1998 57 65 37 Borch E. Kant-Muermans M.L. Blixt Y. Bacterial spoilage of meat and cured meat product Int J Food Microbiol 33 1996 103 120 8913812 38 Nychas G.J.E. Tassou C.C. Growth/Survival of Salmonella enteritidis of fresh poultry and fish stored under vacuum or modified atmosphere Appl Microbiol 23 2 1996 115 119 39 Blixt Y. Borch E. Comparison of shelf life of vacuum-packed pork and beef Meat Sci 60 2002 371 378 22063640 40 Li M.Y. Zhou G.H. Xu X.L. Li C.B. Zhu W.Y. Changes of bacterial diversity and main flora in chilled pork during storage using PRC-DGGE Food Microbiol 23 2006 607 611 16943058 41 Gill C.O. DeLacy K.M. Growth of Escherichia coli and Salmonella Typhimurium on high-pH beef packed under vacuum or carbon dioxide Int J Food Microbiol 13 1991 21 30 1907473 42 Korkeala H.J. Björkroth K.J. Microbiological spoilage and contamination of vacuum-packed cooked sausages J Food Prot 60 1997 724 731 43 Hayashidani H. Iwata T. Yamaguchi S. Survival of pathogenic Yersinia enterocolitica in vacuum-packed or non-vacuum-packed pork at low temperature Biocontrol Sci 13 4 2008 139 144 19127653 44 Schirmer B.C. Langsrud S. A dissolving CO2 headspace combined with organic acids prolongs the shelf-life of fresh pork Meat Sci 85 2010 280 284 20374899 45 Cachaldora A. García G. Lorenzo J.M. García-Fontán M.C. Effect of modified atmosphere and vacuum packaging on some quality characteristics and the shelf-life of “morcilla”, a typical cooked blood sausage Meat Sci 93 2013 220 225 22999312 46 Pothakos V. Devlieghere F. Villani F. Björkroth J. Ercolini D. Lactic acid bacteria and their controversial role in fresh meat spoilage Meat Sci 109 2015 66 74 25972087 47 Holley R.A. Peirson M.D. Lam J. Tan K.B. Microbial profiles of commercial, vacuum-packed, fresh pork of normal or short storage life Int J Food Microbiol 97 2004 53 62 15527918 48 Nychas G.J.E. Skandamis P. Chrysoula C.T. Koutsoumanis K.P. Meat spoilage during distribution Meat Sci 78 2008 77 89 22062098 49 Hulankova R. Borilova G. Steinhauserova I. Influence of modified atmosphere packaging on the survival of Salmonella Enteritidis PT 8 on the surface of chilled chicken legs Acta Vet Brno 79 2010 127 132 50 Pexara E.S. Metaxopoulos J. Drosinos E.H. Evaluation of shelf life of cured, cooked, sliced turkey fillets and cooked pork sausages—“Piroski”-stored under vacuum and modified atmospheres at +4 and+10 °C Meat Sci 62 2002 33 43 22061189 51 Santos E.M. Díez A.M. González-Fernández C. Jaime I. Rovira I. Microbiological and sensory changes in morcilla de Burgos preserved in air, vacuum and atmosphere packaging Meat Sci 71 2005 249 255 22064223 52 Martinez L. Djenane D. Cilla I. Beltran J.A. Roncales P. Effect of varying oxygen concentrations on the shelf life of fresh pork sausages packaged in modified atmosphere Food Chem 94 2006 219 225 53 Ruiz-Capillas C. Jiménez-Colmenero J. Effect of an argon-containing atmosphere on the quality of fresh pork sausages during refrigerated storage Food Control 21 2010 1331 1337 54 Jay J.M. Food preservation with modified atmosphere Modern Food Microbiology 2000 Aspen Publisher Gaithersburg, MD 283 300 55 Tao F. Peng Y. A non-destructive method for prediction of total viable count in pork meat by hyperspectral scattering imaging Food Bioprocess Technol 8 17 2015 30 56 ICMSF Microbiological specifications of food pathogens. Salmonellae Microorganisms in Food 5 1996 Blackie Academic and Professional London 217 264 57 Lambert A.D. Smith J.P. Doods K.L. Physical, chemical and sensory changes in irradiated fresh pork packaged in modified atmosphere J Food Sci 57 1992 1294 1299 58 Berruga M.I. Vergara H. Linares M.B. Control of microbial growth and rancidity in rabbit carcasses by modified atmosphere packaging J Sci Food Agric 85 2005 1987 1991 59 Djenane D. Martinez L. Blanco D. Yanguela J. Beltran J.A. Roncales P. Effect of lactic acid bacteria on extension of shelf life and growth of Listeria monocytogenes in beef stored in CO2 -rich atmosphere Braz J Microbiol 36 2005 405 412 60 Ercolini D. Russo F. Nasi A. Ferranti P. Villani F. Mesophilic and psychrotrophic bacteria from meat and their spoilage potential in vitro and in beef Appl Environ Microbiol 75 7 2009 1990, 2001 61 Labadie J. Consequences of packaging on bacterial growth. Meat is an ecological niche Meat Sci 52 3 1999 299 305 22062579 62 Fernández-López J. Sendra E. Sayas-Barberá E. Navarro C. Pérez-Alvarez J.A. Physico-chemical and microbiological profiles of “salchichón” (Spanish dry-fermented sausage) enriched with orange fiber Meat Sci 80 2008 410 417 22063347 63 Baltić T. Influence of Marinating on Salmonella spp. Growth in Broiler Meat PhD Thesis 2014 Faculty of Veterinary Medicine, University of Belgrade Belgrade, Serbia 64 Karabagias I. Badeka A. Kontominas M.G. Shelf life extension of lamb meat using thyme or oregano essential oils and modified atmosphere packaging Meat Sci 88 1 2011 109 116 21211912 65 Milijašević M. Velebit B. Jovanović J. The effect of different gas mixtures on colour and microbiological compliance of beef packaged in protective atmosphere International 54th meat Industry Conference Vrnjačka Banja, Serbia 2007 93 66 Bozec A. Zuliani V. Le Roux A. Ellouze M. Shelf-life evaluation of pork meat stored under different packaging atmospheres 57th International Congress of Meat Science and Technology Ghent Belgium 2011 1 4 67 Babić J. Matekalo-Sverak V. Borović B. Uticaj pakovanja u modifikovanoj atmosferi na održivost ćevapčića Tehnol Mesa 53 1 2012 36 42