Modified Atmosphere Packaging Systems Research Articles

Investigation of oxygen packaging to maintain beef color stability and microbiology safety after periods of long-term superchilled storage

This study aimed to develop an appropriate modified atmosphere packaging (MAP) system for displayed beef steaks following long-term superchilled (−1 °C) storage. After superchilled storage for 0, 2, 8, or 16 weeks, beef loins were fabricated into steaks and displayed with 20%, 50%, or 80% O2-MAP under chilled conditions. At each storage point, after display for 0, 3, 7, or 10 days, instrumental color, myoglobin redox forms percentage, lipid oxidation, total viable count (TVC), and total volatile basic nitrogen (TVB-N) were evaluated. Meat color stability decreased, with prolonged storage period and display time. When the storage period was within 8 weeks, under all the above MAP conditions, the display time for the beef steaks was up to 10 days. Considering 80% O2-MAP promoted lipid oxidation, 50% and 80% O2-MAP were not recommended for displaying steaks for >10 and 7 days respectively after 16 weeks of storage. However, 20%, 50%, or 80% O2-MAP could maintain 3 days of microbial shelf-life according to TVC and TVB-N results. Additionally, after long-term superchilled storage for 16 weeks, the various O2 concentrations had minimal impact on microbiota succession during the MAP display period. Furthermore, beef steaks packaged under various MAP systems exhibited similar microbial compositions, with the dominant bacteria alternating between Lactobacillus and Carnobacterium. This study provided practical guidance for improving beef color stability after long-term superchilled storage.

Evaluation of modified atmosphere packaging system developed through breathable technology to extend postharvest life of fresh muscadine berries.

Muscadine grapes (Vitis rotundifolia Michx.) are delicate in nature with short shelf life. Postharvest technologies like modified atmosphere packaging (MAP) with reduced oxygen (O2) and elevated carbon dioxide (CO2) could increase the postharvest storage life with better quality. In the current experiment, physical and biochemical quality attributes of black and bronze cultivars of muscadine grapes ('Supreme' and 'Granny Val', respectively) were evaluated in active MAP. Fruit were packed in plastic trays, sealed with impermeable film, and CO2 was introduced into the package. The MAP was created by a rigid microperforated plastic patch coated with a proprietary semipermeable resin, which was applied over a hole in the tray; packages with the same size hole without a patch were the control. Fruit were stored at 4°C for 42 days (6 weeks). MAP resulted in significantly lower decay incidence and better retention of fruit firmness for up to 28 days of storage in both cultivars as well as reducing color changes in 'Supreme' fruit. Although MAP did not affect the biochemical quality of muscadine grapes, total antioxidants increased initially and then decreased during storage, irrespective of packaging treatments. A significant linear increase in total phenolic content was also found during storage, regardless of treatments applied. Overall, the results of the current study demonstrate that MAP can be an affective technology to increase storage duration of muscadines with better retention of physical quality, without affecting the biochemical attributes.

Mathematical modeling of modified atmosphere package/LDPE film combination and its application to design breathing cylinders for extending the shelf life of green asparagus

BackgroundThe O2 levels in food packaging systems play an essential role in the deterioration of food quality and shelf life. Modified atmosphere packaging (MAP) supports the storage of fresh and processed foods by inhibiting chemical and physical changes while reducing the deterioration caused by microorganisms.Materials and methodsThis study established and validated the equations for the relationship between MAP formulation reagents, asparagus respiration, permeability of packaging film, and rates of O2 and CO2 mass transfer in which different interactions occur and affect each other.ResultsThe resulting atmosphere of packaging was determined to be the key to achieving the MAP benefits. The active MAP formulations developed in this study were combined with very-low-density polyethylene films to store green asparagus spears. During storage, the combined films effectively maintained the firmness of green asparagus spears, fiber, and vitamin C content, and outperformed the passive MAP and control groups. The above results confirm all the equations in the passive and active MAP systems established in this study.ConclusionsHence, maintaining the asparagus quality with an active MAP treatment will reduce economic loss and possibly provide new insights into applying active MAP retail packages to preserve fruits and vegetables in post-harvest shelf life.Graphical

Design of a modified atmosphere packaging for apple using concept of mathematical modeling for phytochemicals stability and shelf‐life enhancement

AbstractIn the present investigation, experiments were conducted to model the rate of apple respiration at various temperatures using enzyme kinetics approach and Arrhenius equation. Thereafter, a governing mathematical model based on the mass balance concept was developed to design a modified atmosphere packaging (MAP) system for apple. The respiration rate model and developed equation employed in the MAP design process was verified and proved to be suitable, as indicated by moduli (E < 10%). Thereafter, a combination of biaxially oriented polypropylene (BOPP) and polyvinyl chloride (PVC) film having thickness of 30 and 50 μm, respectively was prepared by tailoring method to match the targeted gas permeability requirement of apple. The MAP system for apple was developed by packaging 1 kg of apple in the prepared film and the packages were stored at 2°C for further quality evaluation. The quality attributes of apple in terms of physico‐chemical properties, individual phenolic compounds, total phenolic content and total antioxidant capacity were assessed at a regular interval of time during storage. Based on physiological weight loss (<10%) and retention of other physicochemical and phytochemical quality till the end of storage period, the shelf life of apple was recorded as 180 days.Practical applicationThe lack of adequate cold storage systems in the supply chain, improper handling and storage facilities for fresh fruits including apple, is the leading source of post‐harvest loss of perishable commodity. The modeling of respiration rate at transient state and design of perm selective modified atmosphere packaging (MAP) system could be an alternative technology which can facilitate the shelf life enhancement of apple during handling and distribution. The uniqueness in the study involves the effect of MAP system on phytochemical compounds of whole apple during storage which has been rarely reported so far. The retention of overall quality of stored apple has proved that MAP is a promising technique for quality retention and achieving better market value.

Evaluation of a Packaging System in Pallets Under Modified Atmosphere to Extend the Shelf-life of ‘Padrón’ Peppers Stored at Refrigeration Temperature

A modified atmosphere packaging (MAP) system in pallets was developed for ‘Padrón’ peppers as a way to extend their shelf-life while maintaining good fruit quality. Peppers were stored at 6 °C in cardboard boxes arranged on pallets wrapped in micro-perforated low-density polyethylene (LDPE) bags. Physico-chemical (moisture, firmness, color, chlorophylls, carotenoids, ascorbic acid, and total phenolic content) and sensory analysis were carried out after 0, 7, 14, and 21 days of storage. An initial mixture of 11.8% O2–8.5% CO2 prevented anaerobic conditions and kept suitable CO2 levels throughout the entire storage period. Silica gel was tested as a moisture absorbent and considerably reduced water vapor condensation inside packaging bags. The MAP system developed maintained the shelf-life of peppers until the end of the 21-day storage period. The fruit always showed a good appearance and color. No rotting or other types of undesirable alterations were observed. MAP markedly reduced the fraction of peppers with water loss as evidenced by a minimum percentage of fruit with wrinkles (12.5%) as compared to unpackaged samples (75%). Good pigment stability was also observed.

New passive modified atmosphere packaging to extend peaches shelf life at ambient temperature to reduce economic losses

PurposeHoney peaches are rich in a variety of vitamins and are well known in China as the queen of fruit. However, as highly climacteric fruit, peach is too easy to affect its economic value. In this paper, a new passive modified atmosphere packaging system was proposed to solve the lack of water vapour removal capacity – which is still the technical bottleneck of passive modified atmosphere packaging. This paper aims to address this issue.Design/methodology/approachUnder the conditions of relative humidity 85−90% and temperature 28°C−38°C, the influence of new passive modified atmosphere packaging on the shelf life and quality of 70% ripe peaches was studied in the paper. The effect of the new passive modified atmosphere packaging (PMAP) on fruit appearance, colour, taste, flavour, soluble solids, Vitamin C and titratable acid was investigated.FindingsRegardless of whether 1-Methylcyclopropene is added or not, the research results show that the new PMAP has a significant effect on extending the shelf life and maintaining the quality of peaches. Compared with the control group, the shelf life of peaches treated with modified atmosphere packaging and 1-Methylcyclopropene was prolonged by 7 and 11 days, increasing the retailer's revenue by 44 and 75%.Originality/valueA new integrated structure, which is composed of two types of films with high oxygen and high water vapour permeability was designed for the retail of peaches at room temperature. The former was mainly responsible for regulating the concentration of O2 and CO2, while the latter was for removing water vapour and regulating the relative humidity in PMAP.

Changes in Volatile Composition of Cape Hake Fillets under Modified Atmosphere Packaging Systems during Cold Storage.

Fresh ready-to-cook fish fillets are susceptible to loss of freshness and accumulation of off-odour due to accelerated microbial spoilage. Suboptimal storage temperature and packaging conditions accelerate this process, limiting the economic potential. This study investigated the effects of modified atmosphere packaging (MAP) and storage temperature (0 °C and 4 °C) on the volatile compounds (VOCs) of Cape hake (Merluccius capensis) fish fillets as a predictor of shelf life and quality. Fresh Cape hake fillets were packaged under active modified atmosphere (40% CO2 + 30% O2 + 30% N2) and passive modified atmosphere (0.039% CO2 + 20.95% O2 + 78% N2) with or without an absorbent pad and stored at 0 °C and 4 °C for 12 d. The results obtained demonstrated that changes in VOCs and concentration were significantly (p < 0.05) influenced by MAP conditions, storage temperature and duration. A total of 16 volatiles were identified in the packaged Cape hake fillets: 4 primary VOCs and 12 secondary VOCs. The spoilage VOCs identified include tri-methylamine (TMA) (ammonia-like), esters (sickeningly sweet) and sulphur group (putrid). The concentration of secondary VOCs increased continuously during storage. Active-MA-packaged fillets performed better and had lower TMA values of 0.31% at 0 °C on day 12 in comparison to 7.22% at 0 °C under passive on day 6. Ethyl acetate was detected in passive-MA-packaged fillets stored at 0 °C on day 3, and the levels increased to 3.26% on day 6, while active-MA-packaged fillets maintained freshness. This study showed that in conjunction with TMA, VOCs such as esters and sulphur-related compounds could be used as spoilage markers for Cape hake fish fillets.

Configuration of biodegradable equilibrium modified atmosphere packages, including a moisture absorber for fresh cape gooseberry (Physalis peruviana L.) fruits

Different equilibrium modified atmosphere packaging systems (EMAP) were evaluated for cape gooseberry fruits, including a moisture adsorber. Three packages were used: cellulose trays with a cellulose film, polylactic acid (PLA) trays and film, and polyethylene terephthalate trays (PET) with a film of polypropylene (PP). The packages’ configuration, perforations, and amount of moisture adsorber were predefined by modeling the gas transfer in the packaging system. The packaged fruits were stored at 6 °C and 75 % RH for 6 weeks. The fruits in the PLA trays without sachets had the maximum shelf life of 42 days, while the fruits in celulose with sachets had a shelf life of 40 days compared to 35 days with the PET/PP trays and 21 days of the control fruits. With similar equilibrium gas levels between the EMAP packages, the higher permeability to water vapor of PLA prevented the formation of condensation with lower dehydration compared to the celulose packages with sachets.

Effect of storage conditions on the shelf-life extension of fungus-colonized substrates based on Metarhizium anisopliae using modified atmosphere packaging

Metarhizium anisopliae is a promising alternative to chemical pesticides against pine wilt disease caused by Bursaphelenchus xylophilus. Herein, we investigated the efficacy of modified atmosphere packaging (MAP) to prolong the shelf-life of the M. anisopliae conidia. The effects of various conditions on its stability were also examined. M. anisopliae-inoculated millet grains were treated in a MAP system with different packaging materials (polypropylene, PP; polyethylene terephthalate, PET; ethylene vinyl alcohol, EVOH), gas compositions (high CO2 atmosphere, ≈ 90%; high O2 atmosphere, > 95%; high N2 atmosphere, > 95%; 30% CO2 + 70% N2; 50% CO2 + 50% N2; 70% CO2 + 30% N2), and storage temperatures (4 and 25 °C). Results revealed EVOH film as the best for the preservation of gases at all concentrations for 28 days. MAP treatment in the high-barrier EVOH film under an atmosphere of 30% CO2 + 70% N2 achieved 80.5% viability of dried conidia (7.4% moisture content), with 44.2–64.9% viability recorded with the other treatments. Cold storage for technical concentrates formulation promoted extension of shelf-life of MAP-treated conidia. These results imply that MAP under optimized conditions could enhance the shelf-life of fungus-based biopesticides in fungus-colonized substrates formulations.

Study of the Quality of Zalacca Fruit on Control Atmosphere Storage (CAS) and Modified Atmosphere Packaging (MAP)

Zalacca fruit has a short shelf life which is about 5-7 days after harvest. Control Atmosphere Storage (CAS) and Modified Atmosphere Packaging (MAP) are alternative technologies that can be applied to increase the shelf life of fruit. In the CAS system, zalacca fruit was stored in a room with a composition of 9% O2 and CO2, a temperature of 8-12ºC, and 90% RH, while in the MAP system the fruit was packed in plastic crates in a capacity of 8 kg then the crates are coated with plastic which is given holes as many as 72 holes measuring 0.5 cm. The results showed that zalacca fruit can be stored in CAS conditions for 26 days with a weight loss of 1.25% and a damage level of 7.3%, while the weight loss and damage levels of zalacca fruit on MAP storage were 2.6% and 29.5%. Microscopically the fruit of zalacca CAS and MAP showed skin wrinkling which was thought to be related to the occurrence of water loss during storage. Based on the data obtained, the storage of zalacca fruit by CAS was more effective than MAP.

Evaluation of a modified atmosphere packaging system in pallets to extend the shelf-life of the stored tomato at cooling temperature

A modified atmosphere packaging (MAP) system in pallets was developed and its effect on physico-chemical and sensory characteristics and shelf-life of tomato was evaluated. Tomatoes were stored at 6 °C in cardboard boxes arranged on pallets wrapped in micro-perforated low-density polyethylene (LDPE) bags. Effects of the storage time and packaging were evaluated after 0, 7, 14, and 21 days of storage. The MAP system with pallets assessed, using a packaging atmosphere composition of 10% O2 - 10% CO2 and silica gel as an adsorbent, extended the shelf-life of the tomato stored at refrigeration temperature. MAP delayed color evolution and reduced the firmness loss, biosynthesis of lycopene, and decay rate of tomato. At the end of storage, 100% of the unpackaged samples showed spots while only 42.9% of MAP samples had them. In addition, the percentage of tomatoes with cracks and stretch marks was reduced from 42.9% (unpackaged tomatoes) to 14.3% (MAP tomatoes).

Investigation of phenolic compounds and antioxidant activity in red and yellow onions and a synergistic utilization of skin extract in modified atmosphere packaging of salmon (Salmo salar)

AbstractThis study investigated potentially synergetic effects of red onion skin extract and modified atmosphere packaging (MAP) on lipid oxidation of salmon. The skin and flesh of red and yellow onions were extracted with water at 25°C, 45°C, 65°C and 90°C, ethanol and acetone in water solutions. Total anthocyanin and polyphenol levels and antioxidant capacity were determined after extraction. Minced salmon samples were mixed with red onion skin extract (ROSE) and packaged under MAP at different O2 concentrations (0%, 5%, 10% and 15% of total package gas composition) with 40% CO2 and balance N2. Polyphenol recovery and antioxidant capacity increased for each sample as the extraction temperature increased with hot water use. Water extraction at 90°C provided higher extraction yields than ethanol and acetone in water solutions. The ROSE treatment of fish with MAP reduced lipid oxidation rates as evidenced by a decrease in peroxide value (43%) and thiobarbituric acid reactive substance (TBARS) (30%). The ROSE might effectively suppress the free radicals in a MAP system. A skin extract and MAP application might increase the shelf life of salmon.

Effects of high-oxygen, carbon monoxide modified atmospheres and vacuum packaging on quality of Longissimus thoracis et lumborum steaks from Nellore cows during ageing

Nellore (Bos indicus) cows play an important role in Brazilian beef production. Here, we investigated whether modified atmosphere packaging (MAP) technology could contribute to improving the quality of Nellore cow steaks. To verify this, steaks obtained from Longissimus thoracis et lumborum (LTL) were stored at 2 °C for 28 days using different packaging systems, with one being vacuum and the others being three MAP systems: 75% O2/25% CO2 (75%O2-MAP), 60% CO2/0.2% CO/39.8% N2 and 40% CO2/0.4% CO/59.6% N2 (0.2%CO-MAP and 0.4%CO-MAP, respectively). Steaks packaged using the CO-MAP showed improved color stability of fresh meat. In turn, the 75%O2-MAP drastically affected the oxidative stability related to proteins and lipids compared to both anaerobic environments (CO-MAP and vacuum). The CO-MAP increased tenderization and ultrastructural changes when compared to the aerobic MAP without affecting pH, collagen or cooking loss, which were influenced by the storage time. In conclusion, MAP technology may improve the quality and appearance of fresh meat originating from Nellore cows, being a promising alternative for the Brazilian beef industry.

The combined impact of calcium lactate with cysteine pretreatment and perforation-mediated modified atmosphere packaging on quality preservation of fresh-cut 'Romaine' lettuce.

The effect of perforation-mediated modified atmosphere packaging (PM-MAP) in combination with calcium lactate (1.5% CaL) and cysteine (0.1, 0.5% Cys) immersion pretreatments on the quality preservation of fresh-cut 'Romaine' lettuce was assessed for 12 days, at 5 and 10 °C. The shredded lettuce was packed in low-density polyethylene films (LDPE, 62µm thickness), including different perforation numbers of 0 (N-MAP), 20 (20-PM-MAP, Diameter = 64µm), and 40 (40-PM-MAP, Diameter = 64µm)per in square meter. Indices of quality maintenance were investigated. The total microbial counts were below the specified limits for ready-to-eat vegetables (< 6 log CFU/g) considering both pretreated 20-PM-MAP and N-MAP samples on day 12. After 8 days, a significant difference (P <0.05) was observed in the browning index (BI), the total color difference (ΔE), and the chlorophyll content between N-MAP and 20-PM-MAP samples with better results in 20-PM-MA packages. At 10 °C, the BI in pretreated 20-PM-MAP samples was 32.44% to 58.35% less than N-MAP samples, on the last day of storage. The 20-PM-MAP samples pretreated with 1.5% CaL/0.5% Cys had the highest (P <0.05) crispness coefficient and water content values. It seems that packaging the pretreated lettuce in 20-PM-MA packages is more effective for maintaining the visual properties (green fresh appearance) of this product, from the 8th to the 12th day of storage. PRACTICAL APPLICATION: The medium to high respiration rate of fresh-cut lettuce causes O2 level drops below its tolerance limit (<1% to 3%) inside the modified atmosphere packaging (MAP). It results in severe browning, off-odors, off-flavor, and growth of anaerobiosis. Perforated-mediated modified atmosphere packaging (PM-MAP) technology can be introduced as an alternative to a nonperforated MAP system (conventional MAP) for fresh-cut lettuce. The application of the PM-MAP system in combination with calcium lactate and cysteine immersion pretreatment (CaL/Cys) may lead to better maintenance of the physicochemical properties of this product.

Oxygen Consumption by Phalaenopsis Plantlets and Chrysanthemum Cuttings as a Function of Temperature and Time: Model Structure Validation

Phalaenopsis spp. and Chrysanthemum are ornamentals with an important economic value. Currently, quality loss during storage and transport of plantlets and cuttings is a limiting factor for spreading the workload, broadening the export range, and the use of slower but more environmentally friendly transport. In the agro-food sector, equilibrium modified atmosphere packaging has enhanced the shelf-life of minimally processed produce. The required properties for an equilibrium modified atmosphere packaging system can be estimated from the respiration rate of the packaged commodity under specified atmospheric composition and storage temperature. In this work, a model structure is validated to estimate the respiration rate as a function of oxygen concentration and temperature for Phalaenopsis and Chrysanthemum. The oxygen concentration as a function of time was monitored in a closed system for different storage temperatures. The models show a good fit to the data. The model coefficients were dependent on the plant species and characteristics. The resulting formulae can be used to estimate the oxygen consumption rate of the produce under a range of oxygen concentrations and a temperature range from 15 °C to 32 °C for Phalaenopsis and from 2 °C to 14 °C for Chrysanthemum. The oxygen concentrations for which the formulae are valid depend on the storage temperature and plant species. The models can be used to estimate a dynamic oxygen consumption rate profile during storage and transport.

Shelf life extension of fresh asparagus using modified atmosphere packaging and vacuum skin packaging in microwavable tray systems

Asparagus (Asparagus officinalis L.) is one of the most popular vegetables because it contains a wealth of fiber and several essential nutrients. It is a very perishable commodity due to its very high respiration rate. To maintain product quality and to satisfy consumer demand as a convenient food, modified atmosphere packaging (MAP), vacuum skin packaging (VSP), and microwaveable containers were used to extend the shelf life of fresh‐cut asparagus as a ready‐to‐eat food product. The objective of this study was to determine the shelf life of fresh‐cut asparagus packed in MAP and VSP microwaveable tray systems at commercial storage conditions, 4°C, 80% RH. Weight loss, moisture content, O2/CO2 concentration in the package headspace, product pH, microbial growth, and sensory evaluation were used to determine the product quality and shelf life. Moreover, the preference of product appearance and the quality of the cooked asparagus in both microwaveable tray systems at different cooking times and microwave power levels was also sensorially evaluated. During storage for 21 days, there was no significant difference (p &gt; 0.05) in weight loss, moisture content, and pH. Sanitation and packaging techniques also helped to retard the microbial growth. Both techniques, combined with refrigeration, help to maintain the freshness and product shelf life up to 21 days for MAP and 18 days for VSP. On the basis of hedonic scale results, consumers preferred the appearance of both packaging types. Both microwavable tray systems, thus, can help to prolong the shelf life of fresh‐cut asparagus and can be eaten directly from the package.

An efficient optimization methodology of respiration rate parameters coupled with transport properties in mass balances to describe modified atmosphere packaging systems

ABSTRACT In this study, we aimed to describe a modern, efficient, and reproducible methodology to optimize respiration rate parameters coupled with transport properties in mass balances describing Modified atmosphere packaging (MAP) systems. We considered mass balances for three different respiration rate j film (exponential, competitive and uncompetitive Michaelis–Menten kinetics) coupled with transport properties for two different packaging films. Experiments were conducted to validate the methodology using grapes placed in a polypropylene container opened on the top and sealed with packaging films. The methodology relies on a numerical optimization procedure called the Trust-Region-Reflective algorithm. We determined the predictive capability of models using goodness-of-fit criteria and assessed parameter uncertainty through standard errors. We also calculated the first-order optimality measure and the relative change in the sum of squares to verify the convergence of the implemented algorithm. Results showed that the respiration rate parameters obtained with this methodology for the exponential model provided a better fit than for the other two models. The fitting for the kinetic models is not very suitable since we found that the normalized standard errors were rather high. In conclusion, the methodology is robust, and we expect that it serves as a tool for assessing MAP technology design.

Development and Evaluation of Pilot Scale Modified Atmosphere Storage and Modified Atmosphere Packaging Systems for Tomatoes

A pilot scale modified atmosphere storage (MAS) structure of 100 kg and modified atmosphere packaging (MAP) of 1 kg capacity have been designed and developed for the storage of tomatoes. A polymeric film (LDPE + LLDPE, 80 µ thickness) has been used as the lining material to act as a regulator for the transport of gases and water vapor. The retail size MA packaging study of medium-size tomatoes were taken and packed in 80 µm (LDPE + LLDPE) polymeric film (size: 25 × 22 cm2) so as to compare with the quality of MAS system. The quality analysis revealed that the parameters namely physiological loss in weight (PLW), firmness, color (L*, a*, b*), TSS, and titratable acidity were found to be 0.3%; 45.88 N; 60.23, − 3.25, 32.16; 4.3; and 0.55 of tomatoes after 21 days of storage in MAS system at ambient temperature (25 °C), respectively, which is comparable with the quality parameters at harvesting maturity and 1 kg MA package. The MAS system increased the shelf life from 7 to 21 days for tomatoes, at ambient temperature. However, the shelf life was achieved up to 35 days at 10 °C in MAS for tomatoes. Thus, developed structure is highly beneficial in retailing and transportation of tomatoes.

Selected Properties of Multilayer Films Applied for Vacuum and Modified Atmosphere Packaging Systems

AbstractThe aim of the research was to determine the selected properties of packaging materials applicable for vacuum and modified atmosphere packaging. Six samples of multilayer films with different composition were tested to evaluate the thickness, basic weight, density and the mechanical properties in elongation and puncture tests. Zwick/Roell apparatus equipped with elongation jaws and a puncture pin was used in the experiments. The tensile modulus, tensile strength, elongation at tensile strength, stress at break and work at break were investigated with the elongation test, whereas the breaking force, puncture work and extension at break were evaluated with the puncture test. The obtained results allow conclusion that the thickness and basic weight of the packaging films used in the vacuum system was higher comparing with the MAP system. Analyzing the results of the elongation modulus and stress at break it was reported that the materials used for food packaging in the MAP system were characterized with better properties, whereas elongation at the tensile strength was higher for films applied in the vacuum system, except for a film with a metalized layer. The highest resistance for puncture was evaluated for OPET/PE film used in MAP packaging. The extension at break under the puncture test was higher for films dedicated for vacuum packaging suggesting their better resistance for the mechanical damage by a thin pin. Several correlations between physical and mechanical properties of multilayer films were found.

Microbiological quality of organic chicken meat during refrigerated storage in air and modified atmospheres

ABSTRACT1. The aim of this study was to assess the incidence of pathogens and the development of spoilage microflora in organic chicken meat originating from a small poultry slaughterhouse and stored for 14 days at 2°C aerobically (control) or in one of two modified atmosphere packaging systems (MAP1: 80% O2, 20% CO2 and MAP2: 70% N2, 30% CO2).2. Campylobacter jejuni survived well during storage; and was found on the skin in 95% of samples (262/276).3. In general, both the skin and meat samples showed a good initial microbiological quality with total viable counts of less than 3 log cfu/g in meat and approximately 5 log cfu/g on skin.4. No difference was found between breast and thigh samples during the experiment.5. Shelf life was limited mainly by the development of mesophilic and psychrotrophic microflora on skin which were found at 7-day storage for the control and MAP1 and 10 days for MAP2.