Measurement of the Oxygen Transmission Rate of Co‐extruded Wine Bottle Closures Using a Luminescence‐Based Technique

The oxygen transmission rate (OTR) is a value commonly measured in different industries to evaluate oxygen flow through all types of packaging. The Mocon^® Ox‐tran^® method (Mocon Inc., Minneapolis, MN, USA) for measuring OTR is globally accepted and is recommended in different standards such as the ASTM (F1307‐02), but in practice, only a limited number of samples can be analysed, and the stabilisation of the measurement takes time. In this paper, a simple, non‐destructive technique allowing measurement of co‐extruded closure OTR is presented. The established protocol allows measurement of oxygen ingress through the closures or at the interface between closures and bottleneck and avoids possible leakages that can happen when bottlenecks are glued onto metallic plates. Oxygen permeating in the bottle is measured by a luminescence‐based technology using separate sensors supplied by PreSens^® (Precision Sensing GmbH, Regensburg, Germany). The simple set‐up and the use of a non‐destructive luminescence‐based technology make this an easy test to perform. Moreover, the development of a predictive model allows us to reduce the analysis time to one week. Comparison with the well‐established Mocon Ox‐tran method shows good accordance between the two techniques. This new method allows the measurement of more samples in less time without compromising analytical performance. This method could become a useful quality control procedure in the wine industry to assess OTR performances of closures. Copyright © 2011 John Wiley & Sons, Ltd.     

A comparative study of oxygen transmission rates through polymer films based on fluorescence quenching

Information on oxygen permeability through polymer films is essential for some applications, especially in food packaging where the control of oxygen levels can be critical in avoiding food spoilage. A permeability testing device using fluorescence‐based optical oxygen sensing was developed as a potential new instrument for measuring the oxygen permeability of packaging films. The fluorescence‐based permeability tester was validated against two existing commercial oxygen permeability measuring devices, the Mocon Ox‐Tran 2/20 and PBI‐Dansensor OPT‐5000. Oxygen transmission rates (OTR) of polylactide (PLA) and nanoclay‐reinforced PLA films, as well as polyethylene/poly(ethylene terephthalate) (PE/PET) and polypropylene/poly(ethylene terephthalate) (PP/PET) laminated films were determined at 23°C and 50% relative humidity using each of these instruments. No significant differences were observed between mean OTR values obtained by the fluorescence method and the corresponding values obtained using the OPT‐5000 but significantly lower values were measured when using the Mocon Ox‐Tran 2/20. In general, oxygen permeability data for the tested films were within the range of values found in the literature; however, in terms of further development, the fluorescence‐based technique gave OTR with relatively high standard deviation compared to the commercial methods and equipment modifications to address this issue are considered desirable. Copyright © 2010 John Wiley & Sons, Ltd.     

Microperforation of Three Common Plastic Films by Laser and Their Enhanced Oxygen Transmission for Fresh Produce Packaging

Three different plastic films of biaxially oriented polypropylene (BOPP), biaxially oriented polyethylene terephthalate (BOPET) and low‐density polyethylene (LDPE) were perforated using Nd‐YAG laser. Effects of laser pulse energy were examined by varying energies from 50 to 250 mJ where the pulse duration and pulse repetition were kept constant at 10 ns and 1 Hz, respectively. It was found that perforation diameters of all films increased with increasing pulse energies. Observed perforations were different among the three film types. Explanation was contributed to material inherent property and its interaction with laser. Incorporation of an inorganic filler (i.e. silica based anti‐blocking agent used in packaging film) of 0.5 wt% into the LDPE films (0.5Si‐LDPE) could improve perforation performance for LDPE. This was attributed to an increased thermal diffusivity of the 0.5Si‐LDPE film. Commercial BOPET and BOPP films containing 97 microholes/m² (hole diameter of ~100 µm) showed an improvement in oxygen transmission rates (OTR) of 18 and 5 times that of the neat films without perforation. In the case of perforated 0.5Si‐LDPE films having similar perforations of 97 microholes/m² and perforation diameter of 100 µm, a two‐fold increase of OTR was obtained. Gas transmission rates of the microperforated films were measured based on the static method. Measured OTR and CO₂TR values of the three films with varying perforation diameters in a range of ~40–300 µm were compared and discussed. Overall results clearly indicate that perforation by laser is an effective process in developing breathable films with tailored oxygen transmission property for fresh produce packaging. Copyright © 2014 John Wiley & Sons, Ltd.     

Measurement of oxygen transmission rate through foamed materials for bottle closures

The determination of the oxygen transmission rate (OTR) through closures in glass bottles is becoming increasingly important for quality control of different batches and for development purposes. The Mocon method for measuring OTR is globally accepted and used in different applications. However, one of the major drawbacks this method presents when applied to bottle/closures systems is the long time required to obtain stable measurements when 40 mm long closures are tested. This paper describes a method to obtain OTR values with samples of reduced thickness with much shorter measurements time, since the condition of steady state during measurements is achieved faster and compares the estimated full‐length commercial closure OTR with experimental values. Copyright © 2009 John Wiley & Sons, Ltd.     

Modelling Gas Transmission in Cylindrical Dynamic Accumulation Oxygen Transmission Rate Chambers to Explore Implications of Oxygen Sensor Location Relative to Samples

A model was developed to simulate oxygen accumulation in space and time within cylindrical dynamic accumulation chambers that are used to measure oxygen transmission rate (OTR) of materials. The model is based on Fick's law of diffusion and was validated against actual OTR measurements of polymer film samples. Measured OTR values and thicknesses were inputted into the model and oxygen concentrations outputted by the model. OTRs determined from the output of the model was in close agreement to within 0.3–3% of the measured OTR. Oxygen concentration versus time curves generated from model output oxygen concentrations and experimentally measured oxygen concentrations for three actual films were also in agreement. The model was then used to simulate results from three hypothetical test films at varying chamber lengths in order to evaluate effects of accumulation chamber dimensions relative to films on resulting OTR measurements. A typical design scenario was used, where the oxygen sensor is mounted on the chamber wall opposite the sample film. Results demonstrate that dynamic accumulation OTR instrument designers have considerable flexibility in choosing accumulation chamber dimensions because deviations in OTR are only expected to occur at impractically extreme chamber lengths (>10 m) for the entire envelope of OTRs expected for typical packaging films. Copyright © 2014 John Wiley & Sons, Ltd.     

Porous Ultrahigh Gas‐Permeable Polypropylene Film and Application in Controlling In‐pack Atmosphere for Asparagus

Porous polypropylene (PP) films with greater gas permeability and lower permeability ratios (β) than existing commercial films were developed for fresh produce packaging. PP containing high content of beta‐form crystal was biaxially stretched under controlled conditions. Resulting porous films with uniquely high oxygen transmission rate (OTR) of 2 659 000 cm³?m^?2?d^?1, water vapor transmission rate of 67 g?m^?2?d^?1, and β value of 0.76 was used as a “breathable window” attached to the less permeable commercial BOPP (biaxially oriented PP) lidding film. Various sizes/areas of the breathable windows were designed and tested on packaging asparagus of 400 g, at 5°C. Results demonstrated that in‐pack O₂ and CO₂ concentrations could be practically controlled and modified by changing areas of the breathable windows. Altered porous high OTR area directly affected total gas permeation of the package. Optimum gas composition of Ο₂ and CΟ₂ within the recommended controlled atmosphere for asparagus, stored at 5°C, was effectively created and maintained in the package containing 25 cm² breathable window (15% of total film lid's area). The shelf life of asparagus under optimum modified atmosphere was extended to 29 days, as compared with <3 days in the normal, low OTR tray sealed with BOPP lidding film. Clearly, these developed porous ultrahigh permeable PP films can be useful materials in designing high OTR package with desirable in‐pack O₂ and CO₂ concentrations. Copyright © 2013 John Wiley & Sons, Ltd.     

Atomic layer deposition on polymer based flexible packaging materials: Growth characteristics and diffusion barrier properties

One of the most promising areas for the industrial application of atomic layer deposition (ALD) is for gas barrier layers on polymers. In this work, a packaging material system with improved diffusion barrier properties has been developed and studied by applying ALD on flexible polymer based packaging materials. Nanometer scale metal oxide films have been applied to polymer-coated papers and their diffusion barrier properties have been studied by means of water vapor and oxygen transmission rates. The materials for the study were constructed in two stages: the paper was firstly extrusion coated with polymer film, which was then followed by the ALD deposition of oxide layer. The polymers used as extrusion coatings were polypropylene, low and high density polyethylene, polylactide and polyethylene terephthalate. Water vapor transmission rates (WVTRs) were measured according to method SCAN-P 22:68 and oxygen transmission rates (O₂TRs) according to a standard ASTM D 3985. According to the results a 10 nm oxide layer already decreased the oxygen transmission by a factor of 10 compared to uncoated material. WVTR with 40 nm ALD layer was better than the level currently required for most common dry flexible packaging applications. When the oxide layer thickness was increased to 100 nm and above, the measured WVTRs were limited by the measurement set up. Using an ALD layer allowed the polymer thickness on flexible packaging materials to be reduced. Once the ALD layer was 40 nm thick, WVTRs and O₂TRs were no longer dependent on polymer layer thickness. Thus, nanometer scale ALD oxide layers have shown their feasibility as high quality diffusion barriers on flexible packaging materials.     

Preparation and properties of polypropylene‐based nanocomposite films for food packaging

Packaging of foods in high barrier and strong materials is essential to attain food safety, and nanocomposite technology leads in search of the above kind of packaging material. The effect of compatibilizer (1.6, 5, 10, 15 and 18.4%), nanoclay (0.6, 2, 4, 6 and 7.4%) and thickness of film (35, 50, 75 100 and 120 µm) on oxygen transmission rate (OTR), water vapour transmission rate (WVTR), tensile strength and per cent elongation of polypropylene (PP)‐based nanocomposite films was studied using response surface methodology. The maximum reduction in OTR of PP‐based nanocomposite films over the control was 21.4% in treatment having 10% compatibilizer, 4% nanoclay and 120 µm thickness. A maximum of 28.1% reduction in WVTR for the treatment with 5% compatibilizer, 2% nanoclay and 100 µm thickness over the control was achieved. The regression models were developed for the prediction of OTR and WVTR of nanocomposite films. The maximum increase in the tensile strength of PP‐based nanocomposite films over the corresponding control was 71.7%. The elongation percentage of nanocomposite films was less than the control and increased with increase of thickness of film and decrease of both nanoclay and compatibilizer. Treatment having 5% compatibilizer, 2% nanoclay and 100 µm thickness of nanocomposite films showed better barrier and strength characteristics than other treatments. This paper helps to design the packaging films according to the requirement of foods to be stored using the developed regression models. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of biaxial‐simultaneous stretching conditions on OTR and CO2 permeation of CO2 laser perforated poly(lactic acid) film

The biaxially oriented poly(lactic acid) films prepared using simultaneous biaxial stretching were perforated by CO₂ laser with the power of 60 W. The focal spot diameter was fixed at 103 μm. Pulse durations were varied from 1 to 30 μs, which corresponds to the fluence from 1.4 to 42.6 J/cm². The perforated microhole size increased with increasing laser energy. The shape of microholes was circular for the films of equi‐biaxial stretching, whereas elliptical microholes were formed with its long and short axes corresponding to the directions of higher and lower stretch ratios, respectively. Comparing the laser perforation behavior of the as‐drawn films and annealed films, the opening of a microhole in the annealed films started at higher laser fluence, and at the same fluence the size of microhole was smaller. Gas transmission rates of the biaxially oriented poly(lactic acid) films with different thicknesses were examined. The oxygen transmission rates (OTR) of film improved with increased microhole diameter. The OTR of films containing 1 microhole/103 cm² (hole diameter of ~110 μm) was 184, 150, and 98 cm³/d in comparison with the OTR for the original films without microhole of only 16, 10, and 8 cm³/d, respectively. Packaging films with OTR higher than 100 cm³/d (equivalent to the 9700 cm³/m²/d) are required to create a modified atmosphere inside the package of fresh produce for shelf‐life extension. Measured OTR and CO₂TR values of the 3 different shapes of microhole were compared and discussed.     

Effect of packaging oxygen transmission rate on the shelf life of ready-to-heat foods susceptible to postcontamination during refrigerated and illuminated storage

Since more and more pressure is exerted to reduce the use of plastic packaging materials, optimizing the use of food packaging is opportune. The aim of this study was to evaluate the combined effect of packaging materials, spanning a range of oxygen transmission rates (OTR), and retail illumination, on the microbial shelf life and safety of refrigerated ready-to-heat foods. Cooked potato slices were packaged in OPA/PP bags with a high OTR (28.85 ccO₂/m²/d) and OPA-EVOH/PP bags with a low OTR (6.57 ccO₂/m²/d). Cooked composite meals were packaged in tray and foil combinations, also spanning a range of OTR: PP trays (2.09 ccO₂/tray/d) with OPA/PP foils (28.85 ccO₂/m²/d), PP trays with OPA-EVOH/PP (6.57 ccO₂/m²/d) foils, and PET trays (0.07 ccO₂/tray/d) with PET top foil (32.86 ccO₂/m²/d) . The packages were stored in a dark environment, or under fluorescent or LED light. Due to the rapid growth of lactic acid bacteria, the microbial shelf life of both food products was largely unaffected by the type of barrier. Illumination at 1000 lux for 12 hours per day led to temperature differences significantly affecting microbial growth. Based on the results, it could be concluded that re-evaluating packaging material choices for these foods may prove valuable, since the use of high-barrier multilayer packaging materials may be considered as a case of overpackaging.     

Synthesis,Characterization and O2 Permeability of Shape Memory Polyurethane Films for Fresh Produce Packaging

The aim of this work was to investigate the effect of film formulations in an effort to obtain a fresh produce packaging film with increased temperature sensitivity for gas permeability. Series of shape‐memory polyurethane (SMPU) were synthesized using poly(ethylene glycol) (PEG), 1,6‐hexamethylene diisocyanate, 1,4‐butanediol and castor oil (CO) and casted into films. The changes in thermal, viscoelastic, shape‐memory properties and oxygen permeability of the films were studied. The polyurethane films with 1500 g mol^?1 PEG showed a phase transition temperature (switching temperature) between 20 and 27°C. The SMPU consisting of 50/50 CO/PEG had a log E′ value of 8.32 Pa and showed good elasticity as low density polyethylene. SMPU prepared from 1500 g mol^?1 PEG with 50/50 CO/PEG and 40/60 butanediol/(PEG + CO) ratios showed excellent shape‐memory properties with shape recovery ratio >85% and shape fixity ratio >90%. This film had higher oxygen permeability and showed up to 67% increase in Q₁₀ value for oxygen permeability compared with commercial packaging films like low density polyethylene. This film can be used to develop smart packaging with increased thermally responsive gas permeability to similar levels observed in respiration rates of fresh produce. Copyright © 2016 John Wiley & Sons, Ltd.     

Oxygen transmission rates of packages at ambient,chill and freezing temperatures measured by the AOIR method

The ambient oxygen ingress rate (AOIR) method is an alternative or supplementary method to Ox‐Tran for measuring the oxygen transmission rate (OTR) of packages. The method has high capacity, requires relatively inexpensive equipment and measures OTR at different temperatures and humidity conditions. The aim of this study was, on the one hand, to study the effect of temperature on the OTR for packages produced from different polymer materials and laminates, and on the other hand to evaluate the suitability of the AOIR method at freezing temperature conditions. The OTR for 10 packages with different polymer compositions was measured at 23°C, 6°C and ?25°C. The AOIR method was shown to be a reliable test method for measuring OTR of packages at all the applied test conditions, also at frozen storage temperature. The OTR for the packages decreased with lower temperatures, especially for the packages with the highest OTR values at 23°C. In order to avoid higher packaging expenses than necessary to obtain the required shelf‐life for different food products, the OTR for alternative packages should be measured at the temperature and humidity conditions of intended use. Copyright © 2004 John Wiley & Sons, Ltd.     

Nanostructuring and Microstructuring of Materials from a Single Agropolymer for Sustainable MAP Preservation of Fresh Food

The main objective of the present work was to determine whether a single agropolymer [wheat gluten (WG)] could fit the modified atmosphere packaging (MAP) requirements of a range of six different fresh produce in key terms of oxygen permeation (Pe_O2) and CO₂/O₂ permselectivity (S) values. The required properties for optimal packaging of fresh fruits and vegetables were first evaluated using the Tailorpack MAP modelling software (UMR IATE, Montpellier, France) with packaging dimensions and respiratory and optimal atmosphere data as input parameters. Then, the modelled values obtained were compared with the properties of a range of WG composite films: monolayer self‐supported or multilayer at microscale or nanoscale, cast or thermoplasticised, with different formulations (percentage of plasticisers or nanofillers). The experimental gas transfer properties that could be covered by these materials ranged from 0.05 × 10^?10 to 2.00 × 10^?10 mol/m² s Pa for Pe_O2 and up to 18.0 for S. These ranges are much larger than conventional plastics that exhibit Pe_O2 from 0.10 × 10^?10 to 0.20 × 10^?10 mol/m² s Pa and S up to 4.5. It was demonstrated from a food‐requirements‐driven (Tailorpack modelling) and a multiscale film structuring (WG‐based composites) approaches, that transfer properties of WG‐based films would fit the requirements of the six selected fruits and vegetables better than conventional plastics. Copyright © 2012 John Wiley & Sons, Ltd.     

Influence of sorbed vegetable oil and relative humidity on the oxygen transmission rate through various polymer packaging films

In this study, the effect of a vegetable oil on the oxygen barrier properties of different polymer packaging materials [i.e. amorphous polyethylene terephtalate (APET), polypropylene (PP) and high density polyethylene (HDPE)] was investigated. The influence of both relative humidity and the combination of relative humidity and sorbed oil on the oxygen transmission rate (OTR) was studied. Regardless of the relative humidity, the APET film remained an excellent oxygen barrier even after storage in rapeseed oil for 40 days. An increased OTR was observed in both the PP and HDPE films stored for 40 days in rapeseed oil. The OTR of the HDPE films was altered to a much greater extent than the OTR of the PP film. The OTR of the HDPE film was also significantly increased for films stored for 20 days in rapeseed oil. The increase in OTR of an HDPE film stored for 40 days in rapeseed oil was between 36 and 44%, depending on the relative humidity, compared to the OTR through the virginal polymer. The amount of oil sorbed by the polymer films used decreased in the following order: HDPE ? APET > PP.     

Protecting and preserving clear barrier layers for flexible packaging materials In‐line thermal evaporation of organic topcoat layer

The end market for transparent flexible barrier films is larger than for metallized films. Presently, the market is still dominated by polymeric barrier layers but the used chemicals may be harmful for the environment. An alternative would be transparent thin layers deposited by vacuum deposition techniques using reactive processes. Ceramic materials like silicon oxide or aluminum oxide are used having a film thickness of just ～10 nm, a coating uniformity of +/?5% across and along the film at a barrier performance below 2.0 sccm/m²d for oxygen transmission rate (OTR) and below 1.0 g/m²d for water vapor transmission rate (WVTR) on PET substrates. In this paper, details will be provided about the deposition processes for these barrier layers using thermal evaporation, plasma‐assisted thermal evaporation as well as deposition by electron beam evaporation. An important factor for these high barrier transparent coatings is also to withstand the downstream processes in the whole packaging stream like slitting, lamination, printing etc. One solution is to protect the barrier layers by a Topcoat. For example, off‐line deposition of lacquers is used in field but the market penetration is low due to high process and material costs. An in‐situ Topcoat deposition is a smart solution to overcome this issue saving time and costs. Such an approach will be also described in the presentation and the impact on the performance of the final package will be discussed.     

Oxygen barrier properties of thermoformed trays manufactured with different drawing methods and drawing depths

A comparison was made of oxygen barrier properties and wall thickness distribution of different thermoformed trays. The thermoformed trays were manufactured with three drawing depths and two different thermoforming methods; with and without plug‐assist. Four different polymer combinations were evaluated. The oxygen transmission rate (OTR) [cm³/(package/day)] was measured at three conditions (23°C/50% relative humidity (RH) with 0% RH inside, 6°C/80% RH with 0% RH inside, and 6°C/80% RH with 100% RH inside. Wall thickness was measured at five different positions in the trays. In general, temperature had more influence on the oxygen transmission rate (OTR) than the humidity. The OTR in the packages increased with increasing drawing depth, but the increase was not linear. Other effects besides thinning, such as orientation, may have influenced the OTR, since the relationship between OTR, given as cm³/(m²/day), and the drawing depth was not linear. Plug‐assisted thermoforming only had an effect on the OTR in trays with 70 mm drawing depth made of 600 µm thick laminate of PP/PE, which was probably due to exceeding the maximum drawing depth of this material. There was no correlation between the OTR value in the packages and the wall thickness in either of the positions, but a quite high correlation between the drawing depth and the relative wall thickness in all measured positions was observed. Copyright © 2004 John Wiley & Sons, Ltd.     

LDPE/PET laminated films modified with FeO(OH) × H2O,Fe2O3, and ascorbic acid to develop oxygen scavenging system for food packaging

The iron compounds (iron(III) oxide‐hydroxide monohydrate FeO(OH) × H₂O, iron(III) oxide Fe₂O₃, and ascorbic acid) were used as oxygen scavengers modifiers in laminating of polymer films. This oxygen‐scavenging system was coated on preselected films (low density polyethylene [LDPE] and polyethylene terephthalate [PET]) from which the laminates were formed. It presents the new form of composite material packaging that has the function of oxygen scavenging, which could be suitable for food packaging. The scope of the research included studies of morphology of oxygen scavengers by scanning electron microscope and their average particle size distribution measure by particle size analyzer, the effect of type, and concentration of these substances on viscosity of adhesive and seal strength of laminates. The Fourier‐transform infrared spectroscopy (FTIR) of laminates was also performed to observe the potential interaction of functional groups of polyurethane adhesives with oxygen scavenger components. The most important ability of the developed system for oxygen scavenging was confirmed by measuring oxygen concentration (% vol) in a headspace with the prepared laminates. The concentrations of selected oxygen scavengers (4‐6 wt%) and their combinations were studied. The most effective oxygen scavenger system integrated within the PE/PET composite film consists of 6 wt% ascorbic acid and 1 wt% FeO(OH) × H₂O, where the oxygen concentration of 1.0 vol% (±0.20 vol%) was obtained after 15 days of storage. It was found that in this system the oxygen scavenging reaction occurs through ascorbate oxidation to dehydroascorbic acid, which is catalyzed by reduction of Fe³⁺ to Fe2⁺ ions.     

Hydrophobic Zeolite‐Filled Polymeric Films with High Ethylene Permselectivity for Fresh Produce Packaging Applications

Gas permselective plastic films have been in a great deal of attention in the area of modified atmosphere packaging of fresh produces. Such films must allow transport of the respiring gases, i.e. oxygen and carbon dioxide, in a controlled manner and, moreover, should efficiently remove ethylene gas. Therefore, the development of highly permeable films with high ethylene permselectivity, i.e. high in both permeability and selectivity, was carried out. The concept of ‘mixed matrix membrane’, by which enhanced gas permselectivity can be obtained by incorporation of zeolite particles into the polymeric film, was applied. Fine particles of hydrophobic zeolites, i.e. zeolite beta and ZSM‐5, and the surface‐modified zeolites were used in this study. The films with uniform distribution of zeolite particles (10% w/w) in 70LDPE/30SEBS (styrene‐b‐(ethylene‐ran‐butylene)‐b‐styrene block copolymer) matrix can be prepared by blow film extrusion. Significantly high ethylene permselectivity, i.e. ethylene permeability of 1.78–2.67 × 10³ cm³ ? mm/m² ? day ? atm and ethylene/O₂ selectivity of 4.67–8.26, was obtained from the films containing octyl‐modified and phenyl‐modified zeolites. Particular enhancement was observed on the films containing phenyl‐modified zeolites. Crystallinity of polyethylene, transition temperatures and decomposition temperature were, however, indifferent among the studied films. Nevertheless, elongation at break and toughness of the films containing surface‐modified zeolites were superior. Particle–polymer interface could thus be improved. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of packaging materials and storage conditions on bacterial growth,off‐odour,pH and colour in chicken breast fillets

A comparison was made of the effect of different packaging materials on bacterial growth, off‐odour, pH and colour of chicken breast fillets stored at 4°C. For one of the packaging materials, the effects of temperature (4°C and 8°C) and initial oxygen present (0%, 2% and 4%) on bacterial growth, off‐odour, pH and colour in chicken breast fillets were also evaluated. Chicken breast fillets stored in the packaging material with the highest oxygen transmission rate (OTR) measured at actual storage conditions had the highest bacterial growth and the highest degree of off‐odour. Chicken breast fillets stored in packaging material mainly consisting of expanded PET had similar bacterial growth and off‐odour as in the barrier display film (BDF) packages, despite a smaller headspace volume and lower initial concentration of CO₂. No differences in discoloration and pH of the chicken breast fillets, due to storage temperature and amount of initial oxygen present, were found when one of the packaging materials was studied. In the early phase of the storage period, Pseudomonas spp. constituted the majority of the total viable counts, while after about 12 days, lactic acid bacteria dominated. At the end of the storage period, both Pseudomonas spp. and Enterobacteriaceae were present in high numbers. Significant differences in counts of Brochothrix thermosphacta were only obtained with initial presence of oxygen. The storage temperature had greater impact on microbial growth and off‐odour than the initial presence of oxygen in the packages. Copyright © 2004 John Wiley & Sons, Ltd.     

A rapid method to determine the barrier requirements for dehydrated oatmeal product using flexible packaging films

Product was packaged in two types of flexible packaging films, poor moisture-high oxygen barrier and high moisture-poor oxygen barrier, and stored under standard tropical conditions. Physical, chemical and biological changes were investigated regularly to find the shelf-life determining factors. Control samples were packaged in glass bottles and stored at 0°C. OTR and WVTR of packaging films were measured. Packaging film permeability and analytical data, obtained from storage tests, were used to determine the barrier requirements for dehydrated oatmeal product, intended for distribution and storage in a tropical climate for 9 months shelf-life. © 1997 John Wiley & Sons, Ltd.