Non‐intrusive Measurements of Headspace Gas Composition in Liquid Food Packages Made of Translucent Materials

The increase in chilled food consumption requires enhanced food safety and quality assurance. Food deteriorating processes are affected by the presence of oxygen, combined with factors such as time and temperature. To slow down deterioration processes and prolong shelf life, traditional packaging methods are being replaced by modified atmosphere packaging, for example. Oxygen, which is naturally present in the headspace of most food packages, is then reduced and controlled. Many sensing techniques for food quality assurance have been developed; however, almost all are intrusive, increasing the complication level and causing sample waste. The purpose of this paper is to introduce a non‐intrusive technique [gas in scattering media absorption spectroscopy (GASMAS)] for measuring gas composition in the headspace of liquid food packages. The GASMAS method uses diode laser absorption spectroscopy combined with diffuse light propagation to analyse gas located inside solids and liquids. By illuminating the package from the outside and analysing the scattered light that emerges, the absorption from the gas inside the headspace can be studied.The GASMAS technique was evaluated on a series of carton packages with a high‐quality orange juice and a nitrogen headspace. A clear variation in oxygen content was measured for samples with different storage times. The results demonstrate the possibility of using the GASMAS method for non‐intrusive quality measurements in food products and packaging. They also indicate the potential for the non‐intrusive quality assurance applications without waste of samples. A further development of the technique could include ‘in‐line’ quality control of packed food items throughout the food packaging supply chain. Copyright © 2011 John Wiley & Sons, Ltd.     

Designing Efficient Oxygen Scavenging Coating Formulations for Food Packaging Applications

Modified atmosphere packaging is widely used to prolong the shelf life of many oxygen‐sensitive items including food, pharmaceuticals, work of art and so on. For food packaging applications, we investigated the effectiveness of oxygen scavenging coatings and flexographic printing ink formulations made using water soluble and water insoluble ascorbate enzyme systems. The present study summarizes the effects of various parameters on the oxygen scavenging rates and other performance aspects of the formulations. It is shown that; the initial oxygen scavenging rate can be increased by increasing the surface area of Calcium Ascorbate crystals and addition of catalyst or edible oil; addition of a catalyst like TiO₂ or Alumina and an edible oil in Ascorbate and laccase‐based formulations induces a synergistic effect upon the rate of scavenging oxygen from the packages; an efficient oxygen scavenging coating formulation can be made using water soluble Calcium Ascorbate and insoluble Ascorbate Palmitate containing enzyme and substrate; designing an efficient oxygen scavenging formulation using water insoluble Ascorbate Palmitate can reduce or eliminate formation of effluent which has potential to change the aperral of food items inside the package; an adverse effect of some binders which cause a reduction in the oxygen scavenging rate can be eliminated by making blends of different binders. Copyright © 2013 John Wiley & Sons, Ltd.     

Development of Palladium‐based Oxygen Scavenger: Optimization of Substrate and Palladium Layer Thickness

Oxygen scavenging films based on vacuum deposited palladium layers were developed to remove residual oxygen remaining in food packages after modified atmosphere packaging. Palladium (Pd) was coated on to a range of packaging films and in different thicknesses using magnetron sputtering technology. To improve the substrate surface, an additional silicon oxide (SiO_x) layer was also applied to the films before Pd deposition. To determine the oxygen scavenging activity, the scavenger films were placed into an airtight cell, which was flushed with a gas mixture containing 2 vol.% oxygen and 5 vol.% hydrogen. The results showed that the oxygen scavenging rate was strongly dependent on the coating substrate as well as on the Pd deposition thickness. Packaging films such as polyethylene terephthalate, aluminium oxide‐coated polyethylene terephthalate, oriented polypropylene and polylactic acid were found to be the most suitable substrates for Pd‐based oxygen scavengers. Moreover, it was demonstrated that the intermediate SiO_x layer between the substrate and the Pd layer led to a substantial increase in the oxygen scavenging activity rate (up to 33‐fold) for all applied packaging films. Additionally, it was shown that the optimal Pd layer thickness for the investigated oxygen scavenging films lies between 0.7 and 3.4 nm. The resulting scavenger films have the potential to scavenge residual headspace oxygen of sensitive foods within a matter of minutes leading to shelf life extension and overall quality improvements. Copyright © 2015 John Wiley & Sons, Ltd.     

Quality changes of treated fresh‐cut tropical fruits in rigid modified atmosphere packaging containers

There has been increasing demand for various fresh‐cut tropical fruits. However, their short shelf‐life has limited the market increase of this product. Quality changes (firmness, colour, total soluble solids (TSS), titratable acidity (TA), sensory quality and microbial safety) of fresh‐cut mangoes, pineapples, melons and mixes of these fruits were evaluated. Chemical treatments to reduce browning, firmness loss and decay of fresh‐cut tropical fruits were investigated. The most effective agents for fresh‐cut mangoes, pineapples and melons were 0.1m ascorbic acid, 0.2m ascorbic acid and 0.2m ascorbic acid + 0.2m calcium chloride, respectively. Fresh‐cut tropical fruits were packaged in various rigid containers (PET, OPS and OPLA). Gas composition in the package headspace and time to reach steady‐state condition varied among fresh‐cut packaging systems and affected their quality and shelf‐life. The effects of package permeability of O₂ and CO₂ on quality and shelf‐life of the fresh‐cut products are discussed. Extended shelf‐life was observed in fresh‐cut mangoes, pineapples and mixes packaged in PET due to reduced O₂ and elevated CO₂ atmosphere. A modified atmosphere of 6% O₂ and 14% CO₂ achieved in PET extended the shelf‐life of fresh‐cut pineapples from 6 to 13 days. Accumulation of CO₂ may impart an off‐odour of fresh‐cut fruits. The results suggested that the shelf‐life of fresh‐cut fruits could be extended by using proper rigid containers. Suitable mixes to create optimal equilibrium modified atmosphere had a potential to extend shelf‐life of short shelf‐life fresh‐cut tropical fruits. Copyright © 2006 John Wiley & Sons, Ltd.     

Predicting changes in oxygen concentration in the headspace of nitrogen flushed packages by the ambient oxygen ingress rate method

The ambient oxygen ingress rate (AOIR) method is an alternative/supplementary method to Ox‐Tran for measuring the oxygen transmission rates of packages. The AOIR method facilitates high‐capacity testing of packages under realistic food storage conditions, on the one hand, and on the other hand provides the possibility to predict the oxygen concentration over time in packages flushed with nitrogen at the time of packaging. The predicted oxygen concentration values showed good agreement with experimental values for flexible packages stored over a period of 91 days at 23°C and 38°C. The prediction of the oxygen concentration in­nitrogen‐flushed packages may be a useful tool, e.g. in shelf life studies, in the selection of the optimal food package as regards to oxygen protection and within quality control purposes. Copyright © 2002 John Wiley & Sons, Ltd.     

Assessment of oxygen levels in convenience‐style muscle‐based sous vide products through optical means and impact on shelf‐life stability

An optical oxygen analyser was used in two small‐scale industrial trials to non‐destructively assess the quality of packaged convenience foods and packaging process. Beef lasagne packed under 70% vacuum and cooked under standard sous vide conditions was monitored for residual oxygen, using disposable sensors incorporated in each pack and a benchtop optical oxygen analyser. High levels of residual oxygen close to ambient were determined in the majority of packs after packaging, as opposed to anticipated levels of 4–5%. Residual oxygen was monitored over product shelf‐life (4 weeks at +4–10°C) along with measurement of microbial growth and lipid oxidation in food by conventional destructive methods. Oxygen levels in packs went down to almost zero between weeks 2 and 3 indicating deterioration of packaged product. Correlation between oxygen profiles and the rate of microbial growth and lipid oxidation was established. The optical oxygen sensor system was shown to provide valuable information about performance of the packaging process, product storage conditions and food quality in a convenient and cost‐efficient fashion and non‐destructively. Copyright © 2004 John Wiley & Sons, Ltd.     

Evaluation of Antimicrobial Active Packaging to Increase Shelf Life of Gluten‐Free Sliced Bread

This paper presents a complete study and comparison of the efficiency of three types of packaging system: active packaging, modified atmosphere packaging (MAP) and combinations of both. To choose the best option, we must take into account microbiological results as well as sensory quality; therefore, a complete sensory study and an in‐depth statistical study were carried out, in order to evaluate each option and their interactions. The results showed that active packaging considerably increases the shelf life of packaged food, so it could be an attractive option to extend the shelf life. The active packaging provided better sensorial properties than the MAP option. Positive factors like characteristic flavour and spongy texture had higher values in the absence of MAP, and negative properties like cinnamon flavour, crumbly texture and hardness reached higher values when MAP was present in the packaged food. So when microbiological and sensorial properties are taken into account, the active packaging is a better option than MAP to increase shelf life because it inhibits microbial growth while maintaining the high quality of sensorial properties for gluten‐free breads. Copyright © 2011 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.     

PVC and LDPE for packing minimally processed garlic

Minimum processing associated with an adequate packing system has shown good results in preserving a large group of perishable horticultural produce. The present work was done to determine the effect of the number of layered of low‐density polyethylene (LDPE) or polyvinyl chloride (PVC) film on the quality of minimally processed packed garlic (Allium sativum), known for its short shelf‐life. Polystyrene trays containing 200 g garlic bulbils were wrapped in one to four layers of PVC or one or two layers of LDPE and stored at room temperature. Changes in weight, bulbil colouration, in‐package gas composition and apparent quality were monitored for 14 days. Best results were obtained by wrapping the packages in four layers of PVC film, with insignificant weight loss (5%), changes in colour tone and saturation, and the in‐pack atmosphere (O₂ = 0.01% and CO₂ = 13.5%) inhibited fungal growth, extending shelf‐life to 13 days at 25 ± 2°C. On the other hand, the high in‐package moisture in LDPE wrapping favoured fungal growth, rapidly depreciating bulbil quality. The shelf‐life of minimally processed garlic can be increased by maintaining an adequate in‐pack atmosphere, which can be achieved by using four layers of PVC or a another film of similar permeability. Copyright © 2002 John Wiley & Sons, Ltd.     

Integral approach for optimizing modified atmosphere packages for elstar apples: A combination of product and packaging constraints

Modified atmosphere packages with Elstar apples in various packaging systems have been investigated. Loss of firmness during shelf-life is used as the quality aspect to judge the performance of the modified atmosphere packages. A system-oriented model is derived that describes the experimentally found concentrations well. In the overall approach the time dependency of the oxygen and carbon-dioxide concentrations are discussed. It is shown that the quality attribute, the softening of apples, can be affected by the choice of packaging material. Hence this approach can be used to optimize modified atmosphere packaging of Elstar apples.     

Oxygen and its reactions in beer

This review examines contemporary literature available on the deteriorative reactions of oxygen in beer and packaged beer. It attempts to identify the shelf‐life factors affected by oxygen, discussing both the reactions and resultant compounds and their role in decreasing the shelf‐life of the product. It attempts to determine whether lowering the total package oxygen to near‐zero in packaged beer would result in an increased shelf‐life. Copyright © 2005 John Wiley & Sons, Ltd.     

Performances of time–temperature indicators in the study of temperature exposure of packaged fresh foods

The diffusion of time–temperature indicators (TTIs), attached as labels onto the packages of perishable food and non‐food products (intelligent packaging), is growing more and more. Aside from checking product shelf‐life, TTI devices can be used to monitor the distribution chain in real conditions. In this respect, the performances of some very common TTIs (A 12 Fresh Check, Lifelines Technologies) were extensively investigated in this work. The aim was to establish a procedure for an accurate, objective and reproducible estimate of the darkening progress of the sensitive area of the indicators and to discover a reliable data treatment to estimate the ‘effective temperature’, T_eff, namely a fictitious average temperature that can replace the overall temperature fluctuations experienced by a packaged fresh food. The image analysis approach was found very useful for an accurate and sensitive definition of the information provided by the indicators, leading to the evidence of a very slow darkening of the sensitive region, even at ?22°C. The kinetic parameterization of TTI responses was implemented in an EXCEL worksheet so as to directly evaluate T_eff on the basis of a set of label brightness values acquired by image analysis. Comparing the calculated ‘effective temperature’ with the average temperature recorded with conventional devices, the reliability of the TTI tags and the accuracy of this procedure was demonstrated. Taking into account the low cost of the TTI tags, their wide usage can be suggested to monitor the various steps of the real distribution chain of a given product, namely, transport, bench and home storage. Copyright © 2001 John Wiley & Sons, Ltd.     

Potency evaluation of a dermaseptin S4 derivative for antimicrobial food packaging applications

Antimicrobial packaging is part of the broader area of active packaging, in which the package absorbs/releases different compounds during the product's storage and plays a major role in maintaining quality, extending shelf‐life and improving the product's safety. Antimicrobial packages are capable of inhibiting the detrimental effects of spoiling microorganisms in food products. There has been very great interest in antimicrobial packaging in recent years and many such packaging materials have been proposed, some of which containing synthetic additives and others natural additives. In the present study, antimicrobial materials containing the antimicrobial peptide (AMP) dermaseptin K₄K₂₀‐S4, which shows cytolytic activity in vitro against a broad spectrum of pathogenic microorganisms, such as bacteria, protozoa, yeast and filamentous fungi, were investigated. The study was aimed at evaluating the potency of this AMP as an antimicrobial agent for antimicrobial food packaging in two forms: (a) an aqueous solution of AMP was applied onto a polyethylene shrink‐wrapping film; (b) the AMP was incorporated in a corn starch‐based coating and applied directly onto the foodstuff (fresh cucumbers). Of these two versions, the latter has shown a greater efficiency against moulds and aerobic bacteria, even at lower surface concentrations of AMP (4.5µg/dm² vs. 3.5–3.8µg/dm²) in the coating. While in the first version the AMP had slowed down the growth of microorganisms only slightly, incorporation of AMP into the coating caused a reduction in their concentration practically to zero. Copyright © 2006 John Wiley & Sons, Ltd.     

The effectiveness of hexamethylenetetramine‐incorporated plastic for the active packaging of foods

The feasibility of LDPE films containing 0.2 or 0.5% (w/w) hexamethylenetetramine (HMT) as antimicrobial packaging material to inhibit microbial growth on the surface of foods was investigated. As HMT is allowed in Europe to be used as a preservative under certain conditions, and as it is mentioned on the list of additives notified to the European Commission as substances which may be used in plastics intended in contact with food products, this compound offers good opportunities for the manufacturing of an antimicrobial packaging material. In a first experiment, fresh orange juice was vacuum packaged in LDPE films containing 0, 0.2 and 0.5% (w/w) HMT and stored at 6°C for 39 days. Every day and later every 3 days, packages of orange juice were analysed for yeasts and lactic acid bacteria. The shelf‐life of orange juice, could not be prolonged significantly by packaging into a 0.2% or 0.5% (w/w) HMT‐containing film. In a second experiment, however, packaging of cooked ham in a 0.5% (w/w) containing LDPE film, significantly affected shelf‐life. After 20 days a significant reduction of total aerobic count and lactic acid bacteria was observed. In an additional migration test, it became clear that the level of HMT released into orange juice was close to the specific migration limit of 15 mg CH₂O/kg imposed by the EC. Copyright © 2000 John Wiley & Sons, Ltd.     

Determination of oxygen and water vapour in modified atmosphere packages for meat sausages with and without an oxygen absorber

A gas chromatographic method has been developed that measures both the residual oxygen concentration and the level of relative humidity during the same run in modified atmosphere packages (N₂/CO₂) with and without an oxygen absorber. A processed meat product with a high content of water served as the foodstuff in those packages. The chromatographic system consists mainly of a loop-injector connected to capillary columns coupled in series and a thermocouple detector. The introduction of an oxygen absorber seems to be attractive, since the concentrations obtained for the residual amount of oxygen in the packages with an oxygen absorber varied between 0.0043 and 0.029%. For packages without an absorber, the oxygen concentrations were much higher and fluctuated between 0.26 and 0.56%. The whole measuring period lasted for 27 days. The relative humidity, also a factor that can cause food deterioration, was 100%. © 1997 John Wiley & Sons, Ltd.     

Large‐Scale Roll‐to‐Roll Patterned Oxygen Indicators for Modified Atmosphere Packages

We demonstrate roll‐to‐roll fabrication of ultraviolet A light‐activated colorimetric oxygen indicators on paper and plastic substrates. Such large‐scale, cost‐effective and non‐toxic oxygen indicator and production method can find applications as a very low‐cost leakage indicator for modified atmosphere packages by printing the material directly or gluing the pre‐printed indicator label inside the lid. The introduction of leakage indicators onto all modified atmosphere packages could result in improved food safety and reduced food spoilage. Copyright © 2017 John Wiley & Sons, Ltd.     

Effect of hinokitiol impregnated sheets on shelf life and quality of “KEK‐1” tomatoes during storage

Hinokitiol (β‐thujaplicin, volatile oil extracted from the wood of Hiba arborvitae [Thujopsis dolabrata var. hondae], cypress family) is a natural preservative, antimicrobial, and chelating agent, used to prevent decay and extend the shelf life of fruits and vegetables. In the present study, we used nonwoven rayon sheets impregnated with hinokitiol to conduct packaging studies. Mature green tomatoes var. “KEK‐1” were packaged under three packaging conditions, ie, modified atmosphere packaging (MAP), MAP + hinokitiol (MH), and perforated film package (as control), and their quality attributes were compared during storage. The packaging materials used were low‐density polyethylene (LDPE) film (40 μm) and fresh sheets of nonwoven rayon impregnated with hinokitiol. O₂ in the MAP packaged tomatoes were retained throughout the storage period (3% to 5% O₂). Results showed that MH had slightly improved quality attributes throughout the storage period when compared with MAP alone. Expression levels of LeACS, LeADH, and LeTBG4 genes were higher in 5 and 9 days of control when compared with MAP and MH. “KEK‐1” tomatoes had longer shelf life under MAP and MH packaging and maintained the quality at 15°C. Hence, the effect of the MAP with bioactive packaging treatments could be effective in the future application for the extension of shelf life and quality of fruits and vegetables.     

The Effect of Active Packaging on Minimizing Food Losses: Life Cycle Assessment (LCA) of Essential Oil Component‐enabled Packaging for Fresh Beef

Packaging plays an important role in ensuring food safety and quality, and the development of active packaging, especially antimicrobial packaging, enables actively inhibiting/killing the microorganisms causing food spoilage and thus extending the product's shelf life. A survey of the publications revealed that generally 50% shelf life extension is possible. The goal of this study is to assess the overall environmental performance of the food and packaging system considering the effect of food loss reduction by using active packaging. A comparative life cycle assessment has been carried out, focusing on a case study: essential oil component‐enabled packaging for fresh beef. Different scenarios were set up to contrast the situations of food using conventional packaging (current situation) and food using novel active packaging (containing active coating). Additionally, a sensitivity analysis has been integrated, aiming to identify the breakeven point of the balance. In the scenarios using the best‐performance active packaging, it was shown that a breakeven point can be achieved across the four impact categories evaluated, including global warming, fossil energy demand, acidification potential and eutrophication potential. It is expected that the obtained results would serve as guidelines for active packaging development striving for a positive eco‐profile of the food and packaging system. Copyright © 2015 John Wiley & Sons, Ltd.     

The influence of packaging materials on the dissolved oxygen content of probiotic yoghurt

The health benefits of probiotic functional foods have been widely reported. However, manufacturers face great challenge in guaranteeing delivering beneficial numbers of viable probiotic bacteria through to the end of the product shelf life. The oxygen toxicity of some probiotic species has been shown to contribute to reduced viable counts. The packaging system favoured by manufacturers may play a negative role, promoting oxygen uptake in the product. The research detailed herein evaluates the performance of current packaging materials and an alternative, oxygen‐barrier material. Commercial stirred‐type probiotic yoghurt was evaluated for dissolved oxygen content over a 6 week period from manufacture to expiry date. The results indicate a rising level of dissolved oxygen in the yoghurts over time. The distribution of oxygen throughout the product was also examined by measuring concentrations in two lateral positions, at three different depths. It was found that oxygen was not distributed homogenously, but was in significantly different concentrations (p < 0.05) at most sampling points. At some locations (near packaging weak spots), readings were approaching saturation, hardly an environment suited to the survival of the anaerobic and probiotic Bifidobacterium species. Yoghurt stored in packaging materials with improved gas‐barrier properties was also tested, displaying a decrease in dissolved oxygen levels during storage. It was concluded that using packaging materials with greater gas‐barrier properties would help remove a hurdle to the viability of the probiotic bacteria within the food. Suggestions for further steps, such as the addition of an oxygen‐scavenging technology, are also made. Copyright © 2002 John Wiley & Sons, Ltd.     

Compensation of Pinhole Defects in Food Packages by Application of Iron‐based Oxygen Scavenging Multilayer Films

To protect sensitive food products from oxidative deterioration, multilayer barrier film systems and also modified atmosphere packaging are widely applied. However, the preservation of food quality in such packaging systems may be compromised by the presence of defects in the sealing layer of the films, especially when these are below a critical size, typically the detection limit of standard leak testers of 10 µm. The addition of an oxygen scavenger (OS) layer in barrier film structures could therefore provide extended protection against O₂ penetration through such defects. In this study, O₂ absorption of different multilayer film structures including an iron‐based OS were investigated under defined gas atmospheres. Measurement cells were thereby covered with plastic films of defined O₂ permeability to simulate conditions in a food package during storage with pinhole defect sizes of 10 and 17 µm. The results indicated that the OS film structures applied could only compensate for a defect size of 10 µm in the sealing layer. Analysis of the O₂ absorption of different multilayer film structures at 85% and 100% relative humidity showed that higher humidity accelerates the activation of the scavenger. After full activation, the scavenger kinetics are the same for 85% and 100% relative humidity. Long‐term storage experiments using the most effective film structure from the preliminary experiments were carried out to compare O₂ absorption of a snack food product in packages with and without an OS. The analyzed linear gradient of the reaction of the OS film and food product, respectively, indicated first‐order reaction kinetics with corresponding reaction constants calculated to be K (food product) 0.021 mg (O₂) mbar (O₂)^?1 day^?1 and K (OS film) 0.066 mg (O₂) mbar (O₂)^?1 day^?1. The reaction velocity of the OS was thus three times faster than that of the food. The applicability of OS multilayer film systems to compensate a critical pinhole defect size of 10 µm for sensitive food products could therefore be confirmed. The measurement of quality parameters for the status of lipid oxidation processes would help to verify this result. Copyright © 2012 John Wiley & Sons, Ltd.