Effect of Different Packaging Methods on Quality and Shelf Life of Fresh Reindeer Meat

The impact of different packaging methods [vacuum, modified atmosphere packaging (MAP) (60% CO₂ and 40% N₂) and MAP + CO₂ emitter] on the quality of fresh reindeer meat (M. semimembranosus) stored at 4°C for 21 days was investigated. Colour and odour of the meat, drip loss, pH, microbial content, antioxidant capacity and cooking loss were measured. The MAP + CO₂ emitter resulted in prolonged microbial shelf life compared with vacuum and MAP without CO₂ emitter as lower level of total viable counts was detected after 13 and 17 days. Samples stored with CO₂ emitter also had lower drip loss. Samples stored in vacuum had significant lower L*‐value, higher a*‐value and lower intensity of freshness (odour and colour) compared with those stored in MAP and MAP with CO₂ emitter. However, MAP with a gas‐to‐product volume ratio of 1 : 1 seems to be too low in quality preserving. Increased partial pressure by adding a CO₂ emitter improved bacterial inhibition compared with vacuum and traditional MAP. Copyright © 2014 John Wiley & Sons, Ltd.     

Effectiveness of modified atmosphere packaging in preserving a prepared ready‐to‐eat food

The effectiveness of modified atmosphere packaging (MAP) was evaluated for a combination prepared food (Korean braised green peppers with dry anchovies). From a preliminary storage test of the ready‐to‐eat dish at 10°C, the aerobic bacterial count on the green peppers was selected as a primary quality index. The effect of MAP with different CO₂ concentrations on the product quality at 10°C was also studied. MAP with a CO₂ concentration of ≥30% extended the lag time and/or reduced the growth rate of bacteria. Finally, the effect of different storage temperatures (5, 10, 15 or 20°C) on the shelf life of the product was investigated. Mathematical modelling of bacterial growth curves under stretch‐wrap air packaging and MAP with 60% CO₂/40% N₂ showed that MAP increased the hypothetical minimum temperature in the square root model that describes the temperature dependence of the lag time and growth rate. MAP conditions of 60% CO₂/40% N₂ extended the shelf life at 10°C by 130% (to 18.4 days) relative to that achieved with stretch‐wrap air packaging (7.9 days) based on the time taken to reach the quality limit of an aerobic bacterial count of 10⁵ CFU/g. The relative extension of shelf life achieved with MAP was greater at lower temperatures. Copyright © 2008 John Wiley & Sons, Ltd.     

Modified atmosphere packaging of fresh mushrooms

The storage life of harvested fruits and vegetables is influenced by their continued respiration and biochemical activity. Lowering the temperature, and modifying the atmosphere surrounding the product, can extend the shelf-life of the produce. Mushrooms (Agaricus bisporus) were placed into different structural containers covered with PVC films and stored at three temperatures. The effect of key variables, such as temperature, respiration rate, critical and optimal concentrations of O₂ and CO₂, package-weight/area ratio and film permeability, were studied. It was concluded that a highly perishable product, such as mushrooms, must be wrapped and refrigerated in order to prevent transpiration and shrivelling. Modified atmosphere packaging (MAP) may be beneficial but was not found to be essential. If a certain batch of mushrooms respires faster than predicted, or is exposed to large temperature fluctuations, MAP could have a damaging effect.     

Effect of different modified atmosphere packaging on microbial quality,oxidation and colour of a seasoned ground beef product (meatball)

The effects of different modified atmosphere packaging (MAP) on microbial quality, oxidation and colour of meatballs were investigated. Meatballs were prepared in our laboratory and packaged in vacuum or in different gases: combinations of O₂ (0, 2, 21%) and CO₂ (0, 33, 66, 100%) with N₂ as balance gas. Total microbial count, thiobarbituric acid reactive substances and colour were determined during storage at 3°C for 3 weeks. Total microbial count remained unchanged at around 6.3 LogCFU/g in vacuum and 100% CO₂ packages after 7 days, and slightly increased afterwards. The microbial count was higher in other packages and increased to 7.6 LogCFU/g after 21 days storage. Oxidation was inhibited by reduced O₂ and increased CO₂ in the packages. Packages with low O₂ maintained colour (a‐values) to a greater extent than the packages with higher O₂ levels. MAP containing 1–3%O₂ with 33%CO₂ inhibited microbial growth, oxidation and colour change in meatballs. Copyright © 2009 John Wiley & Sons, Ltd.     

Mass transfer from and through packaging materials

The use of polymer films for food packaging requires a knowledge of their transport properties under varying conditions. The permeability to gases and water vapour of the packaging films at the specific conditions of use, i.e. temperature, relative humidity and pressure gradient, are needed for selecting the optimum packaging system to ensure the required shelf-life of the packed product. Migration from, and absorption by, plastic films also play an important role in their selection. The 0₂ and CO₂ permeabilities of three plastic films at four different temperatures were evaluated and shown to follow the Arrhenius relationship in the range tested. The effects of four thicknesses of one film on its permeability are also reported. Three methods to evaluate migration from polymeric films were compared using different weight/volume ratios. The extraction method recommended by the FDA, using n-hexane in a stirred flask, was found to be best. The shelf-life of Matzoth (Jewish Passover bread) packed in polyethylene (stored at 25°C) was found to be longer than the shelf-life of those packed in the higher barrier PVDC/PE. This was apparently due to the absorption of undesirable oxidation compounds, given off from the Matzoth by the PE, which were not absorbed at detectable levels by the PVDC/PE.     

Combined effect of chill storage and modified atmosphere packaging on mussels (Mytilus galloprovincialis) preservation

Changes in biochemical indices, microbial growth, headspace and sensory quality of mussels which had been packaged in two modified atmospheres [Modified atmosphere packaging (MAP) 1: 60% CO₂/20% N₂/20% O₂ and MAP 2: 60% CO₂/40% N₂] and under vacuum (VP) were studied for 14 days. The results showed better quality retention and greater shelf life of mussels packaged under MAP 1 as compared to MAP 2 and VP samples. Increase in total volatile basic nitrogen followed the order: MAP 1 < MAP 2, VP < air (control) samples while increase in trimethylamine nitrogen followed the order: MAP 1 < air < MAP 2 < VP. The 2‐thiobarbituric acid (TBA) values of MAP 1 and air samples were significantly higher (p < 0.05) than the TBA values of VP and MAP 2 samples. MAP 1 showed a greater (p < 0.05) inhibition effect on total viable count of mussel samples than all other packaging conditions. Based primarily on odour scores, the MAP 1 samples remained acceptable up to ca. 10–11 days, the MAP 2 and VP up to ca. 7–8 days while the air‐packaged samples up to ca. 5–6 days of storage. Copyright © 2007 John Wiley & Sons, Ltd.     

Effects of active modified atmosphere on lipid and protein oxidation,moisture migration and quality properties of beef steaks

Fresh beef is a typically perishable food because of its high water and protein content; thus, it requires proper packaging condition and storage temperature to ensure its quality. In this study, the beef steaks were stored at 4°C under HiO₂ modified atmosphere packaging (MAP) (78.8% O₂ + 18.8% CO₂ + 2.4% N₂) and HiCO₂ MAP (60.0% CO₂ + 40.0% N₂). The traditional air packaging (AP) and vacuum packaging (VP) were used as the controls. The total viable count (TVC), colour, water holding capacity (WHC), myofibrillar protein (MP) oxidation and lipid oxidation of beef meat were investigated. The moisture distribution and migration were also analysed using the low-field nuclear magnetic resonance (LF-NMR). The association amongst all parameters was analysed by correlation analysis and principal component analysis (PCA). The results showed that the TVC values in the HiCO₂ MAP (5.6 log CFU/g) steaks were lower than those of VP (5.9 log CFU/g), AP (7.0 log CFU/g) and HiO₂ MAP (6.3 log CFU/g) steaks because of the sufficient CO₂ after 15 days of chilled storage. The bright red colour and the higher WHC were maintained in the HiO₂ MAP steaks than in the AP group during storage. However, higher levels of protein and lipid oxidation also occurred. The beef steaks stored under HiCO₂ MAP had the lowest protein and lipid oxidation and highest value of immobile water content and WHC, however, similar to the VP group, the bright red colour was not shown. The moisture attributes (drip loss, cooking loss and P₂₃), protein oxidation (protein solubility and carbonyl content) and lipid oxidation (TBARS value) have shown a close correlation by correlation analysis and PCA. Overall, two different packaging methods of MAP can prolong microbial-shelf life and maintain higher WHC of beef steaks compared to AP and VP steaks, but higher oxidation level in HiO₂ MAP and unattractive colour in HiCO₂ MAP are concerns that need to be addressed.     

Modelling a modified atmosphere packaging system for fresh scallops (Argopecten purpuratus)

Seafood is a highly perishable food, which has a relative short shelf‐life. Modified atmosphere packaging (MAP) is a system that offers a way of extending the shelf‐life of seafood products, maintaining quality and inhibiting bacterial growth. The objective of this research was to study and determine the optimal conditions for packaging scallops in a modified atmosphere system, which includes CO₂/O₂/N₂ mixture, headspace:food ratio and storage temperature, utilizing an integrated mathematical model for MAP systems with its respective experimental validation. For validation purposes, two experiments were conducted, using gas mixtures of: (a) 45% CO₂/10% O₂/45% N₂; and (b) 60% CO₂/10% O₂/30% N₂. In addition, two experiments, at 6°C and 20°C, were conducted to obtain the shelf‐life model, utilizing the following gas mixtures: 30% CO₂/10% O₂/60% N₂; 45% CO₂/10% O₂/45% N₂; 60% CO₂/10% O₂/30% N₂; and 75% CO₂/10% O₂/15% N₂. Gas mixtures with CO₂ concentrations between 30% and 70% and different headspace:food ratios were tested during simulations. The optimal conditions for scallop storage were a 60% CO₂/10% O₂/30% N₂ gas mixture and a headspace:food ratio of 2:1. With these conditions, a simulated shelf‐life of 21 days was obtained. Optimal conditions consider maximum shelf‐life, an adequate film collapse criterion, and time to reach the pseudo‐equilibrium condition. The predictive mathematical model, coupled with experimental studies for specific products, can be efficiently utilized to evaluate packaging alternatives (size, material and selected thickness) for different temperatures and initial gas concentration scenarios of MAP products. Copyright © 2006 John Wiley & Sons, Ltd.     

A Multi‐functional Biofilm Used as an Active Insert in Modified Atmosphere Packaging for Fresh Produce

We developed a multi‐functional agar‐based biofilm for fresh produce packaging by modulating its CO₂ absorption and water vapour absorption functions. The film was prepared from solutions containing agar as a matrix and a water vapour absorbent, glycerol as a plasticizer, and sodium carbonate (SC) and/or sodium glycinate (SG) as a CO₂ absorbent. The optical, mechanical, and CO₂ and water vapour absorption properties of SC, SG, and SC/SG films were investigated. Multi‐functional films tended to show poor mechanical properties, with a hard texture and an opaque and yellowish colour. The three films had different CO₂ absorption capacities and coefficients, with SC film showing the highest absorption, followed by SC/SG and SG films. The water absorption coefficients were much higher than those of CO₂, with the opposite dependence on the absorbent compound. The multi‐functional benefits of the developed film were shown by using the film for modified atmosphere packaging (MAP) of shiitake mushrooms as an insert label. A tailored MAP design for shiitake mushrooms was produced based on mass transfer mathematical models. The package attached with SC film label was capable of generating the desired internal atmosphere and thus showed the best quality preservation in terms of colour, firmness, flavour score, and bacterial growth after 5‐day storage. A tailored MAP system with our multi‐functional film can provide an optimal modified atmosphere for CO₂‐sensitive fresh commodities, preserve their quality, and extend their shelf life. Copyright © 2015 John Wiley & Sons, Ltd.     

Prediction of plastic film thickness based on gas permeability and validation with ‘Kyoho’ table grapes for optimal modified atmosphere packaging

Modified atmosphere packaging (MAP) storage has become a useful technique for extending the shelf life of fruit and vegetables. However, the success of MAP depends on many factors, including types of fresh products, storage conditions, and the characteristics of the packaging films. To achieve the optimal gas composition in the package headspace and improve the postharvest quality of fresh produce, the packaging film with appropriate barrier properties needs to be selected. This study aimed to predict the film thickness by applying produce respiration rate and package film permeability data measured in given product weight and storage conditions. An available film (eg, 25‐μm‐thick low‐density polyethylene) was used to pack fresh produce, and the respiration rate of fresh produce and in‐package O₂ and CO₂ concentrations at steady state were measured. Permeability of the film was calculated based on mass balance, and the thickness of the film could be predicted if the recommended target O₂ and CO₂ concentration was obtained from the literature. To validate the predicted thickness value, an experiment was conducted by packaging fresh table grapes in bags of the predicted thickness. The effect of packaging with different film thicknesses on the quality of the fruit was determined. The results showed good agreement between the predicted and the experimental in‐bag O₂ and CO₂ concentrations, and the MAP with predicted thickness (90 μm) film was more effective in maintaining postharvest quality of grapes during low‐temperature storage than the thinner films (30 and 60 μm) and the control.     

Effect of oxygen concentration on the shelf‐life of fresh pork packed in a modified atmosphere

Freshly slaughtered meat was packed in modified atmosphere packs (MAP) containing 5%, 15%, 25%, 35%, 45% and 55% O₂ along with 20% CO₂ in each package and stored for 8 days at 4°C. The samples were evaluated on the 8th day in terms of TVBN total volatile base nitrogen (TVBN) value, thiobarbituric acid reactive substances (TBARs) value, colour acceptability score, overall acceptability score and total microbial count. The result indicated better effects for 45% and 55% O₂‐containing MAP; however, the TBARs value of 45% O₂ atmosphere was significantly lower, without having significant differences in other evaluation criteria, than in the 55% O₂ package; hence 45% O₂ and 20% CO₂ gas mixture were selected as the most appropriate gas composition for fresh pork packaging. Copyright © 2005 John Wiley & Sons, Ltd.     

Maintaining quality of fresh strawberries through various modified atmosphere packaging

The influence of various modified atmosphere packaging (MAP) (21/0.05, 4/8 and 60/20% O₂/% CO₂) on fresh strawberry qualities [pH, acidity, °Brix, colour ( L, a ) and texture profile analyses] was investigated and compared during storage. Among the gas combinations used, pH of fresh strawberry was 3.281 at 1 day, and increased to 3.561 for air [21/0.05% (O₂/CO₂)], 3.53 for low (4/8) and 3.538 high (60/20) at 12 days. At the end of the storage, °Brix had evolved from the initial 7.07 to 5.47, 5.65 and 5.62 for 21% O₂; 4% O₂ and 60% O₂, respectively. Storage in 60% O₂ or 4% O₂ delayed the decrease of °Brix, titratable acidity and increased pH compared with 21% O₂. At the end of the storage, the strawberry L values had slightly decreased. Initial values of the firmness were 1067 gf and reduced to 501 gf (21% O₂); 613 gf (4% O₂) and 575 gf (60% O₂) at 12 days storage. Higher O₂ resulted in better springiness and chewiness than those treated with 4% O₂ and 21% CO₂, but did not significantly affect resilience. These results show that the use of various MAP gas compositions, including high oxygen, could be a good alternative to maintain fresh strawberry qualities for at least 12 days. Copyright © 2008 John Wiley & Sons, Ltd.     

Decomposition characteristics of carbon dioxide by gas tunnel-type plasma jet

The increase of warm-room gas is thought to cause the rise of atmosphere temperature, which is called the warm-room effect. Therefore, the decomposition treatment of carbon dioxide (CO₂) gas is an important research subject in order to solve the global environmental problem. In this study, a high-energy plasma process was used to decompose CO₂ gas as a warm-room gas, and the decomposition mechanism was clarified by varying the plasma operation conditions. The possibility of transforming of the CO₂ gas to various resources was also discussed. Firstly, the performance test of the gas tunnel-type plasma jet used for decomposition of CO₂ was conducted, and decomposition characteristics of CO₂ gas by the gas tunnel-type plasma jet was determined under various conditions. The decomposition ratio of CO₂ was about 30%, when the power input was P=8 kW, and the CO₂ content in argon was 10%. Secondly, the improvement of operating conditions of the plasma jet was discussed in order to enhance its performance.     

Modified atmosphere packaging affects lipid oxidation,myofibrillar fragmentation index and eating quality of beef

The objective of this study was to evaluate the effects of different modified atmosphere packaging (MAP) systems applied during ageing and retail display on the quality of beef longissimus dorsi. The quality of the steaks was measured by sensory analysis, thiobarbituric acid‐reactive substances (TBARS), myofibrillar fragmentation index (MFI), protein oxidation, weight loss, cooking loss and vitamin E content. The study included 11 different packaging systems investigated in two separate trials, using O₂, CO₂, N₂ gas and vacuum in combination or alone during ageing and retail display. In some systems, loins were sliced into steaks before packaging, and in other systems, loins were vacuum packed and aged for 14–18 days, and thereafter were sliced and repacked in different atmospheres. Systems including high O₂ MAP resulted in a large increase in warmed‐over flavour and in TBARS as well as a decrease in juiciness, tenderness and vitamin E content, compared to anaerobic systems. Also, MFI was lower in high O₂ MAP steaks, and an increase in protein oxidation was seen, suggesting that the decrease in meat tenderness was due to reduced proteolysis and/or protein oxidation. In addition, the cooked steaks of high O₂ MAP looked well done, although the internal temperature was only 62°C, indicating premature browning. Ageing of steaks in N₂ did not affect any measured parameter compared to vacuum thermoforming packed muscle. Steaks stored in vacuum skin pack for 20 days were less tender than steaks stored in 100% N₂ for 18 days followed by 2 days in atmospheric air. In conclusion, packaging in high O₂ concentrations compromises several aspects of meat quality. Copyright © 2008 John Wiley & Sons, Ltd.     

Microbiological quality and shelf-life of chilled cod fillets in vacuum-skin and modified atmosphere packaging

The microbiological quality and shelf-life of fresh cod fillets (Gadus morhua) packed under modified atmospheres (CO₂/N₂/O₂, 40:20:40) were compared to air and vacuum-skin packed fillets. Packed fillets were kept at 0 ± 1°C and chemical and microbiological analyses as well as sensory assessment were carried out after 4, 6 and 8 days. The decomposition process was evaluated through microbial and enzymatic proteolysis by means of total volatile nitrogen measurement, acetic acid values, surface pH and organoleptic tests. The microbiological quality was established by evaluating the growth of microbial species responsible for spoilage (total bacteria count. Gram-negative bacteria, H₂S-producers) and identifying isolated species. Modified atmosphere packaging gave the best results and the high oxygen content did not affect the microbiological quality in the presence of 40% carbon dioxide. Vacuum-skin packed fillets gave less satisfactory results owing to poor chemical and microbiological indices, even if they we-e always better than fillets maintained in air.     

A Digital Variable-Angle Rolling-Ball Viscometer for Measurement of Viscosity,Density, and Bubble-Point Pressure of CO<Subscript>2</Subscript> and Organic Liquid Mixtures

A new apparatus was developed for measuring the viscosity, density, and bubble-point pressure of CO₂ and organic liquid mixtures. The apparatus is based on the rolling-ball principle and consists of a computer-controlled stepper motor that rotates a high-pressure cell that is equipped with a sapphire window, a movable piston, and a position-sensing device. Design of the high-pressure cell was made such that compositions could be determined by mass. The viscosity was determined by sensing the speed of a rolling ball, and the density was determined by sensing the position of the piston with a linear-variable differential transformer. Bubble-point pressures were measured with the synthetic method. The viscosity and density of octane and decane were measured, and the average deviations of these properties compared with reliable literature values were 1.1 % and 0.15 %, respectively. The viscosity and density of CO₂ + tetrahydrofuran system were measured at a temperature of 60 °C, a pressure of 10.2 MPa, and CO₂ mole fractions up to 0.3. Bubble-point pressures for the CO₂ + tetrahydrofuran system were in good agreement with literature data.     

Effect of CO2 fixation reaction on the thermal and dynamic mechanical properties of tetrafunctional epoxy resin

A tetrafunctional epoxy resin was modified using CO₂ fixation process in the presence of tetra-n-butyl ammonium bromide as catalyst. The unmodified tetrafunctional epoxy resin (UMTE) and CO₂ fixated modified tetrafunctional epoxy resin (CFMTE) were cured by diethylenetriamine. A bifunctional glycidyl ether compound was used as a reactive diluent to control the viscosity of CFMTE. The activation energy of curing reaction was computed using the advanced integral isoconversional method. The activation energy, which depends on the conversion, was considerably changed due to the CO₂ fixation process. The thermal stability parameters including the initial degradation temperature, the temperature at the maximum rate of weight loss (T _max), and the decomposition activation energy (E _d) were determined by thermal gravimetry. Dynamic mechanical thermal analysis measurements showed that the CO₂ fixation decreases the T _g of the epoxy resin. The surface morphology of UMTE and CFMTE were determined by scanning electron microscope. It is concluded that CO₂ fixation reaction improves the properties of tetrafunctional epoxy resin.     

The effect of ethanol and oxygen absorption on the shelf-life of packed sliced rye bread

The effect of ethanol emitters, 1% (v/v) ethanol-containing gases and oxygen absorbers on the shelf-life of whole grain rye bread was investigated in two 6 week storage experiments. The bread slices (215 g) were packed in 500 ml plastic containers with headspace volumes of 240 ml. The biggest ethanol emitters (2 and 3 G) extended the microbial shelf-life of rye bread from 8–12 to 26–27 days in the two experiments, and oxygen absorbers correspondingly to the end of the storage period (42 days). Small ethanol emitters (0.6 and 1 G) and 1% (v/v) ethanol-containing gases had no influence on the microbial shelf-life. Ethanol and oxygen absorbers had no effect on changes in texture and moisture during storage. The overall sensory quality of the samples without microbial growth was evaluated as rather good at the end of the storage period. The flavour of ethanol was discovered not to prevent the use of ethanol for the preservation of bread, since ethanol was detected only a few times in the panellist sensory evaluation     

Synthesis of carbon-doped TiO2 nanoparticles using CO2 decomposition by thermal plasma

This study examined the synthesis of carbon-doped titanium dioxide using TiCl₄ and CO₂ as titanium and carbon sources, respectively, by thermal plasma at atmospheric pressure. The effect of the CO₂ gas flow rate on the preparation of TiO₂ was investigated. The results showed that the decomposition rate of CO₂ was 90% at a CO₂ gas flow rate of 1 L/min. When TiCl₄ was added to produce TiO₂, the decomposition rate of CO₂ reached 95% at a CO₂ gas flow rate of 1 L/min. The resulting powders contained mixed anatase and rutile phases with particle sizes ranging from 20 to 50 nm. The carbon in the CO₂ acted as a dopant to produce the carbon-doped TiO₂. The prepared samples were mainly characterized by X-ray diffraction, X-ray photoelectron spectroscopy, specific surface area measurements and ultraviolet-visible spectroscopy.     

Combined effects of hot water treatment (HWT) and modified atmosphere packaging (MAP) on quality of tomatoes

Effects of hot water treatment (HWT) and modified atmosphere packaging (MAP) on quality of tomatoes were studied. Prior to packaging with low‐density polyethylene (LDPE) film (0.02 mm in thickness), tomatoes were immersed in hot water (42.5°C) for 30 min. Control tomatoes were not treated and were stored for 2 weeks at 10°C and then for 3 days at 20°C without packaging. Steady states of O₂ and CO₂ concentrations inside the package were about 5 and 8%, respectively, and were reached after 6 and 4 days of storage, respectively. MAP reduced weight loss of tomatoes to about 41% of that of unpackaged fruit during a 2‐week storage period. The use of a combination of HWT and MAP reduced weight loss and decay, inhibited color development and maintained firmness of tomatoes but had no effect on soluble solids content or titratable acidity. HWT slightly reduced mold growth of tomatoes stored in MAP. Packaging of control fruit in MAP resulted in stimulation of mold growth around the stem end of the fruit after about 1 week of storage and also resulted in cracking and decay. HWT could be used as disinfectant for tomatoes prior to storage in MAP in order to reduce microbial growth, cracking and decay that may be caused by excessive water vapor inside the package. Copyright © 2003 John Wiley & Sons, Ltd.