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1.
The objective of this study was to evaluate the influence of package materials on the preservation of cold‐stored ‘Kumagai’ guavas. The treatments were: PO2, co‐extruded polyolephinic film with gas injection (5% O2/5% CO2/N2); PO3, co‐extruded polyolephinic film with gas injection (5% O2/5% CO2/N2); LDPE, linear low density polyethylene film; LDPE‐gas, linear low density polyethylene film with gas injection (3% O2/8% CO2/N2); PVC, polyvinylchloride stretch film; PO1, co‐extruded polyolephinic film and control: non‐packaged guavas. Guavas were stored at 10 ± 1°C/80–90% RH for 21 days, and then transferred to room temperature. Gas composition within the package headspace was analysed during storage and the physical and chemical characteristics of the guavas were evaluated daily during ripening. The modified atmosphere provided by PO1 film was insufficient to promote the benefit of senescence control. Although PVC provided an atmosphere close to that recommended, it did not preserve the colour and pulp firmness. PO2, PO3, LDPE and LDPE‐gas retarded the senescence process of the guavas during 21 days at 10°C plus 2 days at room temperature, but harmed the normal ripening of guavas in some aspects. This can be explained by reduced O2 and elevated CO2 levels within these four packages. None of the packages influenced the titratable acidity and the soluble solids, but they did harm ascorbic acid synthesis. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

2.
The effects of vacuum or modified atmosphere packaging conditions on the ripening dynamics of kimchi and sensory preference were investigated to determine the potential of initial atmospheric flushing as a method for improving quality at consumption. In all the packaging treatments (control of air, vacuumizing, CO2 flushing and N2 flushing), the partial pressures of O2 and N2 remained at nearly constant initial levels; therefore, the increases of package pressures were dominantly caused by the increases in the CO2 partial pressures as a result of kimchi fermentation. The CO2 production from kimchi was greater in the vacuumed and CO2‐flushed packages. The initial vacuumed treatment helped to maintain relatively lower pressure during extended storage, and the pressure of the CO2‐flushed package could have been reduced as a result of the high solubility of CO2 in the aqueous product. Initial CO2 flushing also provided the packaged product with a pleasant cool flavour at the properly ripened state.  相似文献   

3.
An Agrocybe chaxingu Huang packaged in 5% O2‐ and 10% CO2‐modified atmospheres with different sizes (0, 0.5, 1.0 and 1.5cm2) of silicon gum film window was stored at a temperature of 3 ± 1°C for 20 days. Changes of ascorbic acid content, titratable acidity, electrolyte leakage and sensory characteristic were evaluated. Significant differences were found among the packages with different sizes of silicon gum film window on ascorbic acid content, titratable acidity, electrolyte leakage, general appearance, firmness and odour after 8, 8, 12, 12, 12 and 4 days of storage, respectively. The package with a 1.0cm2 silicon gum film window was the most effective for keeping the quality of Agrocybe chaxingu Huang. Based on the optimum storage condition in this study, an enzyme kinetics respiration model was set successfully and the applicability of the enzyme kinetics respiration model was verified by using the packages of Agrocybe chaxingu Huang with weights of 105 and 125g, respectively. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

4.
Beef steaks from Gluteus medius, Longissimus dorsi, Psoas major and ground beef from Triceps brachii were packed in master packages containing expanded polystyrene trays overwrapped with polyvinyl chloride film under an anoxic atmosphere containing 0.2% CO, 60.0% CO2 and 39.8% N2 (T1) or 0.2% CO/99.8% CO2 plus oxygen scavengers. After 28 days of storage at 1 and 4°C, the meat quality was evaluated. The visual and instrumental colour of the beef steaks and ground beef were similar to that of fresh meat. Pathogenic bacteria were not detected, and psychrotrophic bacterial counts were lower than 7.5 log CFU/g. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

5.
Guavas cv. ‘Kumagai’ were packed in several plastic materials and stored at 10°C and 85–90% relative humidity (RH) for 7, 14, 21 and 28 days (+3 days at 25°C). The plastic materials studied were: multilayer co‐extruded polyolephine film with selective permeability (PSP), low‐density polyethylene film (LDPE), LDPE film with mineral incorporation (LDPEm) and heat‐shrinkable polyolephine film (SHR). Guavas not packed were taken as control samples. The physicochemical characteristics of the fruits, O2 and CO2 transmission rates of the packaging materials and gas composition at the package headspace were evaluated. The LDPE film, 69 µm in thickness, with the lowest permeability to both O2 and CO2, led to anaerobiosis and high CO2 concentration inside the packages and promoted physiological disturbances and changes in fruit flavour. The SHR film, 15 µm in thickness, was the most permeable to CO2 and had quite high O2 transmission, which modified the inner atmosphere of the packages slightly. The fruits packed in this film showed a poorer quality than the controls, possibly due to the heat produced during the shrinking of the film. The LDPEm film, 24 µm in thickness, was almost as permeable to CO2 but had reduced O2 transmission, promoting an atmosphere of equilibrium of 3% O2 and 4.5% CO2. Fruits packed in this film kept their skin colour and pulp firmness, suitable for consumption up to 14 days. The PSP film, 35 µm in thickness, had the greatest O2 transmission but just over half of the CO2 transmission of LDPEm, promoting an atmosphere of equilibrium of 0.5% O2 and 4.5% CO2 inside the packages. Fruits packed in such packages kept their physicochemical characteristics up to 21 days. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

6.
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.  相似文献   

7.
The quality of honey peach fruit stored at 2°C in modified atmosphere packages was studied. Three different thickness low‐density polyethylene (LDPE) films were used as packaging films. Honey peach fruits of ‘chaoyang’ were packaged in LDPE bags 15, 25 and 40µm thick and control (air). The respiration rate, O2 and CO2 concentrations in the packages, flesh colour, total soluble solid (TSS), titratable acidity (TA), flesh firmness (FF) and membrane integrity of the fruits were monitored. Compared to the control, MAP treatments inhibited the climacteric peak, avoided the increase of flesh colour, decreased the development of softness and retarded the reduction of TTS, TA and membrane integrity. Significant differences in the quality of the fruits were found between the three packages and the control (p ≤ 0.05). After 20 days at 2°C within the LDPE25 bags, a steady‐state atmosphere of 5% CO2 + 4% O2 was reached. Honey peaches stored in these bags showed the best quality at the end of the storage. Copyright copy; 2006 John Wiley & Sons, Ltd.  相似文献   

8.
Modified atmosphere packages were designed and used for the packaging of green chili peppers. Respiration of green peppers at 10°C was characterized by the closed-system method as a function of O2 and CO2 concentrations, and was incorporated into mass balance equations of O2 and CO2 gases in order to predict the gas composition inside the package over time. From the prediction of atmospheres inside packages constructed of the available plastic films, three retail packages (110-g peppers) were designed and studied experimentally for their ability to modify the package atmosphere and to retain quality (moisture, ascorbic acid and chlorophyll). Pepper packages using 25 μm low-density polyethylene and 30 μm cast polypropylene could attain modified atmosphere close to the optimal gas concentrations (3% O2 and 5% CO2), and therefore provided better quality retention compared with unpackaged controls.  相似文献   

9.
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.  相似文献   

10.
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.  相似文献   

11.
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.  相似文献   

12.
Pieces of pre‐rigor filleted Atlantic salmon were modified atmosphere (MA)‐packaged (60% CO2 and 40% N2) in eight different ways according to tray sizes (ml), gas/product ratios (g/p ratios), number of fillet layers and capacities of the CO2 emitters being used (based on the fish weight or on the surface area of the fish). All the samples were stored at 2°C for 21 days. Gas measurement showed that the CO2 emitter based on fish weight developed too much CO2, and the emitters based on surface area developed too less during storage. Samples with the lowest CO2 level in the headspace (emitter based on surface area), and also probably the lowest amount of absorbed CO2, had the highest bacterial growth after 17 days of storage for some of the samples. Both the pH and the bacterial growth were similar between the top layer and the bottom layer within the packages of more than one layer in each tray. This indicates that the CO2 was also available for the bottom layers. The liquid loss was similar for the trays with the different emitter types, but it differed between the tray sizes. A model based on the weight and surface area of the fish, and g/p ratio and capacity (ml) of the tray was made in order to more precisely calculate an optimal amount of the CO2 emitter ingredients because of a predefined CO2 level in the headspace. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

13.
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.  相似文献   

14.
The aim of the study was to determine the effect of soaking in chlorinated water (100 ppm chlorine) or mild thermal treatment in water (55°C; 3 min) and modified atmosphere packaging on the quality and shelf life of dry coleslaw stored for 12 days at 4°C. Samples were packaged in low‐barrier film in modified atmosphere containing: 5/10/85, 20/25/55, 50/30/20, 70/30/0 %O2/% CO2/% N2, and air atmosphere. In‐pack gas levels, sensory quality, microbial counts and cell permeability were determined. In comparison to non‐processed coleslaw, pretreatment of coleslaw, both consisting in soaking in chlorine solution and a mild thermal processing, resulted in a reduction by approx. 1 logarithmic cycle for counts of psychrophilic and lactic acid bacteria as well as mesophilic and psychrophilic yeasts, by 1 and 1.7 logarithmic cycle for coliform bacteria and by 2 up to 3 logarithmic cycles for Pseudomonas bacteria. Modified atmosphere (irrespective of its composition) used in product packaging was found to have no effect on the count of mesophilic bacteria. An elevated content of carbon dioxide in modified atmosphere (10, 25 or 30%) inhibited growth of psychrophilic bacteria and Pseudomonas bacteria up to 6 days of storage. In the case of coliform bacteria growth inhibition during storage was recorded both in the samples packaged in air atmosphere and in the atmosphere of 50/30/20 and 70/30/0 %O2/% CO2/% N2. In samples packaged in the atmosphere of 70% O2 and 30% CO2 after 12 days the greatest cell permeability was recorded, which was connected with a deterioration of their microbiological quality. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

15.
Kimchi, a vegetable containing lactic acid bacteria, produces CO2 gas because of its continued fermentation during storage, resulting in a pressure build-up and extensive expansion of its containers. This pressure build-up and volume expansion occurring in packaged kimchi constitute a serious problem, since it makes the product unattractive and difficult to market. As an attempt to solve this problem, a kinetic model for CO2 production in kimchi during storage was established as a function of salt content and temperature to monitor the pressure and volume variations of the packages. The concentrations of CO2 in headspace and CO2 dissolved in brine were related by Henry's law, which allowed easy determination of CO2 production from fermentation and offered a useful estimate of the CO2 partial pressure in the packages. The CO2 production in kimchi consisted of two stages of constant rate and could be described for both stages as R CO 2 ,i =Ki exp(−Eai/RT), where Ki is a function of salt content. In the model, the pressure and volume of the packages were presumed to be the sum of contributions of the CO2 produced during the fermentation as well as O2 and N2 from entrapped air. Variations of pressure and volume due to temperature change were assumed to be governed by the ideal gas law. Measurements of pressure and volume for te kimchi packages stored both at constant and changing temperatures were in good agreement with the predicted values, thus confirming the validity of the proposed model. © 1997 John Wiley & Sons, Ltd.  相似文献   

16.
The old oil refineries are largest chemical industries that are responsible for emission of several pollutants and GHGs. It is possible to minimize energy usage as well as air pollution by some process modification. The main objectives of this investigation were the minimization of air pollution and CO2 emissions in catalytic reforming unit in an oldest and largest refinery in Iran. To assess the air quality, ten sampling stations were selected for measurement of CO, H2S, SO2, and PM10 in ambient air. Also concentrations of C1–C5, H2S, and CO2 were measured in selected unit. In final, structural and process flaws were identified by analyzing real functional circumstances and they were modified. Results show that SO2, H2S, and PM10 concentrations are higher than ambient air standard levels in all seasons. Also, according to achieved results, the cold separator gas flow rate is reduced from 38,936 kg/day (once-through gas process) to 9,649 kg/day (recycle gas process). Beside CO2 and SO2 emission rates will be reduced 1803 and 136.5 kg/day in this unit, respectively. Furthermore, the modification of this process causes prevention of 1654 kg CO2 emission into the atmosphere, during each coke burning and catalytic regeneration.  相似文献   

17.
The pursuit of efficient CO2 capture materials remains an unmet challenge. Especially, meeting both high sorption capacity and fast uptake kinetics is an ongoing effort in the development of CO2 sorbents. Here, a strategy to exploit liquid-in-aerogel porous composites (LIAPCs) that allow for highly effective CO2 capture and selective CO2/N2 separation, is reported. Interestingly, the functional liquid tetraethylenepentamine (TEPA) is partially filled into the air pockets of SiO2 aerogel with left permanent porosity. Notably, the confined liquid thickness is 10.9–19.5 nm, which can be vividly probed by the atomic force microscope and rationalized by tailoring the liquid composition and amount. LIAPCs achieve high affinity between the functional liquid and solid porous counterpart, good structure integrity, and robust thermal stability. LIAPCs exhibit superb CO2 uptake capacity (5.44 mmol g−1, 75 °C, and 15 vol% CO2), fast sorption kinetics, and high amine efficiency. Furthermore, LIAPCs ensure long-term adsorption–desorption cycle stability and offer exceptional CO2/N2 selectivity both in dry and humid conditions, with a separation factor up to 1182.68 at a humidity of 1%. This approach offers the prospect of efficient CO2 capture and gas separation, shedding light on new possibilities to make the next-generation sorption materials for CO2 utilization.  相似文献   

18.
Post-combustion flue gas (mainly containing 5–40% CO2 balanced by N2) accounts for about 60% global CO2 emission. Rational conversion of flue gas into value-added chemicals is still a formidable challenge. Herein, this work reports a β-Bi2O3-derived bismuth (OD-Bi) catalyst with surface coordinated oxygen for efficient electroreduction of pure CO2, N2, and flue gas. During pure CO2 electroreduction, the maximum Faradaic efficiency (FE) of formate reaches 98.0% and stays above 90% in a broad potential of 600 mV with a long-term stability of 50 h. Additionally, OD-Bi achieves an ammonia (NH3) FE of 18.53% and yield rate of 11.5 µg h−1 mgcat−1 in pure N2 atmosphere. Noticeably, in simulated flue gas (15% CO2 balanced by N2 with trace impurities), a maximum formate FE of 97.3% is delivered within a flow cell, meanwhile above 90% formate FEs are obtained in a wide potential range of 700 mV. In-situ Raman combined with theory calculations reveals that the surface coordinated oxygen species in OD-Bi can drastically activate CO2 and N2 molecules by selectively favors the adsorption of *OCHO and *NNH intermediates, respectively. This work provides a surface oxygen modulation strategy to develop efficient bismuth-based electrocatalysts for directly reducing commercially relevant flue gas into valuable chemicals.  相似文献   

19.
The effect of package size and temperature on package volume expansion was investigated when P71197, a high CO2 permeability film of amorphous nylon laminate structure, was applied to packaging kimchi, a Korean ethnic fermented vegetable. The volume expansion, after an initial lag period, rapidly reached a maximum and then either decreased or stayed constant. A higher temperature and a larger package caused greater volume expansion within the experimental time span. Based on the criterion of ≤0.8 ml/g as a tolerable volume change, the appropriate window of package size and temperature has been suggested. The expanded volume was found to consist mainly of CO2 produced from kimchi, resulting in higher CO2 concentrations for higher temperatures and larger package sizes. The effect of package size on the volume expansion and gas composition can be explained by the differences in the ratio of surface area to filled weight among the packages. The effect of storage temperature can be explained by the difference in activation energy between CO2 production from the kimchi and gas permeation through the film. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

20.
The profile of major biogenic amines was investigated in Indian mackerel packed in modified atmosphere for up to 12 days at 5 ± 1°C. Beheaded and gutted Indian mackerel was packed under different carbon dioxide compositions to study the effects on biogenic amines formation. The treatments were control air (C), vacuum packaging (VP), 30% CO2/65% N2/5% O2 (M30C), 60% CO2/35% N2/5% O2 (M60C), 80% CO2/15% N2/5% O2 (M80C) and 100% CO2 (M100C). Each amine responded differently to different CO2 levels. After 12 days of storage, concentrations of histamine were reduced by 6.4%, 8.5%, 70.3%, 78.8% and 90.2% in fish packed under VP, M30C, M60C, M80C and M100C, respectively as compared with control air. Changes in putrescine and cadaverine showed a similar pattern. Gas mix of M30C and VP stimulated the formation of tyramine reaching 203 and 172 ppm, respectively. Higher composition of CO2 had a significant inhibitory effect on tyramine concentration (p < 0.05). There were parallel increases of putrescine and spermidine in C, VP and M30C. No significant effect of CO2 was observed on spermine (p > 0.05). After 9 days of storage, more than 300 ppm of histamine was detected in mackerel packed in VP and M30C; therefore, these atmospheres pose a histamine intoxication risk. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

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