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1.
《Food microbiology》1998,15(5):459-469
To obtain more insight into the specific impact of modified gas conditions on the composition of microflora of minimally processed vegetables, the prevalent bacteria on mungbean sprouts and cut chicory endive were determined during storage under controlled atmospheric (CA) conditions at 8°C. Enumeration of the total mesophilic counts, Enterobacteriaceae,Pseudomonasspecies, and lactic acid bacteria indicated that Enterobacteriaceae andPseudomonasspecies constituted the major populations found on these products before and after CA storage. Identification of the predominant species within these populations revealed that on fresh and CA-stored mungbean sprouts,Enterobacter cloacae, Pantoea agglomerans, Pseudomonas fluorescens, Ps. viridilividaandPs. corrugatawere the prevalent species. On chicory endive,Rahnella aquatilisand severalPseudomonasspecies were found on the fresh product, while after CA storage,Escherichia vulnerisandPs. fluorescenswere the main species. Growth of the predominant epiphytes was subsequently quantified in pure culture, using an agar model system at 8°C under 1.5 or 21% O2with 0, 5, 20, or 50% CO2. In general, these CA conditions did not strongly influence maximum population densities and lag times were not detected. For each of the strains, however, maximum specific growth rates were reduced at increased CO2concentrations, independent of the 02concentration applied. This effect was more pronounced forPseudomonasspecies than forEnterobacteriaceae. Notably, the agar model study showed that individual species ofEnterobacteriaceaeorPseudomonasresponded similarly to the specific CA conditions applied. This did not correlate with the shift in predominant species observed on chicory endive. Our data underline the complexity of the ecological conditions to which micro-organisms on vegetables are subjected during storage under modified gas conditions. 相似文献
2.
Total pressure generally decreases in a sealed rigid package containing respiring produce, whereas total pressure is essentially constant and free volume decreases in a flexible package. We found that predicted O2, CO2, and N2 partial pressures were different for similarly designed (same surface area, thickness, film permeabilities and produce mass) flexible and rigid packages at “quasi steady state” and steady state, respectively. Predicted O2 and CO2 partial pressures were slightly higher in a flexible package than in a rigid package and were a function of the film permeability ratio of N2 to O2 and of CO2 to O2. They also related to the ratio of product CO2 production rate to O2 uptake rate, target steady-state O2 partial pressure, and respiration characteristics. Differences were slight for films such as low-density polyethylene. 相似文献
3.
S. Mangaraj 《International Journal of Food Properties》2013,16(3):609-628
Several experiments were conducted at different storage temperatures for generating respiration data using close system method for respiration. A respiration rate model, based on enzyme kinetics and the Arrhenius equation was proposed for predicting the respiration rates of Guava as a function of O2 and CO2 concentrations and storage temperature. Temperature was found to influence the model parameters. In this model, the dependence of respiration rate on O2 and CO2 was found to follow the uncompetitive inhibition. The enzyme kinetic model parameters, calculated from the respiration rate at different O2 and CO2 concentration were used to fit the Arrhenius equation against different storage temperature. The activation energy and respiration pre-exponential factor were used to predict the model parameters of enzyme kinetics at any storage temperature between 0–30°C. The developed models were tested for its validity at 12°C and it was found to be in good agreement (the mean relative deviation moduli between the predicted and experimental respiration rates were found to be 8.95% and 8.02% for O2 consumption and CO2 evolution, respectively) with the experimentally estimated respiration rates. 相似文献
4.
5.
Sofía Barrios Patricia Lema Claudia Lareo 《International Journal of Food Properties》2013,16(9):2039-2051
A model for strawberry (Fragaria × ananassa cv. San Andreas) respiration rate was determined as a function of O2 and CO2 concentrations and temperature. Strawberries were enclosed in containers under different gaseous compositions (0–24% O2 and 0–15% CO2) and temperatures (10, 19, 23°C). Respiration rate was determined as O2 consumption and CO2 production. Respiration rate data was fitted to Michaelis-Menten models, with temperature dependence according to Arrhenius type equation. Non–linear regression was applied to calculate model parameters. No CO2 inhibition was verified, so a simple Michaelis–Menten model was selected (R2 = 0.91). 相似文献
6.
The evolution of the atmospheric composition (O2 and CO2 and ethylene) passively produced by three varieties of apricots (Beliana, Rouge de Rousillon and Polonais) stored at 10 °C
under four plastic films of different permeabilities was studied. The results corresponding to respiratory intensity (IR)
revealed that, while the IR decreased during the storage period under modified-atmosphere packaging, it increased again with
the opening of the bags and the exposure of the fruits to air. The modified atmosphere inside the bags (O2 and CO2) and the time necessary to reach equilibrium depended on the IR of the fruits and the permeability of the film. The ethylene
concentration decreased from the second day onwards in all the cases studied; this decrease being more pronounced in the films
of least permeability due to a combination of its diffusion through the film and the inhibition of its synthesis as the CO2 concentration increased and O2 concentration decreased. Partial deviations in the metabolism of the three varieties were detected in the two films of lowest
permeability (6060 and 12100 cm3 of O2 and CO2 m−2/24 h−1 atm−1 at 25°C) due to anoxia. The use of the active modified atmosphere, replacing the initial atmosphere of the bags with an atmosphere
enriched with CO2 (20% CO2 and 80% air), did not modify the gas composition at equilibrium, although it shortened the time necessary for it to be reached.
For the Beliana variety a slight decrease in ethylene concentration was observed inside the bags with an active modified atmosphere
in relation to that of the bags with a passive modified atmosphere. The accumulation of ethanol in the tissues was not higher
under the active modified atmosphere than under the passive modified atmosphere.
Received: 19 July 1999 / Revised version: 29 September 1999 相似文献
7.
Respiration of the produce and permeation of gas through the packaging films are the processes involved in creating a modified
atmosphere inside a package that will extend shelf life of agricultural perishables. Thus modeling respiration rate of the
selected produce is crucial to the design of a successful modified atmosphere packaging system. Two different models based
on regression analysis and enzyme kinetics were developed with the help of respiration data generated at temperatures 0, 5,
10, 15, 20, 25, and 30 °C for litchi fruit using the closed system method. Temperature was found to influence the model parameters.
In the model, based on enzyme kinetics, the dependence of respiration rate on O2 and CO2 was found to follow the uncompetitive inhibition. The enzyme kinetic model parameters, calculated from the respiration rate
at different O2 and CO2 concentration were used to fit the Arrhenius equation against different storage temperature. The regression coefficients
values were used for the prediction of respiration rate using regression model. The activation energy and respiration pre-exponential
factor were used to predict the model parameters of enzyme kinetics at any storage temperature. The developed models were
tested for its validity at 2 °C. The models showed good agreement with the experimentally estimated respiration rate. 相似文献
8.
The weevil Sitophilus zeamais (Motschulsky), the maize weevil, is a pest of stored maize that can cause feeding damage and lead to the proliferation of toxigenic fungi. The application of modified atmospheres with a high concentration of CO2 is an alternative method for the control of S. zeamais and the inhibition of fungal growth. The objectives of the study were to determine the effect of S. zeamais infestation, grain damage and grain moisture content on aflatoxin production by Aspergillus flavus on maize, and the impact of high CO2 modified atmosphere packaging on pest infestation and aflatoxin production. Mycotoxin production was only recorded when maize was infested with S. zeamais and had A. flavus inoculum. However, production of mycotoxins was not recorded when the maize was mechanically damaged and stored at 18% moisture content, indicating that the biological activity of the insect was determinant in the production of mycotoxins. The high CO2 modified atmosphere packaging tested (90% CO2, 5% O2 and 5% N2) prevented mycotoxin production. 相似文献
9.
Model for Fresh Produce Respiration in Modified Atmospheres Based on Principles of Enzyme Kinetics 总被引:15,自引:0,他引:15
A respiration model, based on enzyme kinetics, was proposed for predicting respiration rates of fresh produce as a function of O2 and CO2 concentrations. In this model, the dependence of respiration on O2 was assumed to follow a Michaelis-Menten type equation (r = Vm[O2]/{Km+ [O2]}), and the effect of CO2 on respiration to follow an uncompetitive inhibition model (r = Vm[O2]/{Km + (1 + [CO2]/ Ki) [O2]}). The model predictions agreed well with published data for a variety of commodities and with experimental data for cut broccoli. Fresh produce respiration rates (O2 consumption or CO2 evolution) at various O2 and CO2 concentrations, as well as transient and equilibrium gas concentrations within permeable packages, could be accurately predicted with the model equations. 相似文献
10.
Esther Arias Jaime González Pascual López‐Buesa Rosa Oria 《Journal of the science of food and agriculture》2008,88(10):1755-1763
BACKGROUND: Successful processing of pears to render fresh‐cut fruits requires a thorough knowledge of their sensitivity to browning reactions, their respiratory metabolism, and their behaviour under modified atmosphere packaging. RESULTS: First, three different varieties of pear (Williams, Conference, Passacrassana) that had reached their commercial ripening stage were evaluated for suitability for minimal processing. Two antioxidant treatments were tested (treatment 1: 2% ascorbic acid + 1% citric acid + 1% CaCl2; treatment 2: 2% ascorbic acid + 0.01% 4‐hexylresorcinol + 1% CaCl2) to decide which one was the most effective against enzymatic browning. Finally, a modified atmosphere packaging was designed after two previous tests: measurement of respiratory activity of the peeled and cut pear at three temperatures (4, 15 and 25 °C); and evaluation of fruit tolerance to three different atmospheric compositions (21% O2 + 10% CO2; 2% O2 + 0% CO2; 2% O2 + 10% CO2). CONCLUSIONS: Conference pear was found to be the most suitable variety. Among the antioxidant treatments the one consisting of ascorbic acid, 4‐hexylresorcinol and CaCl2 was proven to be the most effective against browning. The samples were packaged in a modified atmosphere with a composition of 10% O2 + 10% CO2 + 80% N2. Copyright © 2008 Society of Chemical Industry 相似文献
11.
M. Helena Gomes Randolph M. Beaudry Domingos P.F. Almeida F. Xavier Malcata 《Journal of food engineering》2010
Respiration rates were measured in fresh-cut ‘Rocha’ pear (Pyrus communis L.) stored at four temperatures (0, 5, 10 and 15 °C) and with oxygen partial pressures ranging from 0 to 18 kPa. Respiratory quotient and ethanol production were used to determine the fermentation threshold. The oxygen concentration effect on the respiration rate was accurately described using Michaelis–Menten kinetics, without non-competitive inhibition by CO2, and the effect of temperature on the respiration rate was well modelled by exponential functions. The oxygen level at which respiration was half its maximum (apparent Km,O2) was similar to or only slightly greater than the fermentation threshold. The narrow range of oxygen between Km,O2 and the fermentation threshold, suggests that modified atmosphere packaging technology has a limited applicability toward extension of the shelf-life of fresh-cut ‘Rocha’ pear. 相似文献
12.
María Teresa Pretel María Serrano Asunción Amorós Felix Romojaro 《European Food Research and Technology》1999,209(2):130-134
Ethylene synthesis and metabolism were studied in apricot fruits (Prunus armeniaca L. cv. Búlida, under controlled atmosphere (CA) conditions (20% CO2 and 20% O2; 20% CO2 and 1% O2; 0.03% CO2 and 1% O2) and at a temperature of 2 °C. In control apricots stored outdoors in air containing 20% O2 and 0.03% CO2, the evolution of the physical and chemical parameters characteristic of ripening (loss of texture, decrease in acidity and
increase in soluble solids) was slow during the storage period. However, for apricots stored in CAs containing 1% O2 and 20% or 0.03% CO2, these parameters did not show significant changes during the storage period. Ethylene production was completely inhibited
in apricots stored in the three CAs, while control fruits showed a maximum ethylene level after 2 weeks of storage. This inhibition
was accompanied by lower levels of 1-aminocyclopropane-1-carboxylic acid, free and total, which were more pronounced in apricots
stored in the CAs containing 20% CO2. In apricots stored in the CAs containing 1% O2, the ethanol content increased after 1 week of storage, and this caused a smell and taste that made the fruits unsuitable
for consumption.
Received: 16 October 1998 相似文献
13.
Gas concentrations in the headspace of hermetically sealed glass packages of seasoned soybean sprouts were monitored and related to their microbial quality, i.e., the change in aerobic bacterial count, in order to examine the potential for using package gas changes as a primary quality index for shelf life control. Aerobic bacterial count, CO2 and O2 concentrations were measured from packages stored at four different temperatures: 0, 5, 10 and 15 °C. The CO2 concentration increased and the O2 concentration decreased with microbial growth. The microbial growth and CO2 concentration change were described by a logistic function to yield kinetic parameters, and their temperature dependence was analysed by a square-root model. The kinetic parameters for microbial growth and CO2 production differed in their magnitude and temperature dependence. The lag time observed for the increase in CO2 concentration could be used as a shelf life index that corresponds to the time to reach a given microbial limit (here, 107 CFU/g) under different temperature conditions, particularly under conditions of temperature abuse. 相似文献
14.
To evaluate the growth/survival of natural flora and Aeromonas hydrophila on refrigerated normal low (pork) and high (turkey) pH meats packaged in modified atmospheres, A. hydrophila was inoculated onto fresh pork and turkey meat slices. Inoculated and control samples were packaged in modified atmospheres (100% N2, 20/80 and 40/60 CO2/O2) or in air in plastic bags and kept at 1 and 7°C. Samples packaged in air showed a similar microbiological pattern to that usually observed in fresh meat stored aerobically. Packaging in modified atmosphere produced a strong inhibition of bacterial growth at 1°C, particularly in samples stored in CO2/O2enriched atmospheres. Aeromonas hydrophila grew on turkey and pork meat stored in 100% N2at 1 and 7°C. Likewise, growth of this bacterium was detected on turkey stored in 20/80 CO2/O2at 7°C. No growth was observed in 40/60 CO2/O2in any meat at both temperatures assayed. 相似文献
15.
Effect of Initial Headspace O2 Level on the Growth and Volatile Metabolite Production of Leuconostoc Mesenteriodes and the Microbial and Sensorial Quality of Modified Atmosphere Packaged Par‐Fried French Fries
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Simbarashe Samapundo Felix Mugove Mujuru Ilse de Baenst Quenten Denon Frank Devlieghere 《Journal of food science》2016,81(2):M454-M462
This study evaluated the effect of residual O2 level (0% to 5%) on microbial growth and volatile metabolite production on par‐fried French fries packaged in a modified atmosphere with 60% CO2 (rest N2) at 4 °C. The results obtained showed that the initial headspace (IH) O2 level had an effect on growth of Leuconostoc mesenteroides on French fry simulation agar, whereby growth was slightly faster under 5% O2. In terms of quantity, ethanol, 2‐methyl‐1‐propanol, and dimethyl disulphide were the most significant volatile metabolites produced by L. mesenteroides. The production of ethanol by L. mesenteroides was highest on simulation agar packaged under low IH O2 levels (0% to 1%), indicating that the fermentative metabolism was induced under these conditions. In agreement with the results observed on the simulation medium, growth of native lactic acid bacteria was faster under an IH O2 level of 5%. In addition, ethanol, 2‐methyl‐1‐propanol, and dimethyl disulphide were also quantitatively the most important volatile metabolites. However, in contrast, greater quantities of ethanol and dimethyl disulphide were produced on par‐fried French fries packaged under 5% O2. This was attributed to the limited growth of the native flora on the par‐fried French fries under residual O2 levels of 0% and 1%. Although some significant differences (P < 0.05) occurred between the French fries packaged in 0%, 1%, and 5 % residual O2 during storage, all products were considered to be acceptable for consumption. The results of this study can be used to optimize the shelf‐life of packaged chill stored potato products. 相似文献
16.
The extinction point of spinach was <0.4% but above 0.2% O2 at 0° and 5°C. Respiration rates were ~2.3 times greater at 5°C than at 0°C and were similar among cultivars. In 0.8% O2 atmosphere, O2 uptake of three cultivars was reduced by an average of 53% and CO2 production was reduced by 35% relative to those stored in air. Deterioration of leaves was reduced by 30 to 54%, while weight loss, color and chlorophyll content were not affected by the 0.8% O2 atmosphere. Thus O2 could be allowed to be depleted to 0.8% in modified atmosphere packaging without quality loss due to anoxia. 相似文献
17.
The respiration rate of dry coleslaw mix at different concentrations of O2 and CO2 was determined in an open flow-through respirometer at 5°C. Product O2 consumption rate fitted an enzyme kinetics model. Vm and Km values of 22.72 mlkg-1h-1 and 1.083 %O2, respectively were calculated. CO2 had an inhibitory effect on respiration rate. The effect of CO2 on respiration gave a good fit with an uncompetitive inhibition enzyme kinetics model (E = 5.11%). Product respiration rate increased with temperature by an Arrhenius type relationship. Activation energies for O2 consumption and CO2 evolution were 74.8 kJ/kg and 84.2 kJ/kg respectively. These results provide information essential for the design and optimization of modified atmosphere packs for this product. 相似文献
18.
Vessels suitable for storing mushrooms [Agaricus bisporus (Lange) Singe] at absolute pressures to 35 atm were constructed from 43 liter (1A) gas cylinders and plumbed for conducting static or continuous-flow experiments. Neither pressurization nor gradual depressurization over 6 hr injured mushrooms. Pressure did not affect respiration, but significantly reduced moisture loss during storage. Mushrooms depleted O2 to very low levels and showed high tolerance to CO2. Pressure was used to safely increase CO partial pressure (p) 35-fold. At 0.035p, CO reduced mushroom browning but not respiration. A completely autonomous storage system with CO2 removal and automatic O2, replenishment was developed. 相似文献
19.
In a series of exploratory experiments, storage of McIntosh apples (Malus domestica Borkh.) in modified atmospheres (MA) (5% CO2+ 3% O2 at 2.8°C) suppressed the development of headspace ethanol and acetaldehyde from that in apples stored in air at 0°C (RA). Acetaldehyde, ethanol, ethyl butyrate and hexanal production from intact fruit was further suppressed when the apples were stored in 1.5% CO2+ 1.5% O2 or 1.5% CO2+ 1.0% O2 at 2.8°C. Placement of fruit in RA following MA storage initially regenerated ethyl butyrate and hexanal in preference to ethanol and acetaldehyde. However storage of fruit in 1.5% CO2+ 1.0% O2 for 320 days completely suppressed the principal headspace volatiles and blocked their subsequent regeneration in RA. 相似文献
20.
Patrick Varoquaux Guy Albagnac Christophe Nguyen The Franoise Varoquaux 《Journal of the science of food and agriculture》1996,70(2):224-230
Freshly harvested beansprouts displayed a respiration rate of about 1 mmol O2 kg−1 h−1 at 10°C which was strongly dependent on temperature, a 10-fold increase being observed every 16·5°C (z=16·5°C, ie Q10=4·4). This commodity is also characterised by a high initial microbial load (about 107 cells g−1). During storage at various temperatures from 1 to 20°C, oxygen uptake rates dramatically increased with time and this phenomenon was well correlated with the development of aerobic microorganisms which reached 109 cells g−1 after 2 days at 20°C or 9 days at 1°C. Beansprouts were packaged in films, with permeabilities ranging from 950 to 200000 ml O2 m−2 day−1 atm−1, and stored at 8°C. Due to plant and microbial metabolism, oxygen concentrations decreased steadily within all packs until the onset of plant tissue decay. The latter occurred after 5–6 days with the least permeable films but did not occur within when the film permeability was over 100000 ml O2 m−2 day−1 atm−1. However, such films favoured brown discolouration, exudation texture and breakdown. The orientated polypropylene film (OPP) induced anoxic condition within 2 days and favoured anaerobic metabolism and necrosis of the sprouts. In all packages there was a rapid development of aerobic microorganisms and lactic acid bacteria that resulted in the accumulation of acetate and lactate and a decrease in pH. Thus, it clearly appeared that tissue decay was enhanced by microbial activity. At 8°C, 0·24 m2 of film per kg of sprouts provided the optimal atmosphere composition (ie 5% oxygen and 15% carbon dioxide) when a film permeability of 50000 ml O2 m−2 day−1 atm−1 was used. These conditions allowed a shelf-life of 4–5 days. 相似文献