Effect of Nitrogen Gas Packaging on the Quality and Microbial Growth of Fresh-Cut Vegetables under Low Temperatures

2002 ◽  
Vol 65 (2) ◽  
pp. 326-332 ◽  
Author(s):  
SHIGENOBU KOSEKI ◽  
KAZUHIKO ITOH
Keyword(s):  
Microbial Growth ◽  
Modified Atmosphere Packaging ◽  
Co2 Concentration ◽  
Coliform Bacteria ◽  
Atmospheric Conditions ◽  
Psychrotrophic Bacteria ◽  
Low Concentrations ◽  
O2 Concentration ◽  
Fresh Cut ◽  
Carbon Dioxide Co2

Nitrogen (N2) gas packaging for fresh-cut vegetables (lettuce and cabbage) has been examined as a means of modified atmosphere packaging (MAP) for extending the shelf life of cut vegetables. Gas composition in enclosed packages that contained cut vegetables and were filled with 100% N2 had an oxygen (O2) concentration of 1.2 to 5.0% and a carbon dioxide (CO2) concentration of 0.5 to 3.5% after 5 days of storage. An atmosphere of low concentrations of O2 and high CO2 conditions occurred naturally in the package filled with N2 gas. Degradation of cut vegetables in terms of appearance was delayed by N2 gas packaging. Because of this effect, the appearance of fresh-cut vegetables packaged with N2 gas remained acceptable at temperatures below 5°C after 5 days. Treatment with acidic electrolyzed water (AcEW) contributed to the acceptability of the vegetables' appearance at 5 and 10°C in the air-packaging system. N2 gas packaging did not significantly affect the growth of microbial populations (total aerobic bacteria, coliform bacteria, Bacillus cereus, and psychrotrophic bacteria) in or on cut vegetables at 1, 5, and 10°C for 5 days. Microbial growth in or on the cut vegetables was inhibited at 1°C for 5 days regardless of atmospheric conditions.

Effect of Modified Atmosphere Packaging on the Persistence and Expression of Virulence Factors of Escherichia coli O157:H7 on Shredded Iceberg Lettuce†

2011 ◽  
Vol 74 (5) ◽  
pp. 718-726 ◽  
Author(s):  
MANAN SHARMA ◽  
SUDESNA LAKSHMAN ◽  
SEAN FERGUSON ◽  
DAVID T. INGRAM ◽  
YAGUANG LUO ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Modified Atmosphere Packaging ◽  
Ambient Air ◽  
Modified Atmosphere ◽  
Escherichia Coli O157 ◽  
Atmospheric Conditions ◽  
E Coli ◽  
Leafy Greens ◽  
Fresh Cut

Fresh-cut leafy greens contaminated with Escherichia coli O157:H7 have caused foodborne outbreaks. Packaging conditions, coupled with abusive storage temperatures of contaminated lettuce, were evaluated for their effect on the potential virulence of E. coli O157:H7. Shredded lettuce was inoculated with 5.58 and 3.98 log CFU E. coli O157:H7 per g and stored at 4 and 15°C, respectively, for up to 10 days. Lettuce was packaged under treatment A (modified atmosphere packaging conditions used for commercial fresh-cut produce, in gas-permeable film with N2), treatment B (near–ambient air atmospheric conditions in a gas-permeable film with microperforations), and treatment C (high-CO2 and low-O2 conditions in a gas-impermeable film). E. coli O157:H7 populations from each treatment were determined by enumeration of numbers on MacConkey agar containing nalidixic acid. RNA was extracted from packaged lettuce for analysis of expression of virulence factor genes stx2, eae, ehxA, iha, and rfbE. E. coli O157:H7 populations on lettuce at 4°C under all treatments decreased, but most considerably so under treatment B over 10 days. At 15°C, E. coli O157:H7 populations increased by at least 2.76 log CFU/g under all treatments. At 15°C, expression of eae and iha was significantly greater under treatment B than it was under treatments A and C on day 3. Similarly, treatment B promoted significantly higher expression of stx2, eae, ehxA, and rfbE genes on day 10, compared with treatments A and C at 15°C. Results indicate that storage under near–ambient air atmospheric conditions can promote higher expression levels of O157 virulence factors on lettuce, and could affect the severity of E. coli O157:H7 infections associated with leafy greens.

Vacuum Packaging Versus Modified Atmosphere Packaging of Lamb Loins

1983 ◽  
Vol 46 (1) ◽  
pp. 47-51 ◽  
Author(s):  
G. C. SMITH ◽  
S. C. SEIDEMAN ◽  
J. W. SAVELL ◽  
C. W. DILL ◽  
C. VANDERZANT
Keyword(s):  
Modified Atmosphere Packaging ◽  
Storage Period ◽  
Co2 Concentration ◽  
Vacuum Packaging ◽  
Modified Atmosphere ◽  
High Co2 ◽  
N2 Atmosphere ◽  
O2 Concentration ◽  
High Co2 Concentration

Lamb loins were allocated (30 loins/treatment) to three packaging treatments: (a) vacuum-packaged, (b) vacuum-packaged followed immediately by injection of a 20% CO2:80% N2 atmosphere, and (c) vacuum-packaged followed immediately by injection of a 40% CO2:60% N2 atmosphere. Loins in each packaging treatment were then assigned (6 loins/period) to one of five storage periods--0, 7, 14, 21 or 28 d. During storage, the CO2 concentration increased in vacuum packages (initial vs. 21 d) and decreased in modified atmosphere packages (initial vs. 7 or 28 d); O2 concentration was higher in vacuum packages than in modified atmosphere packages at every storage period. Vacuum packaging was superior to modified atmosphere packaging for maintaining desirable appearance of wholesale loins, particularly if the atmosphere contained a high CO2 concentration. Appearance of retail chops was not substantively affected by the method used to package (vacuum vs. modified atmosphere) the wholesale loin from which they originated. Palatability of cooked chops was not affected by packaging method in 28 or 30 comparisons among product from loins that had been stored for 0 to 28 d before organoleptic testing.

Effect of Superatmospheric Oxygen Packaging on Sensorial Quality, Spoilage, and Listeria monocytogenes and Aeromonas caviae Growth in Fresh Processed Mixed Salads

2002 ◽  
Vol 65 (10) ◽  
pp. 1565-1573 ◽  
Author(s):  
ANA ALLENDE ◽  
LIESBETH JACXSENS ◽  
FRANK DEVLIEGHERE ◽  
JOHAN DEBEVERE ◽  
FRANCISCO ARTÉS
Keyword(s):  
Listeria Monocytogenes ◽  
Sensory Quality ◽  
Modified Atmosphere Packaging ◽  
Processing Plant ◽  
Visual Appearance ◽  
Plastic Films ◽  
Psychrotrophic Bacteria ◽  
Aeromonas Caviae ◽  
O2 Concentration ◽  
Barrier Film

Atmospheres with O2 levels higher than 70 kPa have recently been suggested as an innovation to modified atmosphere packaging (MAP) for fresh processed vegetables to maintain sensory quality and safety. In the present work, mixed vegetable salad collected from a commercial processing plant and stored with the MAP technique was studied. Two gas mixtures were actively generated by using an initial O2 concentration of 95 kPa and combined with two plastic films. The low-barrier film permeability for O2 was 1,629 mlO2/m2 × 24 h × atm with 30 μm of thickness (Hyplast, Hoogstraten, Belgium) and the O2 permeability of the high-barrier film was 2 mlO2/m2 × 24h × atm with 150 μm of thickness (Euralpack, Wommelgen, Belgium) at 23°C. As control, active conventional MAP with application of 3 to 5 kPa of O2 and 6 to 8 kPa of CO2 was used. Packaged salads were stored up to 8 days at 4°C and at temperatures simulating chilled distribution chain conditions. Microbial safety and sensory quality, as well as the survival of inoculated Listeria monocytogenes and Aeromonas caviae, were monitored. The effect of superatmospheric O2 on the growth of aerobic microflora was variable. Under superatmospheric conditions, lactic acid bacteria and members of Enterobacteriaceae were inhibited. Nevertheless, growth of yeast and A. caviae seem to be stimulated by superatmospheric O2, whereas growth of psychrotrophic bacteria and L. monocytogenes was not affected. The overall visual appearance (mainly color) of the mixed vegetable salads was better maintained and the shelf life prolonged when packaged under O2 concentrations greater than 50 kPa.

Prediction of Microbial Growth in Fresh-Cut Vegetables Treated with Acidic Electrolyzed Water during Storage under Various Temperature Conditions

2001 ◽  
Vol 64 (12) ◽  
pp. 1935-1942 ◽  
Author(s):  
SHIGENOBU KOSEKI ◽  
KAZUHIKO ITOH
Keyword(s):  
Recovery Time ◽  
Microbial Growth ◽  
Microbial Population ◽  
Storage Temperature ◽  
Coliform Bacteria ◽  
Microbial Populations ◽  
Electrolyzed Water ◽  
C Storage ◽  
Fresh Cut ◽  
Kinetics Of

Effects of storage temperature (1, 5, and 10°C) on growth of microbial populations (total aerobic bacteria, coliform bacteria, Bacillus cereus, and psychrotrophic bacteria) on acidic electrolyzed water (AcEW)-treated fresh-cut lettuce and cabbage were determined. A modified Gompertz function was used to describe the kinetics of microbial growth. Growth data were analyzed using regression analysis to generate “best-fit” modified Gompertz equations, which were subsequently used to calculate lag time, exponential growth rate, and generation time. The data indicated that the growth kinetics of each bacterium were dependent on storage temperature, except at 1°C storage. At 1°C storage, no increases were observed in bacterial populations. Treatment of vegetables with AcEW produced a decrease in initial microbial populations. However, subsequent growth rates were higher than on nontreated vegetables. The recovery time required by the reduced microbial population to reach the initial (treated with tap water [TW]) population was also determined in this study, with the recovery time of the microbial population at 10°C being <3 days. The benefits of reducing the initial microbial populations on fresh-cut vegetables were greatly affected by storage temperature. Results from this study could be used to predict microbial quality of fresh-cut lettuce and cabbage throughout their distribution.

scholarly journals A Study on the Effect of Storage of Betel Leaves at Ambient Temperature

2020 ◽  
pp. 44-52
Author(s):  
Srujana Shrunkala ◽  
M. Ramachandra ◽  
K. Venkatachalapathi ◽  
R. Chandru ◽  
R. Munirajappa ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Research Study ◽  
Identical Condition ◽  
Co2 Concentration ◽  
Ambient Condition ◽  
Diffusion Channel ◽  
O2 Concentration ◽  
Varietal Variation ◽  
Carbon Dioxide Co2 ◽  
Satisfactory Quality

A research study was conducted for studying the storage of Madras and Kolkata varieties of betel leaves under ambient temperature with different diffusion storage systems were observed for different treatments. In the treatment T1, the concentration of oxygen, O2 reduced to a minimum of 14.27 per cent and carbon dioxide, CO2 concentration increased to 4.80 per cent on the 14th day of storage in ambient condition (28°C). It was also reported that by the 14th day, betel leaves stored at ambient condition maintained satisfactory quality in the entire diffusion channel chambers. For the Kolkatta leaves the treatment T2, the concentration of O2 was reduced to 12.0 per cent and CO2 concentration increased to 7.87 per cent on the 18th day of storage. Compared to other treatments, the O2 concentration was found to be very low and CO2 concentration was high on the 18th day of storage in T2 diffusion channel. Similarly, on the 18th day, betel leaves stored at ambient condition maintained satisfactory quality in all the treatments. Hence, it is clear that from this present study, different varieties of betel leaves will have different rates of respiration for a particular size of the diffusion channel and temperature. In other words, varietal variation occurs concerning respiration rate under identical condition.

scholarly journals Recent six-year atmospheric CO<sub>2</sub> concentration at the summit of Mt. Fuji observed by a battery-powered CO<sub>2</sub> measurement system

2016 ◽  
Author(s):  
Shohei Nomura ◽  
Hitoshi Mukai ◽  
Yukio Terao ◽  
Toshinobu Machida ◽  
Yukihiro Nojiri
Keyword(s):  
Measurement System ◽  
Measurement Data ◽  
Co2 Concentration ◽  
Average Concentration ◽  
Air Masses ◽  
Low Concentrations ◽  
Annual Average Concentration ◽  
The Difference ◽  
Carbon Dioxide Co2 ◽  
Atmospheric Co2 Concentrations

Abstract. We developed a battery-operated carbon dioxide (CO2) measurement system and successfully observed atmospheric CO2 concentrations at the summit of Mt. Fuji (3776 m a.s.l.) in Japan throughout the year since 2009, in spite of no power supply and severe low temperature over 10 months of a year. The observational results from 2009 to 2015 showed that CO2 concentration at Mt. Fuji in summer and in winter was about 2–10 ppm lower and 2–12 ppm higher than at the Mauna Loa observatory (MLO), respectively. These episodic low concentrations at Mt. Fuji in summer have been cited as evidence that air masses originate from Siberia or China, which are affected by terrestrial CO2 uptakes. The relatively higher concentrations in winter were observed by air masses originated from China or Southeast Asia. The difference in monthly average CO2 concentration between Mt. Fuji and MLO appeared to increase from 2009 to 2015. Interannual variability and growth rate of CO2 concentration were similar both at Mt. Fuji and MLO, 13 ppm increase from 2009 to 2015, but the annual average concentration at Mt. Fuji was about 1 ppm higher than at MLO. Monthly averaged CO2 concentration at Mt. Fuji exceeded 400 ppm in April 2013. Recent CO2 concentration in 2015 at Mt. Fuji was about 62 ppm higher than the previous record measured in 1980. To evaluate a regional representative of our measurement data, CO2 values observed at Mt. Fuji were compared with airborne observations. They showed very good agreement with each other, indicating that Mt. Fuji was a representative site at which to monitor CO2 concentration in the mid-latitude Asian region.

scholarly journals The Synergistic Effect of PM2.5 and CO2 Concentrations on Occupant Satisfaction and Work Productivity in a Meeting Room

2021 ◽  
Vol 18 (8) ◽  
pp. 4109
Author(s):  
Jindong Wu ◽  
Jiantao Weng ◽  
Bing Xia ◽  
Yujie Zhao ◽  
Qiuji Song
Keyword(s):  
Air Quality ◽  
Synergistic Effect ◽  
Work Productivity ◽  
Co2 Concentration ◽  
Human Beings ◽  
Meeting Room ◽  
Negative Effect ◽  
Carbon Dioxide Co2 ◽  
Occupant Satisfaction ◽  
Pm2.5 Concentration

High indoor air quality is crucial for the health of human beings. The purpose of this work is to analyze the synergistic effect of particulate matter 2.5 (PM2.5) and carbon dioxide (CO2) concentration on occupant satisfaction and work productivity. This study carried out a real-scale experiments in a meeting room with exposures of up to one hour. Indoor environment parameters, including air temperature, relative humidity, illuminance, and noise level, were controlled at a reasonable level. Twenty-nine young participants were participated in the experiments. Four mental tasks were conducted to quantitatively evaluate the work productivity of occupants and a questionnaire was used to access participants’ satisfaction. The Spearman correlation analysis and two-way analysis of variance were applied. It was found that the overall performance declined by 1% for every 10 μg/m3 increase in PM2.5 concentration. Moreover, for every 10% increase in dissatisfaction with air quality, productivity performance decreased by 1.1% or more. It should be noted that a high CO2 concentration (800 ppm) has a stronger negative effect on occupant satisfaction towards air quality than PM2.5 concentration in a non-ventilated room. In order to obtain optimal occupant satisfaction and work productivity, low concentrations of PM2.5 (<50 μg/m3) and CO2 (<700 ppm) are recommended.

Sign in / Sign up

Export Citation Format

Share Document