Modified Atmosphere Research Articles

INNOVATIVE TREATMENT OF POMEGRANATES FROM HARVEST TO MARKET

The greatest global marketing challenge is to supply the markets with high quality edible pomegranates throughout the year. Extension of shelf-life requires advanced RD (b) storage over 1-2 months in a regular atmosphere (RA) at temperatures between 0-5°C, produces quality fruit throughout the period. More sophisticated storage techniques that allow extension of shelf life include: (a) modified atmosphere (MA) at 5-7°C allowing storage over 2-3 months while maintaining high quality; (b) controlled atmosphere (CA) at 5-7°C and suitable relative humidity offers the greatest marketing flexibility, including sales even beyond 3-5 months while maintaining high fruit quality and exportability. Special techniques developed in Israel prevent fruit weight loss, protect against storage diseases and allow shipment of desired cultivars to top European markets. The exporters are not limited by the harvest season and have a marketing potential of close to six months. These capabilities require modern cold storage facilities. Investment in such systems under Israeli conditions ranges between € 1,500-2,000 per ton of storage capacity.

Correlation between remote sensing data and ground based measurements for solar reflectance retrieving

Surface and atmospheric modifications due to urbanization generally lead to the urban heat island effect (UHI). This phenomenon is an issue of growing interest and has long been studied by ground based observation. With the advent of remote sensing technologies, observation of UHIs became possible with airborne and spaceborne sensors. Remote sensing data allow urban surfaces characterization to study UHI mitigation methodologies such as the application of cool roofs and cool colors.In this study remote sensing data have been used first to identify urban surfaces and then to retrieve the solar reflectance value of these surfaces.The first area of interest is the city of Modena in the Emilia Romagna region (Italy). On this area orthorectified images by an airborne sensor are used. Available images do not allow to directly obtain the solar reflectance value. Therefore it has been investigated a correlation between satellite remote sensing data and ground based measurements.The solar reflectance was obtained for all urban surfaces of interest such as roofs and pavements. In this way it was possible to assess the real situation and to hypothesize achievable improvements in the solar reflectance of several urban surfaces aimed at improving thermal comfort and energy efficiency of buildings.

Simulating super earth atmospheres in the laboratory

AbstractSeveral space missions, such as JWST, TESS and the very recently proposed ARIEL, or ground-based experiments, as SPHERE and GPI, have been proposed to measure the atmospheric transmission, reflection and emission spectra of extrasolar planets. The planet atmosphere characteristics and possible biosignatures will be inferred by studying planetary spectra in order to identify the emission/absorption lines/bands from atmospheric molecules such as water (H2O), carbon monoxide (CO), methane (CH4), ammonia (NH3), etc. In particular, it is important to know in detail the optical characteristics of gases in the typical physical conditions of the planetary atmospheres and how these characteristics could be affected by radiation driven photochemical and biochemical reaction. The main aim of the project ‘Atmosphere in a Test Tube’ is to provide insights on exoplanet atmosphere modification due to biological intervention. This can be achieved simulating planetary atmosphere at different pressure and temperature conditions under the effects of radiation sources, used as proxies of different bands of the stellar emission. We are tackling the characterization of extrasolar planet atmospheres by mean of innovative laboratory experiments described in this paper. The experiments are intended to reproduce the conditions on warm earths and super earths hosted by low-mass M dwarfs primaries with the aim to understand if a cyanobacteria population hosted on a Earth-like planet orbiting an M0 star is able to maintain its photosynthetic activity and produce traceable signatures.

Changes in the fatty acid profile of intramuscular fat in goose meat packed in different atmospheres

Summary Atmosphere type and storage time had significant effects on the fatty acid (FA) profile of goose breast muscle lipid. The FA profile did not change during 14 days of storage in muscle packed in vacuum. The percent of saturated FA (SFA) and monounsaturated FA (MUFA) increased gradually during 14 days of storage in samples packed in modified atmosphere, whereas the level of polyunsaturated FA (PUFA) decreased in the same period. The muscle packed in vacuum were characterised by a higher PUFA/SFA ratio and greater PUFA content concerning n-3 FA after storage in comparison to the samples packed in modified atmosphere (MA).

Minimal processing and passive modified atmosphere packaging of bread fruit (Artocarpus altilis) sticks for shelf life extension at refrigerated temperature

Bread fruit (Artocarpus altils) is extensively grown in different parts of world and is a less valued fruit due to its short shelf life. Therefore, minimal processing technology was adopted for shelf life extension of this commodity in cut form. The fruits were peeled, sliced and washed with water containing sodium hypochlorite (available chlorine 50 mg.kg−1) followed by additive treatment in soak solution containing sodium benzoate (200 mg.kg−1), potassium meta-bisulphite (200 mg.kg-1), citric acid (2 g.kg−1), ascorbic acid (200 mg.kg−1) and calcium chloride (5 g.kg−1) for 90 min at ambient temperature (28 ± 2 °C) followed by draining and passive modified atmosphere (MA) packing in polyethylene pouches (75 μ). Minimal processing and MA packing was found to be highly helpful in ensuring the microbiological safety without the incidence of coliform and pathogens. The additive treatment could stabilize the respiratory pattern of the slices suggesting physiological stabilization of the product and this was observed in the equilibrated head space O2 and CO2 concentrations during MA storage. Colour profile in terms of L*, a*, b* values of the slices suggested colour stability of the product during MA storage. Texture was also better retained in the treated samples as compared to untreated control. The minimally processed and MA packed bread fruit slices showed a shelf-life of 45 days at low temperature (6 ± 10 C).

Nonthermal Plasma System for Extending Shelf Life of Raw Broiler Breast Fillets

<abstract> <b><sc>Abstract.</sc></b> A nonthermal dielectric barrier discharge (DBD) plasma system was modified and enhanced to treat broiler breast fillets (BBF) in order to improve the microbial quality of the meat. The system consisted of a high-voltage source and two parallel, round aluminum electrodes separated by three semi-rigid polypropylene barriers extending well beyond the electrodes. The broiler samples were packaged in sealed polyolefin plastic bags to allow for adequate gas volume in the package. A modified atmosphere (MA) blend of gas (65% O₂, 30% CO₂, 5% N₂) was used to enhance the generation of reactive oxygen species during treatment. This research investigates the ability of this plasma system to extend the shelf life of BBF by reducing the number of spoilage bacteria. The system was tested on BBF and compared to triplicate untreated controls. Samples were treated outside the plasma generation field at ambient air temperature and pressure for 3 min at 75 kV and then stored at 4°C. Surviving microbes were recovered on days 1, 3, 7, 10, and 14 via standard rinsing and plating on nutrient agar. There was a mean log reduction of 1.53 log₁₀ cfu mL^-1 after 24 h. After 14 days of storage, the treated samples had a mean population of 5.53 log₁₀ cfu mL^-1, which was 2.39 cfu mL^-1 lower than the control packaged in air and 1.52 log₁₀ cfu mL^-1 lower than the control packaged in MA. A level of 5.56 log₁₀ cfu mL^-1 falls below the generally accepted spoilage limit of 10⁷ cfu mL^-1. Results demonstrate the ability of the nonthermal plasma system to reduce natural microflora on the surface of BBF and its applications in food safety and shelf life extension.

Effect of Water Vapor Content and Gas Composition on Quantification of Volatile Organic Compounds from Wild Rocket by SPME

A quantification method based on solid-phase microextraction (SPME) and external standard calibration for analysis of volatile organic compounds (VOCs) emitted from fresh produce in a dynamic environment, such as during storage in modified atmosphere (MA) packages, was investigated in this study. The effects of the water vapor content, temperature, and gas matrix composition on the extraction efficiencies of dimethyl sulfide, nitromethane, 3-methylfuran, dimethyl disulfide, and ethyl 3-methylbutyrate were investigated on an 85-μm carboxen/polydimethylsiloxane fiber. At VOC concentrations of 15.7 to 32.7 ng L−1, the water vapor content and temperature had negative effects on the extraction efficiency of dimethyl sulfide and nitromethane. At high CO2 concentrations (20–50 % CO2 balanced with N2), the extraction efficiency for all of the investigated VOCs decreased. However, the VOC concentrations determined from a 10 % O2 and 10 % CO2 matrix were the same as those measured in 20 % O2 and 0 % CO2 or 0 % O2 and 20 % CO2 matrices. For quantification of VOCs emitted from wild rocket stored under dynamic gas concentrations, a gas matrix composed of 10 % O2 and 10 % CO2 with a relative humidity above 85 % can be used for external standard calibration by maintaining the same temperature during the extraction of VOCs from the samples, as well as during the calibration.

Efficacy of Aqueous Ozone and Chlorine in Combination with Passive Modified Atmosphere Packaging on the Postharvest Shelf-Life Extension of Green Chillies (Capsicum annuum L.)

Aqueous ozone and chlorine treatments were evaluated for their effectiveness on postharvest quality of green chillies packed under passive modified atmosphere (MA) conditions. Ozone (30 mg) treatment was found significantly (p > 0.05) more effective in maintaining the postharvest quality of chillies as compared to chlorine-treated (100 mg kg−1) and untreated samples. Use of passive modified atmospheric packaging further maintained the quality of chillies and increased their shelf-life when stored at (8 ± 1 °C). Ozone washing also delayed senescence and maintained firmness of chillies during storage. The results suggest that microbial population in terms of total plate count, coliforms, as well as yeast and mold counts of fresh green chillies can be reduced without depleting its major bioactive compounds except for ascorbic acid using combined treatments of ozone wash and modified atmosphere packaging (MAP). This combination treatment (ozone + MAP) also maintained pigment stability in chillies during storage and extended the shelf-life up to 36 days against 28 and 22 days in the case of chlorine-washed and untreated samples, respectively.

Recent Developments in Film and Gas Research in Modified Atmosphere Packaging of Fresh Foods

Due to the rise of consumer's awareness of fresh foods to health, in the past few years, the consumption of fresh and fresh-cut produces has increased sturdily. Modified atmosphere packaging (MAP) possesses a potential to become one of the most appropriate technologies for packaging fresh and fresh-cut produces. The MAP has advantages of extending the shelf-life, preserving or stabilizing the desired properties of fresh produces, and convenience in handing and distribution. The success of MAP-fresh foods depends on many factors including types of fresh foods, storage temperature and humidity, gas composition, and the characteristics of package materials. This paper reviews the recent developments highlighting the most critical factors of film and gas on the quality of MAP fresh foods. Although the innovations and development of food packaging technology will continue to promote the development of novel MAP, concentrated research and endeavors from scientists and engineers are still important to the development of MAP that focuses on consumers' requirements, enhancing product quality, environmental friendly design, and cost-effective application.

Biodegradable and Compostable Film and Modified Atmosphere Packaging in Postharvest Supply Chain of Raspberry Fruits (cv. Grandeur)

In this study, noncommercial biodegradable and compostable nonperforated films (F2, F3, F4) were evaluated for modified atmosphere packaging storage for 5 days at 1 ± 1C and 7 days at 20 ± 1C of raspberries cv. Grandeur. After measuring the CO2 (PeCO2) and the O2 (PeO2) permeability of new films at different temperatures, the most important qualitative traits and nutraceutical components of fruits were analyzed and compared with those of unwrapped raspberries and macroperforated film (F1). As the temperature increased, the F2 and F3 were the only films to allow storage of the fruits up to 12 days, but the F3 film (5.7 kPa O2 and values of 31.6 kPa CO2) was the best for maintaining the color parameter (L 29.0, chroma 36.4) close to the value observed at harvest because of a similar ratio between the PeCO2 and the PeO2 (4.2 and 4.1, respectively) at both low and high temperatures. Practical Applications This study of the permeability of new films from renewable sources for packaging raspberries in a temperature range that can simulate the postharvest supply chain could indicate that storing these perishable fruits under modified atmospheric packaging could increase environmental sustainability.

TOLERANCE OF SUGAR SNAP PEAS TO MODIFIED ATMOSPHERES WITH HIGH CONCENTRATIONS OF CARBON DIOXIDE

Current recommendations for maintaining quality of sugar snap peas in storage include low temperatures, but not modified atmospheres (MA). However, sugar snap peas may be unintentionally exposed to MA when shipped in ‘bag in box’ bulk packaging, or intentionally exposed when used as a component in fresh-cut vegetable trays. The aim of this research was to determine the tolerance of sugar peas to MA. Two experiments were conducted in which sugar snap peas (‘Super Sugar Snap’) were stored at 5°C for up to 21 days in air, 3% O2 + 7, 12 or 18% CO2, or 10% O2 + 12% CO2. Overall, storage in air resulted in the best quality based on subjective (overall visual quality, discoloration, aroma, decay) and objective measurements (sugar, ethanol, acetaldehyde, ammonia). The 3% O2 with 12 or 18% CO2 resulted in visible damage (discoloration) to the peas after 9 to 12 days. This was associated with changes in color (increased darkness, loss of greenness), and substantial increases in ammonia, ethanol and acetaldehyde; all indicative of stress. Quality changes in peas stored in 3% O2 + 7% CO2 or 10% O2 + 12% CO2 were intermediate between the stressful atmospheres and air. Further tests showed that peas (‘Sugar Snap’) maintained good quality at 5°C in air, 3% O2, 3% O2 + 6% CO2 or 10% O2 + 12% CO2 atmospheres for 18 days. Best quality was maintained in air at 0°C for over 21 days. At 5°C for 18 days, some MA combinations provided slight benefit over air storage, and importantly did not result in increased concentrations of stress indicators. If peas have to be in MAP with other fresh-cut vegetables, the 3% O2 + 6% CO2 or 10% O2 + 12% CO2 atmospheres are probably the better options.

TOLERANCE OF GRAPE TOMATOES TO CONTROLLED ATMOSPHERES AT LOW TEMPERATURE

Grape and cherry tomatoes comprise about one quarter of retail tomato sales in the United States and are also important components in fresh-cut mixed vegetable trays. The latter require low temperatures and packaging which can produce a range of modified atmospheres (MA) to achieve 14 days of shelf-life. Postharvest handling recommendations for good tomato quality do not usually include low temperatures or MA. Storage studies were conducted to ascertain the effect of low temperatures and MA on grape tomato quality. Grape tomatoes (orange-red or more advanced color) can be stored in clamshells for up to 18 days at 5°C and still be of marketable quality if kept cold. Continuous storage at 5°C in air resulted in minimal weight loss (a significant cause of quality loss in grape tomato stored at warmer temperatures), and retention of vitamin C levels, but no lycopene synthesis, and decreased sugar concentrations. However, if fruit were transferred from 5 or 10°C to warmer temperatures (i.e., 20°C), typical chilling injury symptoms (decay, poor color formation) occurred on fruit stored at 5°C but not at 10°C. Controlled atmospheres (CA) of 3 or 10% O2 with 0, 7, 12 or 18% CO2 provided little or no benefit, but were tolerated by grape tomatoes for up to 21 days at 5°C. These results are based on evaluation of visual appearance, discoloration, decay, aroma, off-odors, flavor, and changes in concentrations of lycopene, sugars, vitamin C, ethanol and acetaldehyde. Although not ideal, near-ripe high quality grape tomatoes perform well as components of fresh-cut vegetable trays at low temperatures and under atmospheres not usually recommended for tomatoes.

ACTIVE MAP OF READY-TO-EAT LETTUCE: INTERPLAY BETWEEN FOOD QUALITY AND SAFETY (THE QUAFETY APPROACH)

Oxidative enzymatic browning of cut edges and microbial spoilage are the two major causes of deterioration of ready-to-eat lettuce. Furthermore, we have demonstrated that these two processes are interrelated and the presence of spoilage pseudomonad bacteria on cut lettuce surface hastens the accumulation of phenolics and enhances browning, presumably as part of the host defense response. Preventing browning by heat treatment promoted bacterial growth and tissue maceration of Pectobacterium-inoculated lettuce core discs. The red-colored phenolic oxidation products have been isolated from cut lettuce and are currently under investigation. Modified atmosphere packaging (MAP) is used to preserve the quality of fresh-cut lettuce by inhibiting both the oxidative browning and the growth of microbial populations. Flushing the packages with a gas mix of desired composition (active MAP) expedites the achievement of favorable atmosphere conditions improving the product quality preservation. At the same time, the active MAP favored the survival of Salmonella on lettuce leaves, possibly due to the elimination of its natural antagonists. Atmosphere modification does not ensure microbiological safety of ready-to-eat lettuce and must be supported by appropriate sanitation practices. Washing with active chlorine followed by potable water rinsing did not taint shredded lettuce with unacceptable level of disinfection byproducts but produced wastewater heavily contaminated with trihalomethanes. The comprehensive approach to quality and safety of ready to eat fresh products is the basis of the EU FP7 QUAFETY project.

Експериментальні та теоретичні дослідження штучної акустичної модифікації атмосфери та іоносфери

Експериментальні та теоретичні дослідження штучної акустичної модифікації атмосфери та іоносфери

Headspace oxygen measurements can be used as a fast and convenient method for shelf‐life assessment of potato snacks

The aim of this study was to explore the influence of different barrier and atmosphere conditions on the complex processes affecting storage stability of potato snacks, and the use of oxygen determination measurements within a packaging atmosphere as a quick quality and shelf‐life assessment method. The subject of investigation was potato snacks packed in transparent and metallised polymeric packaging laminates, filled with air or nitrogen. Samples were analysed for moisture, water activity, hydroperoxide and oxygen concentration in the headspace by two methods: a non‐invasive optical method based on fluorescence quenching and an electrochemical method. High barrier packaging provides better protection against moisture but not against oxidation. The shelf‐life of potato snacks is undermined by oxygen presence in the foam structure of the product. Neither barrier packaging nor modification of atmosphere applied alone bring satisfactory results, therefore a combined strategy is recommended. The study proved that the most optimal solution was the use of metallised packaging with nitrogen. The use of an optical sensor can be an appropriate and effective novel method for a non‐destructive oxidation progress evaluation of food that is stored in translucent packaging.Practical applications: The high linear correlation between hydroperoxides and oxygen content is of great practical value in shelf‐life assessment and screening the correctness of a packaging process.The shelf‐life of potato snacks is undermined by oxidative processes. As processes of fatty acids oxidation are related to oxygen uptake, the presence of a relationship between hydroperoxide content and oxygen concentration or consumption is of great practical value in quality and shelf‐life assessment.

Variations in oxygen concentration cause differential antioxidant response and expression of related genes in Beauveria bassiana

The entomopathogenic fungus Beauveria bassiana is widely used in pest biocontrol strategies. We evaluated both the antioxidant response mediated by compatible solutes, trehalose or mannitol, and the expression of related genes using oxygen pulses at three oxygen concentrations in solid state culture (SSC): normal atmosphere (21 % O2), low oxygen (16 % O2) and enriched oxygen (26 % O2). Trehalose concentration decreased 75 % after atmospheric modifications in the cultures, whereas mannitol synthesis was three-fold higher under the 16 % O2 pulses relative to normal atmosphere (100 and 30 μg mannitol mg−1 biomass, respectively). Confirming this result, expression of the mpd gene, coding for mannitol-1-P dehydrogenase (MPD), increased up to 1.4 times after O2 pulses. The expression of the bbrgs1 gene, encoding a regulatory G protein related to conidiation, was analysed to explain previously reported differences in conidial production. Surprisingly, expression of bbrgs1 decreased after atmospheric modification. Finally, principal component analysis (PCA) indicated that 83.39 % of the variability in the data could be explained by two components. This analysis corroborated the positive correlation between mannitol concentration and mpd gene expression, as well as the negative correlation between conidial production and bbrgs1 gene expression. This study contributes to understanding of antioxidant and molecular response of B. bassiana induced under oxidant conditions.

Seasonal inhomogeneity in cloud precursors over Gangetic Himalayan region during GVAX campaign

Atmospheric aerosols are key elements in cloud microphysics, the hydrological cycle and climate by serving as cloud condensation nuclei (CCN). The present work analyzes simultaneous measurements of number concentration of CCN (NCCN) and condensation nuclei (NCN) obtained at Nainital, in the Gangetic-Himalayan (GH) region, during the frameworks of Ganges Valley Aerosol Experiment (GVAX), June 2011 to March 2012. The NCCN, NCN and activation (AR=NCCN/NCN) at 0.31–0.33% S (supersaturation ratio), exhibit significant daily, monthly and seasonal variations within a range of 684–2065cm−3 for NCCN, 1606–4124cm−3 for NCN, and 0.38–0.60 for AR, suggesting large inhomogeneity in aerosol properties, types and sources, which control the degree of aerosol potential activation. Thus, transported aerosols from the Ganges valley and abroad, the boundary-layer dynamics and atmospheric modification processes play an important role in aerosol–cloud interactions over the GH region. The NCN and NCCN show monthly-dependent diurnal variations with afternoon maxima due to transported aerosols from the Ganges valley up to the Himalayan foothills, while the AR is lower during these hours implying lower hygroscopicities or smaller sizes of the transported aerosols. The dependence of NCCN on S is highest during Dec–Mar and lowest during monsoon (Jun–Sep), suggesting different aerosol chemical composition. Comparison between Nainital and Kanpur shows that NCN and NCCN are much lower at Nainital, while the similarity in AR suggests aerosols of similar type, source and chemical composition uplifted from the Ganges valley to the Himalayan foothills.

EFFECT OF DIFFERENT METHODS OF MODIFIED ATMOSPHERE ON KEEPING QUALITY OF EL-AMAR APRICOT FRUITS DURING MARKETING AND COLD STORAGE

This study was carried out during the two seasons of 2010 and 2011 on El-Amar apricot fruits obtained from Kalubia governorate to compare the effect of some modified atmosphere methods on keeping quality of apricot fruit during marketing and cold storage periods. Fruit moisture loss, firmness, fruit color, respiration rate, physiological disorders and total soluble solids/total acidity ratio were studied during cold storage at 0oC (85-90% RH) and marketing at room temperature 25-30°C (60- 65% RH). The results showed that the main factors limiting the storage life of El-Amar apricot is fruit moisture loss and physiological disorders (browning pitting and shriveling). The storage life of fruits packed in polyethylene bags was three weeks, fruits coated with coat (1) (gelatin) or coat (2) (gelatin + bees wax and glycerol) had a storage life of two weeks with good fruit quality. Also, control fruits had two weeks storage life but fruit quality was less than other treatments. All treated and untreated fruits had three days marketing period at room temperature but fruit appearance was the best in polyethylene bags.

Spatio-Temporal Analysis of UHI using Geo-Spatial Techniques: A case study of Ahmedabad

Spatio-Temporal Analysis of UHI using Geo-Spatial Techniques: A case study of Ahmedabad

Resting of MAP (modified atmosphere packed) beef steaks prior to cooking and effects on consumer quality

This study investigated the meat preparation effects prior to cooking on the sensory consumer quality of modified atmosphere (MA) packed (100ml CO2/100ml pack gas, 50ml O2:20ml CO2:30ml N2/100ml pack gas, 70ml O2:30ml CO2/100ml pack gas and 80ml O2:20ml CO2/100ml pack gas) striploin beef steak. Beef steaks were stored at 4°C for 7days (616lx) to simulate retail display conditions and tested by consumers (n=40) for appearance, liking of flavour, overall acceptability, juiciness, tenderness, oxidation flavour, off-flavour, and sourness of the resulting cooked meat. Additionally, TVC, pH, colour, drip loss, and cooking loss were measured. One steak from each of the experimental treatments was taken immediately from the respective MA packs and cooked before serving straight to consumers. A second steak from each pack was treated similarly, but left in ambient air for 30min prior to cooking and serving. Consumers perceived cooked steak from samples left for 30min prior to cooking as significantly (P<0.05) less sour tasting than those cooked immediately.