High Oxygen Atmosphere Research Articles

Enhanced selective catalytic wet oxidation of H2S to S over Ce–Fe/MgO catalysts at ambient temperature

Abstract In the study we prepare novel MgO supported magnetic Ce–Fe catalysts for selective catalytic wet oxidation of H2S to elemental sulfur at ambient temperature. Characterization of the MgO supported Ce–Fe catalysts and the corresponding catalytic activity for H2S removal were analyzed and evaluated. Compared to the MgO supported Fe catalysts, the Ce incorporation increases significantly catalytic activity for H2S removal due to the oxidation of Fe2+ to Fe3+ improved by the redox couple Ce4+/Ce3+. Besides, we also found that the Ce incorporation reduced sulfates and sulfur deposited on the surface of the catalysts. Under high oxygen atmosphere, contaminants are almost not formed on the surface of the Mg supported Ce–Fe catalysts, extending their lifetime.

Effect of muscle type, aging technique, and aging time on oxidative stability and antioxidant capacity of beef packed in high-oxygen atmosphere

Effect of muscle type, aging technique, and aging time on oxidative stability and antioxidant capacity of beef packed in high-oxygen atmosphere

Prolonging shelf life of lamb cutlets packed under high-oxygen modified atmosphere by spraying essential oils from North-African plants

The aim of this study was to assess the effectiveness of sprayable essential oils for counteracting the pro-oxidant environment created during retail display of lamb cutlets packed under high-oxygen atmosphere. North-African essential oils from Pituranthos chloranthus (PC) and Teucrium ramosissimum (TR) were applied by spraying on the surface of whole-lamb cutlets. The bio-preservative treatment led to a significant increase of their shelf life in terms of protection against lipid and protein oxidative deterioration, discoloration of lean and bone and microbiological stability during 12days of chilled storage. Furthermore, the addition of TR and PC on the surface of lamb cutlets significantly improved their appearance, increasing hence the purchase intention and consumers' preferences towards treated retailed products. This study shows that the application of a high-oxygen active packaging in combination with natural sprayable extracts is a feasible and effective strategy for protecting whole-meat muscle foods against oxidation and microbial deterioration.

Dose-Dependent Effects of Green Tea or Maté Extracts on Lipid and Protein Oxidation in Brine-Injected Retail-Packed Pork Chops.

Background: Phenolic plant extracts are added as antioxidants in meat to prevent lipid oxidation, but depending on the concentration applied, may affect proteins either through covalent interactions or by serving as a prooxidant. Methods: Brine-injected pork chops prepared with green tea extract (25–160 ppm gallic acid equivalents (GAE)), or maté extract (25–160 ppm GAE) and stored (5 °C, 7 days) in high-oxygen atmosphere packaging (MAP: 80% O2 and 20% CO2) were analyzed for color changes, lipid oxidation by thiobarbituric acid reactive substances (TBARS), and protein oxidation evaluated by thiol loss and protein radical formation by electron spin resonance (ESR) spectroscopy, and compared to a control without antioxidant. Results: Extract of maté and green tea showed significant and comparable antioxidative effects against formation of TBARS in brine-injected pork chops for all concentrations applied compared to the control. Protein radical formation decreased significantly by addition of 25 ppm maté extract, but increased significantly by addition of 80–160 ppm green tea extract, when monitored as formation of protein radicals. Meanwhile, protein thiol groups disappeared when applying the extracts by reactions assigned to addition reactions of oxidized phenols from the extracts to protein thiols. Conclusion: Maté is accordingly a good source of antioxidants for protection of both lipids and proteins in brine-injected pork chops chill-stored in high-oxygen atmosphere, though the dose must be carefully selected.

Protein Oxidation and Sensory Quality of Brine-Injected Pork Loins Added Ascorbate or Extracts of Green Tea or Maté during Chill-Storage in High-Oxygen Modified Atmosphere.

Background: Ascorbate is often applied to enhance stability and robustness of brine-injected pork chops sold for retail, but may affect protein oxidation, while plant extracts are potential substitutes. Methods: Brine-injected pork chops (weight-gain ~12%, NaCl ~0.9%) prepared with ascorbate (225 ppm), green tea extract (25 ppm gallic acid equivalents (GAE)), or maté extract (25 ppm GAE) stored (5 °C, seven days) in high-oxygen atmosphere packaging (MAP: 80% O2 and 20% CO2) were analyzed for color changes, sensory quality, and protein oxidation compared to a control without antioxidant. Results: No significant differences were observed for green tea and maté extracts as compared to ascorbate when evaluated based on lipid oxidation derived off-flavors, except for stale flavor, which maté significantly reduced. All treatments increased the level of the protein oxidation product, α-aminoadipic semialdehyde as compared to the control, and ascorbate was further found to increase thiol loss and protein cross-linking, with a concomitant decrease in the sensory perceived tenderness. Conclusions: Green tea and maté were found to equally protect against lipid oxidation derived off-flavors, and maté showed less prooxidative activity towards proteins as compared to ascorbate, resulting in more tender meat. Maté is a valuable substitute for ascorbate in brine-injected pork chops.

The oxygen concentration in cultures modulates protein expression and enzymatic antioxidant responses in Metarhizium lepidiotae conidia

Conidia from Metarhizium spp. are used for integrated pest control; however, environmental factors diminish the effectivity of these programs. Several approaches tried to improve conidia resistance to overcome this limitation, although little is known about the mechanisms involved in this effect. Here we measured the activity of antioxidant enzymes and conidia virulence, comparing the proteomic profiles of Metarhiziumlepidiotae CP-OAX conidia produced under normal (21% O2) and high oxygen atmospheres (pulses with 30% O2). We detected a higher virulence against Tenebrio molitor larvae, in addition to an increase in ultraviolet light tolerance in conidia produced under 30% O2, which correlates with increased glutathione reductase activity. Two-dimensional gel electrophoresis (2D SDS–PAGE) of proteins extracted in conidia harvested from both experimental conditions revealed a group of proteins that was observed only in conidia from oxidant atmospheres. Some of those proteins were directly involved in oxidative stress responses, whereas others were involved in conidial virulence, thermo-tolerance, and the central metabolism. Thus, a high atmospheric oxygen concentration (30%) activates antioxidant defence and general stress response mechanisms involved in conidia resistance to adverse environmental factors, which can ultimately translate into higher effectivity for the use of entomopathogenic fungi conidia in pest control.

Influence of modified atmosphere and vacuum packaging with and without nanosilver-coated films on different quality parameters of pork.

Pork is often marketed in packages with high oxygen atmosphere (MAP) or vacuum to improve shelf life and appearance. As silver ions have antibacterial effects, food contact films coated with silver might improve the shelf life of meat. In the present study, pork was wrapped in commercially available films, coated with nanosilver particles, and stored in the two packaging variants MAP and vacuum for 12days. During storage, samples were analyzed on days 1 (before packaging), 4, 8 and 12 for microbiological contamination, meat quality (e.g., pH, color), and for the percentages of the myoglobin (Mb) redox forms. In addition, the effects of the film were examined after inoculation of the meat with high quantities of methicillin-resistant Staphylococcus aureus (MRSA) cells before vacuum storage for 8days. MAP storage resulted in higher lightness (L*) values, lower liquid loss and higher Mb oxidation compared to vacuum. Microbiological spoilage was partly affected by the packaging variants with reducing effects of the MAP. The nanosilver-coating only affects the Mb redox form percentages of the pork cutlets and on day 4 the L* values, whereas microbiological parameters were not influenced. As the nanosilver coating had no influence on the total viable bacteria counts as well as Pseudomonas spp., Enterobacteriaceae and MRSA counts, an advantage of the nanosilver coating on the shelf life could be excluded.

Preservation of fresh ground beef patties using plant extracts combined with a modified atmosphere packaging

High oxygen modified atmosphere packaging of raw ground beef patties favors bright red oxymyoglobin color but also lipid oxidation. Therefore, the effect of the addition of phenolic-rich plant extracts selected for their in vitro antioxidant and antimicrobial activities on microbiological (total viable count, psychrotrophic aerobic bacteria, and coliforms), physico-chemical [pH, exudate mass, thiobarbituric acid-reactive substances (TBARS)], and organoleptic (instrumental color and sensory analysis of cooked patties) quality attributes of beef patties was monitored for 12 days at 4 °C in a high oxygen atmosphere. Prune flesh, pomegranate peel, green tea leaves, grape seed extracts, and Gaillac red wine powder were added at 10 g kg−1 in beef patties. All extracts except prune flesh extract, which had the lowest total phenolic content (3.4 mg gallic acid equivalent (GAE) g−1 against from 81.2 to 570.0 mg GAE g−1 in other extracts), reduced the increase in TBARS in beef patties over 12 days by more than 93% (P 0.05). In vitro and in situ antioxidant activities of plant extracts were correlated with their total phenolic content (R 2 = 0.99) unlike in vitro (R 2 = 0.18) and in situ (R 2 = 0.17) antibacterial activities. Interestingly, pomegranate peel extract and Gaillac red wine powder retarded lipid oxidation and color variation, and maintained the redness index of meat.

Quality changes of goose breast meat during cold storage under modified atmosphere and vacuum

Summary The comparison between the high-oxygen atmosphere (MA) and vacuum showed essential differences between these two atmosphere types. Based on the total viable count data, the shelf life of meat packed under MA was established as 11 days, whereas for samples stored in vacuum it was 14 days. Lactobacillus spp. grew quicker under vacuum, whereas the total viable count, Pseudomonas spp. and Enterobacteriaceae, grew better under the oxygen atmosphere. High oxygen levels used in MA promoted lipid oxidation in goose meat, causing changes of odour intensity.

Diesel exhaust characteristics of high temperature and low oxygen atmosphere combustion

Diesel exhaust characteristics of high temperature and low oxygen atmosphere combustion

Influence of red wine pomace seasoning and high-oxygen atmosphere storage on carcinogens formation in barbecued beef patties

Polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatic amines (HAs) are carcinogenic compounds formed in barbecued meat. Conditions that reduce their formation are of major interest. This study aims to evaluate the influence of red wine pomace seasoning (RWPS) and high-oxygen atmosphere storage on the formation of PAHs and HAs in barbecued beef patties. In general, the levels of PAHs and HAs quantified were low. The storage (9days) promoted higher formation of PAHs in control patties without increase of HAs. RWPS patties cooked at preparation day presented higher levels of PAHs and HAs than control. Nevertheless, RWPS patties cooked after storage presented lower levels of PAHs and HAs than control. ABTS assay pointed out that higher radical scavenging activity may be related to with lower PAHs or HAs formation. In conclusion, RWPS can be an interesting ingredient to inhibit the formation of cooking carcinogens in barbecued patties stored at high-oxygen atmosphere.

Antioxidant effect of seasonings derived from wine pomace on lipid oxidation in refrigerated and frozen beef patties

This work evaluates the ability of three different seasonings (obtained from wine pomace) to inhibit lipid oxidation in raw and cooked beef patties. Seasonings were incorporated to beef patties recipe as other solid ingredient at the level of 2 g/100 g. The storage conditions assayed were: refrigeration (4 °C, 15 days) with high-oxygen atmosphere (70% O2, 30% CO2) and freezing (−18 °C, 6 months). Two independent experiments with 3 replicates were carried out. Furthermore, the inhibitory effect on lipid oxidation was compared with the effectiveness of sulfites, an antioxidant widely used in the meat industry. Both types of storage significantly induced increases of thiobarbituric acid reactive substances (TBARS) and volatile organic compounds (VOCs) (hexanal, 1-pentanol, 1-hexanol, 1-octen-3-ol, 2,3-octanedione, and 2-pentylfuran) measured with gas chromatography–mass spectrometry (p-value < 0.05). The three seasonings showed different effectiveness to inhibit lipid oxidation under the three conditions studied, being the seasoning made from seedless wine pomace the most effective. This seasoning significantly inhibited the formation of VOCs, revealing their potential capacity to delay the formation of rancid odors during storage of meat products. Samples with sulfites presented contrary results respect to TBARS levels, which were reduced in refrigerated samples but promoted in the frozen patties.

Metabolic activity, microbial growth and sensory quality of arugula leaves (Eruca vesicaria Mill.) stored under non-conventional modified atmosphere packaging

Arugula compositional characteristics linked to vitamin content, polyphenols and other health beneficial compounds have increased consumer interest to include it in the diet. This leafy vegetable is very susceptible to yellowing and dehydration, reducing its shelf life period. This study evaluated the effects of non-conventional modified packaging atmospheres, i.e. Argon (75–80% Ar+10–11% O2, balance N2), Nitrogen (10–11% O2+89–90%N2), High Oxygen (85–90% O2+10–15%N2), Helium (75–80% He+10–11% O2, balance N2) and Nitrous Oxide (75–80%N2O+10–11% O2, balance N2), on metabolic activity, microbiological growth and sensory characteristics of fresh cut arugula (Eruca vesicaria Mill.) leaves. The High Oxygen atmospheres reduced the respiration rate until 5days of storage, but there were no differences among treatments at the end of the storage period. There were no differences in ethylene emission among treatments at any of the evaluation dates. Non-conventional atmospheres had 0.5–1 log unit lower microbial growth counts than air packaging after 8days of storage. Color and sensory characteristics were not affected by the storage conditions. The non-conventional atmospheres maintained some quality characteristics of arugula leaves, suggesting it could be an alternative to conventional modified atmosphere used to maintain arugula shelf life.

Controlling Microbial Safety Challenges of Meat Using High Voltage Atmospheric Cold Plasma.

Atmospheric cold plasma (ACP) is a non-thermal technology, effective against a wide range of pathogenic microorganisms. Inactivation efficacy results from plasma generated reactive species. These may interact with any organic components in a test matrix including the target microorganism, thus food components may exert a protective effect against the antimicrobial mode of action. The effect of an in-package high voltage ACP process applied in conjunction with common meat processing MAP gas compositions as well as bacteria type and meat model media composition have been investigated to determine the applicability of this technology for decontamination of safety challenges associated with meat products. E. coli, L. monocytogenes, and S. aureus in PBS were undetectable after 60 s of treatment at 80 kVRMS in air, while ACP treatment of the contaminated meat model required post-treatment refrigeration to retain antimicrobial effect. The nutritive components in the meat model exerted a protective effect during treatment, where 300 s ACP exposure yielded a maximum reduction of 1.5 log using a high oxygen atmosphere, whilst using air and high nitrogen atmospheres yielded lower antimicrobial efficacy. Furthermore, an ROS assay was performed to understand the protective effects observed using the meat model. This revealed that nutritive components inhibited penetration of ROS into bacterial cells. This knowledge can assist the optimization of meat decontamination using ACP technology where interactions with all components of the food matrix require evaluation.

Shift of superconducting transition temperatures in magnetic superconductor RuSr2(Eu1.5Ce0.5)Cu2O10-d under influence of annealing in high pressure oxygen atmosphere

Shift of superconducting transition temperatures in magnetic superconductor RuSr2(Eu1.5Ce0.5)Cu2O10-d under influence of annealing in high pressure oxygen atmosphere

Development of spoilage bacterial community and volatile compounds in chilled beef under vacuum or high oxygen atmospheres

Research into microbial community development and metabolism is essential to understand meat spoilage. Recent years have seen the emergence of powerful molecular techniques that are being used alongside conventional microbiology approaches. This enables more accurate studies on meat spoilage. The aim of this study was to investigate the influence of packaging (under vacuum and in high oxygen atmosphere) on the development of microbial communities and metabolic activities at 6°C by using culture-dependent (cultivation, ribotyping) and culture-independent (amplicon sequencing) methods. At the beginning of shelf life, the microbial community mostly consisted of Carnobacterium and Lactobacillus. After two weeks of storage, Lactococcus and Lactobacillus were the dominant genera under vacuum and Leuconostoc in high oxygen meat packages. This indicates that oxygen favoured the genus Leuconostoc comprising only heterofermentative species and hence potential producers of undesirable compounds. Also the number of volatile compounds, such as diacetyl, 1-octen-3-ol and hexanoic acids, was higher in high oxygen packages than under vacuum packages. The beef in high oxygen atmosphere packaging was detected as spoiled in sensory evaluation over 10days earlier than beef under vacuum packaging. Leuconostoc gelidum, Lactococcus piscium, Lactobacillus sakei and Lactobacillus algidus were the most common species of bacteria. The results obtained from identification of the isolates using ribotyping and amplicon sequencing correlated, except for L. algidus, which was detected in both types of packaging by amplicon sequencing, but only in vacuum packaged samples using the culture-based technique. This indicates that L. algidus grew, but was not cultivable in high oxygen beef using the Nordic Committee on Food Analysis standard method.

ZrO2-induced crack-healing mechanism of ZrB2–SiC–Graphite composite in high temperature atomic oxygen environment

The ZrO2-induced crack-healing mechanism of ZrB2–SiC–Graphite (ZSG) composite is investigated under high temperature atomic oxygen atmosphere, which characterizes the real condition of hypersonic flight. This differs greatly from the borosilicate glass-induced crack-healing mechanism in previous studies. The cracks are healed limitedly in high temperature atomic oxygen condition with a 39.09% maximum improvement in residual strength compared to the pre-cracked specimens. The crack-healing is induced by ZrO2, and the crack-healing mechanism involves three main aspects: A. Local particle rearrangement, which is induced by expansion from the chemical reaction (ZrB2→ZrO2), the phase transition (t-ZrO2→m-ZrO2), and the thermal expansion. B. The crack volume filling by ZrO2 driven by the liberation of the reaction gases. C. Diffusion controlled sintering around the ZrO2 sintering temperature. The spontaneous crack-healing ability in high temperature atomic oxygen atmosphere is helpful to improve the reliability of ZSG composites in service.

Effect of Skin Wine Pomace and Sulfite on Protein Oxidation in Beef Patties During High Oxygen Atmosphere Storage

Meat storage in high oxygen atmosphere has been reported to induce protein oxidation reactions decreasing meat quality. The incorporation of antioxidants has been proposed to reduce the extent of these reactions. In this study, the ability of red and white skin wine pomaces as well as sulfites to inhibit protein oxidation were tested in beef patties stored for up to 15 days at 4 °C in a high oxygen atmosphere (70 % O2 and 30 % CO2). SO2 (300 ppm) effectively protected against protein oxidation measured as radical formation by electron spin resonance (ESR) spectroscopy, as thiol loss by the DTNB assay and as myosin heavy chain (MHC) disulfide cross-linking by SDS-PAGE. Pomace from red wine production with a total phenol of 9.9 mg gallic acid equivalent/g protected against protein radical formation and against MHC cross-linking, but not against thiol loss by addition of 2.0 % (w/w) to the beef patties. Pomace from white wine production with a total phenol of 4.0 mg gallic acid equivalent/g only protected against MHC cross-linking. For both types of wine pomace, protein modifications not seen for sulfite addition were observed and were proposed to involve covalent phenol addition to proteins. Red wine pomace may be an alternative to sulfite as a meat additive for protection of beef patties against protein oxidation.

Protein thiols undergo reversible and irreversible oxidation during chill storage of ground beef as detected by 4,4'-dithiodipyridine.

Quantification of protein thiols and disulfides in ground beef during storage under high-oxygen atmosphere at 4 °C was performed by thiol detection using 4,4'-dithiodipyridine (4-DPS) before and after disulfide reduction using sodium borohydride. Two independent storage trials were performed, and in trial 1, only reversible thiol oxidation was observed (thiol loss was 30%). In trial 2, irreversible thiol oxidation occurred during the first days of storage, while further loss of thiols was caused by reversible disulfide formation (thiol loss was 33%, of which ca. half was lost because of irreversible oxidation). The results were compared to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of cross-linked myosin heavy chain formed by disulfide bonding. Both methods confirmed increasing disulfide formation because of thiol oxidation in meat during storage, but the 4-DPS method showed higher disulfide percentages than the SDS-PAGE method (22.2 ± 0.3% and 8.5 ± 1.2%, respectively). The 4-DPS assay provides an accurate method to evaluate the thiol-disulfide redox state in meat.

High oxygen atmospheres can induce russet spotting development in minimally processed iceberg lettuce

High oxygen modified atmospheres have been suggested as an alternative preservation technique to classical low O2 modified atmosphere packaging (MAP) for fresh-cut lettuce. The advantages of high O2 storage would be a strong reduction of browning, avoidance of low O2 levels linked to off-odors, and the inhibition of microbial growth. However, storage under high O2 potentially could increase both production of ethylene and sensitivity to this hormone in lettuce tissue, leading to the development of quality problems linked to ethylene. In this study, different quality parameters (sensory quality, microbiological load, electrolyte leakage, volatile metabolites) were studied on fresh-cut iceberg lettuce stored under different gas conditions at 7°C: (low O2 MAP (3% O2 compensated with N2), atmospheric conditions, high O2 MAP (50 or 90% O2 compensated with N2)). Furthermore, additional experiments using ethylene absorbers were performed in order to assess the link between high O2 storage, ethylene accumulation, and russet spotting. There was no significant difference between storage conditions regarding growth of mesophilic bacteria and yeasts, electrolyte leakage, or ethanol production. On the other hand, high O2 atmospheres reduced browning but promoted russet spotting development compared with low O2 and atmospheric conditions. In further specific experiments the relationship between high O2 storage, ethylene production, and russet spotting in fresh-cut iceberg lettuce were made evident.