Microbial and Quality Attributes of Beef Steaks under High-CO2 Packaging: Emitter Pads versus Gas Flushing.

Over 21 days of cold storage, the quality and microbial composition of beef steaks in response to different high-CO2 packaging conditions achieved by flushing gas mixtures or embedding gas emitters into the packages were studied. The results revealed that the high levels of CO2, achieved by either the gas flushing or the CO2 emitter pads, effectively controlled the number of aerobic counts. The headspace CO2 increased quickly in response to using the CO2 emitter pads, and the meat samples presented different pH levels and surface color (a* and b*) values compared to the samples packaged with the gas flushing technique. Excessive accumulation of gas in the packages that contained CO2 emitters resulted in package swelling and higher levels of drip loss. The longest overall quality and attractive red color of the meat samples were observed when the packages were initially flushed with the headspace gas mixture containing high levels of oxygen. Overall, using CO2 emitters for meat packaging can be suggested when a topfilm with proper permeability to O2 and CO2 gases is used to regulate the internal CO2/O2 and gas/product ratios.

Tailor-made packaging strategies of fresh pork belly with different fat content: Enhancing shelf life while minimizing environmental impact.

Pork belly is a meat cut valued for its rich flavour and texture, attributed to its high fat content, which also makes it susceptible to oxidation. Therefore, meat producers and processors must carefully select packaging options to maximise shelf life while meeting consumer preferences. This study aimed to develop customised packaging strategies for sliced pork belly with varying fat content to extend shelf life while minimizing environmental impact. The research compared three packaging solutions: modified atmosphere packaging (MAP1: 70:30% O2:CO2, MAP2: 30:40:30% O2:CO2:N2) and vacuum skin packaging (VSP) for pork bellies with low (LF: 16.07 ± 1.87%), medium (MF: 37.39 ± 4.41%), and high fat content (HF: 57.57 ± 2.36%). Samples packaged in VSP exhibited the longest shelf life (13-14 days) with lower purge and reduced fat and colour oxidation compared to MAP-packaged samples for all studied belly types. Nonetheless, the impact of MAP on shelf life depended on the belly type. HF bellies, with lower proportions of unsaturated fatty acids, showed less purge, and greater colour and fat stability, resulting in a longer shelf life compared to LF and MF bellies. LF and MF bellies in MAP2 showed the shortest shelf life (around 6 days), followed by LF and MF in MAP1 (around 7-8 days). Life Cycle Assessment indicated VSP generally as the most environmentally favourable option for LF and MF bellies, whereas for HF bellies, the choice among the three packaging solutions depended on the specific impact category under consideration.

Janus hydrogel loaded with a CO2-generating chemical reaction system: Construction, characterization, and application in fruit and vegetable preservation.

In this study, we inserted a dynamic chemical reaction system that can generate CO2 into Janus hydrogel (JH) to develop a multidimensional preservation platform that integrates hygroscopicity, antibacterial activity, and modified atmospheric capacity. The double gel system developed using sodium alginate/trehalose at a 1:1 ratio effectively encapsulated 90% of citric acid. Furthermore, CO2 loss was avoided by separately embedding NaHCO3/cinnamon essential oil and citric acid microcapsules into a gelatin pad to develop JH. Freeze-dried JH exhibited a porous and asymmetric structure, very strongly absorbing moisture, conducting water, and rapidly releasing CO2 and essential oils. Furthermore, when preserving various fruits and vegetables in practical settings, JH provided several preservation effects, including color protection, microbial inhibition, and antioxidant properties. Our study findings broaden the application of JH technology for developing chemical reaction systems, with the resulting JH holding substantial promise for cold chain logistics.

The impact of ozone and equilibrium-modified atmosphere packaging on storage stability and health-promoting indicators of fresh "Angelino" plums.

Effectiveness of ozone concentrations (2, 5, and 10 ppm) and exposure time (3 and 9 min) on selected physicochemical properties (pH, soluble solids, color values (L*, a*, and b*), and texture) and health-promoting indicators such as organic acids, total phenolics (TP), and anthocyanins of "Angelino" fresh plums was evaluated during storage (0, 30, 90, and 120 days) in equilibrium modified atmosphere packaging (EMAP). Total anthocyanin contents and organic acid profiles were significantly affected by storage times. Malic acid (MA) was the main organic acid in "Angelino" plums. MA content (4663 and 4764 mg/L) was the highest value in the ozonated 2-ppm/9-min and 5-ppm/3-min than other ozonated groups and also control at 120 days of the storage. The ozone treatments especially 2-ppm/9-min and 5-ppm/3 min can significantly retard the degradation of MA content (8294 to 2688-2694 mg/L) during the storage (p < .05). Total phenol content were most significantly decreased in the control during storage, with the loss at the level of 31.7% of TPs, while the lowest one 2-ppm/9-min (20.8%) and 5-ppm/-3 min (21.9%). The color and texture are maintained for the ozone applications compared to the control during storage. Ozonation with 2-ppm/9-min and 5-ppm/-3 min showed the best performance while maintaining the storage stability based on the physicochemical properties including hardness and bioactive compounds (such as anthocyanins and organic acids), visual appearance due to the more attractive color (L*, a*, b*) the plums.

Effect of VP, MAP and combined packaging systems on the physicochemical properties and microbiological status of veal from unweaned calves.

The packaging system is one of the factors influencing the preservation of the nutritional value, microbiological safety, and sensory attributes of meat. The study investigated changes in physicochemical and microbiological properties taking place during 15-day refrigerated storage of two calf muscles, the longissimus lumborum (LL) and semitendinosus (ST), packaged in three systems, respectively, vacuum packing (VP), modified atmosphere packaging (MAP, 80% O2 + 20% CO2), and a combined system (VP + MAP, 8 d in VP followed by 7 d in MAP). LL and ST stored in VP had significantly lower levels of lipid oxidation, higher α-tocopherol content, and higher instrumentally measured tenderness in comparison with the samples stored in MAP. On the other hand, the MAP samples had lower purge loss at 5 and 15 days, a higher proportion of oxymyoglobin up to 10 days of storage, and a better microbiological status. Calf muscle samples stored in the VP + MAP system had intermediate values for TBARS and α-tocopherol content and at the same time were the most tender and had the lowest counts of Pseudomonas and Enterobacteriaceae bacteria at 15 days. All packaging systems ensured relatively good quality of veal characteristics up to the last day of storage. However, for MAP at 15 days of storage, unfavourable changes in colour (a high level of metmyoglobin and a decrease in oxymyoglobin, redness and R630/580 ratio) and in the lipid fraction (a high TBARS value and a significant decrease in α-tocopherol content) were observed.

Investigation of oxygen packaging to maintain beef color stability and microbiology safety after periods of long-term superchilled storage.

This study aimed to develop an appropriate modified atmosphere packaging (MAP) system for displayed beef steaks following long-term superchilled (-1 °C) storage. After superchilled storage for 0, 2, 8, or 16 weeks, beef loins were fabricated into steaks and displayed with 20%, 50%, or 80% O2-MAP under chilled conditions. At each storage point, after display for 0, 3, 7, or 10 days, instrumental color, myoglobin redox forms percentage, lipid oxidation, total viable count (TVC), and total volatile basic nitrogen (TVB-N) were evaluated. Meat color stability decreased, with prolonged storage period and display time. When the storage period was within 8 weeks, under all the above MAP conditions, the display time for the beef steaks was up to 10 days. Considering 80% O2-MAP promoted lipid oxidation, 50% and 80% O2-MAP were not recommended for displaying steaks for more than 10 and 7 days respectively after 16 weeks of storage. However, 20%, 50%, or 80% O2-MAP could maintain 3 days of microbial shelf-life according to TVC and TVB-N results. Additionally, after long-term superchilled storage for 16 weeks, the various O2 concentrations had minimal impact on microbiota succession during the MAP display period. Furthermore, beef steaks packaged under various MAP systems exhibited similar microbial compositions, with the dominant bacteria alternating between Lactobacillus and Carnobacterium. This study provided practical guidance for improving beef color stability after long-term superchilled storage.

Transcriptome responses of Lactococcus paracarnosus to different gas compositions and co-culture with Brochothrix thermosphacta.

Lactococcus (Lc.) paracarnosus and the phylogenetically closely related Lc. carnosus species are common members of the microbiota in meat stored under modified atmosphere and at low temperature. The effect of these strains on meat spoilage is controversially discussed. While some strains are known to cause spoilage, others are being studied for their potential to suppress the growth of spoilage and pathogenic bacteria. In this study, Lc. paracarnosus DSM 111017T was selected based on a previous study for its ability to suppress the growth of meat spoilers, including Brochothrix thermosphacta. The mechanism by which this bioprotective strain inhibits competing bacteria and how it contributes to spoilage are not yet known. To answer these two questions, we investigated the effect of four different headspace gas mixtures (simulated air (21 % O2/79 % N2); HiOx-MAP (70 % O2/30 % CO2); nonOx-MAP (70 % N2/ 30 % CO2); simulated vacuum (100 % N2) and the presence of Brochothrix (B.) thermosphacta TMW 2.2101 on the growth and transcriptional response of Lc. paracarnosus DSM 111017T when cultured on a meat simulation agar surface at 4 °C. Analysis of genes specifically upregulated by the gas mixtures used revealed metabolic pathways that may lead to different levels of spoilage metabolites production. We propose that under elevated oxygen levels, Lc. paracarnosus preferentially converts pyruvate from glucose and glycerol to uncharged acetoin/diacetyl instead of lactate to counteract acid stress. Due to the potential production of a buttery off-flavour, the strain may not be suitable as a protective culture in meat packaged under high­oxygen conditions. 70 % N2/ 30 % CO2, simulated vacuum- and the presence of Lc. paracarnosus inhibited the growth of B. thermosphacta TMW 2.2101. However, B. thermosphacta did not affect gene regulation of metabolic pathways in Lc. paracarnosus, and genes previously predicted to be involved in B. thermosphacta growth suppression were not regulated at the transcriptional level. In conclusion, the study indicates that the gas mixture used in packaging significantly affects the metabolism and spoilage potential of Lc. paracarnosus and its ability to inhibit B. thermosphacta growth.

Comparative proteomic analyses to investigate premature browning in high­oxygen modified atmosphere packaged beef patties.

This study compared the proteomics of beef patties under high­oxygen modified atmosphere packaging (HiOx-MAP) and vacuum packaging (VP) during heating. The color and oxidation stability of fresh patties, and myoglobin denaturation of cooked patties were also measured. The results suggested that HiOx-MAP patties contained more oxymyoglobin in fresh meat and had higher myoglobin denaturation during heating than VP patties, resulting in premature browning (PMB) during cooking. Proteomic analysis found that the overabundance of proteasome subunit beta type-2 (PSMB2) and peroxiredoxin-2 (PRDX2) in HiOx-55 °C, which can remove the damaged proteins and inhibit oxidation respectively, are of benefit to meat color stability during storage, however, this was still insufficient to inhibit the occurrence of PMB during cooking. The high abundance of lamin B1 (LMNB1) in VP-55 °C can maintain the stability of meat color. This research provides greater understanding, based on proteomic perspectives, of the molecular mechanism of PMB.

High­oxygen-modified atmospheric packaging delays flavor and quality deterioration in fresh-cut broccoli.

The purpose of this study was to investigate the impact of high­oxygen-modified atmospheric packaging (HOMAP) on aroma changes in fresh-cut broccoli during storage and to explore its regulatory mechanisms. The results showed that HOMAP reduced the levels of undesirable aroma substances hexanoic acid, isobutyric acid, cyclopentanone and increased glucosinolate accumulation by inhibiting the expression of arogenate/prephenate dehydratase (ADT), bifunctional aspartate aminotransferase and glutamate/aspartate-prephenate aminotransferase (PAT), thiosulfate/3-mercaptopyruvate Transferase (TST) to reduce the odor of fresh-cut broccoli. HOMAP inhibited the expression of respiratory metabolism related genes 6-phosphate fructokinase 1 (PFK), pyruvate kinase (PK), and NADH-ubiquinone oxidoreductase chain 6 (ND6). In HOMAP group, the low expression of phospholipase C (PLC), phospholipase A1 (PLA1), linoleate 9S-lipoxygenase 1 (LOX1) related to lipid metabolism and the high expression of naringenin 3-dioxygenase (F3H), trans-4-Hydroxycinnamate (C4H), glutaredoxin 3 (GRX3), and thioredoxin 1 (TrX1) in the antioxidant system maintained membrane stability while reducing the occurrence of membrane lipid peroxidation.

Improving the storage quality and suppressing off-flavor generation of winter jujube by precise micro-perforated MAP.

Introduction: Traditional modified atmosphere packaging (MAP) cannot meet the preservation requirements of winter jujube, and the high respiration rate characteristics of winter jujube will produce an atmosphere component with high CO2 concentration in traditional MAP. Micro-perforated MAP is suitable for the preservation of winter jujube due to its high permeability, which can effectively remove excess CO2 and supply O2. In this study, a microporous film preservation system that can be quickly applied to winter jujube was developed, namely PMP-MAP (precise micro-perforated modified atmosphere packaging). An experiment was designed to store winter jujube in PMP-MAP at 20°C and 2°C, respectively. The quality, aroma and antioxidant capacity, etc. of winter jujube at the storage time were determined. Methods: In this study, the optimal micropore area required for microporous film packaging at different temperatures is first determined. To ensure the best perforation effect, the effects of various factors on perforation efficiency were studied. The gas composition within the package was predicted using the gas prediction equation to ensure that the gas composition of the perforated package achieved the desired target. Finally, storage experiments were designed to determine the quality index of winter jujube, including firmness, total soluble solids, titratable acid, reddening, and decay incidence. In addition, sensory evaluation, aroma and antioxidant capacity were also determined. Finally, the preservation effect of PMP-MAP for winter jujube was evaluated by combining the above indicators. Results and discussion: At the end of storage, PMP-MAP reduced the respiration rate of winter jujube, which contributed to the preservation of high total soluble solids and titratable acid levels, and delayed the reddening and decay rate of winter jujube. In addition, PMP-MAP maintained the antioxidant capacity and flavor of winter jujube while inhibiting the occurrence of alcoholic fermentation and off-flavors. This can be attributed to the effective gas exchange facilitated by PMP-MAP, thereby preventing anaerobic stress and quality degradation. Therefore, the PMP-MAP approach is an efficient method for the storage of winter jujube.

Application of poly(L-lactic acid)-based films for equilibrium modified atmosphere packaging of "Kyoho" grapes and its favorable protection for anthocyanins.

Grapes were packaged by different Poly (L-lactic acid)-based packaging films (PLTL-PLEL) and stored at 5 °C for 35 days to investigate the effects of equilibrium modified atmosphere packaging on the quality of "Kyoho" grapes during storage. Changes in physiochemical quality, antioxidant content and senescence of grapes were studied. Furthermore, UPLC-Q-TOF-MS/MS was used to observe and identify key factors influencing the variation of grape anthocyanins under different atmosphere conditions. Alterations in gas components and enzyme activities significantly impacted anthocyanin levels, highlighting oxygen concentration as the primary influence on total anthocyanin levels. The PLTL-PLEL50 packaging resulted in an approximate 5.7% lower weight loss and increased soluble solids by approximately 14.4%, vitamin C, total phenols and flavonoids reaching 60.2 mg/100 g, 8.4 mg/100 g and 7.2 mg/100 g, respectively. This packaging also preserved higher anthocyanin levels, with malvidin-3-glucoside and peonidin-3-glucoside at 0.55 µg/mL and 1.62 µg/mL, respectively, on the 35th day of storage.

An analysis of conventional and modern packaging approaches for cut flowers: a review article.

Fresh-cut flowers are considered to be one of the most delicate and challenging commercial crops. It is important to take into consideration how to minimize loss during storage and transportation when preserving cut flowers. Many impinging (bad effect) forces can interact to shorten the flowers' vase life. In the flower industry, effective methods need to be developed to extend freshly cut flowers' life. Fresh-cut flowers' vase life can be shortened by a variety of interlocking causes. The flower industry must develop new techniques to extend the flowers' vase lifespan. This review provides comprehensive, up-to-date information on classical, modified atmosphere packaging (MAP), and controlled atmosphere packaging (CAP) displays. According to this review, a promising packaging technique for fresh flowers can be achieved through smart packaging. A smart package is one that incorporates new technology to increase its functionality. This combines active packaging, nanotechnology, and intelligence. This technology makes it easier to keep an eye on the environmental variables that exist around the packaged flowers to enhance their quality. This article offers a comprehensive overview of creative flower-saving packaging ideas that reduce flower losses and assist growers in handling more effectively their flower inventory. To guarantee the quality of flowers throughout the marketing chain, innovative packaging techniques and advanced packaging technologies should be adopted to understand various package performances. This will provide the consumer with cut flowers of standard quality. Furthermore, sustainable packaging is achieved with circular packaging. We can significantly reduce packaging waste's environmental impact by designing reused or recyclable packaging.

Comparison of Gas Treatments of High Oxygen, Carbon Monoxide, and Nitric Oxide on Ground Beef Color in Modified Atmosphere Packaging.

The objective of this study was to evaluate the viability and performance of nitric oxide modified-atmosphere packaging (MAP) as a novel alternative to high oxygen and carbon monoxide MAP for ground beef. Packages of ground beef under high oxygen (HI-OX), carbon monoxide (CO), and nitric oxide (NO) atmospheres were evaluated for descriptive and instrumental color every 12 h during a 120 h display period. Surface myoglobin percentages, internal cooked color, thiobarbituric acid reactive substances (TBARS), and residual nitrite and nitrate were also evaluated. There were gas × time interactions for descriptive color, discoloration, a* values, b* values, deoxymyoglobin percentages, and metmyoglobin percentages (p < 0.05). There were also gas-type main effects for cooked color and TBARS (p < 0.05). Carbon monoxide maintained the most redness and least discoloration throughout the display period, while HI-OX started with a bright red color but rapidly browned (p < 0.05). Nitric oxide started as dark red to tannish-red but transitioned to a dull red (p < 0.05). However, NO had increased redness and a* values for internal cooked color (p < 0.05). Although CO outperformed NO packages, NO exhibited a unique color cycle warranting further research to optimize its use.

Oxidative Modification, Structural Conformation, and Gel Properties of Pork Paste Protein Mediated by Oxygen Concentration in Modified Atmosphere Packaging.

The objective of this study was to investigate the effect of pork oxidation through modified atmosphere packaging (MAP) on gel characteristics of myofibrillar proteins (MP) during the heat-induced gelation process. The pork longissimus thoracis (LT) was treated by MAP at varying oxygen concentrations (0, 20, 40, 60, and 80% O2) with a 5-day storage at 4 °C for the detection of MP oxidation and gel properties. The findings showed the rise of O2 concentration resulted in a significant increase of carbonyl content, disulfide bond, and particle size, and a decrease of sulfhydryl content and MP solubility (p < 0.05). The gel textural properties and water retention ability were significantly improved in MAP treatments of 0-60% O2 (p < 0.05), but deteriorated at 80% O2 level. As the concentration of O2 increased, there was a marked decrease in the α-helix content within the gel, accompanied by a simultaneous increase in ß-sheet content (p < 0.05). Additionally, a judicious oxidation treatment (60% O2 in MAP) proved beneficial for crafting dense and uniform gel networks. Our data suggest that the oxidation treatment of pork mediated by O2 concentration in MAP is capable of reinforcing protein hydrophobic interaction and disulfide bond formation, thus contributing to the construction of superior gel structures and properties.

Evaluation of the Shelf life of Ready-to-Eat Fresh Bamboo Sprouts (Phyllostachys edulis) Packaged in a Modified Atmosphere or Vacuum: A Comparative Study.

During the last decades, the consumption of bamboo sprouts (Phyllostacys edulis) has increased because they are considered a "superfood". However, this product is characterized by a short shelf life due to the deterioration in quality parameters. The aim of this study was to investigate the application of two modified atmosphere packaging (MAP) systems (MAP1: 2% O2, 5% CO2, 93% N2 and MAP2: 3% O2, 7% CO2, 90% N2) to fresh-shelled ready-to-eat bamboo sprouts and compare these packaging systems with vacuum packaging during storage for 28 days at 4 °C using heat-sealable polyamide and polyethylene (PA/PE) trays. Several chemical-physical parameters (moisture content, water activity, pH, headspace composition, and firmness) were monitored, as well as CIELab colorimetric parameters and microbial growth. The quantification of selected organic acids was performed via UHPLC. Mathematical kinetic models were applied to study the evolution of total phenol (TPC), flavonoid (TFC), and carotenoid content (TCC) during storage. The evolution of antioxidant potential investigated by ABTS, DPPH, and ß-carotene bleaching tests was also assessed. Results showed that at the end of the storage period, significant variations in the colorimetric parameters are detectable between the sprouts apical portion and the basal one, regardless of both applied MAPs. A linear reduction in both DPPH and ABTS radical scavenging activity was evidenced during storage, regardless of the type of packaging applied. In DPPH test samples packaged in MAP after 28 days of storage, they retain good antioxidant activity, whereas in vacuum, this activity is reduced by 50% compared to the initial value (IC50 values from 24.77 to 32.74 µg/mL and from 24.77 to 71.12 µg/mL for MAP2 and vacuum, respectively).

Combined effect of electrolyzed water (EW) and sonication with equilibrium modified atmosphere packaging for prolonging storage stability of fresh strawberry.

This research focuses on the effectiveness of electrolyzed water (50 and 100 ppm for 3 min), ultrasonication (80 W for 3 min), and their combinations on fresh strawberries, which are then packaged using microperforated film to enhance their storage stability. The gas composition in the headspace, pH, soluble solids, color (L*, a*, b*, and ΔE* values), anthocyanins, total phenolics, and texture profile was evaluated for the 35 days of storage at +4 °C. The lowest weight loss was measured at about 100 ppm electrolyzed water (EW; 0.47%), and the highest one was in the control group (0.57%) after storage. At the end of the storage, O2 in the headspace decreased from 20.90% to 10.50-8.10% and CO2 was accumulated from 0.03% to 16.4-14.34%. The results showed that soluble solids decreased (9.95 to 8.48-7.85 °Bx) and pH values increased (3.34 to 3.79-3.91) during storage. At the end of the storage, the total phenolics in the control group decreased by the most during storage (from 1209.09 ppm to 808.00 ppm), whereas the 50 ppm EW group had the highest (931.66 ppm). Further, the significantly highest anthocyanin amount was found to be 143.86 ppm in the 100 ppm EW group at the end of 28 days of storage. The EW can significantly delay the degradation of anthocyanin over the storage period. The sonication at 100 ppm EW damages strawberry tissues, reducing their hardness. The lowest decay rate was found in fruits treated with 100 ppm EW (41.67%), followed by 50 ppm EW (58.33%), compared to the control (75.00%). This study reveals that applications of the 50 ppm EW and also 50 pm EW combined with ultrasonication have great potential in the extending storage stability of the fresh strawberries.

Design of equilibrium modified atmosphere packaging for postharvest cabbages preservation based on introducing available active sites into film materials as gas transport channels.

This work aims to explore an available avenue to design an equilibrium modified atmosphere packaging (EMAP) by the modification of gas permeability of material. In this work, the introduction of available active sites endowed materials with adjustable gas permeability properties. With varying concentrations of the resulting materials with various gas permeability, the CO2 and O2 gas permeability of the blending films were modified at the range of 3.92 âˆ¼ 17.84 barrier and 0.65 âˆ¼ 3.46 barrier, respectively. On this basis, the films were used as EMAP to preserve postharvest cabbages. The results indicated that each EMAP achieved an equilibrium atmosphere containing 6.8 % ∼ 3.8 % CO2 and 2.1 % ∼ 5.2 % O2 within 15 h and maintained it continuously. In these atmosphere, the respiratory rate of the preserved cabbages was significantly inhibited, thereby delaying the deterioration of their storage quality. As the results, sensory scores of the preserved samples were maximally maintained. Declines of color indexes and texture indexes were obviously inhibited. Chemical variations in chlorophyll content, total phenolics content, total flavonoids content, ascorbic acid and nitrite content were significantly suppressed. The overall findings revealed that this method is suitable and promising to develop EMAP for the postharvest vegetables.

Circular genomes of two bacterial strains capable of growing in a CO2-containing atmosphere.

The bacterial strains Brochothrix thermosphacta DH-B18 and Rathayibacter sp. DH-RSZ4 were isolated from raw sausage and escalope samples and grown in a CO2-rich modified atmosphere. Here, we present both circular genomes obtained by nanopore sequencing.

The effect of modified atmosphere packaging at an early postmortem stage on lamb meat quality during subsequent aging.

This study explores the influence of modified atmosphere packaging (MAP) on fresh lamb meat quality with respect to gas concentration, rigor state, and post-mortem aging time. A comparison was done for the quality characteristics of lamb Longissimus thoracis lumborum chops that had been packaged separately in air, 75%O2  + 25%CO2 MAP or 50%O2  + 50%CO2 MAP at 1, 6, and 24 h post-mortem and then stored for 6, 12, 24, 72, and 144 h post-mortem, and the quality of lamb chops had been evaluated at each post-mortem period separately. Chops packaged at 1 and 6 h post-mortem in MAP had reduced pH decline, less purge loss, and enhanced redness at early post-mortem storage times. Lamb color stability was evidently greater in 75%O2  + 25%CO2 MAP than in 50%O2  + 50%CO2 MAP during the early storage period when a* and R630/R580 were taken into account. Shear force values were lowest in lambs packaged at 1 h post-mortem with 75%O2  + 25%CO2 MAP at 12 h post-mortem and then increased until 72 h post-mortem, suggesting that rigor has been delayed by such a high O2 MAP. Thus, fresh lamb quality was maintained most effectively when packaged at 1 h post-mortem in 75%O2  + 25%CO2 MAP for consumption at 12 h post-mortem. The exact mechanisms and optimization of MAP based on Chinese retail conditions should be considered in future studies. PRACTICAL APPLICATION: In this study, three slaughter patterns in the meat industry involving boning immediately after dressing (hot-boning) and chilling for a short period (warm-boning) or overnight (cold-boning) are considered, as well as the behavior of non-immediate consumption after purchase. Modified atmosphere packaging provides an effective preservation of early post-mortem muscles with enhanced color stability, water holding capacity, and texture during refrigerated storage. This could provide new insights into how to process lamb muscles in the early post-mortem period to improve and stabilize lamb quality.

Effects of CO2 on the physicochemical, microbial, and sensory properties of pork patties packaged under optimized O2 levels.

The storage quality characteristics of fresh pork patties were investigated under 80% O2 modified atmosphere packaging (MAP80:20 = 80% O2/20% CO2) and 40% O2 MAP with various CO2 levels (MAP40:20 = 40% O2/20% CO2/40% N2; MAP40:40 = 40% O2/40% CO2/20% N2; MAP40:60 = 40% O2/60% CO2). Packaged patties were stored for 16 days at 4 °C to monitor their physicochemical (pH, instrumental color, oxidative stability, and fatty acid profile), microbial, and sensorial changes. Results suggested that decreasing O2 levels from 80% to 40% significantly inhibited the lipid oxidation of patties but led to a lower (P < 0.05) color stability. Elevating CO2 levels from 20% to 60% in combination with 40% O2 significantly suppressed bacterial growth and total volatile basic nitrogen production, and thus rendered patties with a better sensory quality and a similar meat color to 80% O2. However, increased CO2 levels promoted lipid oxidation through reducing the antioxidant capacity of patties, which was attributed to a CO2-induced reduction in superoxide dismutase and glutathione peroxidase activities during storage rather than a pH reduction or changes in fatty acid composition. Overall, 40% O2/40% CO2/20% N2 is a realistic alternative for pork patties to improve meat quality and extend the shelf-life to over 16 days.