High-oxygen modified atmosphere packaging system induces lipid and myoglobin oxidation and protein polymerization

Beef steaks from longissimus lumborum, semimembranosus, and adductor muscles (n = 10; respectively) were cut at 24 h postmortem, randomly assigned to either high-oxygen modified atmosphere packaging (HiOx-MAP; 80% O₂, 20% CO₂) or vacuum (VAC), and displayed for 9 days at 1 °C. HiOx-MAP packaged beef steaks had a rapid increase in lipid oxidation and a decrease in color stability during display. The steaks in HiOx-MAP had significantly lower tenderness and juiciness scores, and higher off-flavor scores compared to steaks in VAC. HiOx-MAP condition did not affect the postmortem degradation of troponin-T or desmin. Furthermore, autolysis of μ-calpain was not influenced by packaging. SDS–PAGE, immunoblotting, and diagonal-PAGE revealed oxidative cross-linking of myosin heavy chain in meat packaged in HiOx-MAP. These results suggest that the HiOx-MAP system may negatively affect meat quality characteristics by inducing lipid and myoglobin oxidation and cross-linking/aggregation of myosin by protein oxidation.     

The effects of high oxygen modified atmosphere packaging on protein oxidation of bovine M. longissimus dorsi muscle during chilled storage

Modified atmosphere packaging (MAP) extends the shelf life of beef, especially in the context of visual colour. High O₂ MAP (70-80%) may cause quality deterioration through lipid and protein oxidation, the latter linked to a reduction in meat tenderness. The objective of this study was to investigate the effects of MAP in comparison to vacuum packaging (VP) on protein oxidation and subsequent tenderness of LD (M. longissimus dorsi) beef steaks during chilled storage (4 °C) of periods up to 14 days. Steaks were analysed for carbonyl content, free thiol groups, drip loss, Warner-Bratzler shear force (WBSF) and SDS-PAGE of extracted myofibrillar proteins. Free thiol groups were lower in high O₂ MAP (80% O₂/20% CO₂) steaks, after 14 days of storage, indicating protein oxidation compared to VP steaks. SDS-PAGE (non reducing conditions) showed the presence of high molecular weight cross linked myosin heavy chain aggregates in the high O₂ atmosphere packaged steaks, which were absent in VP steaks.     

The combined effect of antioxidants and modified atmosphere packaging on protein and lipid oxidation in beef patties during chill storage

Effect of rosemary extract and ascorbate/citrate (1:1) in combination with modified atmosphere packaging (100% N(2), 80% O(2)/20% N(2)) on protein and lipid oxidation in minced beef patties during storage in the dark for up to 6 days at 4°C was investigated. A high level of oxygen in the packaging atmosphere was found to increase both lipid and protein oxidation during storage as evaluated by TBARS analysis of secondary lipid oxidation products and by 2,4-dinitrophenylhydrazine derivatization of protein carbonyls. Both antioxidant systems tested were found to inhibit lipid oxidation but not protein oxidation. In contrast, ascorbate/citrate was found to promote protein oxidation. Rosemary extract was found to regenerate or protect α-tocopherol whereas the packaging atmospheres had no effect on α-tocopherol stability. In high oxygen atmospheres both antioxidants protected the fresh red meat colour with ascorbate/citrate being more efficient than the rosemary extract, whereas no effect of antioxidant on meat colour was found in beef patties stored in 100% nitrogen.     

The effect of protein oxidation on hydration and water-binding in pork packaged in an oxygen-enriched atmosphere

This study investigated the in situ oxidative process of myofibrillar proteins in boneless pork loin chops (Longissimus lumborum) packaged in an oxygen-enriched atmosphere (HiOx: 80% O₂/20% CO₂), an air-permeable polyvinylchloride (PVC) overwrap, or a partial vacuum (VP) throughout display at 2 °C for up to 14, 7, and 21 days, respectively. Samples stored in HiOx were susceptible to lipid (TBARS) and protein (carbonyls, sulfhydryls, and aggregation) oxidation, while samples in PVC and VP showed lesser oxidative changes. Water-holding capacity of raw muscle decreased (P < 0.05) when stored in HiOx but not in PVC and VP. Upon salt and phosphate brine marination, HiOx and PVC muscle samples had improved hydration capacity during display compared with non-stored control, but display generally decreased hydration of VP samples. The result was in agreement with myofibril structural changes. Despite the enhanced hydration, HiOx muscle was least capable of withholding moisture upon cooking.     

Packaging-specific influence of chitosan on color stability and lipid oxidation in refrigerated ground beef

We examined the influence of chitosan on lipid oxidation and color stability of ground beef stored in different modified atmosphere packaging (MAP) systems. Ground beef patties with chitosan (1%) or without chitosan (control) were packaged either in high-oxygen MAP (HIOX; 80% O₂ + 20% CO₂), carbon monoxide MAP (CO; 0.4% CO + 19.6% CO₂ + 80% N₂), vacuum (VP), or aerobic packaging (PVC) and stored at 1 °C. Chitosan increased (P < 0.05) redness of patties stored in PVC and CO, whereas it had no effect (P > 0.05) in HIOX. Chitosan patties demonstrated lower (P < 0.05) lipid oxidation than controls in all packaging. Control patties in PVC and HIOX exhibited greater (P < 0.05) lipid oxidation than those in VP and CO, whereas chitosan patties in different packaging systems were not different (P > 0.05) from each other. Our findings suggested that antioxidant effects of chitosan on ground beef are packaging-specific.     

Color stability of ground beef packaged in a low carbon monoxide atmosphere or vacuum

Ground beef was either packaged in an atmosphere of 0.4% CO, 30% CO₂, and 69.6% N₂ (CO-MAP) or vacuum. After storage (48 h, 2–3 °C), packages of CO-MAP and vacuum were opened and overwrapped with polyvinyl chloride. Other CO-MAP and vacuum packages were left intact. Packages were initially displayed for 7 days (2–3 °C). Intact packages were further displayed up to 35 days before being opened and displayed (1 or 3 days). Intact CO-MAP packaged ground beef was always more red than intact vacuum-packaged ground beef. Color was relatively stable for both types of intact packages over 35 days of display. Upon opening CO-MAP packaged ground beef, the red color decreased slower than in ground beef from vacuum packages.     

Effects of oxygen concentration on the sensory evaluation and quality indicators of beef muscle packed under modified atmosphere

Beef steaks are commonly displayed under high oxygen concentrations in modified atmosphere packs (MAP) in order to promote colour stability. Such conditions, however, may also cause quality deterioration through lipid oxidation and decreased tenderness. The objective of this study was to investigate the effects of oxygen concentration (0%, 10%, 20%, 50% and 80%) on the quality of MAP beef steaks (M. longissimus dorsi). Steaks were stored at 4°C for 15 days and tested for lipid and protein oxidation, heme iron, colour, oxymyoglobin concentration, tenderness and sensory acceptability (up to day 12) for the resulting cooked meat. Sensory panellists expressed a preference for steaks stored in packs containing 50% oxygen, despite detecting oxidised flavours under these conditions. This could be the result of adaptation to, or familiarity with, oxidised flavours by panellists.     

Effects of lactate and modified atmospheric packaging on premature browning in cooked ground beef patties

Our objectives were to determine the effects of lactate and modified atmosphere packaging on raw surface color, lipid oxidation, and internal cooked color of ground beef patties. Eight chubs (85% lean) were divided in half and each half was either assigned to the control (no lactate) or mixed with 2.5% lactate (w/w). Following treatment, patties were prepared and packaged in either vacuum, PVC (atmospheric oxygen level), high-oxygen (80% O₂ + 20% CO₂), or 0.4% CO (30% CO₂ + 69.6% N₂) and stored for 0, 2, or 4 days at 2 °C. After storage, raw surface color and lipid oxidation were measured and patties were cooked to either 66 °C or 71 °C. Lactate improved (p < 0.05) color stability of PVC, high-oxygen, and vacuum packaged raw patties, but had no effect (p > 0.05) on the a∗ values and visual color scores of patties in 0.4% CO. Lactate decreased (p < 0.05) lipid oxidation in all packaging atmospheres. Nevertheless, high-oxygen and PVC-packaged patties had more (p < 0.05) lipid oxidation than patties in CO and vacuum. Lactate had no effect (p > 0.05) on premature browning, whereas patties packaged in high-oxygen demonstrated premature browning. Conversely, cooked patties in 0.4% CO and vacuum were more red (p < 0.05) than both high-oxygen and PVC-packaged patties. Although lactate improved raw color stability, it did not minimize premature browning in cooked ground beef patties.     

Effect of aging time in vacuum on tenderness,and color and lipid stability of beef from mature cows during display in high oxygen atmosphere package

The effect of aging time in vacuum on tenderness, and lipid and color stability of modified-atmosphere packaged (MAP) beef during display was evaluated in eight Friesian mature cows. Longissimus thoracis et lumborum (LTL) sections were vacuum packaged and aged for 0, 3, 6, 8, 14 and 21 days. After each aging time, the LTL sections were cut into steaks and packaged in high oxygen atmosphere (80% O₂: 20% CO₂). Meat shear force, and color and lipid stability were evaluated at 0, 3, 6, and 9 days of simulated retail display. Aging for 6 or 8 days improved beef tenderness with color stability, instrumental discoloration (R₆₃₀–R₅₈₀) and visual color evaluation in MAP similar to those of short-time aged (3 d) or un-aged (0 d) beef. Longer aging times (14 and 21 d) resulted in tenderness values similar to those obtained with meat aged for 8 days but affected negatively color and lipid stability and, consequently, reduced the shelf life of beef in MAP.     

Evaluation of cholesterol and lipid oxidation in raw and cooked minced beef stored under oxygen-enriched atmosphere

Oxygen-enriched modified atmosphere packaging (MAP) represents an important means to stabilize meat colour but may lead to an increase in lipid oxidation, influencing the acceptability and safety of the product. In this work, the effect on cholesterol and lipid susceptibility to oxidation was investigated in commercial minced beef held under MAP (80% O(2)/20% CO(2)). Cholesterol oxidation products (COPs), peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) were determined, before and after pan frying, at 1, 8 and 15 days since packaging under refrigerated storage (3-4°C). 7α-Hydroxycholesterol, 7β-hydroxycholesterol and 7-ketocholesterol were the more abundant COPs identified. COPs significantly increased in raw beef during storage: after 1, 8 and 15 days since packaging COPs were at the levels of 10.4, 30.7 and 60.5μg/g of fat, respectively. Cooking did not affect cholesterol oxidation in freshly packaged minced beef but led to a rise in COPs amount with respect to raw muscle after 8 and 15 days of storage. The trend in cholesterol oxidation reflected the progressive increase in lipid peroxidation rate brought by MAP conditions.     

Effect of varying the gas headspace to meat ratio on the quality and shelf-life of beef steaks packaged in high oxygen modified atmosphere packs

Beef steaks (M. longissimus dorsi) were stored in modified atmosphere packs (MAP) (80% O₂:20% CO₂) with gas headspace to meat ratios of 2:1, 1:1 and 0.5:1 for 14 days at 4 °C. The pH, surface colour, texture and microbiology of beef steaks were unaffected (P > 0.05) by varying the gas headspace to meat ratio. APLSR (ANOVA-partial least squares regression) and jack-knife uncertainty testing indicated that lipid oxidation (TBARS) was significantly positively correlated with days 10 (P < 0.05) and 14 (P < 0.001) of storage. Chemical and sensory detection of lipid oxidation in beef steaks were in agreement on day 14 of storage. The sensory quality and acceptability of beef steaks were similar in gas headspace to meat ratios of 2:1 or 1:1 and unacceptable in 0.5:1. Results indicate that pack size and gas volume can be reduced without negatively affecting fresh beef quality and shelf-life.     

Mild protein oxidation enhanced hydration and myofibril swelling capacity of fresh ground pork muscle packaged in high oxygen atmosphere

Abstract: This study investigated the influence of an oxygen‐enriched modified atmosphere packaging (HiOx: 80% O₂/20% CO₂) in comparison with air‐permeable polyvinylchloride (PVC) wrapping and partial vacuum (VP: 60%) packaging on the ability of myofibrils to imbibe water during retail display of fresh ground pork at 2 to 4 °C. Both HiOx and PVC muscles after 4 d showed maximum myofibril swelling and A‐band dissolution when isolated myofibrils were subjected to a graded series of salt solutions (0.2→0.4 M NaCl with 10‐mM sodium pyrophosphate, pH 6.2), while VP samples exhibited no remarkable change. Protein carbonyl content increased substantially from day 0 to 4 in all muscle samples. For HiOx, muscle hydration capacity increased linearly (P < 0.05) during storage up to 14 d, corresponding to protein carbonyl production. No significant changes in hydration properties were noted in VP muscle samples, which also maintained lower levels of protein oxidation, during storage up to 21 d. These results indicated that packaging in modified atmosphere with high levels of oxygen could result in increased protein oxidation but enhanced hydration capacity of fresh meat. Practical Application: Packaging of fresh meat, including ground pork, under an oxygen‐enriched atmosphere condition is widely used in the industry to preserve red color of meat. Results from the present study indicate that high oxygen packaging has a discordant effect on fresh ground pork: it enhances hydration but decreases water‐binding, and this seems to be caused by increased swelling of muscle fibers due to mild protein oxidation. Hence, it is advisable to employ a water‐binding agent in this type of packaging system so as to retain the moisture in stored fresh pork products while maintaining the color stability.     

Effect of white grape extract and modified atmosphere packaging on lipid and protein oxidation in chill stored beef patties

The oxidative stability of beef patties added 500 ppm white grape extract (WGE), packed in four different modified atmospheres (MAP) with varying oxygen and carbon dioxide levels (70% or 0% O₂, 30% or 0% CO₂, balanced with N₂ in all four combinations) and stored for up to 9 days (4 °C) was evaluated by a sensory panel, formation of TBARS, formation of protein carbonyl, appearance of myosin cross-links, and thiol loss. Formation of secondary lipid oxidation products, as detected by TBARS, and the rancidity, as perceived by sensory analysis, were inhibited in WGE beef patties independent of MAP compared to control beef patties. The protein carbonyl formation was also reduced in WGE beef patties, but no significant effects were observed in relation to different MAP. Loss of thiol groups in control beef patties was consistent with the formation of myosin cross-linkages. In the presence of WGE, thiol groups decreased faster but showed less myosin cross-link formation compared to control beef patties, indicating that WGE interacts with the thiol groups of the myofibrillar proteins, and thus reduces the cross-link formation in beef patties stored in high-oxygen MA.     

Measurement of lipid oxidation and porphyrins in high oxygen modified atmosphere and vacuum-packed minced turkey and pork meat by fluorescence spectra and images

This paper illustrates that fluorescence spectroscopy and imaging can be used to measure the extent and distribution of lipid oxidation in meat. Minced turkey thighs and pork semimembranosus muscles were stored for 7 and 12 days at 4°C in high oxygen (O(2)) modified atmosphere packages and vacuum. Turkey meat packed in high O(2) atmosphere was oxidised already after 7 days of storage. The sensory rancid odour score was 4.7 (on a scale from 1 to 9) and the TBARS value was 1.86mg MDA/kg. There was also an increase in fluorescence emission intensity in the 410-550nm region, which arises from lipid oxidation products. The combination of unsaturated fatty acids and access to O(2) resulted in lipid oxidation gradients in the turkey meat samples, and these gradients were clearly visualised by fluorescence images. In comparison, pork meat was more stable against lipid oxidation, with TBARS values <0.2mg MDA/kg and no development of fluorescent lipid oxidation products was detected. The fluorescence spectra measured in the present experiment suggest that turkey thighs and pork semimembranosus muscle in addition to protoporphyrin also have a natural content of Zn protoporphyrin. The porphyrin content was higher in pork meat than in turkey meat. It increased during storage time when the meat was packed in vacuum, and it decreased with O(2) availability. The distribution of porphyrins in the meat was visualised by fluorescence imaging.     

High-oxygen packaging atmosphere influences protein oxidation and tenderness of porcine longissimus dorsi during chill storage

The effect of modified atmosphere packaging (70% O(2)/30% CO(2)) and skin packaging (no oxygen) on protein oxidation and texture of longissimus dorsi was investigated during storage for 14 days at 4°C. High oxygen atmosphere resulted in reduced tenderness and juiciness and SDS-PAGE revealed cross-linking of myosin heavy chain through disulfide bonding, and the content of protein thiols was reduced indicating protein oxidation. Myofibril fragmentation was reduced in meat stored in high oxygen atmosphere indicating less proteolysis and/or cross-linking of proteins. Protein carbonyl content was not affected by the packaging atmospheres. This study shows that packaging in modified atmosphere containing a high level of oxygen can result in protein cross-linking and reduced tenderness and juiciness of the meat.     

Effect of carbon monoxide and high oxygen modified atmosphere packaging and phosphate enhanced, case-ready pork chops

The objective of this study was to evaluate the effects of CO-MAP compared to traditional high oxygen MAP (HiOx-MAP) packaging and enhanced with different phosphate on enhanced pork quality. Pork loins were enhanced to 10.5% over initial weight to contain 0.3% salt and 0.4% phosphate (either sodium tripolyphosphate [STP] or a blend of STP and sodium hexametaphosphate) on a finished weight basis. Chops were cut, packaged in atmospheres containing 0.4% CO/30.0% CO₂/69.6% N₂ (CO-MAP) or 80% O₂/20% CO₂ (HiOx-MAP), aged in the dark, then placed in a lighted retail display case for 48 h. Chops packaged in CO-MAP were redder (higher Minolta a^* values) and darker (lower Minolta b^* values) than chops packaged in HiOx-MAP. Based on sensory scores, the CO-MAP chops were pinker than the HiOx chops after cooking. CO-MAP chops also experienced less purge loss than chops in HiOx-MAP. Results indicate that CO-MAP had no effect on flavor or consumer acceptability and only minimal effects on other characteristics.     

The effects of modified atmosphere gas composition on microbiological criteria, color and oxidation values of minced beef meat

This paper reports the effects of modified atmosphere gas compositions with different concentrations of CO(2)/O(2)/N(2) on color properties (L*, a* and b* values), oxidation stability (TBARS value) and microbiological properties of minced beef meat stored at +4 °C. Sampling was carried out on the 1st, 3rd, 5th, 7th, 9th, 11th and 14th day of storage. The gas mixtures used were as follows: (i) %30O(2) + %70CO(2) (MAP1), (ii) %50O(2) + %50CO(2) (MAP2), (iii) %70O(2) + %30CO(2) (MAP3), (iv) %50O(2) + %30CO(2) + %20N(2) (MAP4), and (v) %30O(2) + %30CO(2) + %40N(2) (MAP5). Control samples (AP) were packaged under atmospheric air. Pseudomonas, lactic acid bacteria, Brochothrix thermosphacta, and Enterobacteriaceae members were monitored. Among these five modified atmosphere gas compositions, the best preservation for minced beef meat was in MAP4 gas combination maintaining acceptable color together with oxidation stability and acceptable microbial loads until the end of storage period of fourteen days.     

Effect of illumination on the display life of fresh pork sausages packaged in modified atmosphere. Influence of the addition of rosemary, ascorbic acid and black pepper

Pork forelegs were used for manufacturing fresh sausages, treated with different natural antioxidants (rosemary, ascorbic acid and black pepper), packaged in 80% O₂ + 20% CO₂ atmosphere and displayed at 2 ± 1 °C under different lightings (darkness, standard fluorescent, low-UV colour-balanced lamp and standard fluorescent plus a UV-filter). Two packs for each treatment were opened every 4 days for subsequent analysis of colour CIE L^∗, a^∗, b^∗, TBARS, microbial psychrotrophic aerobes and sensory discolouration and off-odour. Lighting with standard fluorescent was highly deleterious for sausage display life, which fell from 12 to 8 days due mainly to early discolouration. Inserting a UV-filter extended display life to 12 days, while the use of a low-UV lamp was not effective in protecting from discolouration. Addition of rosemary plus ascorbic acid, in the absence of black pepper, retarded discolouration only in sausages illuminated with the UV-filter, reaching a display life of 16 days, equal to that of sausages maintained in the dark.     

Sensory comparison of commercial low and high oxygen modified atmosphere packed sirloin beef steaks

The objectives of this study were to investigate the effects of using commercially low and high modified atmosphere packaging (MAP) on quality characteristics of sirloin beef steaks. Gas mixtures used included 80% O₂:20% CO₂ (O₂80), 70% O₂/30% CO₂ (O₂70) and 50% O₂/30% CO₂:20% N₂ (O₂50) and for commercial packs O₂75 ± 5%, CO₂25 ± 5%, < 5% N₂-(O₂Com). All samples were packed in similar tray and packaging film formats. The experimental parameters monitored included microbiological, physiochemical and sensory measurements (naïve assessors). Microbial counts did not exceed the recommended legal ranges over the storage period. However the numbers of LAB (lactic acid bacteria) were the highest for commercially-packed samples (O₂Com) in comparison to laboratory packaged samples (O₂80, O₂70 and O₂50). Commercially-packaged samples eventually spoiled due to the occurrence of off-flavours and off-odours and subsequently were the least acceptable to sensory naïve assessors.