Ageing of large cuts of beef loin in vacuum or high oxygen modified atmosphere – Effect on shear force, calpain activity, desmin degradation and protein oxidation

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.

The effect of storage method on selected physicochemical and microbiological qualities of wild boar meat

BACKGROUND

This study investigated the influence of the storage method on the physicochemical characteristics and microbial growth of m. longissimus thoracis et lumborum (LTL), m. biceps femoris (BF) and m. vastus lateralis (VL) of wild boar. Muscles were stored in a vacuum (VAC), in a modified high-oxygen atmosphere (MAP) or meat seasoning cabinet (DRY-AGED) for 21 days.

RESULTS

Wild boar meat was characterised by a high protein and low fat content and a good amount of potassium, sodium, calcium, magnesium, zinc and iron. Significantly higher (P < 0.05) pH values were noted for DRY-AGED muscles stored for 21 days (up to 5.89 for VL). On day 21, a significant decrease in pH was noted for all MAP muscles (down to 5.23 for BF). Storage losses due to desiccation and water loss were significantly higher for DRY-AGED samples and ranged from 25.63% to 32.89% on day 21. MAP affected protein and lipid oxidation, which was also reflected in Warner-Bratzler shear force VAC and DRY-AGED had positive results regarding tenderness, whereas on day 21 the MAP-stored meat had toughened significantly (from 35.3 N to 50.7 N in LTL). Lipids were oxidised much faster than proteins during prolonged storage in MAP. Compared to the other methods, DRY-AGED had the best effect on microbial growth.

CONCLUSION

These results indicate that the recommended methods for the storage of wild boar meat are either vacuum packing or dry ageing. The high oxygen content of MAP negatively affected the quality of wild boar meat and carried a risk of increased protein carbonylation. © 2022 Society of Chemical Industry.

Effects of oxygen concentrations in modified atmosphere packaging on pork quality and protein oxidation

This study aimed to investigate the effects of oxygen concentrations in modified atmosphere packaging (MAP) on pork color and protein oxidation under refrigerated storage. Pork steaks were vacuum packaged or MAP packed with different levels of oxygen (40%, 60% and 80%), and stored for 14 days at 4 °C. After storage, the instrumental color, purge loss, cooking loss and shear fore were measured, and levels of protein oxidation in both the sarcoplasmic and myofibrillar proteins were quantified separately by the determination of carbonyl contents, thiol contents, loss of specific amino acid residues, and formation of α-aminoadipic semialdehyde. Results suggested that 40% of oxygen in MAP was sufficient to obtain highest redness, and higher oxygen levels showed little improvement but led to further protein carbonylation and meat toughening. Meanwhile, the sarcoplasmic proteins seemed to be more vulnerable to protein oxidation than the myofibrillar proteins. In particular, the formation of α-aminoadipic semialdehyde might contribute little to the carbonylation of both protein fractions, and possible reasons were discussed.

Haem-mediated protein oxidation affects water-holding capacity of beef during refrigerated storage

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Both deoxymyoglobin and oxymyoglobin in muscle were converted to highly oxidised metmyoglobin.

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More free iron in muscle led to protein and lipid oxidation.

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Myoglobin, haemoglobin, protein and lipid oxidation occured simultaneously in beef during refrigeration.

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Free iron and metmyoglobin were the main oxidation catalysts in beef.

Haem is considered to be a potential producer of meat oxidation and the effect of its mediated oxidation on the water holding capacity (WHC) of beef is not yet clear. This work investigated the interrelationships between haem, protein and lipid oxidation, and WHC in beef during refrigerated storage. The increase in juice loss during storage (p < 0.05) indicates a reduction in WHC. Haem was oxidised, resulting in its structural disruption and an increase in the proportion of random coil in the protein secondary structures (p < 0.05). Extractable haem iron content was decreased and non-haem iron content was increased (p < 0.05), indicating the degradation of haem and the release of iron during storage. The levels of lipid and protein oxidation products significantly increased throughout the storage time (p < 0.05). Furthermore, Spearman analysis verified significant correlations between these changes. In conclusion, these processes are mutually reinforcing and may exacerbate muscle juice loss.

Effect of Packaging Type and Aging on the Meat Quality Characteristics of Water Buffalo Bulls

Simple Summary

The water buffalo is found worldwide, but mainly in Asian countries, i.e., India, Pakistan, and China. Buffalo meat can be a viable option to fulfill the future protein demands of the world’s population. Presently, very little information is available regarding buffalo meat quality attributes under different packaging types. Therefore, this study was designed to evaluate the effect of packaging type and aging time on the meat quality characteristics (instrumental color, WBSF, cooking loss, thiobarbituric acid reactive substances (TBARS), and total volatile basic nitrogen (TVB-N) of longissimus lumborum steaks. The results showed that vacuum packaging and aging were the most effective in decreasing the WBSF values of buffalo meat.

Abstract

The present study determined the effect of the packaging type and aging time on the meat quality of water buffalo (Bubalus bubalis) bulls. A total of n = 36 longissimus lumborum (LL) muscles from n = 18 buffalo bulls were obtained. Half LL muscles were packed in modified atmosphere packaging (Hi-O₂ MAP), vacuum packaging (VP), and oxygen-permeable packaging (OP) on day 1, while the other half were aged for 7 days. Meat instrumental color, cooking loss, Warner–Bratzler shear force (WBSF), thiobarbituric acid reactive substances (TBARS), and total volatile basic nitrogen (TVB-N) of the LL steaks were analyzed, both on unaged and aged buffalo meat. Color CIE L* and C* values on all display days and a* on the first 4 days of the simulated retail display under Hi-O₂ MAP packaging were significantly higher than those of the VP and OP. WBSF and TBARS values were also higher under Hi-O₂ MAP as compared to the other packaging. Steaks under OP exhibited lower cooking loss but higher TVB-N values than the MAP and VP. The 7-day-aged buffalo meat indicated higher instrumental color (L*, a* and C*), cooking loss, and lower WBSF values than fresh meat. This study concluded that Hi-O₂ MAP improved the color; however, it negatively influenced the buffalo meat’s WBSF and TBAR values. Furthermore, VP and aging were the most effective in decreasing the WBSF values of buffalo meat.

Towards Impact of Modified Atmosphere Packaging (MAP) on Shelf-Life of Polymer-Film-Packed Food Products: Challenges and Sustainable Developments

In this article, we report in detail the use of protective gases to extend the shelf-life of polymer-film-packed foodstuff and reduce the most typical bacteria and microorganisms that negatively affect the quality and lifetime of a given packaging. This article provides significant information about the most important advantages of using protective gases and examples of gases or gas mixtures which can be used for almost every kind of foodstuff depending on the application. We also discuss how protective gases change the level of microorganisms in food using gases and how the shelf-life of food can be enhanced using correct gases or gas mixtures. The article also provides imperative information on the selection of correct protective gases for specific applications, especially for food production, to preserve against the most typical threats which can appear during the packaging or production process. Packaging innovations can reduce the environmental impact of food and polymer packaging waste by prolonging products’ shelf-lives and by reducing waste along the production and distribution chain and at the household level.

Meat tenderness: advances in biology, biochemistry, molecular mechanisms and new technologies

Meat tenderness is an important quality trait critical to consumer acceptance, and determines satisfaction, repeat purchase and willingness-to-pay premium prices. Recent advances in tenderness research from a variety of perspectives are presented. Our understanding of molecular factors influencing tenderization are discussed in relation to glycolysis, calcium release, protease activation, apoptosis and heat shock proteins, the use of proteomic analysis for monitoring changes, proteomic biomarkers and oxidative/nitrosative stress. Each of these structural, metabolic and molecular determinants of meat tenderness are then discussed in greater detail in relation to animal variation, postmortem influences, and changes during cooking, with a focus on recent advances. Innovations in postmortem technologies and enzymes for meat tenderization are discussed including their potential commercial application. Continued success of the meat industry relies on ongoing advances in our understanding, and in industry innovation. The recent advances in fundamental and applied research on meat tenderness in relation to the various sectors of the supply chain will enable such innovation.

Assessment of quality characteristics and bacterial community of modified atmosphere packaged chilled pork loins using 16S rRNA amplicon sequencing analysis

Modified atmosphere packaging (MAP) is widely applied in packaging meat and meat products. While most studies had employed culture-dependent microbiological analyses or polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), the recent application of high-throughput sequencing (HTS) has been effective and reliable in detecting the microbial consortium associated with food spoilage. Since MAP application is limited in China, applying HTS in assessing the microbial consortium of meat and meat products in the country becomes imperative. In this study, quality indexes and bacterial enumeration often used as spoilage indicators were employed to assess MAP fresh pork under chilled (4 °C) storage for 21 d. The results indicated that 70%O₂/30%CO₂ (Group A) retained more redness (a*) content, while 70%N₂/30%CO₂ (Group B) markedly reduced spoilage indicators compared to the control group. Notably, high-throughput sequencing indicated that Group B and 20%O₂/60%N₂/20%CO₂ (Group C) inhibited the growth of abundant spoilers, Pseudomonas spp. and Brochothrix spp. Thus, MAP (Group B and C) has promising potential in inhibiting predominant meat spoilers during chilled storage. This study provides valuable information to food industries on the potential application of MAP to control meat spoilage in Chinese markets.

Effects of Pulsed Electric Field Processing and Sous Vide Cooking on Muscle Structure and In Vitro Protein Digestibility of Beef Brisket

Pulsed electric fields (PEF) in conjunction with sous vide (SV) cooking has been explored for meat tenderisation. The aim of this experiment was to study the effect of PEF–SV treatment on the muscle structure and in vitro protein digestibility of beef brisket. Pulsed electric field treatment (specific energy of 99 ± 5 kJ/kg) was applied to bovine Deep and Superficial pectoral muscles in combination with sous vide (SV) cooking (60 °C for 24 h). A similar micro- and ultrastructure was detected between the control SV-cooked and PEF-treated SV-cooked pectoral muscles. The combined PEF–SV treatment increased the in vitro protein digestibility of the pectoral muscles by approximately 29%, in terms of ninhydrin-reactive free amino nitrogen released at the end of simulated digestion. An increment in proteolysis of the PEF-treated SV-cooked meat proteins (e.g., myosin heavy chains and C-protein) during simulated digestion was also observed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. More damaged muscle micro- and ultrastructure was detected in PEF-treated SV-cooked muscles at the end of in vitro digestion, showing its enhanced digestive proteolysis compared to the control cooked meat.

Effect of Dietary Anthocyanin-Extracted Residue on Meat Oxidation and Fatty Acid Profile of Male Dairy Cattle

This research aimed to evaluate the effects of anthocyanin-extracted residue (AER) in the diet of cattle on meat oxidation during storage and on the fatty acid profiles of the meat. Sixteen male dairy cattle (average body weight 160 ± 10.6 kg) were allotted to feed in a completely randomized design (CRD) with four levels of AER supplementation, 0, 20, 40, and 60 g/kg dry matter (DM) in the total mixed ration (TMR). These TMR diets were fed ad libitum to the cattle throughout the trial. At the end of the feeding trial (125 days), all cattle were slaughtered and meat samples from the Longissimus dorsi (LD) muscle were collected to assess meat oxidation and fatty acid profile. The antioxidant effect of AER on meat oxidation was investigated during 14 days of storage based on color, myoglobin redox forms, lipid, and protein oxidation. The results showed meat from cattle fed AER had better color stability, lower oxidation of lipid, protein and myoglobin than did meat from cattle fed the control diet (0 g/kg AER). Furthermore, fatty acid profiles were affected by AER supplementation with an increase in the concentration of n-3 polyunsaturated fatty acids (PUFA). These results support the inclusion of AER supplementation as a natural antioxidant in cattle to reduce meat oxidation and increase PUFA in meat.

Ag@TiO2 nanogranular films by gas phase synthesis as hybrid SERS platforms

The synthesis of hybrid metallic-dielectric substrates as reliable SERS platforms relies on core-shell nanoparticles, obtained by wet chemistry, with an outer dielectric shell composed of SiO₂ or TiO₂. Apart from the shell composition, the nanoparticle density and aggregation type strongly affect the surface-enhanced SERS. Going beyond a single layer by building random aggregates of hybrid NPs would result in a step forward in the production of reliable hybrid SERS platforms. Here we achieve the fabrication of a 3D nanogranular film of Ag metallic cores not fully enclosed in a TiO₂ capping layer, defined as a Ag@TiO₂ quasi-shell-isolated Raman substrate (Ag@TiO₂ QuaSIRS) by an environmentally friendly gas phase synthesis technique (SCBD). The Ag core drives the electromagnetic enhancement with plasmonic hotspots while the TiO₂ shell passivates it and leads to different possible surface functionalization. The SERS capabilities of the Ag@TiO₂ QuaSIRS peak at a film thickness of 60 nm providing a detection limit of 10^-9 M concentration for Methylene Blue at 632.81 nm. The importance of the nanogranular 3D morphology is evidenced by the very good detection of analytes dispersed in aqueous solutions, since the liquid can penetrate the pores hence exploiting most of the plasmonic hotspots present in the film. The versatility of SCBD to deposit such reliable hybrid SERS platforms by a single step at room temperature over different substrates provides an opportunity to design a new generation of hybrid SERS-active substrates based on hybrid nanoparticles.

Meat packaging solutions to current industry challenges: A review

Many advances have occurred in the field of smart meat packaging, and the potential for these to be used as tools that respond to challenges faced by industry is exciting. Here, we review packaging solutions to several immediate concerns, encompassing dark cutting, purge and yield losses, product traceability and provenance, packaging durability, microbial spoilage and safety, colour stability, environmental impacts, and the preservation of eating quality. Different active and intelligent packaging approaches to each of these were identified and are discussed in terms of their usefulness - to processors, retailers and/or consumers. From this, it became apparent that prior to selecting a packaging solution, industry should first define their criteria for success (e.g. How much purge is too much? What is a reasonable shelf-life to facilitate product turnover? Is the customer willing to pay for this?), and understand that packaging is not the sole solution, but acts as part of a holistic response to these issues.

Carbon Monoxide in Meat and Fish Packaging: Advantages and Limits

Due to increased demands for greater expectation in relation to quality, convenience, safety and extended shelf-life, combined with growing demand from retailers for cost-effective extensions of fresh muscle foods’ shelf-life, the food packaging industry quickly developed to meet these expectations. During the last few decades, modified atmosphere packaging (MAP) of foods has been a promising area of research, but much remains to be known regarding the use of unconventional gases such carbon monoxide (CO). The use of CO for meat and seafood packaging is not allowed in most countries due to the potential toxic effect, and its use is controversial in some countries. The commercial application of CO in food packaging was not then considered feasible because of possible environmental hazards for workers. CO has previously been reported to mask muscle foods’ spoilage, and this was the primary concern raised for the prohibition, as this may mislead consumers. This review was undertaken to present the most comprehensive and current overview of the widely-available, scattered information about the use of CO in the preservation of muscle foods. The advantages of CO and its industrial limits are presented and discussed. The most recent literature on the consumer safety issues related to the use of CO and consumer acceptance of CO especially in meat packaging systems were also discussed. Recommendations and future prospects were addressed for food industries, consumers and regulators on what would be a “best practice” in the use of CO in food packaging. All this promotes high ethical standards in commercial communications by means of effective regulation, for the benefit of consumers and businesses in the world, and this implies that industrialized countries and members of their regulatory agencies must develop a coherent and robust systems of regulation and control that can respond effectively to new challenges.

Influence of modified atmosphere packaging on protein oxidation, calpain activation and desmin degradation of beef muscles

BACKGROUND

Protein oxidation is widespread in biochemical systems. The objective of the study was to investigate the differences in protein oxidation, μ-calpain activity, desmin proteolysis and protein solubility of beef psoas major (PM) and semi-membranosus (SM) muscles under three packaging systems during postmortem ageing. At 24 h postmortem, beef muscles were packaged respectively in air-permeable film overwrap (AP), vacuum pack (VP) or modified atmosphere (MAP, 80% O₂ + 20% CO₂ ), and then displayed for 10 days at 4 °C.

RESULTS

Carbonyl group values and thiol group content were significantly influenced by packaging type and storage time. The SM muscles from AP and MAP showed greater μ-calpain activity compared to VP. Desmin of PM and SM from AP and MAP samples showed decreased proteolysis compared with VP.

CONCLUSION

The results suggested that the inhibition of μ-calpain activity of beef samples from AP and MAP could be closely associated with protein oxidation which further lowered the level of desmin degradation compared to VP. © 2017 Society of Chemical Industry.

Effect of reduction of oxygen concentration in modified atmosphere packaging on bovine M. longissimus lumborum and M. gluteus medius quality traits

This paper reports the impact of modified atmosphere gas compositions with different concentrations of CO₂/O₂/N₂ on physicochemical traits of beef steaks from M. longissimus lumborum and M. gluteus medius. Samples were stored at +2°C for 12days. The gas compositions were as follows: (i) 50% O₂/20% CO₂/30% N₂ (MAP1), (ii) 65% O₂/20% CO₂/15% N₂ (MAP2) and (iii) 80% O₂/20% CO₂ (MAP3). Packaging atmosphere did not affect CIEL*a*b* colour coordinates, which were affected by storage time and by muscle type. Lipid oxidation in M. longissimus lumborum was affected by packaging treatment; however packaging treatment×storage time interaction affected lipid oxidation significantly. Results showed that reduction of oxygen from the commercially used 80% to 50% does not negatively impact colour properties and state of myoglobin, but significantly lowers oxidative deterioration of M. longissimus lumborum at the end of storage.

Novel DNPH-based method for determination of protein carbonylation in muscle and meat

Protein oxidation is considered an ongoing deteriorative process during storage of fresh and processed meat. Carbonyl compounds have traditionally been detected spectrophotometrically after derivatization with 2,4-dinitrophenylhydrazine (DNPH) to form protein-bound hydrazones with absorbance at 370 nm. Here we describe a novel DNPH-based method to quantify protein carbonylation in muscle and meat. The additional steps of the novel method aimed at increasing the protein solubility and inducing protein unfolding before labeling with DNPH. Compared to the traditional method, the new procedure reflected an increased protein carbonylation level measuring overall two to fourfold more carbonyls in muscles from different species as well as in soluble, salt-soluble and insoluble protein fractions. The study suggested that protein unfolding is a more important phenomenon than solubilization for increased DNPH labeling. The novel method resulted in three to fourfold larger carbonyl content determined in chicken, pork and beef (2.8, 3.6 and 3.1 nmol/mg of protein, respectively).

Meat composition and quality of young growing Belgian Blue bulls offered a fattening diet with selenium enriched cereals

Mehdi, Y., Clinquart, A., Hornick, J.-L., Cabaraux, J.-F., Istasse, L. and Dufrasne, I. 2015. Meat composition and quality of young growing Belgian Blue bulls offered a fattening diet with selenium enriched cereals. Can. J. Anim. Sci. 95: 465–473. The objective of this study was to evaluate the effects of selenium (Se) enrichment of cereals on the performance of Belgian Blue bulls, meat quality and chemical composition. Twenty-three bulls were used in the present study. Twelve bulls were offered a control diet containing Se at a basal concentration of 58 µg kg−1 of dry matter (DM) and the other 11 bulls were given a diet containing 173 µg kg−1 DM of Se by means of Se-enriched spelt and barley. The Se enrichment of the diet did not affect the growth performance, the slaughter data or meat quality (P > 0.05). There were no effects of Se on tenderness, oxidative rancidity and water losses. However, there were some effects of Se enrichment on the meat chemical composition. The ether extract was decreased from 2.1 to 1.7% DM (P<0.05). There was also significant Se enrichment (P<0.001) in the longissimus thoracis muscle (177 vs. 477 ng g−1 DM) and organs: liver (474 vs. 1126 ng g−1 DM) and kidney (4956 vs. 5655 ng g−1 DM), Under such conditions, the human consumption of a piece of such meat or liver can provide a large part of the recommended daily Se intake, estimated between 30 and 57%.

Effect of multiple vacuum packs on colour development and stability in beef steaks

Avilés, C., Juárez, M., Larsen, I. L., Rodas-González, A. and Aalhus, J. L. 2014. Effect of multiple vacuum packs on colour development and stability in beef steaks. Can. J. Anim. Sci. 94: 63–69. The aim of this study was to compare the colour stability of steaks from longissimus dorsi muscle previously submitted to four treatments of vacuum packaging and aged for 15 d. Muscle portions were either vacuum packed and aged for 15 d (NRP), or repacked after 2 h (RP2h), 8 d (RP8d) and after 2 h and 8 d (RP2h+8d). Purge loss values from RP8d and RP2h+8d treatments were higher (P=0.019) than those from NRP and drip loss was higher (P=0.001) for RP2h and RP8d. Colour changes during a 30-min period of exposure to atmospheric oxygen immediately after opening the packages were similar for repackaged-aged steaks and NRP steaks (P>0.05). Nevertheless, colour stability during subsequent retail display under atmospheric air conditions was affected by the packaging treatment. The decrease in chroma values (P=0.043) and the increase in hue (P=0.011) between day 3 and day 6 was minimum for RP2h+8d, compared with NRP, RP2h and RP8d. Also, the proportion of pigment in the myoglobin form in these three treatments dramatically increased from day 3 to day 6, while no effect was observed for RP2h+8d (P=0.005). Similarly, the decrease over time in the proportion of pigment in the oxymyoglobin form in meat from the RP2h+8d treatment was much lower (P=0.002) than for the other three packaging treatments. Changes in colour stability associated with multiple vacuum packagings may confound results in experimental designs. Thus, if beef colour is to be evaluated, repeated vacuum packaging should be limited.

Potential mechanisms of carbon monoxide and high oxygen packaging in maintaining color stability of different bovine muscles

The objectives were to compare the effects of packaging methods on color stability, metmyoglobin-reducing-activity (MRA), total-reducing-activity and NADH concentration of different bovine muscles and to explore potential mechanisms in the enhanced color stability by carbon monoxide modified atmosphere packaging (CO-MAP, 0.4% CO/30% CO2/69.6% N2). Steaks from longissimus lumborum (LL), psoas major (PM) and longissimus thoracis (LT) packaged in CO-MAP, high-oxygen modified atmosphere packaging (HiOx-MAP, 80% O2/20% CO2) or vacuum packaging were stored for 0day, 4days, 9days, and 14days or stored for 9days then displayed in air for 0day, 1day, or 3days. The CO-MAP significantly increased red color stability of all muscles, and especially for PM. The PM and LT were more red than LL in CO-MAP, whereas PM had lowest redness in HiOx-MAP. The content of MetMb in CO-MAP was lower than in HiOx-MAP. Steaks in CO-MAP maintained a higher MRA compared with those in HiOx-MAP during storage. After opening packages, the red color of steaks in CO-MAP deteriorated more slowly compared with that of steaks in HiOx-MAP.

Improvement of the Quality and the Shelf Life of the High Oxygen Modified Atmosphere Packaged Veal by Superficial Spraying with Dihydroquercetin Solution

The improvement of quality and the shelf life of veal by combination of 80%O₂/20%CO₂ modified atmosphere packaging and superficial spraying with 0.02% dihydroquercetin solutions was studied. The control samples C, air packaged only, D, air packaged sprayed by 0.02% dihydroquercetin solution, MAP, modified atmosphere packaging only, BMAP, modified atmosphere packaging sprayed by 0.02% butylated hydroxytoluene solution, and DMAP, modified atmosphere packaging sprayed by 0.02% dihydroquercetin solution, were measured. The best results were obtained in modified atmosphere packaging sprayed by 0.02% dihydroquercetin solution. Comparisons with control samples were expressed as reduction in acid value with 27.72%, peroxide value with 64.74%, 2-thiobarbituric acid reactive substances (TBARS) with 65.71%, and the pH with 6.18%. The acid and peroxide values, TBARS, and pH were decreased linearly in response when applying the combination of 80%O₂/20%CO₂ modified atmosphere packaging and superficial spraying with 0.02% dihydroquercetin solutions (P < 0.05). The changes of amino nitrogen content of modified atmosphere packaging veal were not influenced statistically significantly by 0.02% dihydroquercetin solution (P > 0.05). According to results obtained it was concluded that 80%O₂/20%CO₂ modified atmosphere packaged veal stored at 0 ± 0.5°C after 0.02% dihydroquercetin solution treatment can preserve its quality and shelf life to 15 d postmortem.

Phenolic antioxidant scavenging of myosin radicals generated by hypervalent myoglobin

The scavenging activity of extracts of green tea (GTE), white grape (WGE), and rosemary (RE), all plant material with high phenolic content, and of the phenolic compounds 4-methylcatechol (4-MC), (+)-catechin, and carnosic acid toward long-lived myosin radicals generated by reaction with H2O2-activated myoglobin at room temperature (pH 7.5, I=1.0) was investigated by freeze-quench ESR spectroscopy. Myosin radicals were generated by incubating 16 μM myosin, 800 μM metmyoglobin, and 800 μM H2O2 for 10 min, and the phenolic extracts were subsequently added (1% (w/w) phenolic compounds relative to myosin). GTE was able to scavenge myosin radicals and reduce the radical intensity by 65%. Furthermore, a low concentration of 4-MC (33 μM) was found to increase the radical concentration when added to the myosin radicals, whereas a higher concentration of 4-MC and catechin (330 μM) was found to scavenge myosin radicals and reduce the overall radical concentration by ∼65%.

Kinetics of colour and texture changes of beef during storage

The influence of the packaging films, aerobic and vacuum conditions, and refrigeration storage temperature (0, 4 and 10 °C) on colour and texture of raw meat were studied during a 2-week storage period in order to analyze kinetics of colour and texture changes. The rate of redness decrease was most noticeable at the highest storage temperature and aerobic conditions and these changes were well described by the first-order reaction. Texture parameter reflected a progressive softening during storage for both films. Decrease on shear force of raw beef during storage followed a first-order kinetic model. Temperature dependence of colour and texture change was adequately modelled with the Arrhenius equation.

Fish proteins as targets of ferrous-catalyzed oxidation: identification of protein carbonyls by fluorescent labeling on two-dimensional gels and MALDI-TOF/TOF mass spectrometry

Protein oxidation in fish meat is considered to affect negatively the muscle texture. An important source of free radicals taking part in this process is Fenton's reaction dependent on ferrous ions present in the tissue. The aim of this study was to investigate the susceptibility of cod muscle proteins in sarcoplasmic and myofibril fractions to in vitro metal-catalyzed oxidation and to point out protein candidates that might play a major role in the deterioration of fish quality. Extracted control proteins and proteins subjected to free radicals generated by Fe(II)/ascorbate mixture were labeled with fluorescein-5-thiosemicarbazide (FTSC) to tag carbonyl groups and separated by two-dimensional gel electrophoresis. Consecutive visualization of protein carbonyl levels by capturing the FTSC signal and total protein levels by capturing the SyproRuby staining signal allowed us to quantify the relative change in protein carbonyl levels corrected for changes in protein content. Proteins were identified using MALDI-TOF/TOF mass spectrometry and homology-based searches. The results show that freshly extracted cod muscle proteins exhibit a detectable carbonylation background and that the incubation with Fe(II)/ascorbate triggers a further oxidation of both sarcoplasmic and myofibril proteins. Different proteins exhibited various degrees of sensitivity to oxidation processes. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH), nucleoside diphosphate kinase B (NDK), triosephosphate isomerase, phosphoglycerate mutase, lactate dehydrogenase, creatine kinase, and enolase were the sarcoplasmic proteins most vulnerable to ferrous-catalyzed oxidation. Moreover, NDK, phosphoglycerate mutase, and GAPDH were identified in several spots differing by their pI, and those forms showed different susceptibilities to metal-catalyzed oxidation, indicating that post-translational modifications may change the resistance of proteins to oxidative damage. The Fe(II)/ascorbate treatment significantly increased carbonylation of important structural proteins in fish muscle, mainly actin and myosin, and degradation products of those proteins were observed, some of them exhibiting increased carbonylation levels.