Novel needle-probe single-fiber reflectance spectroscopy to quantify sub-surface myoglobin forms in beef psoas major steaks during retail display

Meat discoloration starts at the interface between the bright red oxymyoglobin layer and the interior deoxymyoglobin layer. Currently, limited tools are available to characterize myoglobin forms formed within the sub-surface of meat. The objective was to demonstrate a needle-probe based single-fiber reflectance (SfR) spectroscopy approach for characterizing sub-surface myoglobin forms of beef psoas major muscles during retail storage. A 400-μm fiber was placed in a 17-gauge needle, and the assembly was inserted into the muscle at five depths of 1 mm increment and 1 cm lateral shift. Metmyoglobin content increased at all depths during display and content at 1 mm was greater compared to that of 2 to 5 mm depth. The a* values decreased (P < 0.05) during retail display aligning with the sub-surface formation of metmyoglobin. In summary, the results suggest that needle-probe SfR spectroscopy can determine interior myoglobin forms and characterize meat discoloration.

Effects of Early Weaning on Performance and Carcass Quality of Nellore Young Bulls

This study compared early weaning (EW; 150 days) with conventional weaning (CW; 240 days) in Nellore young bulls, evaluating performance, carcass characteristics, and meat quality. A total of 74 non-castrated male calves were divided into two weaning strategies: EW (n = 37) and CW (n = 37). During the growth phase, which lasted 454 ± 14 d for EW calves and 359 ± 16 d for CW calves, animals received a protein-energy supplement at a ratio of 5 g per kg of body weight while grazing Brachiaria brizantha cv. Marandu. The animals were managed for an 87d finishing phase in three collective feedlot pens, with a 3-week adaptation protocol, starting with corn silage to a concentrate ratio of 55:45 and reaching a ratio of 30:70 in the final diet. Body weight, average daily gain (ADG), dry matter intake (DMI), feed efficiency (FE), carcass characteristics, and meat quality were evaluated. The EW group was approximately 44 kg lighter than the CW at the time of conventional weaning (p < 0.001). However, this weight difference did not influence ADG, DMI, and FE in the finishing phase. No significant differences were observed in carcass characteristics such as yield percentage, loin area, subcutaneous fat thickness, and meat quality, except for the weight of primal cuts, which was greater in the CW group (p < 0.001). Thus, although calves weaned early are lighter throughout subsequent production phases than those weaned conventionally, performance, efficiency, carcass yield, and meat quality are not affected.

Comparing the effects of packaging normal-pH and atypical dark-cutting beef in modified atmosphere conditions on surface color

Limited studies have determined the effects of modified atmospheric packaging (MAP) on atypical dark-cutting beef surface color. The objective was to compare the impacts of using vacuum packaging, carbon monoxide (CO-MAP), and HiOx-MAP (high‑oxygen) on the retail color of normal-pH and atypical dark-cutting beef aged 14 d. Atypical dark-cutting beef (pH 5.63) had numerically greater (P > 0.05) pH than normal-pH beef (pH 5.56). Atypical dark-cutting steaks were darker in color (lower L* values; P < 0.05) than normal-pH steaks. Atypical dark-cutting steaks had greater (P < 0.05) oxygen consumption, lower (P < 0.05) relative oxygenation, and less inter-muscle bundle space (P < 0.05) than normal-pH steaks. There were no differences (P > 0.05) in redness between normal-pH and atypical dark-cutting steaks when packaged in HiOx-MAP. Although a minimal increase in pH was observed in atypical dark-cutting beef, steaks in CO-MAP had lower redness than normal-pH steaks.

Effects of ultrasound-assisted cooking on the physicochemical properties and microstructure of pork meatballs

This research aims to investigate the effect of different ultrasonic powers cooking on the quality of pork meatballs. Pork meatballs treated with ultrasound-assisted cooking at 450 W had the most uniform and smooth structures displayed by scanning electron microscopy. Furthermore, with increasing ultrasonic powers, the water retention capacity of pork meatballs first increased and then decreased, compared with the non-ultrasound group, when the ultrasonic power was 450 W, the cooking yield of pork meatballs increased from 82.55% to 92.87%, and the centrifugal loss decreased from 25.35% to 11.52%. Additionally, ultrasound-assisted cooking had a positive effect on the moisture migration, tenderness, and sensory property of pork meatballs, and 450 W sample exhibited the highest overall acceptability score (P < 0.05). In conclusion, the physicochemical properties and microstructure of pork meatballs could be improved by appropriate ultrasonic power, and ultrasonic technology was considered as an effective processing method for improving the quality of meat products.

The effect of succinate on color stability of Bos indicus bull meat: pH-dependent effects during the 14-day aging period

Bos taurus indicus bulls are very susceptible to pre-slaughter stress, which directly impacts the decline in muscle pH, leading to darker meat. The aim was to investigate the effect of succinate and atmosphere on the color stability of Nellore (Bos taurus indicus) Longissimus lumborum steaks classified by ultimate pH (pHu): normal pHu (5.40 ≤ pHu ≤ 5.79) and high pHu (pHu ≥ 5.80). The experimental treatment systems were: (i) vacuum packaging without succinate injection, (ii) HiOx-MAP (80 % O2 + 20 % CO2), and (iii) HiOx-MAP (80 % O2 + 20 % CO2) enhanced with sodium succinate injection (pH 5.4). Steaks from all treatment systems were stored at 4 °C for 14 days and tested for instrumental color, myoglobin content, oxygen consumption (OC), metmyoglobin-reducing activity (MRA), lipid oxidation, and microbiological analysis. High and normal pHu vacuum-packaged steaks exhibited greater color stability due to higher MRA. High and normal pHu steaks packaged with HiOx-MAP or HiOx-MAP enhanced with succinate showed improved color due to lower deoxymyoglobin content (%DMb) and OC up to the eighth day of storage. Still, succinate injection promoted increased (P < 0.05) lipid oxidation in normal pHu steaks and reduced MRA after 14 days. These findings emphasize the intricate interplay between pHu and packaging systems on Bos taurus indicus meat quality. Further research in this area could contribute to a better understanding of meat color abnormalities and provide insights into potential meat preservation and enhancement strategies.

The color of fresh pork: Consumers expectations, underlying farm-to-fork factors, myoglobin chemistry and contribution of proteomics to decipher the biochemical mechanisms

The color of fresh pork is a crucial quality attribute that significantly influences consumer perception and purchase decisions. This review first explores consumer expectations and discrimination regarding pork color, as well as an overview of the underlying factors that, from farm-to-fork, contribute to its variation. Understanding the husbandry factors, peri- and post-mortem factors and consumer preferences is essential for the pork industry to meet market demands effectively. This review then delves into current knowledge of pork myoglobin chemistry, its modifications and pork discoloration. Pork myoglobin, which has certain peculiarities comparted to other meat species, plays a weak role in determining pork color, and a thorough understanding of the biochemical changes it undergoes is crucial to understand and improve color stability. Furthermore, the growing role of proteomics as a high-throughput approach and its application as a powerful research tool in meat research, mainly to decipher the biochemical mechanisms involved in pork color determination and identify protein biomarkers, are highlighted. Based on an integrative muscle biology approach, the available proteomics studies on pork color have enabled us to provide the first repertoire of pork color biomarkers, to shortlist and propose a list of proteins for evaluation, and to provide valuable insights into the interconnected biochemical processes implicated in pork color determination. By highlighting the contributions of proteomics in elucidating the biochemical mechanisms underlying pork color determination, the knowledge gained hold significant potential for the pork industry to effectively meet market demands, enhance product quality, and ensure consistent and appealing pork color.

Effects of Metabolites, Sex, Sire, and Muscle Type on Chilled Lamb Meat Colour

Meat is an important source of high-value protein providing sustainable nutrition for human health. The discolouration of meat results in significant waste, which threatens the sustainability of meat production in terms of availability, affordability, and utilisation. Advancing the knowledge of factors and underlying mechanisms for meat discolouration supports the sustainability transformation of meat production practices. Previous studies found that colour stability may be associated with signature changes in certain metabolites, including NADH, glutamate, methionine, and testosterone. This study aimed to confirm the effect of these metabolites and sex, sire, and muscle type on lamb meat colour. NADH and glutamate improved colour stability as evidenced by the increased metmyoglobin reductase activity, while methionine and testosterone had detrimental effects. Overall, lamb meat was discoloured with retail display for up to 10 days at 4 °C. The semitendinosus muscle had higher L*, b*, and hue angle and lower a* (p < 0.05) than other muscles, especially in ewes. Lamb meat from rams had a higher L* and hue angle and lower a* than the ewes (p < 0.05), especially in the colour-labile group, suggesting an interaction between sex and sire. The outcomes of this study will help make the production of meat more sustainable by assisting the meat industry in improving the selection of animals for meat production and processing practices to reduce meat waste due to discolouration.

In-depth characterization of the sarcoplasmic muscle proteome changes in lambs fed with hazelnut skin by-products: Relationships with meat color

This study investigated the effect of agro-industrial hazelnut skin by-products supplementation on lamb meat color variation and the changes in the sarcoplasmic muscle proteome during post-mortem storage (0, 4 and 7 days). Gel-based proteomics and bioinformatics approaches were applied to better understand the potential role of feeding strategies in modulating the mechanisms underpinning meat discoloration and post-mortem changes during storage. Therefore, twenty-two Valle del Belice male lambs were randomly assigned to two dietary treatments: control (C), lambs fed with maize-barley diet, and hazelnut skin (H), lambs fed hazelnut skin by-product as maize partial replacer in the concentrate diet. Hazelnut dietary treatment led to better lamb meat color stability as evidenced by the lowest decrease in redness and saturation index values. Proteomics and bioinformatics results revealed changes in the abundance of 41 proteoforms, which were mainly involved in glycolytic processes, responses to oxidative stress, and immune and endocrine system. The proteins allowed revealing interconnected pathways to be behind meat color variation as a consequence of using hazelnut skin by-products to sustainable feed lamb. The proteins can be used as potential predictors of lamb meat color variation. Accordingly, the regression equations developed in this paper revealed triosephosphate isomerase (TPI1) as a reliable candidate biomarker of color stability in lamb meat. SIGNIFICANCE: The use of agro-industrial by-products in animal feeding can be a potential sustainable strategy to reduce the environmental impacts of the food production chain and consequently improve animal welfare and product quality. The inclusion of hazelnut skin by-products in the animal's diet, due to the high concentration of polyphenols, represents an effective strategy to improve the oxidative stability of meat, with significant implications on color. The use of proteomics combined with bioinformatics on the sarcoplasmic proteome is a powerful approach to decipher the underlying mechanism. Accordingly, this approach allowed in this trial a deeper understanding of the molecular mechanisms involved in the post-mortem processes through the discovery of several biological pathways linked with lamb meat color variation. Glycolysis, followed by responses to oxidative stress, and other proteins involved in the immune and endocrine system were found as the major interconnected pathways that could act as potential predictors of lamb meat color stability. Candidate proteins biomarkers were further revealed in this study to be related with multiple meat color traits.

Proteomics and metabolomics profiling of meat exudate to determine the impact of postmortem aging on oxidative stability of beef muscles

The objective of this study was to characterize the major proteomes and metabolites in beef exudate and determine their relationship to color and oxidative quality of beef muscles. Beef loin (LD) and tenderloin (PM) muscles were cut into sections, individually vacuum-packaged, and aged for 9, 16 and 23 days at 2 °C. Following aging, beef exudates were collected and analyzed for both proteomics and metabolomics profiles. Proteome analysis indicated clustering by muscle types, while metabolomics profiling further clustered the samples based on the aging periods. The PM exudate had a greater concentration of oxidative enzymes, while the LD exudate contained more glycolytic enzymes. Greater lipid, nucleotide, carnitine and glucoside metabolites were observed in LD and 23d exudates. HSP70 and laminin proteins, together with glucosides metabolites, were correlated to muscle oxidative stability. The results indicated that meat exudate could be a viable analytical matrix to determine changes in quality attributes of meat with aging.

Improvement of Color and Oxidative Stabilities in Nellore Bull Dark Meat in High-Oxygen Package by Lactate and Rosemary Oil Extract

This study aimed to improve the color and oxidative stabilities of dark Nellore bull steaks with greater-than-normal ultimate pH (pH_u) by the injection (8% raw wet weight basis) of a solution with L-lactate (2.5%), phosphate (0.3%) and rosemary extract (0.06%), with further packaging in high oxygen atmosphere (HiOx MAP). Longissimus lumborum muscles from pasture-fed Nellore bulls were divided into three pH_u ranges: normal (<5.80), intermediate (5.81-6.19), and high (≥6.2). Muscles were then halved, with sections were randomly assigned to non-enhanced (C, n = 6/pH_u range) or injected (E, n = 6/pH_u range) groups, at 72 h postmortem. Each section was cut into 2 cm-slices, which were HiOx-packed and then stored for 5 days (dark) and displayed for 9 days (fluorescent lighting) at 2 °C. Higher pH_u steaks exhibited greater a*, b*, h*, C* and surface oxymyoglobin and lower surface deoxymyoglobin and oxygen consumption compared to those of normal pH_u between days 0 and 5 (p < 0.05). Over the time, normal-pH_u muscles showed oxidative protection (lower TBARS and greater metmyoglobin reducing ability values, p < 0.05) in enhanced-steaks. Therefore, enhancement and HiOx MAP seem to produce greater-than-normal pH_u Nellore bull steaks with a preferable color and quality, even after display time.

Effects of sex, sire and in-bag dry-ageing on the physicochemical and microbial properties, colour and fatty acids stability of lamb

Forty legs from twenty lamb of different sexes and sires (colour stable and labile) were aged using in-bag dry- (BD) and wet-ageing (W) for 21 days. BD resulted in significantly lower moisture content, cook loss, colour (L*, a*, b* and chroma) and % polyunsaturated fatty acids (FAs), higher levels of microbial growth and saturated FAs compared to W. Similar NADH content was observed regardless of sex, sire and ageing. Samples from ram and labile sire had significantly higher pH and saturated FAs and reduced monounsaturated FAs composition compared to those from ewe and stable sire. Lamb from labile sire had significantly higher fat melting point than the stable. Thus, the superior stability of stabile sire was observed only in ram and was not impaired by BD. The sex × sire interaction on oxidative stability demonstrated potential to tailor the quality of dry-aged lamb through altering sex and sire of animals.

- Invited Review - Factors affecting beef quality and nutrigenomics of intramuscular adipose tissue deposition

Beef quality is characterized by marbling (marbling degree and marbling fineness), physiochemical (shear force, meat color, fat color, texture, and maturity), and sensory (tenderness, flavor, juiciness, taste, odor, and appearance) traits. This paper summarizes and addresses beef-quality characteristics and the beef-grading systems in Korea, Japan, the USA, and Australia. This paper summarizes recent research progresses on the genetic and nutritional factors that affect beef quality. Intramuscular (i.m.) adipose tissue deposition or marbling is a major determinant of beef quality. This paper addresses the mechanisms of i.m. adipose tissue deposition focused on adipogenesis and lipogenesis. We also address selected signaling pathways associated with i.m. adipose tissue deposition. Nutrients contribute to the cellular response and phenotypes through gene expression and metabolism. This paper addresses control of gene expression through several nutrients (carbohydrates, fat/fatty acids, vitamins, etc.) for i.m. adipose tissue deposition. Several transcription factors responsible for gene expression via nutrients are addressed. We introduce the concept of genome-based precision feeding in Korean cattle.

Integrative proteomics and metabolomics profiling to understand the biochemical basis of beef muscle darkening at a slightly elevated pH

Previous studies investigated the biochemical basis of dark-cutting conditions at elevated muscle pH (above 6), but the molecular basis at slightly above normal pH (between 5.6 and 5.8) is still unclear. The objective was to determine protein and metabolite profiles to elucidate postmortem muscle darkening at slightly elevated pH. Loins were selected based on the criteria established in our laboratory before sample collections, such as pH less than 5.8, L* values (muscle lightness) less than 38, and not discounted by the grader (high-pH beef with dark color are discounted and not sold in retail stores). Six bright red loins (longissimus lumborum) at normal-pH (average pH = 5.57) and six dark-colored strip loins at slightly elevated pH (average pH = 5.70) from A maturity carcasses were obtained within 72-h postmortem from a commercial beef purveyor. Surface color, oxygen consumption, metmyoglobin reducing activity, protein, and metabolite profiles were determined on normal-pH and dark-colored steaks at slightly elevated pH. Enzymes related to glycogen metabolism and glycolytic pathways were more differently abundant than metabolites associated with these pathways. The results indicated that oxygen consumption and metmyoglobin reducing activity were greater (P < 0.05) in darker steaks than normal-pH steaks. Enzymes involved with glycogen catabolic pathways and glycogen storage disease showed lower abundance in dark beef. The tricarboxylic acid metabolite, aconitic acid, was overabundant in darker-colored beef than normal-pH beef, but glucose derivative metabolites were less abundant. The majority of glycogenolytic proteins and metabolites reported as overabundant in the previous dark-cutting studies at high pH (>6.4) also did not show significant differences in the current study. Therefore, our data suggest enzymes involved in glycogen metabolism, in part, create a threshold for muscle darkening than metabolites.

Supranutritional Supplementation of Vitamin E Influences Myoglobin Post-Translational Modifications in Postmortem Beef Longissimus Lumborum Muscle

Post-translational modifications (PTM) in myoglobin (Mb) can influence fresh meat color stability. Dietary supplementation of vitamin E improves beef color stability by delaying lipid oxidation–induced Mb oxidation and influences proteome profile of postmortem beef skeletal muscles. Nonetheless, the influence of vitamin E on Mb PTM in postmortem beef skeletal muscles has yet to be investigated. Therefore, the objective of the current study was to examine the effect of dietary vitamin E on Mb PTM in postmortem beef longissimus lumborum muscle. Beef longissimus lumborum muscle samples (24 h postmortem) were obtained from the carcasses of 9 vitamin E–supplemented (VITE; 1,000 IU vitamin E diet/heifer·d−1for 89 d) and 9 control (CONT; no supplemental vitamin E) heifers. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used to separate Mb from other sarcoplasmic proteins of beef longissimus lumborum muscle. Tandem mass spectrometry identified multiple PTM (phosphorylation, acetylation, 4-hydroxynonenalalkylation, methylation, dimethylation, trimethylation, and carboxymethylation) in the protein bands (17 kDa) representing Mb. The amino acids susceptible to phosphorylation were threonine (T) and tyrosine (Y), whereas lysine (K) residues were prone to other PTM. The same sites of phosphorylation (T34, T67, Y103), carboxymethylation (K77, K78), and 4-hydroxynonenal alkylation (K77, K78, K79) were identified in Mb from CONT and VITE samples, indicating that these PTM were not influenced by the vitamin E supplementation in cattle. Nonetheless, differential occurrence of acetylation, methylation, dimethylation, and trimethylation were identified in Mb from CONT and VITE samples. Overall, a greater number of amino acids were modified in CONT than VITE, suggesting that the supplementation of vitamin E decreased thenumbers of post-translationally modified residues in Mb. Additionally, PTM at K87, K96, K98, and K102 were unique to CONT, whereas PTM at K118 were unique to VITE. These findings suggested that dietary supplementation of vitamin E in beef cattle might protect amino acid residues in Mb—especially those located spatially close to proximal histidine—from undergoing PTM, thereby improving Mb redox stability.

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.

Predicting the Oxidative Degradation of Raw Beef Meat during Cold Storage Using Numerical Simulations and Sensors—Prospects for Meat and Fish Foods

Preventing animal-source food waste is an important pathway to reducing malnutrition and improving food system sustainability. Uncontrolled color variation due to oxidation is a source of waste as it prompts food rejection by consumers. Evaluation of oxidation–reduction potential (ORP) can help to predict and prevent oxidation and undesirable color changes. A new sensor and two modeling approaches—a phenomenological model and a reaction–diffusion model—were successfully used to predict the oxidative browning of beef ribeye steaks stored under different temperature and oxygen concentration conditions. Both models predicted similar storage durations for acceptable color, although deviating for higher and lower redness levels, which are of no interest for meat acceptance. Simulations under higher oxygen concentrations lead to a few days of delay in the redness change, as observed in practice, under modified atmosphere packaging. In meat juice, variation in ORP measured by the sensor correlated with the redness variation. However, in meat, sensors promote oxidation in the adjacent area, which is unacceptable for industrial use. This paper discusses the potential, limits, and prospects of the mathematical models and sensors, developed for beef. A strategy is proposed to couple these approaches and include the effect of microorganisms.

Economic loss, amount of beef discarded, natural resources wastage, and environmental impact due to beef discoloration

Consumers associate a bright-cherry red color of beefwith freshness and wholesomeness. Any deviation from a bright red color leadsto a discounted price or beef is discarded. Limited data is currently availableon the economic losses due to retail beef discoloration. Therefore, theobjective of the study was to estimate economic losses, the amount of beefdiscarded, natural resource wastage, and environmental impact due to beefdiscoloration. One-year data of total beef sales, total beef discarded, and discountedsale values were collected from two national retail chains and one retailstore. The two retail chains were located throughout the US, and the one retailstore was located in Southern US. The US beef system life cycle parameters frompublished literature were used to calculate the impact of discarded meat on waterand energy use and greenhouse gas emissions. The data from three stores weremodeled to calculate annual loss due to discoloration from the US retail beefsales. The data indicated that total beef sales from two major retail chainsand one retail store was 1.1 billion pounds of steaks and ground beef for theone-year period. This amount of beef corresponds to approximately 6.5% of totalretail sales of steaks and ground beef in the US. The amount of beef discardedfrom two major retail chains and one retail store corresponds to 29.7 millionpounds. Based on modeled data, the amount of beef discarded annually due todiscoloration within the US retail beef industry corresponds to 429 millionpounds, with another 1.8 billion pounds sold at a discount. The results indicatethat the US beef industry losses $3.745 billion annually due to discoloration. Thetotal amount of beef discarded per year in the US corresponds to 429 millionpounds, which represents wasting 780,000 animals and the associated naturalresources used in their production. A 1% decrease in discolored beef in the UScould reduce natural resource waste and environmental impacts by 23.95 billionL in water, 96.88 billion mega Joules in energy consumed, and 0.40 million tonsof carbon dioxide equivalent emission along the beef upstream value chain.Therefore, novel technologies to improve meat color stability could improvebeef production’s sustainability and limit wastage of nutritious beef.&nbsp;&nbsp;

Repackaging Nitrite-Embedded Dark-Cutting Steak in Aerobic Polyvinyl Chloride Film Decreases Surface Redness

The overall goal was to evaluate the effects of repackaging nitrite-embedded dark-cutting steaks in polyvinylchloride (PVC) film on surface color. Dark-cutting beef strip loins (n = 8; pH = 6.39) and USDA Low Choice beef strip loins (USDA Choice, n = 6; pH = 5.56) were selected at a commercial packing plant. Dark-cutting loins were bisected and randomly assigned to nonenhanced dark-cutting and enhanced dark-cutting with glucono delta-lactone and rosemary treatments. USDA Choice and nonenhanced dark-cutting steaks were vacuum packaged (VP) and served as controls, whereas enhanced dark-cutting steaks were packed in nitrite-embedded packaging (NP). Steaks from nonenhanced USDA Choice VP, nonenhanced dark-cutting VP, and enhanced dark-cutting NP loins were randomly assigned to 3, 6, or 9 d of dark storage.Following dark storage, steaks were repackaged in PVC and displayed for 6 d at 2°C. Instrumental color, visual color, and aerobic plate count were evaluated for all steaks. Enhanced dark-cutting steaks in NP increased (P &lt; 0.05) a* values compared with USDA Choice and nonenhanced dark-cutting VP during 24 h of dark storage. Enhanced dark-cutting steaks packaged in NP had greater a* and L* values (P &lt; 0.05) than nonenhanced dark-cutting VP steaks during dark storage. Upon repackaging the enhanced dark-cutting steaks from NP, nitric oxide myoglobin decreased (P &lt; 0.05) during the first 12 h of display. Loss of nitric oxide myoglobin corresponds with a darker red appearance, increased surface discoloration, and decreased a* values.There were no differences (P &gt; 0.05) in aerobic plate count between enhanced dark-cutting NP steaks and nonenhanced dark-cutting VP steaks after repackaging. In conclusion, NP improved surface redness; however, repackaging enhanced dark-cutting from NP steaks in PVC decreased color stability and redness of dark-cutting beef.

Tandem Mass Tag Labeling-Based Analysis to Characterize Muscle-Specific Proteome Changes during Postmortem Aging of Bison Longissimus Lumborum and Psoas Major Muscles

The objective of the study was to examine the variations in sarcoplasmic proteomes of bison longissimus lumborum (LL) and psoas major (PM) muscles during postmortem aging utilizing tandem mass tag (TMT) isobaric labeling coupled with liquid chromatography mass-spectrometry (LC-MS/MS) for the categorization of muscles with muscle-specific inherent color stability. A total of 576 proteins were identified (P < 0.05) in both bison LL and PM muscles, where 97 proteins were identified as differentially abundant (fold change > 1.5, P < 0.05) from the three comparisons between muscles during postmortem aging periods (PM vs LL at 2 d, 7 d and 14 d). Among those proteins, the most important protein groups based on functions are related to electron transport chain (ETC) or oxidative phosphorylation, tricarboxylic acid cycle (TCA), ATP transport, carbohydrate metabolism, fatty acid oxidation, chaperones, oxygen transport, muscle contraction, calcium signaling, and protein synthesis. In PM, most of the proteins from ETC, TCA cycle, fatty acid oxidation, ATP and oxygen transport, and muscle contraction were more abundant or exhibited increased expression during aging compared to LL. On the other hand, the proteins involved in carbohydrate metabolism, chaperone function and protein synthesis mostly exhibited decreased expression in PM muscle relative to LL. These results clearly demonstrate that the proteins associated with oxidative metabolism showed increased expression in PM muscles. This indicates that oxidative damage or subsequent color deterioration resulted in bison PM muscles being attacked by the reactive oxygen species produced during those metabolic process. In contrast, proteins involved in glycolysis and chaperone activity exhibited a decrease in expression in bison PM muscles, resulting decline in color stability compared with LL. Because glycolytic enzymes and chaperones maintain oxidative and/or color stability by producing reducing equivalents in glycolytic pathway and with the protein folding ability of chaperones, respectively in LL muscles.

Evaluating the failure to bloom in dark-cutting and lactate-enhanced beef longissimus steaks

Previous studies have noted lower L* (lightness) values for both dark-cutting beef and normal-pH beef enhanced with lactate. In the current study, absorption-coefficient, scattering-coefficient, CIE L*a*b* values, refractive index of sarcoplasm, and inter-muscle bundle space were evaluated for dark-cutting beef, normal-pH beef enhanced with lactate, normal-pH beef enhanced with water, and normal-pH beef not enhanced with either water or lactate. Compared with non-enhanced loins, lactate-enhancement had lower a*, chroma, oxymyoglobin, reflectance, scattering, and inter-muscle bundle space as well as greater absorption and refractive index. Dark-cutting steaks had lower a*, chroma, oxymyoglobin values, reflectance, and scattering as well as less inter-muscle bundle space compared with lactate-enhanced steaks. Sarcoplasm refractive index values were greater in lactate-enhanced steaks than dark-cutting steaks. The results suggest that changes in muscle structure and optical properties due to either pH or lactate addition can alter muscle darkening and blooming properties.

Effects of Modified Atmospheric Packaging on Ground Chicken Color and Lipid Oxidation

The objective of the current study was to evaluate the color changes and lipid oxidation of ground chicken patties packaged in polyvinyl chloride (PVC) film, high-oxygen (HiOx)–modified atmospheric packaging (MAP; 80% oxygen + 20% carbon dioxide [CO2]), and carbon monoxide (CO)-MAP (0.4% CO + 19.6% CO2 + 80% nitrogen) and stored at 2°C. Surface color was measured using a HunterLab MiniScan spectrophotometer on days 0, 1, 2, and 4. Lipid oxidation, pH, and aerobic plate count were determined on days 0 and 4 of storage. Fatty acid profiles were determined on day 0 to characterize saturated and unsaturated fatty acids. Patties packaged in PVC had greater (P &lt; 0.05) pH than HiOx-MAP and CO-MAP. Gas chromatography analysis indicated that ground chicken has 72.8% unsaturated fatty acids and 27.2% saturated fatty acids (based on total lipids and fatty acid methyl ester). The formation of carboxymyoglobin on ground chicken patty surface was confirmed by peaks at 420 and 570 nm, whereas oxymyoglobin had peaks at 410 and 580 nm. Instrumental color analysis indicated both HiOx-MAP and CO-MAP had greater (P &lt; 0.05) redness (a* values) than PVC on day 4 of storage. Patties packaged in HiOx-MAP had greater (P &lt; 0.05) chroma values than CO-MAP and PVC on day 4 of storage. Visual panelists noted less (P &lt; 0.05) surface discoloration in CO-MAP than PVC and HiOx-MAP on day 4 of storage. Lipid oxidation was greater (P &lt; 0.05) in PVC and HiOx-MAP than CO-MAP. CO inclusion at 0.4% level effectively inhibited lipid oxidation and stabilized surface redness during refrigerated storage of ground chicken.

Antioxidant, Antimicrobial and Metmyoglobin Reducing Activity of Artichoke (Cynara scolymus) Powder Extract-Added Minced Meat during Frozen Storage

The present study aimed to investigate the bioactive compounds in artichoke (Cynara scolymus) powder, having antioxidant and antimicrobial activity, and to determine the effectiveness of artichoke (C. scolymus) powder extract within the minced meat. C. scolymus was extracted using two different methods. The method incorporating high phenolic and flavonoid content levels was used in other analyses and the phenolic and flavonoid contents in C. scolymus extract was determined using LC-QTOF-MS. Antioxidant, antimicrobial, and metmyoglobin (metMb) reducing activities and pH values of the extract-added minced meat samples were measured for 10 days during storage. DPPH, FRAP, and ABTS were used in the antioxidant analyses. The antimicrobial activity of C. scolymus extract was evaluated on five different food pathogens by using the disc diffusion method. The most resistant bacterium was found to be Listeria monocytogenes (18.05 mm ± 0.24). The amount of metMb was measured in the minced meat sample that was added to the extract during storage (p < 0.05). MetMb formation and pH value on the sixth day of storage were found to be at lower levels than in the control group. In conclusion, C. scolymus exhibited a good antimicrobial and antioxidant effect and can be used in storing and packaging the food products, especially the meat and meat products.

The Relationship between Lipid Content in Ground Beef Patties with Rate of Discoloration and Lipid Oxidation during Simulated Retail Display

The relationships between the lipid content, lipid oxidation, and discoloration rate of ground beef during a simulated retail display were characterized in this study. A total of 276 batches of ground beef were manufactured with inside rounds and subcutaneous fat from 138 beef carcasses at different targeted levels of lean:fat. There was a total of four different targeted grind levels during the manufacture of the ground beef, and the lipid content for the samples used in this study ranged from 2% to 32% total lipid. Fatty acid composition was determined based on subcutaneous fat, whereas the proximate composition of moisture and total lipids, instrumental color, visual discoloration, and lipid oxidation measured as thiobarbituric acid reactive substances were evaluated on ground beef patties during 7 days of simulated retail at 4 °C display under LED lights. Analysis for the correlation and the creation of linear regression models indicated that lipid content played a more critical role in the discoloration rate compared to lipid oxidation and fatty acid composition. Lipid oxidation could be more reliably predicted by lipid content and instrumental color compared to visual discoloration. Overall, ground beef formulated with greater lipid content is expected to experience greater rates of lipid oxidation and discoloration during retail display.

Variations in Low Electrical Stimulator Voltage Settings Minimally Influence Beef Longissimus Muscle Slice Shear Force Values

The objective of the current study was to evaluate the effect of differing electrical stimulation (ES) voltage levels on beef longissimus muscle tenderness, postmortem temperature, pH decline, and carcass quality. Beef carcasses from 3 commercial beef processing plants (A, B, C) were exposed to 3 varying voltage levels: (1) control (no ES), (2) ES level 1 (ES1; 60 Hz for 17 s each at 16, 20, 24, and 28 V), and (3) ES level 2 (ES2; 60 Hz for 17 s each at 25, 35, 45, and 55 V) prior to chilling. Ninety beef carcasses were selected from each of the 3 plants, and within a carcass, paired sides were randomly assigned to one of 3 ES treatments (n = 60 sides/treatment/plant). The results indicated that ES affected (P &lt; 0.05) muscle pH at 3 h postmortem in 2 of the 3 plants. However, ES did not affect (P &gt; 0.05) pH at the time of grading (postrigor). Although the slice shear force (SSF) values were lower (P &lt; 0.05) for ES steaks compared with controls, voltage did not affect (P &gt; 0.05) SSF values. Variation in SSF was observed among the plants (P &lt; 0.05), with steaks from Plant C having greater (P &lt; 0.05) SSF values compared with steaks from Plants A and B, which exhibited similar (P &gt; 0.05) SSF values. Overall, although ES steaks had lower SSF values compared with control steaks, the lack of difference in postmortem tenderness between ES1 and ES2 voltage settings indicated that the low ES voltages minimally influenced SSF values.

Effects of Pork Quality Types, Packaging, and Degree of Doneness on Trained Sensory and Instrumental Tenderness, Color, and Consumer Perception

The objective of this study was to evaluate the palatability and retail display differences of 3 types of pork loins. Enhanced (n = 10), nonenhanced (n = 10), and high-quality (n = 10) pork loins were selected from a commercial food distribution company. Loins were cut into 2.54-cm-thick chops and randomly assigned to retail display, sensory, or Warner-Bratzler shear force analyses. For retail display, chops were randomly assigned to 1 of 3 packaging treatments: polyvinyl chloride overwrap, carbon monoxide-modified atmosphere packaging, and high-oxygen modified atmospheric packaging. Instrumental and visual color measurements were taken during 5 d of retail display. For trained sensory panel and Warner-Bratzler shear force analyses, chops were evaluated at 3 different degrees of doneness (63°C, 68°C, and 74°C). Consumer sensory panelists (N = 50) evaluated the overall liking, flavor, juiciness, and tenderness of chops cooked to 68°C. A treatment × packaging interaction (P &lt; 0.05) occurred for L* and a* values. High-quality chops packaged in polyvinyl chloride overwrap were lighter in color (P &lt; 0.05) compared with other treatment and packaging types. However, high- quality chops had lower (P &lt; 0.05) a* values than other treatment and packaging types during retail display. Trained panelists reported no difference (P &gt; 0.05) in tenderness for enhanced chops when cooked at 3 different degrees of doneness. Consumer panelists preferred the enhanced chops for overall liking, tenderness, and juiciness (P &lt; 0.05) compared with high-quality and nonenhanced chops. The results suggest that enhanced, nonenhanced, and high-quality pork loins avail- able in the market vary in color and marbling. Both pork loin type and packaging can influence display color and palatability.

Myoglobin Post-Translational Modifications Influence Color Stability of Beef Longissimus Lumborum

Post-translational modifications (PTM) of proteins play critical roles in biological processes. PTM of muscle proteins influence meat quality. Nonetheless, myoglobin (Mb) PTM and their impact on fresh beef color stability have not been characterized yet. Therefore, our objectives were to identify Mb PTM in beef longissimus lumborum muscle during postmortem aging and to characterize their influence on color stability. The longissimus lumborum muscles from 9 (n = 9) beef carcasses (24 h postmortem) were subjected to wet aging for 0, 7, 14, and 21 d. At the end of each wet-aging period, steaks were fabricated. One steak for analyses of PTM was immediately frozen at −80°C, whereas other steaks were assigned to refrigerated storage in the darkness under aerobic packaging. Instrumental color and biochemical attributes were evaluated on day 0, 3, or 6 of storage. Mb PTM were analyzed using two-dimensional electrophoresis and tandem mass spectrometry. Surface redness (a* value), color stability, and Mb concentration decreased (P &lt; 0.05) upon aging. Gel image analyses identified 6 Mb spots with similar molecular weight (17 kDa) but different isoelectric pH. Tandem mass spectrometry identified multiple PTM (phosphorylation, methylation, carboxymethylation, acetylation, and 4-hydroxynonenal alkylation) in these 6 isoforms. The amino acids susceptible to phosphorylation were serine (S), threonine (T), and tyrosine, whereas other PTM were detected in lysine (K), arginine (R), and histidine residues. Additionally, distal histidine (position 64), critical to heme stability, was found to be alkylated. Overall, Mb PTM increased with aging. The aging-induced PTM, especially those occurring close to hydrophobic heme pocket, could disrupt Mb tertiary structure, influence heme affinity, and compromise oxygen binding capacity, leading to decreased color stability of fresh beef. Furthermore, PTM at K45, K47, and K87 were unique to Mb from non-aged beef, whereas PTM at R31, T51, K96, K98, S121, R139, and K147 were unique to Mb from aged counterparts, indicating that these Mb PTM could be used as novel biomarkers for fresh beef color stability.

Insights on meat quality from combining traditional studies and proteomics

Following a century of major discoveries on the mechanisms determining meat colour and tenderness using traditional scientific methods, further research into complex and interactive factors contributing to variations in meat quality is increasingly being based on data-driven "omics" approaches such as proteomics. Using two recent meta-analyses of proteomics studies on beef colour and tenderness, this review examines how knowledge of the mechanisms and factors underlying variations in these meat qualities can be both confirmed and extended by data-driven approaches. While proteomics seems to overlook some sources of variations in beef toughness, it highlights the role of post-mortem energy metabolism in setting the conditions for development of meat colour and tenderness, and also points to the complex interplay of energy metabolism, calcium regulation and mitochondrial metabolism. In using proteomics as a future tool for explaining variations in meat quality, the need for confirmation by further hypothesis-driven experimental studies of post-hoc explanations of why certain proteins are biomarkers of beef quality in data-driven studies is emphasised.

Effects of Enhancement and Modified Atmosphere Packaging on Flavor and Tenderness of Dark-Cutting Beef

The objective of this study was to evaluate the effects of rosemary/beef flavor enhancement and modified atmosphere packaging (MAP) on retail display color and palatability of beef longissimus lumborum muscle. Dark-cutting beef strip loins (n = 8; pH &gt; 6.0) and USDA Low Choice beef strip loins (n = 5) were selected from a commercial packing plant within 72 h of harvest. Dark-cutting strip loins were divided into 2 equal sections and randomly assigned to either nonenhanced or rosemary/beef flavor–enhanced treatments. Dark-cutting enhanced loins were injected to 110% of their green weight with a rosemary/beef flavor enhancement to attain 0.1% rosemary, 0.5% salt, and 0.55% beef flavor in the final product. Six 2.54-cm-thick steaks were cut from nonenhanced USDA Choice, nonenhanced dark-cutting, and enhanced dark-cutting strip loins and randomly assigned to one of 3 packaging treatments: vacuum packaging, carbon monoxide MAP (0.4% CO, 69.6% N, and 30% CO2), and high-oxygen MAP (80% O2 and 20% CO2). Following 3-d retail display, instrumental color measurements were recorded, and one steak from each packaging type was evaluated by a trained sensory taste panel and another used to measure Warner-Bratzler shear force. Enhanced dark-cutting steaks packaged in high-oxygen MAP and carbon monoxide MAP had greater a* values (P &lt; 0.0001) than dark-cutting steaks in vacuum packaging. Enhanced dark-cutting steaks were lighter (P &lt; 0.0001, greater L* values) than nonenhanced dark-cutting steaks. Nonenhanced dark-cutting steaks exhibited a lower (P = 0.03) overall juiciness compared to enhanced dark-cutting steaks. Enhanced and nonenhanced dark-cutting steaks were more tender (P = 0.002) than the USDA Choice steaks. Enhanced dark-cutting steaks had higher (P = 0.006) sour flavor in vacuum packaging than other packaging types. The results suggest that rosemary/beef flavor enhancement has the potential to improve the surface color of dark-cutting beef while improving or maintaining palatability.

Strategies to limit meat wastage: Focus on meat discoloration

Limiting meat waste is a significant factor that can help meet future needs to provide high-quality animal protein while maximizing the utilization of natural resources. Fresh meat waste occurs during production, processing, distribution, and marketing to various points of consumption. Consumers' expectation for muscle food quality is often associated with its appearance, and a bright-red color of red meat is an indicator of freshness and wholesomeness. Meat discoloration is a natural process resulting from interactions between the physical structure of meat and the oxidation of the ferrous forms of myoglobin. Understanding the biochemical processes that influence discoloration such as oxygen consumption, metmyoglobin reducing activity, lipid oxidation, and microbial growth help to develop innovative strategies to limit meat waste. The focus of this chapter is to discuss the factors involved in meat discoloration and any other color deviations that may lead to discounted pricing and/or meat loss. The impact of meat waste, economic loss, the role of packaging, and the application of high-throughput techniques to understand the biochemical basis of meat discoloration are also discussed.