Effects of postmortem storage time on color and mitochondria in beef

Influence of lipid and metabolite profiles of mitochondrial fraction on pH and color stability of longissimus lumborum muscle with different ultimate beef pH

This study aimed to explore the differences in the lipidome and mitochondrial fraction metabolome of Nellore cattle meat in different ranges of ultimate pH (pHu) normal (≤5.79), intermediate (5.80 to 6.19) and high (≥ 6.20) after 3- and 21-d postmortem. Instrumental color, myoglobin redox state, oxygen consumption, and metmyoglobin-reducing activity were measured during storage. A total of 472 lipids and 22 mitochondrial fraction metabolites were identified. Beef with high pHu showed positive regulation of ceramides involved in apoptosis and negative regulation of lipid classes related to membrane permeability and stability. In addition, lower carnitine content was noted in high-pHu beef than in normal-pHu beef. Acylcarnitines, phosphatidylinositol, and IMP showed upregulation in beef with intermediate pHu, indicating changes mainly related to energy, purine and pyruvate metabolism. Aging time impacted on the lipid content and metabolites involved in different metabolic pathways. These results provided new insights into beef's mitochondrial fraction lipid and metabolic profile with different pHu. In addition, beef with intermediate pHu differs from beef with high pHu due to changes in energy metabolism.

The importance of including metmyoglobin levels in reflectance-based oxygen consumption measurements

Reflectance-based oxygen consumption measurement utilizes changes in oxymyoglobin levels between bloomed and vacuum-packaged meat, assuming that oxymyoglobin is converted to deoxymyoglobin. However, the interconversion of oxymyoglobin to deoxymyoglobin depends on the age of the meat and the length of display; hence, oxygen consumption calculations might yield inaccurate interpretations if deoxymyoglobin is not the final form. The objective was to evaluate the effectiveness of determining metmyoglobin levels during oxygen consumption analysis and its relationship to beef color stability. Seven psoas major (color labile) and longissimus (color stable) were displayed in retail for 6 d and evaluated for oxygen consumption on the retail (oxygen exposed) and interior (non‑oxygen exposed) surfaces. The retail surface had greater (P < 0.05) metmyoglobin formed during oxygen consumption than the interior surface on d 6 of the display. Furthermore, the psoas major muscle exhibited greater (P < 0.05) metmyoglobin content during oxygen consumption than the longissimus on the retail surface paralleling with the decline in color stability. Therefore, the study indicates that sampling location and including metmyoglobin content in oxygen consumption calculations, along with changes in oxymyoglobin, will better explain meat color stability.

Acerola Cherry and Rosemary Extracts Improve Color and Delay Lipid Oxidation in Previously Frozen Beef

Extending the shelf life of exported beef could increase international demand and producer profits. The objective was to evaluate the effects of topically applying combinations of acerola cherry powder and rosemary extract on the shelf life of frozen-thawed bone-in beef short rib and chuck roll steaks. Chuck rolls (IMPS 116A; N = 9) and bone-in short ribs (IMPS 123A; N = 18) were aged (7 d; 0 °C), frozen (30 d; -20 °C), and thawed (60-72 h; 0 °C). Steaks measuring 1.02 cm thick were treated and subjected to a 4 d retail display. Steaks were left untreated (control) or sprayed topically with acerola cherry powder (0.05%; A), rosemary extract (0.10%; R), or a combination (M1 = 0.05% A + 0.1% R; M2 = 0.1% A + 0.1% R; M3 = 0.05% A + 0.2% R; M4 = 0.1% A + 0.2% R). Chuck roll M2- and M4-treated steaks were redder than the control steaks on days 3 and 4 (p = 0.008), and antioxidant-treated steaks had less lipid oxidation on day 4 than the control steaks (p = 0.021). Bone marrow samples treated with R, M3, and M4 were redder than the control on days 1-3 (p = 0.014), and bone marrow treated with M3 was subjectively redder compared to the control on days 0 and 1 (p = 0.033). Topical antioxidants improve the redness and delay the oxidation of frozen-thawed beef.

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 effect of pH and aging on mitochondrial reduction of bovine myoglobin's affinity for oxygen

In skeletal muscles, mitochondria have been shown to decrease the oxygen affinity of myoglobin. In this study, we investigated whether the mitochondrial function of decreasing myoglobin affinity for oxygen persists and operates at the final pH of postmortem bovine skeletal muscle. The oxygen affinity and myoglobin consumption in the presence of mitochondria obtained from fresh and wet-aged beef were evaluated and compared at pH 5.1, 5.6, and 5.7. The results showed that mitochondria obtained from fresh beef preserved myoglobin oxygen consumption and affinity interference, whereas those obtained from wet-aged beef did not. Oxygen consumption and affinity interference were mostly absent at pH 5.1 and were higher at pH 5.7 than those at pH 5.6. Our findings suggest that mitochondria contribute both to an increase in the oxygen affinity of myoglobin in aged meat and a decrease in the oxygen affinity of myoglobin in high-pH meat, such as dark-cutting beef.

Dietary oregano essential oil supplementation alters meat quality, oxidative stability, and fatty acid profiles of beef cattle

This study was conducted to elucidate the effects of oregano essential oil (OEO) supplementation on the meat quality, antioxidant capacity, and nutritional value of the longissimus thoracis muscle in steers. Steers were divided into three groups (n = 9) and fed either a basal diet, or a basal diet supplemented with 130 mg/d OEO, or 230 mg/d OEO for 390 days. The results demonstrated that dietary OEO supplementation increased the total antioxidant capacity and activity of catalase, glutathione peroxidase, and superoxide dismutase, and decreased pH30min, pH24h, cooking loss, and malondialdehyde content. OEO increased the concentrations of polyunsaturated fatty acids and conjugated linoleic acid. In contrast, saturated fatty acids decreased, accompanied by increased essential amino acids, flavor amino acids, and total amino acids in the longissimus thoracis muscle. In summary, dietary OEO supplementation promotes the nutritional and meat quality of beef by maintaining its water-holding capacity and meat color, enhancing its antioxidative capacity, and preventing lipid oxidation.

Application of portable Vis-NIR spectroscopy for rapid detection of myoglobin in frozen pork

Myoglobin content is considered as a crucial index to evaluate the quality of frozen pork. In this study, a portable visible and near-infrared (Vis-NIR) spectrometer combined with chemometrics was used to detect myoglobin content in frozen pork. Metmyoglobin, deoxymyoglobin, oxymyoglobin, and total myoglobin were assessed spectrophotometrically. The raw Vis-NIR spectra of frozen pork samples were pre-processed using 1^st derivatives (FD). Afterward, Synergy Interval Partial Least Square (Si-PLS) coupled Competitive Adaptive Reweighted Sampling algorithm (Si-CARS-PLS) was applied to select characteristic variables. The Si-CARS-PLS models revealed the probability of estimating myoglobin content in frozen pork, with predictive correlation coefficients (R_p) for metmyoglobin, deoxymyoglobin, oxymyoglobin, and total myoglobin as 0.9095, 0.9004, 0.8578, and 0.9133, respectively. The findings of this study showed that Vis-NIR spectroscopy coupled with Si-CARS-PLS is a promising method and offered a way forward for determining the myoglobin content in frozen pork.

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.

Effect of dietary resveratrol supplementation on muscle fiber types and meat quality in beef cattle

In order to investigate the effect of dietary resveratrol supplementation on muscle fiber types and meat quality in beef cattle, a feeding experiment was undertaken. Longissimus lumborum, Psoas major and Semitendinosus muscles were collected 24 h post-mortem from two groups of cattle, which were fed with a total mixed ration (Control - CON) or supplemented with resveratrol (5 g/animal/day, RES) for 120 d before slaughter. The results showed that dietary resveratrol increased the gene expression of MyHC I and enhanced the proportion of type I fibers in three muscles. The cooking loss and Warner-Bratzler shear force of all muscles during aging for 21 days were decreased. However, the increased proportion of type I fibers resulted in a darker initial color, but did improve color stability, as the a* value of RES samples was lower initially but higher in the later stage of aging. This study indicates the supplementation potential of resveratrol for beef cattle for tenderness and color stability.

Effect of Animal Age, Postmortem Calcium Chloride Marination, and Storage Time on Meat Quality Characteristics of M. longissimus thoracis et lumborum of Buffalo Bulls

This study investigated the effect of animal age, calcium chloride marination, and storage time on meat quality characteristics of buffalo bulls to suggest a cost-effective method of improving buffalo meat quality. The current study was designed considering the importance of buffalo meat and the usage of meat from spent buffalo animals in local markets of South Asian countries. A total of 36 animals comprised of 18 young and 18 spent buffalo bulls were selected. After slaughtering and 24 h of postmortem chilling, striploins were separated and cut into 16 steaks and equally divided into two groups, i.e., either marinated with calcium chloride or not. Meat quality characteristics were recorded on 0, 2, 4, 6, 8, and 10 days of storage. The results showed that the pH value of young animals was higher than the value of spent animals and pH was increased over the storage time. Color b*, C*, and h* values were higher in spent animals as compared with the young animals; however, values of colors L* and h* were higher and a* was lower in marinated samples than the values of non-marinated samples. Color a* and C* values were increased and h* was decreased with lengthening the storage time. The meat cooking loss was higher in marinated and the water-holding capacity was higher in non-marinated meat samples. Shear force values were lower in young animals and marinated samples than the values of spent animals and non-marinated meat samples, respectively. Sensory characteristic scores of marinated samples were better than the non-marinated samples. In conclusion, calcium chloride marination can be used to improve the quality characteristics of buffalo meat.

The Effect of Weaning and Slaughter Age on the Physicochemical and Sensory Characteristics of Arouquesa Beef-A PDO Portuguese Meat

(1) Background: Autochthonous breeds meat is well accepted due to its sensory characteristics, perceived low environmental impact, and animal welfare. We aimed to evaluate the effect of weaning and slaughter age on the physicochemical and sensory characteristics of Arouquesa, a Portuguese Protected Designation of Origin (PDO) meat and to evaluate the psychological effect of knowing the weaning age on the consumer's hedonic evaluation. (2) Methods: Meat from 26 animals was assigned to 4 groups, with combinations of weaning (W) at 9 or 5 months and slaughter (S) at 9 or 12 months: W9-S9, W9-S12, W5-S9, and W5-S12. The meat was analysed for pH24h, colour (L*a*b*), cooking losses and shear force. A Check All that Apply test was made with 70 consumers; they were also asked to punctuate the hedonic appreciation of anonymous and weaning age-identified meat. (3) Results: W9-S9 were more tender, had lower shear force, and was juicier than W5-S9. When animals were slaughtered at 12 months, there were no differences in the physicochemical and sensory characteristics between the weaning ages. The effect of information about the weaning age influences the consumer's hedonic evaluation, as revealed by the comparison between the anonymous and identified samples. (4) Later weaning resulted in more tender meat when the slaughter was at 9 months and positively impacted consumer perception.

Weighted Single-Step GWAS Identifies Genes Influencing Fillet Color in Rainbow Trout

The visual appearance of the fish fillet is a significant determinant of consumers' purchase decisions. Depending on the rainbow trout diet, a uniform bright white or reddish/pink fillet color is desirable. Factors affecting fillet color are complex, ranging from the ability of live fish to accumulate carotenoids in the muscle to preharvest environmental conditions, early postmortem muscle metabolism, and storage conditions. Identifying genetic markers of fillet color is a desirable goal but a challenging task for the aquaculture industry. This study used weighted, single-step GWAS to explore the genetic basis of fillet color variation in rainbow trout. We identified several SNP windows explaining up to 3.5%, 2.5%, and 1.6% of the additive genetic variance for fillet redness, yellowness, and whiteness, respectively. SNPs are located within genes implicated in carotenoid metabolism (β,β-carotene 15,15'-dioxygenase, retinol dehydrogenase) and myoglobin homeostasis (ATP synthase subunit β, mitochondrial (ATP5F1B)). These genes are involved in processes that influence muscle pigmentation and postmortem flesh coloration. Other identified genes are involved in the maintenance of muscle structural integrity (kelch protein 41b (klh41b), collagen α-1(XXVIII) chain (COL28A1), and cathepsin K (CTSK)) and protection against lipid oxidation (peroxiredoxin, superoxide dismutase 2 (SOD2), sestrin-1, Ubiquitin carboxyl-terminal hydrolase-10 (USP10)). A-to-G single-nucleotide polymorphism in β,β-carotene 15,15'-dioxygenase, and USP10 result in isoleucine-to-valine and proline-to-leucine non-synonymous amino acid substitutions, respectively. Our observation confirms that fillet color is a complex trait regulated by many genes involved in carotenoid metabolism, myoglobin homeostasis, protection against lipid oxidation, and maintenance of muscle structural integrity. The significant SNPs identified in this study could be prioritized via genomic selection in breeding programs to improve fillet color in rainbow trout.

Color attributes and myoglobin chemistry exhibit relationships with tenderness and calpain-1 abundance in postmortem Longissimus lumborum muscles from Holstein heifers

The objective of this study was to determine the extent that myoglobin and beef color are associated with calpain-1 relative abundance relative and tenderness. Longissimus lumborum (LL) samples from the left side of Holstein beef carcasses (n = 31) were collected immediately post-evisceration for 0 h analyses. At 48 h postmortem six steaks were removed from the right side of each carcass for analyses at 48 and 336 h postmortem. Myoglobin concentrations resulted in negative correlations (P < 0.05) to Warner-Bratzler shear force (WBSF) values at 336 h postmortem. L*, a*, and b* values at 48 h resulted in positive correlations (P < 0.05) with WBSF values at 48 and 336 h. Values for b* at 336 h had positive correlations with calpain-1 concentration at 0 and 336 h. Data from this study indicate a potential relationship between myoglobin concentration and meat color with tenderness aspects and calpain-1 relative abundance.

Beef Carcass Size and Aging Time Effects on Yield and Color Characteristics of Top Round Steaks

Variation in cut size and weight of fabricated subprimals is a challenge of increased beef carcass weights. Subsequently, variation in carcass size has resulted in consistency challenges during retail display. The objective of this study was to assess three aging periods of commercially available top rounds from varying carcass weights as it relates to yield and color characteristics. In the current study, 21 industry average weight (AW; 340 to 409 kg; no industry discount) beef carcasses and 21 oversized (OS; exceeding 454 kg; receive a discount) beef carcasses were evaluated. Carcasses were selected at a commercial beef packing plant, where the left and right (paired) top round subprimals of each carcass were procured. Paired top rounds were assigned to a short (8 d), average (23 d), or extended (42 d) postmortem aging period. After wet-aging, subprimals were fabricated into steaks for additional analysis. Steaks were evaluated as whole top round steaks or further fabricated into “ superficial ” and “ deep ” portions at 5.08 cm from the superficial edge of the Semimembranosus and the Adductor muscle. Top rounds and steaks from OS carcasses were larger (P &lt; 0.01) than those from AW carcasses. Quantitative color of the anatomically deep locations of the OS steaks had the greatest mean L* (lightness; P &lt; 0.01), a* (redness; P &lt; 0.01) and b* (yellowness; P &lt; 0.01) values. Extending the aging timeline increased L* (lightness; P &lt; 0.01), decreased a* (redness; P &lt; 0.01), and decreased b* (yellowness; P &lt; 0.01). Alternative top round steak fabrication that separates the deep and superficial anatomical locations could be an effective means of providing more uniform steaks.

Extending the Shelf Life of Beef Steaks Using Acerola Cherry Powder and Rosemary Extract

Improvements in retail shelf life of exported beef will help with merchandising and increase competitiveness in the worldwide market for United States beef products. The objective of this study was to determine the effect of topically applying acerola cherry powder or rosemary extract from various suppliers on beef bone-in short rib steak and chuck roll steak shelf life. USDA Choice beef bone-in short ribs (IMPS 123A) and chuck rolls (IMPS 116A) were aged (0°C) for 28 d postfabrication. Following aging, 1.02-cm-thick steaks were cut (N = 126) and systematically assigned to a treatment based on steak location within the subprimal. Treatments included untreated control (C), topically sprayed (2 mL) with an acerola cherry powder solution (0.05%) from 1 of 3 suppliers (C1, C2, C3), or topically sprayed (2 mL) with a rosemary extract solution (0.10%) from 1 of 3 suppliers (R1, R2, R3). Half of the steaks were assigned to day 0 lipid oxidation, metmyoglobin-reducing activity (MRA), and oxygen consumption; the remaining steaks were assigned to color evaluation over 4 d of retail display followed by day 4 lipid oxidation and MRA. Short rib steaks treated with antioxidants had a brighter oxygenated lean color than control steaks (P &lt; 0.001). There was an interaction (P = 0.028) between time of retail display and MRA. Short rib steaks treated with C3 and R2 did not change in MRA between day 0 and 4 (P = 0.620, P = 0.428, respectively). Chuck roll steaks treated with C1, C2, C3, R2, and R3 all had a higher, or more desirable, MRA than the control steaks on day 0 (P &lt; 0.001). Applying topical antioxidants improves the shelf-life stability of steaks from beef bone-in short ribs and chuck rolls aged for an extended period.

The Effects of Using Pineapple Stem Starch as an Alternative Starch Source and Ageing Period on Meat Quality, Texture Profile, Ribonucleotide Content, and Fatty Acid Composition of Longissimus Thoracis of Fattening Dairy Steers

The effects of different starch sources (ground corn (CO), ground cassava (CA) and pineapple stem starch (PI)) and ageing period (14 and 21 days) on meat characteristics of Holstein steers were investigated. Starch sources had no effect on meat characteristics, while meat aged for 14 days had less thawing loss than that aged for 21 days. Meat from steers fed PI had higher levels of inosine monophosphate (IMP) than the others (p < 0.05). With increasing duration of ageing, the content of IMP and guanosine monophosphate in the meat decreased, while the content of hypoxanthine increased (p < 0.05). Meat from steers fed CO had the highest oleic acid but the lowest erucic acid (p < 0.05) in contrast to meat from steers fed PI, which had the lowest oleic acid but the highest erucic acid. Steers fed CO appeared to produce healthier meat as this was positively associated with monounsaturated fatty acid content. Meat from steers fed PI had higher levels of IMP, which may be associated with good taste.

Ageing as a method to increase bloom depth and improve retail colour in beef graded AUS-MEAT colour 4

Meat colour is an important attribute for consumer acceptance but there is an interval between colour grading and retail display. This experiment investigates the effect of time post-slaughter (5, 14 and 40 days) on colour and bloom depth (after 1 and 24 h) for beef carcasses graded AUS-MEAT colour 4 (MC 4). Sixteen carcasses were selected at grading, 8 carcasses were graded MC 4 and 8 as compliant colour (AUS-MEAT score 2 or 3). At 5 days post-slaughter, compliant loins had greater overall bloom depth and were more red than MC 4 loins. Bloom depth (24 h) increased with ageing time but reached maximum bloom at 14 days for both treatments. After ageing for 14 and 40 days, the bloom depth of MC 4 loin was no different to the 5 day aged compliant loins after 24 h on display. Colour at grading may not be a reliable measure of retail colour considering the changes post slaughter.

Effect of Wet Aging on Color Stability, Tenderness, and Sensory Attributes of Longissimus lumborum and Gluteus medius Muscles from Water Buffalo Bulls

Simple Summary

The water buffalo is found in many tropical countries worldwide. In the current world scenario, where meeting the protein requirements of the population is one of the biggest future challenges, buffalo meat could be a good source of protein and other nutrients. Currently, very little information is available regarding buffalo meat quality attributes. Therefore, this study was designed to evaluate the effects of aging time and muscle type on meat quality attributes (pH, color, tenderness, water holding capacity, and sensory acceptance) of buffalo meat. The results showed that color, tenderness, and sensory attributes were improved with aging time; the suitable aging time required to enhance meat quality attributes in Longissimus lumborum and Gluteus medius muscles is 28 and 21 days, respectively.

Abstract

The present study aimed to investigate the effect of wet aging on meat quality characteristics of Longissimus lumborum (LL) and Gluteus medius (GM) muscles of buffalo bulls. Meat samples from six aging periods, i.e., 0 day (d) = control, 7 d, 14 d, 21 d, 28 d, and 35 d, were evaluated for pH, color, metmyoglobin content (MetMb%), cooking loss, water holding capacity (WHC), myofibrillar fragmentation index (MFI), Warner–Bratzler shear force (WBSF), and sensory evaluation. The pH, instrumental color redness (a *), yellowness (b *), chroma (C *), and MetMb% values were increased, while the lightness (L *) and hue angle (h *) values showed non-significant (p > 0.05) differences in both LL and GM muscles in all aging periods. The cooking loss increased while WHC decreased till 35 days of aging. MFI values significantly (p < 0.05) increased, while WBSF values decreased; in addition, sensory characteristics were improved with the increase in the aging period. Overall, the color, tenderness, and sensory characteristics were improved in LL and GM muscles until 28 and 21 days of aging, respectively. Based on the evaluated meat characteristics, 28 days of aging is required to improve the meat quality characteristics of LL, whereas 21 days of aging is suitable for GM muscle.

Extended Aging and Marbling Class Effects on Color Stability of Beef Longissimus lumborum, Gluteus medius, and Biceps femoris Steaks

Postmortem aging improves palatability of various muscles, especially those from lower quality grades. This study evaluated postmortem aging and marbling class effects on the color stability of longissimus lumborum, gluteus medius, and biceps femoris steaks. Carcasses were selected at grading to have Lower Small (Small00 to Small50; n = 50) or Upper Slight (Slight50 to Slight90; n = 50) marbling scores. Strip loin and top sirloin subprimals from each carcass side were assigned to aging treatments (14, 21, 28, or 35 d) in an incomplete block arrangement. After aging, subprimals were cut into longissimus lumborum, gluteus medius, and biceps femoris steaks, respectively. Steaks were placed in a simulated retail display for 11 d. Changes in redness (a* and hue angle) were much slower and less extensive (P &lt; 0.001) in longissimus lumborum steaks than in gluteus medius steaks, which had slightly slower and less extensive (P &lt; 0.01) redness changes than biceps femoris. Increasing aging time increased (P &lt; 0.001) the rate and extent of overall color change (ΔE) during simulated retail display. Steaks from Lower Small carcasses had higher (P &lt; 0.01) L* values than steaks from Upper Slight carcasses at 14, 28, and 35 d postmortem. In steaks from Upper Slight carcasses, L* values were lower (P &lt; 0.01) in steaks aged for 28 d compared to other aging times. In steaks from Lower Small carcasses, L* values were highest (P &lt; 0.001) when aged for 14 d. Increased aging time generally decreased (P &lt; 0.05) a*, b*, and chroma values. However, within each aging time, only b* values of steaks aged for 35 d differed (P = 0.01) with regard to marbling class. Results indicate that increasing aging time decreased color life of beef muscles, and that marbling class had minimal impact on lean color stability.

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.

Dietary Supplementation With Chlorogenic Acid Derived From Lonicera macranthoides Hand-Mazz Improves Meat Quality and Muscle Fiber Characteristics of Finishing Pigs via Enhancement of Antioxidant Capacity

Chlorogenic acid (CGA), one of the most abundant polyphenol compounds in nature, is regarded as a potential feed additive to promote animal health and enhance the meat products’ quality via its various biological properties. The current study aims: (1) to determine whether dietary CGA supplementation improves meat quality and muscle fiber characteristics, and (2) to ascertain whether the corresponding improvement is associated with enhancing the antioxidant capacity of the finishing pigs. Thirty-two (Large × White × Landrace) finishing pigs with an average initial body weight of 71.89 ± 0.92 kg were allotted to 4 groups, and each was fed diets supplemented with 0, 0.02, 0.04, or 0.08% (weight/weight) of CGA. The meat quality traits, muscle fiber characteristics, and the serum and muscle antioxidant capacity were assessed. Results suggested that, compared with the control group, dietary CGA supplementation at a level of 0.04% significantly decreased the b^∗ value and distinctly increased the inosinic acid content of longissimus dorsi (LD) and biceps femoris (BF) muscles (P < 0.01). Moreover, dietary supplementation with 0.04% of CGA markedly improved the amino acid composition of LD and BF muscles, as well as augmented the mRNA abundance of Nrf-2, GPX-1, MyoD, MyoG, and oxidative muscle fiber (I and IIa) in LD muscle (P < 0.05). This result indicates that a diet supplemented with 0.04% of CGA promotes myogenesis and induces a transformation toward more oxidative muscle fibers in LD muscle, subsequently improving meat quality. Besides, dietary supplementation with 0.02% and 0.04% of CGA notably enhanced the serum GSH-PX level (P < 0.01). Considering all these effects are closely related to the alteration of antioxidant activities of the finishing pigs, the underlying metabolism is likely connected to the boosting of their antioxidant capacity induced by dietary CGA.

Effects of high-oxygen, carbon monoxide modified atmospheres and vacuum packaging on quality of Longissimus thoracis et lumborum steaks from Nellore cows during ageing

Nellore (Bos indicus) cows play an important role in Brazilian beef production. Here, we investigated whether modified atmosphere packaging (MAP) technology could contribute to improving the quality of Nellore cow steaks. To verify this, steaks obtained from Longissimus thoracis et lumborum (LTL) were stored at 2 °C for 28 days using different packaging systems, with one being vacuum and the others being three MAP systems: 75% O₂/25% CO₂ (75%O₂-MAP), 60% CO₂/0.2% CO/39.8% N₂ and 40% CO₂/0.4% CO/59.6% N₂ (0.2%CO-MAP and 0.4%CO-MAP, respectively). Steaks packaged using the CO-MAP showed improved color stability of fresh meat. In turn, the 75%O₂-MAP drastically affected the oxidative stability related to proteins and lipids compared to both anaerobic environments (CO-MAP and vacuum). The CO-MAP increased tenderization and ultrastructural changes when compared to the aerobic MAP without affecting pH, collagen or cooking loss, which were influenced by the storage time. In conclusion, MAP technology may improve the quality and appearance of fresh meat originating from Nellore cows, being a promising alternative for the Brazilian beef industry.

Effect of slaughter age and post-mortem days on meat quality of longissimus and semimembranosus muscles of Boer goats

This study investigated the effects of age of animal and days post-mortem (PM) on meat quality of Boer goats. Twenty-four (24) wether Boer goats of two age groups (2YO group: 2 years old and 9MO: 6-9 months, with 12 animals/group) were slaughtered in a commercial processing plant. The pH@Temp18 was estimated to be above 6 in both age groups with higher (P < 0.01) values in 2YO goats. The PM storage for 14 days reduced the shear force in both age groups (P < 0.01). 2YO goat muscles (longissimus and semimembranosus) exhibited higher (P < 0.01) Thiobarbituric acid reactive substance values (TBARS), indicating increased lipid oxidation. Glycogen (P < 0.01) and lactate content (20 min post-slaughter) in longissimus of 9MO were lower compared to 2YO, and total muscle glycogen concentration was lower (P < 0.01) in both age groups below the threshold levels. Hence, as hypothesized, age and days PM proved to play crucial roles on Boer meat quality.

Vascular infusion with concurrent vascular rinsing on color, tenderness, and lipid oxidation of hog meat

Market hogs were conventionally chilled (CN, n = 12) or Rinse & Chill® processed (RC, n = 13, MPSC Inc.). Muscles (Longissimus lumborum, LL; picnic shoulder, PS) were processed (chops, ground), packaged, and displayed or stored in the dark. Color, pH, moisture fat free (MFF), expressible moisture (EM), oxygen consumption, Warner-Bratzler shear (WBS), total pigment, TBARS, and hexanal content were determined. RC generally resulted in a lower pH during the first 4 h compared to CN. RC compared to CN had lower fat, but were not different in moisture fat free, expressible moisture, and total pigments. RC did not affect cooler shrink, cook loss and WBS force. RC PS was redder than RC LM. RC had greater deoxymyoglobin than CN on 7 d display. RC chops (LL) were lighter and had less deoxymyoglobin compared to CN. RC ground pork had greater oxygen consumption, lower TBARS and hexanal values compared to CN. RC has the potential to improve color and reduce lipid oxidation.

Ultimate pH effects on dry-aged beef quality

This study aimed to evaluate pH effects on moisture loss and meat quality characteristics of dry-aged beef. Strip loins from six normal pH carcasses (pH = 5.47 ± 0.02) and dark cutting (DC) strip loins from six high pH carcasses (pH = 6.69 ± 0.09) were obtained. One strip loin from each carcass was dry aged and one was wet aged, giving four treatments: DRY, DRY-DC, WET, and WET-DC. Loins were aged for 42 d. Ultimate pH did not affect the rate or amount of moisture loss, trim loss, yield, or tenderness in dry-aged beef (P > 0.05). In general, DC steaks had the lowest lightness (L*), redness (a*), and yellowness (b*) values, regardless of aging method (P < 0.05). Discoloration scores and TBARS values for DC steaks remained low throughout retail display. Dry aging significantly reduced bacterial counts mitigating the microbial damages associated with DC. Flavor characteristics of DC were not improved by dry aging when compared to dry-aged loins from carcasses with normal pH.

The Applicability of Total Color Difference ΔE for Determining the Blooming Time in Longissimus Lumborum and Semimembranosus Muscles from Holstein-Friesian Bulls at Different Ageing Times

This study was conducted to determine the optimal blooming time in beef muscles based on ΔE, and to analyze the effects of muscle type and ageing time on beef color and blooming. Beef color was determined on freshly cut longissimus lumborum (LL, n = 8) and semimembranosus (SM, n = 8) muscles on days 1, 9, and 14 of ageing during 60 min blooming at 5 min intervals. It was found that ΔE0, representing the difference in color between freshly cut muscles and subsequently analyzed samples, supported the determination of the optimal blooming time, which varied across ageing times (15, 20, 25 min for the LL muscle, and 10, 15, 20 min for the SM muscle on days 1, 9, and 14 of ageing, respectively). Beef color was affected by both muscle type and ageing. The values of color parameters increased between days 1 and 9 of ageing. The results may have practical applications because beef should be presented to consumers and restaurant owners approximately 25 min after cutting, when its color has fully developed.

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.

Genome-wide association study identified genomic regions and putative candidate genes affecting meat color traits in Nellore cattle

Single and multiple-trait GWAS were conducted to detect genomic regions and candidate genes associated with meat color traits (L*, lightness; a*, redness; b*, yellowness) in Nellore cattle. Phenotypic records of 5000 animals, and 3794 genotypes for 614,274 SNPs were used. The BLUPF90 family programs were used through single step GWAS approach. The top 10 genomic regions from single-trait GWAS explained 13.64%, 15.12% and 13% of genetic variance of L*, a* and b*, which harbored 129, 70, and 84 candidate genes, respectively. Regarding multiple-trait GWAS, the top 10 SNP windows explained 17.46%, 18.98% and 13.74% of genetic variance of L*, a* and b*, and harbored 124, 86, and 82 candidate genes, respectively. Pleiotropic effects were evidenced by the overlapping regions detected on BTA 15 and 26 associated with L* and a* (genetic correlation of -0.53), and on BTA 18 associated with a* and b* (genetic correlation of 0.60). Similar genomic regions located on BTA 2, 5, 6, and 18 were detected through single and multi-trait GWAS. Overlapped regions harbored a total of 30 functional candidate genes involved in mitochondrial activity, structural integrity of muscles, lipid oxidation, anaerobic metabolism, and muscular pH.

Effects of A Concentrate Rich in Agro-Industrial By-Products on Productivity Results, Carcass Characteristics and Meat Quality Traits of Finishing Heifers

Finishing diets in intensive beef production systems are mainly based on cereals, which does not take advantage of the capacity of the ruminant digestive system to digest fibrous feeds, cannot be considered sustainable and does not contribute to the circular bioeconomy. Our aim was to investigate the effects of an alternative concentrate rich in agro-industrial by-products for finishing crossbred Limousine heifers. Four pens with 12 heifers and four pens with 13 heifers were randomly allocated to one of two treatments: control (CON), a commercial concentrate with a 43.3% cereal composition, and alternative (ALT), a concentrate with a composition of 26% cereals and up to 73.5% agro-industrial by-products. Growth performance data were collected along the 91 days of the experimental period. Carcass characteristics were collected after slaughter and 24 h later. Vacuum-packaged samples from longissimus muscle were aged for 7, 21 or 28 days to study meat quality traits. Feed intake was higher and feed conversion rate was lower in the ALT treatment, but no differences were found in average daily gain and feeding costs. Treatment had no effects on any of the measured carcass traits (grading, hot and cold carcass weight, dressing out, chilling losses, subcutaneous fat depth, pH, temperature and lean and fat colour) nor on the meat quality traits (drip loss, cooking loss, shear force, oxidative stability, chromatic indices and pigment contents). Ageing time decreased drip loss and shear force, increased lightness and did not affect redness or surface colour stability. In conclusion, feeding crossbred Limousine heifers a finishing diet rich in agro-industrial by-products did not have any negative effects on performance, carcass and meat quality traits, which might be considered positive from the point of view of sustainability of beef production. Under the conditions assayed, ageing for 21 and 28 days improved tenderness of meat, without detrimental effects on oxidative stability or traits related to visual acceptability.

Recent Updates in Meat Color Research: Integrating Traditional and High-Throughput Approaches

Deviation from a bright cherry-red color of fresh meat results in less consumer acceptance and either discounted or discarded products in the value chain. Tissue homeostasis changes immediately after exsanguination, leading to acidification of muscle. Any alteration in pH drop can influence both muscle structure and enzymatic activity related to oxygen consumption and the redox state of myoglobin. This review focuses on both fundamental and applied approaches to under-stand the effects of pH on biochemical changes, oxygen diffusion, and its impact on meat color. Recent updates utilizing high-throughput “omics” approaches to elucidate the biochemical changes associated with high-pH meat are also dis-cussed. The fundamental aspects affecting fresh meat color are complex and highly interrelated with factors ranging from live animal production to preharvest environmental issues, muscle to meat conversion, and numerous facets along the merchandising chain of marketing meat to consumers.

Colour characteristics of beef longissimus thoracis during early 72 h postmortem

This study aimed to investigate the characteristics of beef meat colour during the initial 72 h postmortem to assess the possible effects of mitochondria on meat colour development. Bovine longissimus thoracis muscles (n = 5) were collected from one side of carcasses at 0.5, 4, 8, 12, 24, and 72 h postmortem and displayed in air for 6 days to measure colour and detect mitochondrial morphology and function. The results showed that beef had higher L^⁎, a^⁎, and b^⁎ at 24 and 72 h postmortem and less colour change during 6 days of display in comparison with meat from 0.5, 4, and 8 h postmortem. Changes in mitochondrial morphology were observed at 24 and 72 h postmortem. Mitochondria presented a metabolic pattern early postmortem in that the MRA and NADH content did not change. Both the increase in beef colour stability and tissue oxygen consumption were observed within 72 h postmortem.

Impact of myoglobin oxygenation level on color stability of frozen beef steaks

The emerging market of frozen meat emphasizes the need to better understand beef surface discoloration and the ideal parameters of freezing beef to retain an acceptable color. The objectives of this study were to determine the impacts of myoglobin oxygenation level prior to freezing and frozen storage duration on frozen beef color. USDA Choice strip loins (n = 36) were aged for 4 d or 20 d. Steaks were randomly assigned to a myoglobin oxygenation level [deoxygenated (DeOxy; immediately packaged after cutting), oxygenated (Oxy; oxygenated in air for 30 min), or highly oxygenated (HiOxy; packaged for 24 h in 80% O2)]. Steaks were then vacuum packaged in oxygen permeable or impermeable film and immediately frozen (-5 °C). Following either 0, 2, 4, or 6 mo of frozen storage, steaks were removed from the packaging and immediately analyzed for instrumental color (L*, a*, and b*), percent oxymyoglobin, metmyoglobin, and deoxymyoglobin, delta E, redness ratio, a*:b* ratio, hue angle, subjective discoloration, and lipid oxidation. The HiOxy steaks had greater oxygen penetration and the greatest a* values compared with DeOxy and Oxy steaks, regardless of packaging (P < 0.0005). With 4 d of aging, HiOxy steaks had greater a* values than DeOxy and Oxy at all storage times (P = 0.0118). The HiOxy steaks aged for 20 d and frozen for 6 mo had significantly higher delta E values than all other myoglobin oxygenation levels and postmortem aging periods (P < 0.0001). Redness and percent oxymyoglobin were highest for HiOxy steaks within each storage period (P < 0.0002). The HiOxy steaks had the highest percent oxymyoglobin and DeOxy had the lowest percent oxymyoglobin within each aging and storage period (P < 0.01). Conversely, DeOxy steaks had the highest percent metmyoglobin and HiOxy had the lowest percent metmyoglobin when packaged in impermeable film (P < 0.0001). The HiOxy steaks from 20 d of aging had the highest discoloration compared with 4 d aging and more discoloration than all other myoglobin treatments at 6 mo of storage (P < 0.0001). The HiOxy 20 d aged steaks exhibited the highest lipid oxidation values at 2, 4, and 6 mo (P = 0.0224) and HiOxy steaks exhibited a brighter and deeper cherry red color compared with the DeOxy steaks. The HiOxy steaks were greater in redness or similar when compared with Oxy steaks, but experienced more detrimental effects when frozen storage was extended.

Attitudinal Determinants of Beef Consumption in Venezuela: A Retrospective Survey

Consumer surveys were conducted in the Western, Central, and Eastern regions of Venezuela to determine buying expectations, motivations, needs, perceptions, and preferences of beef consumers, and their acceptance of domestic (and foreign) beef, as affected by different intrinsic and extrinsic factors. Data (n = 693) were gathered by face-to-face interviews on the way out of fresh markets, butcher stores, supermarkets, and, in some cases, at home by using a 45-question structured questionnaire. Responses were subjected to factorial analysis of correspondence (FA) and hierarchical cluster analysis. From the FA, the first two factors explain 74% of the common variance. Factor 1 comprises intrinsic attributes such as color, smell, tenderness, flavor, juiciness, and freshness; while Factor 2 contains extrinsic attributes, mostly related to the origin. The FA profiling data showed that it is possible to concentrate on the traits that consumers usually use as a criterion to perceive beef quality, and to purchase beef. Using cluster analysis, four groups of consumers were mainly distinguished by region, intrinsic attributes, and credence attributes related to production system, aging, traceability, and hygiene. Results from this study will be helpful in designing strategies for recovering and enhancing the future, domestic beef demand.

Comparison of meat quality, fatty acid composition and aroma volatiles of dry-aged beef from Hanwoo cows slaughtered at 60 or 80 months old

OBJECTIVE

The objective of this study was to compare the quality of dry-aged beef from cull Hanwoo cows slaughtered at 60 or 80 months old.

METHODS

A total of eight cull Hanwoo carcasses with a quality grade of 3 (low-grade) were selected and divided into two age groups: 63.5±2.5 months old (n = 4) and 87.8±4.5 months old (n = 4). Whole longissimus thoracis et lumborum from the 11th rib to the last lumbar vertebrae, including the back fat, was removed from the carcass at 24 h postmortem and aged for 50 days in darkness at a temperature of 2°C±1°C, a relative humidity of 85% and an air flow of 2 m/s. The sampling was performed aseptically after 0, 20, 24, 40, and 50 days of aging.

RESULTS

Regardless of the aging period, aging increased the lightness (p<0.05), redness (p<0.05) and yellowness (p<0.05) at initial blooming (90 min after slicing) and the overall acceptance (p<0.05). No further tenderization effect was found after 20 days of aging, but aging for 50 days significantly increased the lipid oxidation (p<0.05). The generation of aroma volatiles in the roast steak from aged samples was higher (p<0.05) than that of non-aged samples. No significant effect of age at slaughter was found on the color, pH, water-holding capacity, cooking loss, shear force value, bacterial counts, volatile basic nitrogen, consumer acceptance, lipid oxidation, fatty acid composition or aroma volatiles.

CONCLUSION

The quality of dry-aged beef obtained from cull Hanwoo cows slaughtered at either 60 or 80 months old with similar quality grade was comparable and extending dry aging for more than 40 days is not recommended considering the costs and further lipid oxidation.

Aging Condition and Retail Display Lighting Impact Retail Display Life and Lipid Oxidation of Beef Biceps Femoris Steaks

The objective of this study was to determine the impact of aging method and retail display lighting type on the discoloration and oxidation of a beef muscle with low color stability. Beef biceps femoris (BF; n = 38) were fabricated 48 h postmortem and aged for 16 d post fabrication in either wet (vacuum packaged) or dry conditions. After aging steaks (n = 9) were cut from each BF and randomly assigned to 1 of 3 retail display lengths: 1, 3, or 5 d and 3 light treatments: light emitting diode (LED), high-UV fluorescent (HFLO), or low-UV fluorescent (FLO). Steaks were removed from retail display, and were subjected to instrumental color analysis (L*, a*, b*), surface myoglobin redox forms, lipid oxidation, and metmyoglobin reducing activity. Dry aging resulted in greater (P < 0.05) redness, as determined by a*, saturation index, and hue angle values of beef BF steaks, compared to wet aging. Significant interactions (P < 0.05) between aging method and retail display day were reported for a/b ratios, hue angle, deoxymyoglobin concentrations, and lipid oxidation values. Dry aging resulted in increased (P < 0.05) lipid oxidation over the duration of retail display, as determined by thiobarbituric acid reactive substances (TBARS), in comparison to wet aging. Light by day interactions (P < 0.05) occurred for b*, metmyoglobin concentrations, oxymyoglobin concentrations, and saturation index values. Data indicate that utilization of fluorescent light sources promoted greater redness retention in a muscle with low color and oxidative stabilities over the duration of retail display in comparison to LED light sources.

Capturing consumer value and clustering customer preferences in the Indonesian halal beef market

The Indonesian consumer behavior has changed over the last decades, and hence reviewing consumer value is crucial for the halal beef industry. This study explores halal beef consumer preferences and its segmentation. The research design constituted descriptive with a quantitative approach. Focus group discussions and consumer surveys were conducted through face-to-face interview toward 440 middle-class Muslim households in Indonesian top ten cities. The data analysis uses conjoint and clusters analysis. The essential attributes of halal beef in the order of priority are a red color, zero residues, latest production, halal guarantee label positions for each cluster, clean, tender, and flavor (p-value = 0.000). Beef consumers consist of four clusters comprising sanctity, clarity, quality, and safety. Based on demographic characteristics, the age and family size differences among groups were not significant, with each p-value at 0.356 and 0.189, while based on consumption and buying preference, each cluster has not significantly different in their beef consumption level, with a p-value at 0.102.

Effects of immunocastration on the performance and meat quality traits of feedlot-finished Bos indicus (Nellore) cattle

This study aimed to evaluate the effects of immunocastration on the performance, testosterone concentration, carcass traits and meat quality of feedlot-finished Nellore cattle. Fifty-eight males (430 ± 36 kg bodyweight; 24 months old) were separated into three groups in a randomised complete design: surgically castration (n = 15), immunocastrated (anti-gonadotropin-releasing hormone (Bopriva®) vaccine, n = 21) and non-castrated (n = 22). The animals were housed in individual pens and fed ad libitum for 90 days with a common diet comprising 70% concentrate and 30% roughage (corn silage). The non-castrated animals had a greater average daily gain, feed efficiency, hot carcass weight and carcass yield than the surgically castrated and immunocastrated animals (P &lt; 0.05). Surgically castrated cattle grew faster and more efficiently than those castrated immunologically (P &lt; 0.05). The surgically castrated and immunocastrated animals had higher colour values L*, a* and b* and cooking loss than non-castrated animals (P &lt; 0.05). In conclusion, immunocastration decreased cattle performance compared with surgically castrated or non-castrated animals. However, immunocastration resulted in better meat quality compared with non-castrated, making it an alternative to surgical castration with no negative effects on animal welfare.

Mitochondrial Degeneration, Depletion of NADH, and Oxidative Stress Decrease Color Stability of Wet-Aged Beef Longissimus Steaks

Interrelationship between mitochondria and myoglobin function influence beef color. NADH level in postmortem muscle is an important determinant of mitochondrial activity and metmyoglobin reduction. Increased aging time promotes discoloration of steaks; however, the mechanism of this effect is not clear. The objective was to characterize the role of wet-aging in beef longissimus lumborum muscle mitochondrial function and to characterize the global metabolome to determine the mechanism of that can regenerate NADH. Beef longissimus lumborum muscles were randomly assigned to 3, 7, 14, 21, and 28 days aging periods. Surface color, biochemical, mitochondrial, and metabolite profiles were determined at each aging period and at the end of 6-day display. During 6-day display, sections aged for 28 days had 30.4% decrease in redness than sections aged for 3 days. Aging time decreased (P <0.05) muscle oxygen consumption, mitochondrial protein content, and antioxidant capacity. Metabolites such as fumaric acid, creatinine, and fructose, that can take part in glycolytic/TCA cycle and regenerate NADH decreased (P <0.05) with aging and display time. In support, NADH levels also decreased (P <0.05) with aging time, but aging time had no effect (P = 0.44) on NADH-dependent reductase activity. The results suggest that decreased color stability in aged beef can be attributed to increased mitochondrial damage, depletion of metabolites that can regenerate NADH, and increased oxidative stress. PRACTICAL APPLICATION: Beef aging time results in increased discoloration of steaks under retail display. The current research determines the fundamental basis of lower color stability in aged beef. The results indicate that mitochondrial degeneration, depletion of metabolites that produce NADH, and increased oxidative stress can limit shelf-life of aged steaks. Hence, application of post-harvest strategies to minimize mitochondrial damage and oxidative changes may have the potential to increase shelf-life of aged beef.

Role of Mitochondria in Beef Color: A Review

In postmortem muscle, mitochondria remain active and can influence beef color by oxygen consumption and metmyoglobin reduction. Enzymes involved in glycolysis and the tricarboxylic acid cycle can generate reducing equivalents such as succinate or NADH. Mitochondrial activity is critical to maintain steaks that are bright cherry-red and improve color stability. This review seeks to characterize the role of mitochondria in beef color; more specifically to understand the effects of mitochondrial function on myoglobin redox stability.

Muscle-Specific Mitochondrial Functionality and Its Influence on Fresh Beef Color Stability

Fresh beef color stability is a muscle-specific trait. Mitochondria remain biochemically active in postmortem beef muscles and influence meat color. Although several intrinsic factors governing muscle-specific beef color have been studied extensively, the role of mitochondrial functionality in muscle-dependent color stability is yet to be examined. Therefore, the objective of this study was to examine mitochondrial oxygen consumption rate (OCR), mitochondrial metmyoglobin reducing activity (MMRA), and instrumental color attributes in beef Longissimus lumborum (LL) and Psoas major (PM) during retail display. Using a split-plot design, six (n = 6) beef LL and PM muscles were fabricated into 2.54-cm-thick steaks, packaged in polyvinylchloride overwrap, and randomly assigned to instrumental color measurement for six days and mitochondrial isolation for days 0, 1, 3, or 5 of display at 4 °C. Mitochondria isolated from steaks were used to assess the effects of muscle and display time on OCR and MMRA. The PM steaks were less color-stable (p < 0.05) during display compared with the LL counterparts. For both muscles, OCR decreased during display, albeit the decrease was more rapid in PM than in the LL. Similarly, MMRA decreased during display for the LL and PM. However, this decrease was less (p < 0.05) for mitochondria from LL steaks, which were more resistant to display-mediated effects on OCR and MMRA. These results indicated that the muscle-specific differences in mitochondrial activity may contribute partially to the variations in color stability of beef LL and PM muscles.

PRACTICAL APPLICATION

During retail display tenderloin steaks packaged in PVC overwrap discolor quicker than strip loin steaks. This research determines the basis for muscle-specific differences in color stability. The results indicate that mitochondria present in tenderloin lose its functionality faster than strip loin mitochondria. Developing strategies to minimize muscle-specific differences in mitochondrial changes can increase color stability and value of fresh beef.

Impact of Light Source on Color and Lipid Oxidative Stabilities from a Moderately Color-Stable Beef Muscle during Retail Display

Consumers’ purchasing decisions are heavily impacted by fresh meat color, which they consider an indicator of quality in a retail setting. The objectives of this study were to evaluate the impact of light source on surface color and lipid oxidation during retail display of fresh steaks from semimembranosus (SM), a beef muscle with moderate oxidative and color stabilities. Steaks (n = 240) from the SM (n = 20) were packaged on Styrofoam trays and overwrapped with oxygen-permeable polyvinyl chloride. Steaks were then assigned to 1 of 3 lighting treatments, high UV fluorescent (HFLO), low UV fluorescent (FLO), and light emitting diode (LED) to mimic current storage conditions with a variety of industry available fluorescent bulbs, and evaluate emerging lighting conditions with LED. Steaks were removed on retail display d 1, 3, 5, and 7 for evaluation of instrumental color (L*, a*, and b* values), surface myoglobin redox forms, metmyoglobin reducing activity, and lipid oxidation. Light source influenced (P < 0.05) redness (a* values), with HFLO-displayed steaks having greatest (P < 0.05) a* values and LED-displayed steaks exhibiting lowest (P < 0.05) a* values. Surface redness decreased (P < 0.05) over retail display day. Steaks displayed in HFLO and FLO had greater (P < 0.05) oxymyoglobin percentages than those displayed under LED, indicating that LED accelerated surface discoloration compared to HFLO and FLO lights. Metmyoglobin (MMb) percentages increased over retail display, with LED-exposed steaks having greater (P < 0.05) percentages of MMb than those displayed in HFLO and FLO. By d 7 of retail display, HFLO-exposed steaks had lower (P < 0.05) MMb percentages than the steaks displayed in both FLO and LED. Lighting type did not influence (P > 0.05) lipid oxidation in SM steaks, however, lipid oxidation increased (P < 0.05) over retail display. The findings indicated that light source influenced the color stability in SM steaks during retail display and that HFLO light can minimize surface discoloration in moderate color stability beef muscles.

Intramuscular Variations in Color and Sarcoplasmic Proteome of Beef Semimembranosus during Postmortem Aging

Beef semimembranosus exhibits intramuscular difference in color stability, and the inside region (ISM) of the muscle is color-labile, whereas the outside region (OSM) is color-stable. Variations in sarcoplasmic proteins are known to contribute to this intramuscular color difference. Sarcoplasmic proteome and beef color are affected by postmortem aging. The objective of the present study was to examine the effect of aging on intramuscular color variations and the sarcoplasmic proteome of beef semimembranosus. Semimembranosus muscles obtained from 8 beef carcasses (n = 8) were subjected to aging at 2°C for 0, 7, 14, and 21 d. On each aging day, the muscles were fabricated into ISM and OSM steaks and allotted to refrigerated storage (2°C) under aerobic packaging. Instrumental color and metmyoglobin reducing activity were evaluated on d 0, 3, and 6 of storage. Samples frozen on d 0 and d 21 of aging were utilized for sarcoplasmic proteome analysis. Color attributes of both ISM and OSM steaks were influenced by aging, with steaks aged for 21 d having the lowest (P < 0.05) color stability. The ISM steaks had greater (P < 0.05) lightness than OSM counterparts, and the difference in lightness was not negated by aging. The ISM and OSM had similar (P > 0.05) redness on d 0 of storage, whereas ISM had lower (P < 0.05) redness compared to OSM on d 3 and d 6 of storage. Several proteins associated with glycolysis and energy metabolism were of greater abundance (P < 0.05) in OSM than in ISM after 21-d aging. Furthermore, the influence of 21-d aging on sarcoplasmic proteome was observed at a greater extent in OSM than in ISM, indicating that the effect of aging on sarcoplasmic proteome of beef semimembranosus was influenced by the location within the muscle.