Beef Muscle Research Articles

Evaluation of the Physicochemical Attributes of Beef, Chicken, and Pork Muscles Injected with Microbial Proteases for Designing Senior-Friendly Processed Meat Products

In developed countries, the growing elderly population has increased the demand for senior-friendly processed meat products. This study investigated the effects of four commercial microbial proteases (Alcalase, Flavourzyme, Neutrase, and Protamex) on the general physicochemical attributes of beef top round, chicken breast, and pork loin, which are lean muscle cuts suitable for developing senior-friendly meat products. Muscle samples were injected with microbial protease solutions (0.7% and 1.2% (w/w)), cooked, and used for analysis. The microbial protease injection significantly reduced the hardness of cooked muscles. Despite the evident degradation of the myosin heavy chain in Alcalase treatment, the lowest hardness values were observed in Protamex-treated samples, suggesting that myosin degradation alone does not fully account for tenderness improvement. Unfortunately, microbial protease treatments increased cooking loss in beef and chicken muscles (p < 0.05). The surface color characteristics, including redness and yellowness, remained unaffected by the enzymatic treatments, supporting the practical use of these proteases for meat tenderization without inducing color defects. While microbial proteases demonstrate potential for improving meat tenderness, future research should focus on mitigating cooking loss and ensuring desirable taste and flavor for the commercial production of senior-friendly processed meat products using the microbial proteases.

Changes in freezing parameters and temperature distribution of beef induced by AC electric field: Alleviation on freezing damage and myowater loss

In this study, a specialized experimental device integrating infrared thermal imaging, real-visual photography, and a time-temperature data collector was designed to investigate the effects of alternating electric field (AEF) assisted freezing on the temperature histories and freezing parameters in different layers of beef as well as the freezing damage and myowater loss. The findings revealed distinct differences in the freezing curves (e.g., slope) and parameters (e.g., Tnuc, TF, tptand Fmiz) between the surface, middle, and inner layers of beef cubes under both AEF and traditional freezing conditions. AEF treatment regulated the freezing curves and key parameters of middle and surface layers, influencing ice crystallization. The equivalent ice areas for the surface, middle, and inner samples under AEF treatment were 8.16, 14.40, and 20.56%, respectively, significantly lower than those in traditional freezing (15.87, 24.60, and 28.8%). Compared to traditional freezing, AEF-assisted freezing decreased myofibrillar fragmentation index (MFI) of beef muscle, preserving its texture integrity. AEF treatment inhibited water migration and reduced water-holding capacity (WHC) loss. In conclusion, AEF-assisted freezing changed ice formation characteristics and alleviated freezing damage by regulating the freezing curve traits and parameters.

Novel bioactive peptides with antihypertensive activity generated from beef muscle during fermentation with Lactobacillus rhamnosus FERM P-15120

Novel bioactive peptides with antihypertensive activity generated from beef muscle during fermentation with Lactobacillus rhamnosus FERM P-15120

Evaluation of green kiwifruit juice extract on physicochemical properties, antioxidant activity, and tenderness of beef M. semitendinosus with in vitro digestion.

This study focused on the physicochemical properties and tenderness of vacuum-packaged beef M. semitendinosus as affected by various dilution ratios (DRs, 1:4, 1:2, and 1:1) of green kiwifruit juice extract (GKJE) with phosphate buffer during storage at 4°C for 7 days. In addition, the formation of peptides with antioxidant activity for GKJE ability to hydrolyze proteins present in beef was evaluated at different steps of in vitro digestion. Beef with GKJE showed higher tenderness than control (CTL, beef with brine solution alone) during storage, and the increased DR increased tenderness as compared to lower DRs. The addition of GKJE increased protein digestibility during in vitro digestion. To increase the antioxidant activity in the body, GKJE having a DR of 1:2 and 1:1 should be applied to the beef muscle with effective antioxidant activity. These results suggest that DRs of phosphate buffer and kiwifruit juice of 1:1 and 1:2 have the potential to be used as a meat-tenderizing agent and could increase the digestibility of meat as well as the antioxidant capability of bioactive peptides. PRACTICAL APPLICATION: The dilution ratio of kiwi juice with phosphate buffer at 1:1 has the potential to be used as a meat-tenderizing agent during refrigerated storage and also increase the digestibility of beef.

PSLBI-11 Relevance of mitochondrial-mediated apoptotic processes in color and oxidative stabilities of five different beef muscles

Abstract Fresh meat color stands as one of the most critical quality indicators influencing consumer perception of meat freshness and purchase decision. Variation in color and color stability among different muscle types exists due to differences in chemical compositions, including lipids and metabolites, and other redox stability-related biochemical properties. Understanding biochemical mechanisms governing color stability in different muscles will offer insights for the industry to develop practical strategies aimed at reducing food waste attributed to discoloration. The objective of the current study was to identify metabolites and lipid compounds potentially linked to oxidative stabilities and relevant biochemical properties across different bovine muscles. Five different muscles [longissimus lumborum (LL), gluteus medius (GM), biceps femoris (BF), semitendinosus (ST), and infraspinatus (IF)] were collected from 16 beef carcasses (USDA Choice) at 2-d postmortem. Multiple cuts were made from each muscle for meat color measurements including instrumental and sensory color evaluations during display, and biochemical attributes, including total reducing activity (TRA), mitochondria-swelling, mitochondrial-lipid oxidation, cytochrome c redox ability (CytC). For the lipidome and metabolome analyses, beef samples were extracted and profiled using non-targeted UPLC-MS analyses. Data analysis was conducted with Metaboanalyst 6.0. The correlation analysis was conduct with Pearson’s correlation and considered the significance level at P < 0.05. In brief, LL and ST maintained greater color stability, redox stability, and lipid/protein oxidative stabilities compared with BF and GM, with IF showing the least (P < 0.05). Also, IF had the greatest levels of mitochondrial-swelling, mitochondrial-lipid oxidation, and oxidized CytC compared with LL (P < 0.05). The ANOVA results found 1,410 significant features in the metabolome analysis and 531 in the lipidome analysis of beef samples. Utilizing partial least square-discriminant analysis (PLS-DA), scatter plots grouped the five muscle types into three distinct clusters: LL and ST, BF and GM, and IF. Pro-apoptotic factors such as phosphatidylserine and lysophosphatidylserine were greater in IF compared with LL and ST (P < 0.05). From the metabolome results, anti-apoptotic factors like creatine and glutathione were increased in LL and ST compared with IF, whereas pro-apoptotic spermidine and adenosine monophosphate (AMP) were greatest in IF (P < 0.05). CIE a* showed a positive correlation with phospholipids and mitochondria-swelling (P < 0.05). Chroma exhibited a positive correlation with TRA, creatine, cyclic AMP, and GMP (P < 0.05). The results suggest that variations in meat color stability among the five beef muscles were likely attributed to differences in the abundance of lipids and metabolites associated with redox and oxidative stabilities, as well as mitochondrial-mediated apoptotic pathways. Specifically, the varying abundance of pro-/anti-apoptotic factors across muscles indicates potential mechanistic biochemical linkages between the apoptosis and meat color. Further research is warranted to investigate the effects of extended aging periods on changes in apoptotic features and color stability of beef muscles.

PSVII-19 Effects of silage particle size on beef quality and muscle lipogenesis of finishing Nellore heifers

Abstract The objective of this study was to evaluate the effect of corn silage particle size on beef quality and expression of gluconeogenic and lipogenic genes in feedlot-finished Nellore heifers. Nellore heifers (n = 94), with an initial body weight (BW) of 249.71 ± 34.62, were allotted into 32 pens (three animals per pen) in a completely randomized design, with 2 treatments and 16 repetitions. The treatments were corn silage with a particle size of 13 mm (short) or 24 mm (long). The feeding period lasted 101 d, with the first 15 d for diet adaptation. After slaughter, samples of the longissimus thoracis muscle (LT) from the left side of the half carcass and liver were taken for beef quality and gene expression analyses. The chemical composition of the beef was analyzed using near infrared according to the AOAC method 2007-04, using the FoodScanTM equipment (AOAC method: 2007-04; FOSS, Hillerod, Denmark). RT-qPCR analyses of each gene investigated were carried out using cDNA from 16 biological replicates per treatment (1 heifer chosen randomly in each pen), with each biological replicate subjected to 2 technical replicates. Relative gene expression analyses were calculated using the delta delta ct method and the reference genes used were ACTB and GAPDH. The normality of all experimental data was checked using the Shapiro-Wilk test in SAS software. When the data did not present a normal distribution, transformation was performed using PROC RANK. The model included particle size as a fixed effect and pen as a random effect. There was no treatment effect on collagen, moisture, and mineral content (P > 0.10), but muscles from heifers fed short particle sizes tended to have greater protein content (23.3 versus 22.9; P = 0.098), while muscles from heifers fed with long particles had greater intramuscular fat content (2.62 versus 3.28; P = 0.05). For liver gene expression, heifers fed short particle sizes tended to have greater expression of the PC gene (1.00 versus 0.82; P = 0.06), while PEPCK2 had higher expression in heifers fed long particles (1.00 versus 1.18; P = 0.04). In addition, the long particle size of corn silage affected the expression of PPARA (P = 0.001), and there was no effect of diets (P > 0.05) on PPARG and SREBF1 expressions (Table 1). Expression of LPL, FABP4, SCD1, CPT2 (P < 0.001), and ACACA (P = 0.017) genes increased in the muscle of heifers fed long particle size. Therefore, it is concluded that the use of corn silage with long particle size in feedlot diets has the potential to increase the expression of genes involved in lipogenesis and then increase intramuscular fat in Nellore heifers.

Changes in tenderness of beef M. semitendinosus and modification of actomyosin mediated by Fe(III)-protoporphyrin IX, protoporphyrin IX and free iron

The objective of the present study was to explore the effect of Fe(III)-protoporphyrin IX (hemin), protoporphyrin IX (PPIX) and free iron on beef M. semitendinosus tenderness and its molecular mechanism. Hemin, PPIX and FeCl3 treatment of beef muscles under heating tremendously decreased shear force of beef meat by approximately 24%, 26%, and 30% respectively and weakened the association of actin-myosin. The protein carbonyl content increased and sulfhydryl content decreased significantly in FeCl3 and hemin treated groups, indicating the oxidative modification of actomyosin. The higher surface hydrophobicity and intrinsic fluorescence intensity demonstrated that hemin, PPIX and FeCl3 increased the unfolding of actomyosin, and the crosslinking was formed by hydrophobic interaction and disulfide bonds. Hemin treatment increased the α-helices/random coil and initiated more structural changes in actomyosin as compared to that of PPIX and FeCl3. These biochemical changes might contribute to the dissociation of actomyosin. The obtained results established a link between meat tenderness and porphyrins/free iron content, and gave new insights into the mechanism of how hemin and released PPIX and free iron affect the physicochemical properties of actomyosin.

The Influence of Cooking Methods and Muscle on Beef Aroma Profile and Consumer Satisfaction: Insights from Volatile Compound Analysis

The objective of this study is to determine the effect of two distinct cooking techniques, namely roasting and stewing, on the formation of volatile compounds in various beef muscles (Semimembranosus, Biceps femoris, and Rectus femoris) and how this relates to consumer acceptance. The research employs the concept of volatile “marker” compounds to discern the influence of cooking techniques on the flavor profile of beef. Eighteen “marker compounds” were selected to represent a number of the mechanisms of formation and quantified in beef subjected to two different cooking methods. While no statistically significant differences were observed in consumer evaluations between the two cooking methods, notable disparities emerged in the consumer assessments of specific muscle cuts. Notably, the Rectus femoris muscle received the highest ratings (p < 0.05) among other evaluated muscles. The utilization of Solid-Phase Microextraction (SPME) and gas chromatography–mass spectrometry (GC-MS) methods for the analysis of volatile “marker compounds” in beef proved effective in highlighting significant differences in flavor compound classes between cooking methods, and these differed between muscles. The main effect was of the cooking method with stewed beef aroma having approximately 39× more dimethyl trisulphide, 9× more dimethyl disulphide, 7× more pentanal, 3× more hexanal, and twice as much benzaldehyde and 2-methylthiophene. Dimethyldisulphide, dimethyltrisulphide, hexanal, and heptanal, therefore, emerged as characteristic volatile compounds associated with the stewing cooking technique, suggesting their potential as markers for lipid and other oxidation reactions. This work indicates that certain lipid oxidation compounds, Strecker aldehydes, and sulfur compounds can be markers for the undesirable and/or desirable flavors of cooked beef, but that this depends on the cooking method chosen. It shows that flavor differences may be understood through the analysis of volatile flavor compounds in association with palatability and other chemical measurements.

Beef muscle discrimination based on two-trace two-dimensional correlation spectroscopy (2T2D COS) combined with snapshot visible-near infrared multispectral imaging

The purpose of this work was to assess the potential of 2T2D COS PLS-DA (two-trace two-dimensional correlation spectroscopy and partial least squares discriminant analysis) in conjunction with Visible Near infrared multispectral imaging (MSI) as a quick, non-destructive, and precise technique for classifying three beef muscles -Longissimus thoracis, Semimembranosus, and Biceps femoris- obtained from three breeds - the Blonde d'Aquitaine, Limousine, and Aberdeen Angus. The experiment was performed on 240 muscle samples. Before performing PLS-DA, spectra were extracted from MSI images and processed by SNV (Standard Normal Variate), MSC (Multivariate Scattering Correction) or AREA (area under curve equal 1) and converted in synchronous and asynchronous 2T2D COS maps. The results of the study highlighted that combining synchronous and asynchronous 2T2D COS maps before performing PLS-DA was the best strategy to discriminate between the three muscles (100% of classification accuracy and 0% of error).

Identifying the Potential Apoptotic Metabolites in Postmortem Beef Muscle by Targeted Metabolomics.

Apoptotic cells may release specific metabolites to act as messengers during the apoptotic process. This study represents the first attempt to identify potential apoptotic metabolites in postmortem muscle. Ninety potential apoptotic metabolites in beef were selected and analyzed through targeted metabolomics, with 84 of them exhibiting significant differences over the postmortem time. Following the addition of the mitochondria-targeted antiapoptotic agent mitoquinone to postmortem muscle, metabolomic analysis revealed that 73 apoptotic metabolites still underwent significant changes, even against the backdrop of altered apoptosis. Of these 73 apoptotic metabolites, 54 exhibited similar trends at various treatment times with adding mitoquinone, including lipids (6), amino acids (27), nucleosides (11), and carbohydrate and energy metabolism (10). Mitoquinone significantly reduced the levels of most apoptotic metabolites, and inhibition of apoptosis resulted in a significant decrease in the levels of numerous apoptotic metabolites. Consequently, these apoptotic metabolites are considered complementary to apoptosis in postmortem muscle, with their increased levels potentially promoting apoptosis. Noteworthy apoptotic metabolites, such as glycerol 3-phosphate, serine, AMP, ATP, GMP, and creatine, were identified as active signaling molecules that attract and recruit phagocytes during apoptosis, assisting in recognizing apoptotic cells by phagocytes. This study provides, for the first time, insights into potential apoptotic metabolites in postmortem muscle, contributing to a better understanding of meat biochemistry.

The potential of the mineral composition to discriminate between beef from different cattle diets and between individual muscles

The effect of the diet of cattle on the mineral composition of various beef muscles was investigated. Both dietary treatment and muscle type influenced the mineral composition (Na, Mg, P, K, Ca, Mn, Fe, Ca, Zn and Se) of beef. The possibility of discriminating beef according to its dietary background and between muscle types was also investigated. Two canonical discriminant analysis models were developed and validated using the mineral concentrations in four muscles (supraspinatus, semitendinosus, longissimus lumborum and psoas major) from cattle reared completely on grass pasture, barley-based concentrate or grass silage with added concentrate combinations. The results demonstrate that the models could correctly classify grass-, partially grass- and concentrate-fed beef (accuracy = 80.7–94.9%) and the different muscles (accuracy = 81.4%). The discriminant models extracted characteristics of Irish grass-fed beef from the mineral composition and this has the potential for distinguishing grass-fed beef from beef raised on other diets.

Effect of mitochondrial calcium homeostasis-mediated endogenous enzyme activation on tenderness of beef muscle based on MCU modulators

The mitochondrial calcium uniporter (MCU) occupies a noteworthy position in the regulation of mitochondrial calcium uptake. This study investigated the effects of MCU modulator-mediated mitochondrial calcium on mitochondrial dysfunction, oxidative stress, endogenous enzyme activities, and tenderness during postmortem aging. Spermine, as an activator of MCU, resulted in an increase in mitochondrial calcium levels, not only disrupting mitochondrial morphology but also triggering mitochondrial oxidative stress and downregulation of antioxidant factors. Additionally, the spermine group underwent later activation of calpain and earlier activation of caspases, as well as the myofibril fragmentation index was initially lower and then higher compared with control group, indicating that endogenous enzymes played an indispensable role in different aging periods. Interestingly, the results of the Ru360 (an inhibitor of MCU) group were opposite to those aforementioned findings. Our data provide a novel perspective on the regulatory mechanism of mitochondrial calcium homeostasis mediated by MCU on tenderness.

Effect of wet-aging on meat quality and exudate metabolome changes in different beef muscles

The aim of this study was to evaluate meat quality and changes in the meat exudate metabolome of different beef muscles (5 d postmortem, longissimus lumborum and psoas major muscles) during wet-aging (additional 3, 7, 14, 21, and 28 d of aging). Shear force of meat declined significantly (P < 0.001) with aging, meanwhile, increased myofibril fragmentation index, lipid and protein oxidation with aging were observed (P < 0.01). Psoas major (PM) showed significantly higher (P < 0.05) purge loss, centrifugal loss, and cooking loss, as well as higher tenderness and more severe lipid and protein oxidation (P < 0.01) than longissimus lumborum (LL) during aging. Principal component analysis of the metabolomic profiles revealed distinct clusters according to the period of aging and the type of muscle simultaneously. Overabundant amino acids, peptides, oxidized fatty acids, and hydroxy fatty acids were found in long-term aged meat exudates, and forty metabolites were significantly correlated with meat quality characteristics. Fifty-nine metabolites were significantly affected by muscle type. These results demonstrated the potential possibility of evaluating meat quality using meat exudate metabolomics.

Exploration of the shelf-life difference between chilled beef and pork with similar initial levels of bacterial contamination

This study compared the shelf-life of beef and pork longissimus lumborum muscles (loins) that had the same initial bacterial loads and were held under the same chilled storage conditions. To identify the underlying pathways, comparisons were conducted from the perspective of the spoilage indicators; protease/lipase activity, and the volatile organic compounds (VOC) generated over 28 d of chilled storage. The initial total viable microbial count (TVC) on Day 0 for both type of meat was 4.3 log10 CFU/g. It was found that the TVC of beef and pork did not differ throughout the total chilled storage period and both ultimately exceeded 7 log10 CFU/g after 28 d. Based on total volatile basic nitrogen (TVB-N) guidelines, pork was spoilt after 21 d of chilled storage and therefore 7 d earlier than beef. Changes in the concentration of VOC spoilage biomarkers, including 1-octen-3-ol, 1-octanol, nonanal, and others, confirmed that pork had a shorter shelf-life than beef. An important reason for the difference in shelf-life between the two types of meat was that pork had a higher protease activity, although the beef had higher levels of total lipase activity. These findings help us understand the differences in the spoilage process of raw meat from different species and explore specific measures to control the spoilage of beef or pork.

Establishment of enzyme-linked immunosorbent assay for beef and lamb contents in cooked meat

In this study, an enzyme-linked immunosorbent assay (ELISA) was established to detect beef and lamb components, and its performance was tested. Double-antibody sandwich ELISA was adopted and determined a coating concentration of capture antibody 3G5 of 1:4 000, a working concentration of enzyme-labeled antibody 2E7-horseradish peroxidase (HRP) of 1:1 000, a sample incubation time of 60 min and a detection antibody reaction time of 60 min. The specificity, sensitivity, repeatability and stability of this assay were determined. The limit of detection for beef and lamb skeletal muscle troponin I was 45 mg/kg, the inter-assay and intra-assay recovery rates ranged from 80.4% to 115.7%, the coefficients of variation were below 13.6%, and the cross reaction rates of the tissue components of chicken, duck and fish were below 13.4%. The sandwich ELISA method established in this study is stable and has high accuracy. The test results were consistent with the polymerase chain reaction (PCR) method at 50 and 100 g/kg. Therefore, this ELISA method can be used to quantitatively detect beef and lamb components in meat products.

Effects of ageing on longissimus thoracis et lumborum muscle of local beef

The ageing process significantly influences the quality parameters of beef, including water holding capacity (WHC), drip loss, tenderness, pH, and cooking loss. This study aimed to investigate the impact of ageing on these parameters and establish ageing as a valuable method for enhancing beef (LTL muscle) tenderness while minimally affecting other quality attributes. Using beef samples subjected to ageing periods of 1 day, 3 days, and 7 days, and 9 days, a comprehensive analysis was conducted to assess changes in WHC, drip loss, tenderness, pH, and cooking loss over time. The research findings revealed nuanced variations in these parameters across the ageing periods. While WHC, drip loss, pH, and cooking loss exhibited minimal changes throughout the ageing process, a notable improvement in tenderness was observed with increasing ageing duration. This enhancement in tenderness underscores the effectiveness of ageing in softening beef muscle fibers and improving eating quality. Moreover, the study explored the underlying mechanisms driving the observed changes in beef quality during ageing, including proteolysis, collagen degradation, and moisture redistribution. Understanding these mechanisms is crucial for optimizing ageing conditions and maximizing the beneficial effects on beef tenderness. Overall, the findings of this study contribute to the body of knowledge on the effects of ageing on beef quality parameters and provide practical insights for meat industry professionals and stakeholders. By establishing ageing as a valuable process for enhancing beef tenderness, this research has implications for meat processing practices, product development, and consumer satisfaction.

In plane quantification of in vivo muscle elastic anisotropy factor by steered ultrasound pushing beams

Objective. Skeletal muscles are organized into distinct layers and exhibit anisotropic characteristics across various scales. Assessing the arrangement of skeletal muscles may provide valuable biomarkers for diagnosing muscle-related pathologies and evaluating the efficacy of clinical interventions. Approach. In this study, we propose a novel ultrafast ultrasound sequence constituted of steered pushing beams was proposed for ultrasound elastography applications in transverse isotropic muscle. Based on the propagation of the shear wave vertical mode, it is possible to fit the experimental results to retrieve in the same imaging plane, the shear modulus parallel to fibers as well as the elastic anisotropy factor (ratio of Young’s moduli times the shear modulus perpendicular to fibers). Main results. The technique was demonstrated in vitro in phantoms and ex vivo in fusiform beef muscles. At last, the technique was applied in vivo on fusiform muscles (biceps brachii) and mono-pennate muscles (gastrocnemius medialis) during stretching and contraction. Significance. This novel sequence provides access to new structural and mechanical biomarkers of muscle tissue, including the elastic anisotropy factor, within the same imaging plane. Additionally, it enables the investigation of multiples parameters during muscle active and passive length changes.

New Implications of Metabolites and Free Fatty Acids in Quality Control of Crossbred Wagyu Beef during Wet Aging Cold Storage.

Efficient cold-chain delivery is essential for maintaining a sustainable global food supply. This study used metabolomic analysis to examine meat quality changes during the "wet aging" of crossbred Wagyu beef during cold storage. The longissimus thoracic (Loin) and adductor muscles (Round) of hybrid Wagyu beef, a cross between the Japanese Black and Holstein-Friesian breeds, were packaged in vacuum film and refrigerated for up to 40 days. Sensory evaluation indicated an increase in the umami and kokumi taste owing to wet aging. Comprehensive analysis using gas chromatography-mass spectrometry identified metabolite changes during wet aging. In the Loin, 94 metabolites increased, and 24 decreased; in the Round, 91 increased and 18 decreased. Metabolites contributing to the umami taste of the meat showed different profiles during wet aging. Glutamic acid increased in a cold storage-dependent manner, whereas creatinine and inosinic acid degraded rapidly even during cold storage. In terms of lipids, wet aging led to an increase in free fatty acids. In particular, linoleic acid, a polyunsaturated fatty acid, increased significantly among the free fatty acids. These results provide new insight into the effects of wet aging on Wagyu-type beef, emphasizing the role of free amino acids, organic acids, and free fatty acids generated during cold storage.

Early postmortem beef muscle proteome and metabolome variations due to supranutritional zinc and ractopamine hydrochloride supplementation.

It was hypothesized that the longissimus thoracis (LT) muscle proteome, phosphoproteome, and metabolome could explain postmortem metabolism and tenderness differences in muscle from cattle supplemented zinc (Zn) and/or ractopamine hydrochloride (RH). High percentage Angus steers (N = 20) were fed in a 2 × 2 factorial assigned to Zn and RH treatments: control (CON; n = 10; analyzed 36mg Zn/kg dry matter [DM]) or supranutritional Zn supplementation (SUPZN; n = 10; control diet + 60mg Zn/kg DM [from ZnSO4] + 60mg Zn/kg DM [from Zn-amino acid complex]) for the entire 89-d trial. During the 28 d before harvest, steers were blocked by body weight within Zn treatments to RH treatments of 0 (NO; n = 10) or 300mg (RAC; n = 10) per steer per day. Steers were harvested at the Iowa State Meat Laboratory, where pH decline (1, 3, 6, and 24h postmortem) was measured. At 24h postmortem, LT muscle sections were removed from carcasses, and steaks were analyzed for Warner-Bratzler shear force (WBSF) values at 1, 3, 7, and 14 d postmortem. Muscle samples were taken at 1h, 1, 3, 7, and 14 d postmortem for the following analysis: troponin-T degradation (1, 3, 7, and 14 d postmortem), myosin heavy chain analysis (1h postmortem), sarcoplasmic proteome analysis through tandem mass tagging analysis (1h and 1 d postmortem), metabolome analysis (1h and 1 d postmortem), and phosphoproteome analysis (1h postmortem). SUPZN-NO tended to have a lower (P = 0.06) pH at 6h postmortem and a lower WBSF value (P = 0.06) at 1 d postmortem. CON-RAC had a higher (P = 0.04) pH at 6h postmortem and WBSF value (P < 0.01) at 1 d postmortem. A lower pH at 6h postmortem and lower WBSF value at 1 d postmortem in the SUPZN-NO treatment was accompanied by more sorbitol and fructose at 1 d postmortem, and less myosin regulatory light chain 2 at 1h postmortem, and less adenosine monophosphate deaminase 1 (AMPD1) at 1 d postmortem than all other treatments. A higher pH at 6h postmortem and higher WBSF value at 1 d postmortem in CON-RAC and SUPZN-RAC was accompanied by more soluble structural proteins (troponin-T and myosin-7) at 1h postmortem than CON-NO. At 1h postmortem, CON-RAC had more glyceraldehyde-3-phosphate dehydrogenase than CON-NO or SUPZN-RAC. Differences in energy metabolism enzymes, metabolites, and structural proteins may affect ATP production, rigor development, and lactate buildup which may explain the differences in postmortem metabolism and tenderness development at 1 d postmortem.

Evaluation of Beef Palatability Following Extended Storage at Low Temperature

Extending the shelf life of fresh meat without having an adverse effect on its quality attributes is critical to the meat industry to reduce waste, stabilize supply, and facilitate export. Low temperature (LT) storage of beef muscles at or slightly above their freezing point slows down microbiological spoilage while maintaining the product’s fresh status.This study evaluated the impact of 60, 75, or 90 d of LT storage (−2.7°C±0.3°C) on the palatability characteristics of steaks from inside rounds (IR), bone-in ribeyes, and striploins (SL) from 10 (n=10) upper two-thirds Choice beef carcasses. Two steaks fabricated from each subprimal were vacuum-packaged, wet-aged for 21 d (3°C), and frozen (−20°C) for Warner-Bratzler shear force (WBSF) and sensory analyses. These steaks served as the control with regard to storage condition and time. The remainder of each subprimal was fabricated into 3 portions, vacuum packaged, and randomly allocated to an LT storage time (60, 75, or 90 d). After each storage time, subprimals were fabricated into steaks, vacuum-packaged, and stored (−20°C) for WBSF and consumer sensory analyses. Consumers (N=238) evaluated cooked samples for juiciness, tenderness, flavor liking, and overall liking. Data were analyzed using a mixed model with storage time as the fixed effect and individual carcasses as the random blocking factor. The WBSF values decreased (P&amp;lt;0.05) with increased storage time for all the cuts. Similarly, consumer tenderness rating scores increased with the LT storage time, particularly in IR and SL steaks. However, storage time did not influence (P≥0.05) the juiciness, flavor, and overall liking of any of the cuts.The results of this study suggest it would be feasible to extend the storage time of beef while preserving or improving the sensory quality when held at optimal conditions above the freezing temperature.