The effects of degree of dark cutting on tenderness and sensory attributes of beef

Sensory quality of beef with different ultimate pH values - A Brazilian perspective

This study evaluated Brazilian consumer perceptions of beef with different pH values at 48 h post-mortem (pHu) through sensory analysis. A total of 138 consumers evaluated raw and grilled steaks. The steaks were divided according to their pHu (normal pH < 5.8, atypical darkness, firmness, and dryness [DFD] > 5.8 pH < 6, and typical DFD pH ≥ 6). There was no difference in the visual evaluation of raw steaks or purchase intention. Evaluation of the grilled steaks showed that consumers preferred typical DFD steaks in terms of tenderness, and there was a tendency for the same behavior in terms of juiciness. No differences were observed in other evaluated parameters. Cluster analysis identified three consumer segments for visual evaluation, indicating a preference for steaks with higher pHu in terms of freshness. Additionally, four segments were identified for evaluation, with some groups expressing a preference for higher pHu meat in terms of freshness appearance, tenderness liking, and overall liking. The developed regression models for overall liking and purchase intention exhibited favorable adjustment indices, with r2 values of 0.86 and 0.57, respectively, for raw steaks and 0.90 for grilled steaks for in overall liking. Regression models indicated a strong influence of color and freshness appearance, in addition to tenderness liking and juiciness liking, on the overall liking scores of consumers. These results indicate that Brazilian consumers do not dislike dark cutting and, despite differentiating their greater tenderness, do not show a preference between the different pHu values.

A current review of U.S. beef flavor II: Managing beef flavor

Beef flavor continues to be one of the largest drivers of beef demand and a differentiation point of beef from other competing proteins. Tenderness has long been identified as the most important palatability trait for consumer satisfaction. However, as technological advancements and industry practices evolve and improve in response to tenderness management, flavor has emerged as a key driver of consumer satisfaction. In response, the beef industry has recently invested in research focused on beef flavor development, measurement, and management to better understand the factors impacting flavor and help beef maintain this advantage. The current review paper is the second of two such papers focused on summarizing the present knowledge and identifying knowledge gaps. While the other review focuses on current practices related to beef flavor measurement, this review will cover research findings related to beef flavor management. Numerous production and product management factors influence beef flavor. Pre-harvest factors including marbling level, animal genetics/cattle type, diet, and animal age, can influence beef flavor. Moreover, numerous post-harvest product management factors, including product type, aging length and conditions, cookery methods, product enhancement, muscle-specific factors, packaging, retail display factors, and antimicrobial interventions, have all been evaluated for their impact on beef flavor characteristics. Results from numerous studies evaluating many of these factors will be outlined within this review in order to present management and production chain factors that can influence beef flavor.

Assessment of beef sensory attributes and physicochemical characteristics: A comparative study of intermediate versus normal ultimate pH striploin cuts

The quality of beef, defined by key attributes such as the intrinsic sensory qualities texture, flavour, and juiciness, is shaped by various intrinsic and extrinsic factors. This study conducted a detailed examination of Nellore beef, focusing on two categories based on ultimate pH (pHu) levels: intermediate (pHu ≥ 5.8) and normal (pHu < 5.6) beef. A comprehensive approach was taken, involving twenty trained assessors who applied the Optimised Descriptive Profile (ODP) method to evaluate grilled striploin steak samples. In parallel, consumer preferences were measured through a hedonic test and a Check-all-that-apply (CATA) task, involving 135 participants. The ODP results revealed that the intermediate pHu samples were juicier (P < 0.05) compared to the normal pHu group. The CATA analysis highlighted differences in both intermediate and normal pHu beef, especially in juiciness, a crucial factor for consumer satisfaction. Notably, variations in deoxymyoglobin content linked to ageing were observed, with higher levels at the 3rd day compared to the 28th day, especially in the intermediate pHu samples (P < 0.05). Moreover, colour-related aspects such as L*, b*, chroma (C*), and oxymyoglobin were significantly influenced (P < 0.05) by both the pHu category and ageing time. Regarding consumer acceptance, the study found no significant difference in perception between the intermediate and normal pHu groups (P > 0.05). These findings revealed the complex interactions between pHu levels, sensory characteristics, and consumer preferences in beef quality, offering valuable insights for both the industry and research community.

Muscle of dark and normal beef differs metabolically

Reduction in muscle glycogen triggered by adverse antemortem handling events alters postmortem energy metabolism and results in a high ultimate pH and dark, firm and dry beef, often referred to as 'dark-cutting'. However, the relationship between atypical dark (AT) beef, postmortem energy metabolism and underlying tissue characteristics remains somewhat unclear. Cattle harvested in the US and Canada representing normal (pH < 5.6), AT dark (pH 5.6-5.8) and dark cutting (DC; pH > 5.8) beef were analyzed for tissue characteristics related to energy metabolism. Results show AT dark beef is more oxidative but similar to normal beef in glycolytic potential and nucleotide abundance. Mitochondria DNA content (P < 0.05, Canada; P < 0.005, US) and oxidative enzymes for DC and AT dark beef were greater (P < 0.01; Canada and US) compared to normal beef. Myoglobin tracked (P < 0.01) with color classification. These findings show both DC and AT beef are inherently more oxidative and raise the possibility that more oxidative muscle may be more prone to develop dark beef.

Descriptive beef flavor and texture attributes relationships with consumer acceptance of US light beef eaters

Consumer acceptance and overall liking has been shown to be related to beef instrumental and trained sensory attributes related to beef flavor, tenderness, and juiciness. Our objective was to understand the relationships between descriptive beef flavor and texture attributes, Warner-Bratzler shear force (WBSF), and consumer liking attributes for light US beef eaters. It is not known if light beef eaters have different drivers of overall liking. Treatments were created to differ in beef flavor and texture by utilizing different beef cuts (Choice top loin, high pH top loin, Select top sirloin, Choice tenderloin steaks, and Select and Choice bottom rounds roasts) cooked to 58 °C or 80 °C. Cooking methods included either a George Forman grill, food-service grill, or crock-pot. Cooking method, cut, and internal temperature impacted beef descriptive flavor and texture attributes, WBSF and consumer liking ratings (P ≤ 0.05) similarly. Descriptive juiciness and tenderness attributes were highly related to each other and with consumer juiciness and tenderness liking ratings. Consumer overall liking was closely related to descriptive fat-like, overall sweet, sweet and salty attributes. Musty/moldy, liver-like, and sour aromatic attributes were negatively associated with consumer liking. Overall flavor accounted for 85% of the variation in overall liking and tenderness liking contributed an additional 4%. While light beef eaters used different parts of the scale, they rated beef across treatments similarly. When beef flavor and texture descriptive attributes differed, consumer liking was impacted for light beef eaters.

Investigating the impact of pre-slaughter management factors on meat quality outcomes in cattle raised for beef: A scoping review

Introduction

The pre-slaughter management period is a critical juncture in the beef supply chain, having implications not only for animal welfare and product quality, but also for profitability. During this period, cattle are exposed to many stressors in a short time, many of which have been shown to impact meat quality. Understanding how cattle management during this terminal step in the production chain affects meat quality and economic outcomes is crucial.

Methods

The objective of this study was to investigate, synthesize, and report on research evaluating the impact of management factors during the pre-slaughter period on beef meat quality. A systematic approach was used to search for peer-reviewed and primary studies published in English in CAB Abstracts, PubMed, and Web of Science. A total of 3,217 non-duplicate records were screened for eligibility; articles were deemed eligible for inclusion if they included beef cattle in the pre-slaughter period and reported at least one meat quality outcome. After three screening rounds, 85 articles met all inclusion criteria. Data pertinent to the scoping review’s aims were extracted, including study location, population characteristics, pre-slaughter factors reported, and outcomes of interest.

Results

Europe (35, 41%) and South America (21, 25%) represented approximately two-thirds of the studies. Bulls (37, 43.5%) and steers (34, 40.0%) were the most reported sex classes, with the most frequent breed types reported as predominantly British or Continental and Bos indicus breeds (24, 28.2%; 24, 28.2%, respectively). Transportation (n=46), lairage (n=36), and handling (n=35) practices were the most reported pre-slaughter factors. Overall, 59 studies reported pH as an outcome of interest – almost double that of the next highest outcome, bruising (n=35). Muscle pH was most assessed with predictors at the abattoir (n=37); conversely, the effects of transportation were most evaluated on bruising (n=23).

Discussion

A trend across all the categories was that there were relatively few studies evaluating the impact of pre-transport factors on meat quality. Charting the relevant literature is a critical step towards understanding the relationship between pre-slaughter management and end-product quality; doing so will help industry stakeholders in the beef production chain optimize management practices that improve meat quality and enhance profitability.

Feedlot Factors Influencing the Incidence of Dark Cutting in Australian Grain-Fed Beef

It has been well-established that dark cutting (DC) is a multifactorial issue that is associated with numerous animal and management factors. However, there is limited understanding of the feedlot-based factors that contribute to the influence of DC. The aim of this study was to evaluate the effect of climate, animal, and feedlot factors on the incidence of pH non-compliance in Australian grain-fed cattle. For this study, feedlot and abattoir records from 142,228 individual cattle over a 1-year period were investigated. These data incorporated records from seven feedlots that consigned cattle to three abattoirs. The average incidence of DC in these carcasses was 2.8%. The production factors that were associated with increased risk of DC included feedlot, sex, hormone growth promotants (HGP), cattle health, and days on feed (DOF). Additionally, DC also increased by reduced solar radiation (SR, W/m2), lower wind speeds (WS, m/s), increased ambient temperature (TA, °C), higher rainfall, a higher average temperature–humidity index (THI), and increased duration of time above heat-load-index threshold of 86 (HLI ≥ 86) during the 7 days prior to feedlot departure. This study identified the feedlot factors that increase the risk of DC from a feedlot-management perspective.

Are muscle fiber types different between normal and dark-cutting beef?

Muscle fiber (MF) characteristics of Longissimus thoracis (LT) muscles from heifer (n = 11) and steer (n = 12) carcasses graded Canada AA (AA, normal, n = 4/sex) or dark-cutting (Canada B4) were examined and related to beef quality. Atypical (AB4, pH < 5.9, n = 4/sex) and typical (TB4, pH > 5.9, n = 3 and 4 for heifers and steers, respectively) dark-cutting carcasses were represented. Muscle fiber type proportions did not differ between AA, AB4 and TB4 muscles, although type I and IIB muscle fiber diameters were greater in TB4 than in AA LT. That AB4 muscle fiber proportions were not different from AA and TB4 muscles suggests that the increased MF diameter of TB4 muscle was due to water retained by muscle proteins at high ultimate pH, as evidenced by decreased cooking loss. Dark-cutting was therefore unrelated to muscle fiber proportions, and increased Type I and IIB diameters in dark cutting LT were likely driven by elevated intramuscular ultimate pH.

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

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

Effects of extended postmortem aging and intramuscular location on protein degradation, muscle fiber morphometrics, and tenderness of beef longissimus lumborum and semitendinosus steaks

The objective of this study was to determine effects of extended aging and intramuscular location on Warner-Bratzler shear force (WBSF), muscle fiber cross-sectional area (CSA), and protein degradation of semitendinosus (ST) and longissimus lumborum (LL) steaks. Left ST and LL were removed from 40 carcasses at 6 d postmortem. The ST was fabricated into five locations (LOC), with LOC 1 being most proximal and LOC 5 being most distal. The posterior LL was fabricated into 3 LOC, with LOC 1 being most anterior. Vacuum sealed ST steaks were aged 7, 14, 28, 56, or 112 d postmortem, while LL steaks were aged 7, 28, or 112 d postmortem at 2 ± 1 °C. A steak from each LOC was assigned to WBSF or laboratory analyses. There were no Day of Aging (DOA) × LOC interactions for all dependent variables (P > 0.06). There were DOA effects for ST and LL WBSF values and degraded 38-kDa desmin (DES; P < 0.01). Day-7 ST-steak WBSF value was greater than all other days (P < 0.01) and day-14 steaks had greater WBSF value than remaining days (P < 0.05). Day-28 ST-steak WBSF values were greater than day 56 and 112 (P < 0.01), which did not differ (P = 0.53). In the LL, day-7 steaks had greater WBSF values than the other two timepoints (P < 0.01) and day-28 steaks had greater (P < 0.01) WBSF values than day-112 steaks. Degraded ST 38-kDa DES content was less on day 7 and 14 compared to all other days (P < 0.03), but did not differ (P = 0.79) from each other. Days 28 and 56 38-kDa DES content was less than day 112 (P < 0.01), but did not differ (P = 0.34) from each other. Degraded LL 38-kDa DES content was less on day 7 than day 28 and 112 (P < 0.02), which did not differ (P = 0.67). There were LOC effects for only ST WBSF and muscle fiber CSA (P < 0.05). Semitendinosus steak LOC 1 and 2 had greater WBSF values than all other locations (P < 0.01), but did not differ (P = 0.32) from each other. Semitendinosus steak LOC 3 and 5 had greater WBSF values than LOC 4 (P < 0.01), but did not differ (P = 0.85) from each other. The CSA of all ST fiber types were largest in LOC 1 compared to all other fiber types (P < 0.01). The CSA of all LOC 2 and 3 fiber types was greater than LOC 4 and 5 (P < 0.01), but were not different from each other (P > 0.81), and LOC 4 had greater CSA than LOC 5 (P < 0.01). Steak aging WBSF value improvements seemed proteolysis catalyzed, while the ST intramuscular tenderness gradient was more likely due to muscle fiber CSA.

Dark-cutting beef: A brief review and an integromics meta-analysis at the proteome level to decipher the underlying pathways

Comprehensive characterization of the post-mortem muscle proteome defines a fundamental goal in meat proteomics. During the last decade, proteomics tools have been applied in the field of foodomics to help decipher factors underpinning meat quality variations and to enlighten us, through data-driven methods, on the underlying mechanisms leading to meat quality defects such as dark-cutting meat known also as dark, firm and dry (DFD) meat. In cattle, several proteomics studies have focused on the extent to which changes in the post-mortem muscle proteome relate to dark-cutting beef development. The present data-mining study firstly reviews proteomics studies which investigated dark-cutting beef, and secondly, gathers the protein biomarkers that differ between dark-cutting versus beef with normal-pH in a unique repertoire. A list of 130 proteins from eight eligible studies was curated and mined through bioinformatics for Gene Ontology annotations, molecular pathways enrichments, secretome analysis and biological pathways comparisons to normal beef color from a previous meta-analysis. The major biological pathways underpinning dark-cutting beef at the proteome level have been described and deeply discussed in this integromics study.

Impact of Extraction Method on the Detection of Quality Biomarkers in Normal vs. DFD Meat

The objective of this work was to demonstrate how the extraction method affects the reliability of biomarker detection and how this detection depends on the biomarker location within the cell compartment. Different extraction methods were used to study the sarcoplasmic and myofibrillar fractions of the Longissimus thoracis et lumborum muscle of young bulls of the Asturiana de los Valles breed in two quality grades, standard (Control) or dark, firm, and dry (DFD) meat. Protein extractability and the expression of some of the main meat quality biomarkers—oxidative status (lipoperoxidation (LPO) and catalase activity (CAT)), proteome (SDS-PAGE electrophoretic pattern), and cell stress protein (Hsp70)—were analyzed. In the sarcoplasmic fraction, buffers containing Triton X-100 showed significantly higher protein extractability, LPO, and higher intensity of high-molecular-weight protein bands, whereas the TES buffer was more sensitive to distinguishing differences in the protein pattern between the Control and DFD meat. In the myofibrillar fraction, samples extracted with the lysis buffer showed significantly higher protein extractability, whereas samples extracted with the non-denaturing buffer showed higher results for LPO, CAT, and Hsp70, and higher-intensity bands in the electrophoretic pattern. These findings highlight the need for the careful selection of the extraction method used to analyze the different biomarkers considering their cellular location to adapt the extractive process.

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.

Preliminary study on the characterization of Longissimus lumborum dark cutting meat in Angus × Nellore crossbreed cattle using NMR-based metabolomics

The aim of this preliminary study was to evaluate meat quality properties, muscle metabolite profile and metabolic pathways associated with the occurrence of dark cutting meat in Angus x Nellore crossbreed cattle. After 14 days' ageing, dark cutting meat presented a higher pH, lower cooking loss and colour parameters, and greater tenderness compared with normal meat. Dark cutting meat had a higher ATP level and lower concentrations of glucose-6-phosphate, lactate, glucose, serine, threonine, creatine phosphate, inosine, leucine, methionine, succinate and glucose-1-phosphate compared to normal meat. In dark cutting samples, the ultimate pH was positively correlated with carnitine and negatively correlated with glucose-6-phosphate. However, in normal meat, the ultimate pH presented a positive correlation with arginine, leucine, methionine, proline, threonine, tyrosine and valine. Pathway analysis showed that differentiation of the groups was linked to energetic pathways such as starch and sucrose metabolism, the pentose phosphate pathway, amino sugar, nucleotide sugar metabolism, and glycolysis or gluconeogenesis. In conclusion, the occurrence of dark cutting meat has a notable impact on meat quality attributes and concentrations of post-mortem glycolytic metabolites, appears to be correlated with mitochondrial activity and affects energetic metabolic pathways.

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

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

Evaluation of Meat Quality on High pH Strip Loins Injected with Buffered Acetic Acid

This experiment evaluated the effects of injection of buffered vinegar [e(Lm)inate V, Hawkins Inc., Minneapolis, MN] at pH 5.0 on quality attributes of high pH beef strip loins. Strip loins (n = 16) were sectioned and treatments assigned to evenly represent each section, and on d 6 after harvest and fabrication treatments were injected into each section using a multi needle injector. One control and three treatments were used: 0 (T0), 0.4 (T0.4), 1.2 (T1.2), and 1.6% (T1.6) of the green weight of steaks was injected, and quality characteristics of strip loins were evaluated. Sections were then vacuumed packaged for an additional 3 d to simulate transport to retail outlets, then fabricated into steaks and overwrapped for an addition 3 d for simulation of retail storage. High pH control (T0) final pH (FpH) values were the highest, with a pH of 5.87. While there were similarities between treatments, overall as percentage of injection increased, FpH decreased. There was no difference among location (P > 0.05) when evaluating FpH. There were no difference in cook loss or TBARS for location or treatment. Drip loss was greatest for T1.2 injection and in the most caudal section. Warner-Bratzler shear force (WBSF) was different due to the location of the section (P ≤ 0.05), with section Y (the third section) having the greatest value. Off flavor intensity increased (P ≤ 0.05) as percentage of injection increased. Final L*, a*, and b* values were different (P ≤ 0.05) for treatment levels in the loins with the control having the lowest L* and b* values. While this product was sufficient at altering final raw color and pH, it may not be feasible for industry use, due to minimal impacts on drip loss, cook loss, oxidation, and sensory characteristics with an increase in off flavor. Nonetheless, investigation of application with an antioxidant and/or functional ingredient could prove beneficial for industry use.