Variation in palatability and biochemical traits within and among eleven beef muscles

Identification of differentially expressed genes in distinct skeletal muscles in cattle using cDNA microarray

The 788-gene microarray was manufactured using selected elements from three different cDNA libraries in order to identify molecular processes that determine phenotypic characteristics between loin (M. longissimus thoracis) and round (M. semimembranosus) muscles. Microarray analyses identified 24 differentially expressed genes between the two muscles investigated. Five of the genes were verified by quantitative RT-PCR and three of them were mapped on bovine chromosomes using 5,000 rad bovine radiation hybrid (RH) panel. The map locations indicated that they were mapped in the same chromosomal regions where IMF and growth QTLs were located, suggesting that they are most possible positional candidate genes for the traits.

Development of the Meat Standards Australia (MSA) prediction model for beef palatability

In this paper, the statistical aspects of the methodology that led to the Meat Standards Australia (MSA) prediction model for beef palatability are explained and described. The model proposed here is descriptive: its intention is to describe the large amounts of data collected by MSA. The model is constrained to accord with accepted meat science principles. The combined dataset used in development of the prediction model reported is around 32 000 rows × 140 columns. Each row represents a sample tasted by 10 consumers; each column specifies a variable relating to the sample tested. The developed model represents the interface between experimental data, scientific evaluation and commercial application. The model is used commercially to predict consumer satisfaction, in the form of a score out of 100, which in turn determines a grade outcome. An important improvement of the MSA model relative to other beef grading systems is that it assigns an individual consumer-based grade result to specific muscle portions cooked by designated methods; it does not assign a single grade to a carcass.

International perspective: characterisation of United States Department of Agriculture and Meat Standards Australia systems for assessing beef quality

The intent, in this manuscript, is to characterise the United States Department of Agriculture (USDA) and Meat Standards Australia (MSA) systems for assessing beef quality and to describe the research evidence that supports the principles involved in grade application. USDA beef quality grading standards rely on carcass-trait-only assessments of approximate age of the animal at harvest and amount of intramuscular fat (as marbling) inside the muscles. USDA beef quality grading started 82 years ago. Then, as now, because no traceability system was in place, each animal’s history (exact age, feeding regimen, management practices, etc.) was incomplete; those who assigned quality grades used indicators of age (physiological maturity) and plane of nutrition (amount of marbling), and they do so still. Since 1926, research studies have identified a multitude of palatability-determining live-animal factors (e.g. genetics, use of hormonal growth promotants, high-energy diet finishing) and carcass-treatment factors (e.g. electrical stimulation, tenderstretch carcass suspension, postmortem aging) that cannot be incorporated into a carcass-trait-only quality assessment system. The USA beef industry has depended on development of more than 100 beef brands – some using palatability assurance critical control point plans, total quality management (TQM) philosophies, USDA certification and process verification programs, or combinations of live-animal factors, carcass-treatment factors and carcass-trait constraints – to further differentiate fresh beef products. The MSA grading system is a TQM grading approach that incorporates animal-specific traits (e.g. genetics, sex, age), control of certain pre-harvest and post-harvest processes in the beef chain, cut-specific quality differences and consumer preferences, into a beef pricing system. A unique aspect of the MSA grading system is that the grades are assigned to cuts or muscles, not carcasses; cuts or muscles from the same carcass are assigned individual (and in many cases, different) grades that reflect differences in expected eating quality performance among the various cuts of beef further adjusted to reflect the influence of cut or muscle aging and alternative cooking methods. The MSA grading system is still being modified and refined (using results of an extensive, ongoing consumer testing program), but it represents the best existing example of a TQM grading approach for improving beef quality and palatability. Research studies have shown that the accuracy of palatability-level prediction by use of the two systems – USDA quality grades for US customers and consumers and MSA grades for Australian customers and consumers – is sufficient to justify their continued use for beef quality assessment.

Beef longissimus slice shear force measurement among steak locations and institutions

The objectives of this study were 1) to determine which longissimus thoracis et lumborum steaks were appropriate for slice shear force measurement and 2) to determine the among and within institution variation in LM slice shear force values of 6 institutions after they received expert training on the procedure and a standard kit of equipment. In experiment 1, longissimus thoracis et lumborum muscles were obtained from the left sides of 50 US Select carcasses. Thirteen longissimus thoracis and 12 longissimus lumborum steaks were cut 2.54 cm thick from each muscle. Slice shear force was measured on each steak. Mean slice shear force among steak locations (1 to 25) ranged from 19.7 to 27.3 kg. Repeatability of slice shear force (based on variance) among steak locations ranged from 0.71 to 0.96. In experiment 2, the longissimus thoracis et lumborum were obtained from the left sides of 154 US Select beef carcasses. Eight 2.54-cm-thick steaks were obtained from the caudal end of each frozen longissimus thoracis, and six 2.54-cm-thick steaks were obtained from the cranial end of each frozen longissimus lumborum. Seven pairs of consecutive steaks were assigned for measurement of slice shear force. Seven institutions were assigned to steak pairs within each carcass using a randomized complete block design, such that each institution was assigned to each steak pair 22 times. Repeatability estimates for slice shear force for the 7 institutions were 0.89, 0.83, 0.91, 0.90, 0.89, 0.76, and 0.89, respectively, for institutions 1 to 7. Mean slice shear force values were least (P <0.05) for institutions 3 (22.7 kg) and 7 (22.3 kg) and were greatest (P <0.05) for institutions 5 (27.3 kg) and 6 (27.6 kg). Institutions with greater mean slice shear force (institutions 5 and 6) used cooking methods that required more (P <0.05) time (32.0 and 36.9 min vs. 5.5 to 11.8 min) to reach the end point temperature (71 degrees C) and resulted in greater (P <0.05) cooking loss (both 26.6% vs. 14.4 to 24.1%). Differences among institutions in the repeatability of slice shear force were partially attributable to differences among institutions in the consistency of steak thawing and cooking procedures. These results emphasize the importance of sample location within the muscle and cooking method in the measurement of tenderness and indicate that with proper training and application of the protocol, slice shear force is a highly repeatable (R approximately 0.90) measure of beef LM tenderness.

A fresh look at meat flavor

Hundreds of compounds contribute to the flavor and aroma of meat. Complex interactions between various compounds influence the perception of meat flavor. Inherent flavor of a meat product can be influenced by oxidation, lipid content, feeding/diet, myoglobin, and pH. Diet plays an important role in both ruminants and nonruminants. New research reveals important relationships in flavor among multiple muscles within a single animal carcass. This animal effect includes the presence of off-flavors. Diets high in polyunsaturated fatty acids may be contributing to the appearance of off-flavors in beef. Compounds associated with liver-like off-flavor notes in beef have been identified in raw tissue.

Effects of postmortem aging and USDA quality grade on Warner-Bratzler shear force values of seventeen individual beef muscles1

Forty USDA Select and 40 upper two-thirds USDA Choice beef carcasses were used to determine the effects of postmortem aging on tenderness of 17 individual beef muscles. Biceps femoris-long head, complexus, gluteus medius, infraspinatus, longissimus dorsi, psoas major, rectus femoris, semimembranosus, semitendinosus, serratus ventralis, spinalis dorsi, supraspinatus, tensor fasciae latae, teres major, triceps brachii-long head, vastus lateralis, and vastus medialis muscles were removed from each carcass. Seven steaks (2.54-cm thick) were cut from every muscle, and each steak was assigned to one of the following postmortem aging periods: 2, 4, 6, 10, 14, 21, or 28 d postmortem. After completion of the designated aging period, steaks were removed from storage (2 degrees C, never frozen), cooked to a peak internal temperature of 71 degrees C, and evaluated using Warner-Bratzler shear force (WBSF). Analysis of WBSF revealed a 3-way interaction (P = 0.004) among individual muscle, USDA quality grade, and postmortem aging period. With the exception of the Select teres major, WBSF of all muscles (both quality grades) decreased with increasing time of postmortem storage. Nonlinear regression was used to characterize the extent (aging response) and rate of decrease in WBSF from 2 through 28 d postmortem for each muscle within each quality grade. In general, WBSF of upper two-thirds Choice muscles decreased more rapidly from 2 to 10 d postmortem than did corresponding Select muscles. Muscles that had greater aging responses generally had greater 2-d WBSF values. The upper two-thirds Choice psoas major, serratus ventralis, and vastus lateralis muscles required similar aging times to complete a majority of the aging response (< or =0.1 kg of aging response remaining) compared with analogous Select muscles. The upper two-thirds Choice complexus, gluteus medius, semitendinosus, triceps brachii-long head, and vastus medialis muscles required 4 to 6 d less time to complete a majority of the aging response than did comparable Select muscles. Aging times for Select biceps femoris-long head, infraspinatus, longissimus dorsi, rectus femoris, semimembranosus, spinalis dorsi, supraspinatus, and tensor fasciae latae muscles were > or =7 d longer than those for corresponding upper two-thirds Choice muscles. Results from this study suggest that muscle-to-muscle tenderness differences depend on quality grade and aging time and that postmortem aging should be managed with respect to individual muscle and USDA quality grade.

Lateral and longitudinal characterization of color stability, instrumental tenderness, and sensory characteristics in the beef semimembranosus

The objectives of this study were to evaluate longitudinal and lateral variations in color stability and sensory characteristics of the semimembranosus from each muscle location (dorsal=D, medial=M, ventral=V), and within each steak subsequently divided into four regions (caudal-distal=CaD, cranial-distal=CrD, caudal-proximal=CaP, cranial-proximal=CrP). Instrumental color assessment indicated that L(∗) (lightness) values tended to be lower for the CaD and CrD regions of all muscle locations, with higher L(∗) values recorded for the CrP regions of muscle sections. Instrumental tenderness measurements for Meullenet-Owens razor and Warner-Bratzler shear force values were generally lower for the CaD region of the D section, whereas regions within the V section were tougher and required greater shear force. Sensory panelists perceived lower amounts of connective tissue in the CaD of the D section, which tended to be more tender, whereas higher levels of connective tissue and greater toughness occurred in the CaP and CrP regions of the M and V sections. These results provide a detailed muscle profile of the quality variation within the semimembranosus, and may be used to further enhance the fabrication and marketability of this beef subprimal cut.

Flavor characterization of top-blade, top-sirloin, and tenderloin steaks as affected by pH, maturity, and marbling

Little information is available in the literature on the interrelationships and interactions among pH, aging time, marbling, and maturity on the flavor profile of some beef muscles commonly used for steaks. To investigate these effects on beef flavor, the infraspinatus (top-blade steak) from the chuck clod, the gluteus medius (top-sirloin steak) from the sirloin, and the psoas major (tenderloin steak) from the loin were obtained from A- (n = 80) and B-maturity (n = 60) carcasses with either Slight (n = 68) or Small (n = 72) marbling, and with either normal (< or = 5.7; n = 80) or high (> or = 6.0; n = 60) pH. Muscles were selected from two commercial processing plants at six different sampling times to evaluate factors that affect the flavor profile of cooked beef steaks. Muscles were vacuum-aged for 7, 14, 21, or 35 d, and a highly trained, flavor-profile sensory panel evaluated charbroiled steaks from these muscles. Numerous statistical interactions (P < 0.05) were detected for flavor attributes of the different muscles. In general, muscles from high pH (dark cutting) carcasses had less typical beef flavor identity and less brown-roasted flavor than those from carcasses with normal pH. Aging longer than 21 d generally decreased beef flavor identity. Top-blade steaks generally had less intense beef flavor identity and more intense bloody/serumy flavor than did top-sirloin and tenderloin steaks. Tenderloin and top-sirloin steaks of normal pH generally had the most brown-roasted flavor, especially when aged 21 d or less. Small degree of marbling generally resulted in a more rancid flavor compared with Slight marbling, but marbling had no other appreciable effects on the flavor profile. Aging steaks for 35 d increased (P < 0.05) the metallic flavor compared with aging for only 7 or 14 d. Top-sirloin steaks had a more intense (P < 0.05) sour flavor than did top-blade steaks, and steaks from carcasses with a high pH were more rancid (P < 0.05) than steaks from carcasses with normal pH. Vacuum-aging top-blade, top-sirloin, and tenderloin steaks to 21 or 35 d postmortem generally increased metallic and rancid flavors and increased sour flavor in top-sirloin steaks that were high in pH.

Muscle profiling: Characterizing the muscles of the beef chuck and round

To fully characterize properties of the muscles of the beef chuck and round, and to reveal potential opportunities to upgrade the value, 39 different muscles were dissected from 142 beef carcasses differing in carcass weight, yield grade, and quality grade. Numerous physical and chemical properties of the muscles were determined. Muscle effects were observed for all traits (objective color, expressible moisture, proximate composition, emulsion capacity, pH, total collagen content, total heme-iron concentration, and Warner-Bratzler shear force). USDA quality grade generally had the most effect on muscle traits, with carcass weight and yield grade having lesser effects. These muscle profile data will allow for more informed decisions to be made in the selection of individual muscles from the beef chuck and round for the production of value-added products.

Supplemental vitamin D3 concentration and biological type of steers. II. Tenderness, quality, and residues of beef

Vitamin D3 was orally supplemented to determine the supplemental dose that improved beef tenderness in different cattle breed types. Feedlot steers (n = 142) were arranged in a 4 x 3 factorial arrangement consisting of four levels of supplemental vitamin D3 (0, 0.5, 1, and 5 million IU/steer daily) administered for eight consecutive days antemortem using three biological types (Bos indicus, Bos Taurus-Continental, and Bos Taurus-English). Warner-Bratzler shear force (WBSF) was measured at 3, 7, 10, 14, and 21 d postmortem, and trained sensory analysis was conducted at 7 d postmortem on LM, semimembranosus, gluteus medius, and supraspinatus steaks. Concentrations of vitamin D3 and the metabolites 25-hydroxyvitamin D3, and 1,25-dihydroxyvitamin D3 were determined in the LM, liver, kidney, and plasma. Biological type of cattle did not interact (P > 0.10) with vitamin D3 supplementation for sensory or tenderness traits, suggesting that feeding vitamin D3 for 8 d before slaughter affected the different biological types of cattle similarly. Supplementing steers with 0.5, 1, or 5 million IU/(steer(d) decreased (P < 0.05) LM WBSF at 7, 10, 14, and 21 d postmortem compared with controls, and vitamin D3 treatments of 0.5, 1, and 5 million IU decreased (P < 0.05) semimembranosus WBSF at 3, 7, and 14 d postmortem. In general, vitamin D3-induced improvements in WBSF were most consistent and intense in LM steaks. Sensory panel tenderness was improved (P < 0.05) by all vitamin D3 treatments in LM steaks. Sensory traits ofjuiciness, flavor, connective tissue, and off-flavor were not (P > 0.05) affected by vitamin D3 treatments. All vitamin D3 treatments decreased micro-calpain activity and increased muscle Ca concentrations (P < 0.05). Vitamin D3 concentrations were increased (P < 0.05) by supplementation in all tissues tested (liver, kidney, LM, and plasma); however, cooking steaks to 71 degrees C decreased (P < 0.05) treatment residue effects. The vitamin D metabolite 1,25-dihydroxyvitamin D3 was increased (P < 0.05) only in plasma samples as a result of the vitamin D3 treatments. These results indicate that supplementation with vitamin D3 at 0.5 million IU/steer daily for eight consecutive days before slaughter improved tenderness in steaks from different subprimal cuts by affecting muscle Ca concentrations, micro-calpain activities, and muscle proteolysis, with only a small effect on tissue residues of vitamin D3.