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

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.

Effect of beef long-storage under different temperatures and vacuum-packaging conditions on meat quality, oxidation processes and microbial growth

BACKGROUND

The global beef market demands the meat industry to ensure product quality and safety in markets that are often very distant. The present study aimed to evaluate the effects of chilled (CH, 120 d) and chilled-then-frozen (CHF, 28 d + 92 d) storage conditions of beef vacuum packaged (VP) and vacuum packaged with antimicrobial (VPAM) on meat quality, oxidative status and microbial loads. Treatments resulted from the combination of storage condition and packaging type: VP + CH, VP + CHF, VPAM + CH and VPAM + CHF.

RESULTS

Warner-Bratzler shear force values decreased in all treatments after 28 d of chilling. Except for VP + CH, L* values (lightness) of meat color did not differ in each treatment as the storage time increased. Meat from VP + CH had greater a* values than CHF treatments on day 120 of storage. A consumer panel did not detect differences in tenderness, flavor and overall liking between VP and VPAM beef, but they preferred CHF steaks rather than CH beef. TBARS values did not differ between VP and VPAM and between CH and CHF at any time during the storage period. At the end of storage time, all treatments except VP + CHF presented a greater concentration of thiols than at 48 h post-mortem. On day 120 of storage, VP + CH had greater catalase enzyme activity than CHF treatments while VP + CH and VP + CHF showed a greater superoxide dismutase activity than VPAM + CHF. Storage condition (CH or CHF) had a greater impact on microbial counts than the type of packaging.

CONCLUSION

Freezing meat after an ageing period represents a suitable strategy to extend beef storage life without a detrimental impact on its quality. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

- Invited Review - Postmortem skeletal muscle metabolism of farm animals approached with metabolomics

Skeletal muscle metabolism regulates homeostatic balance in animals. The metabolic impact persists even after farm animal skeletal muscle is converted to edible meat through postmortem rigor mortis and aging. Muscle metabolites resulting from animal growth and postmortem storage have a significant impact on meat quality, including flavor and color. Metabolomics studies of postmortem muscle aging have identified metabolisms that contain signatures inherent to muscle properties and the altered metabolites by physiological adaptation, with glycolysis as the pivotal metabolism in postmortem aging. Metabolomics has also played a role in mining relevant postmortem metabolisms and pathways, such as the citrate cycle and mitochondrial metabolism. This leads to a deeper understanding of the mechanisms underlying the generation of key compounds that are associated with meat quality. Genetic background, feeding strategy, and muscle type primarily determine skeletal muscle properties in live animals and affect post-mortem muscle metabolism. With comprehensive metabolite detection, metabolomics is also beneficial for exploring biomarker candidates that could be useful to monitor meat production and predict the quality traits. The present review focuses on advances in farm animal muscle metabolomics, especially postmortem muscle metabolism associated with genetic factors and muscle type.

Comparative Study on Muscle Fiber Types of Longissimus Dorsi of Xinjiang Brown Cattle and Angus Cattle of Different Months

The longissimus dorsi muscle of Xinjiang brown cattle and Angus cattle at the age of 3, 7, 12, and 24 months under the same feeding and management conditions were selected to explore the differences of muscle 4 fiber types in this study. The muscle histological and molecular biological reasons for the quality difference between Xinjiang brown cattle and Angus beef were discussed. The morphology of the muscle was compared by ATP enzyme staining and SDH enzyme staining, and its gene expression was detected by qRT-PCR. The mRNA expression levels of Myhc-I in 3-month-old Xinjiang brown cattle were significantly higher than those in Angus cattle of the same age ( $P<0.01$ ). The 4 fiber types of 7-month-old Xinjiang brown cattle were significantly lower than those of Angus cattle of the same age ( $P<0.01$ ). The expression level of type I and IIb in 12-month-old Xinjiang brown cattle was significantly higher than that in 12-month-old Angus cattle ( $P<0.05$ ). Type I and IIa of 24-month-old Xinjiang brown cattle were significantly lower than those of Angus cattle of the same age ( $P<0.05$ ). However, in our study, the basic characteristics of longissimus dorsi of Xinjiang brown cattle and Angus cattle, such as color, pH, shearing force, and other characteristics were not detected, which is lacking in this aspect. Overall, with the increase of age, the growth trend of muscle fiber morphology of Xinjiang brown cattle and Angus cattle is roughly the same, but from the point of view of muscle fiber types, the Xinjiang brown cattle are more suitable for the production of early fat calves and to make some reference for improving the quality of beef cattle in China.

Characterization of Four Rearing Managements and Their Influence on Carcass and Meat Qualities in Charolais Heifers

The study aim was to identify the effects of the rearing management applied throughout the heifers’ life on the carcass (e.g., conformation, marbling, fat) and meat (color, texture, and sensory profiles) properties. From the individual data of 171 heifers from 25 commercial farms, a typology of four rearing managements was established from 50 rearing factors. The managements had an effect on the conformation, the color (fat and muscle), and the rhomboideus grain meat, for the carcass, and the lightness, the atypical flavor, and the overall acceptability for the longissimus (LM) meat. The carcass traits compared to the meat were more sensitive to a change of rearing management. Our results confirmed that it was possible to target the same carcass or meat quality from different managements. Moreover, according to the aims of the targeted carcass and LM meat quality, management 3 could be an interesting trade-off to jointly manage the quality of both products. For example, the carcasses that were produced had a high conformation, smooth meat grain and the LM meat was more liked. This management was intermediate compared to the other rearing managements and had a long fattening period with a diet mainly based on conserved grass and a high concentrate quantity.

Influence of aging temperature and duration on spoilage organism growth, proteolytic activity, and related chemical changes in vacuum-packaged beef longissimus

Each carcass was assigned to a storage temperature (-2, 0, 4℃). Strip loins were portioned into half loins and assigned to an aging duration (14, 28, 42, 56 d) and vacuum packaged. Loins were aged in commercial upright refrigerators. At each aging interval, loin portion packages were aseptically opened and loins were surface swabbed for microbial analysis before fabrication into 2.54 cm strip steaks. Steaks assigned to slice shear force (SSF) were cooked to 71℃. A raw steak was used to track proteolytic activity, free amino acid content, and volatile compounds. Two-way interactions were observed for all spoilage organisms (P &lt; 0.001). Aging for 42 and 56 d at -2℃ produced lower microbial counts compared to 4℃ (P &lt; 0.05). &nbsp;Loins aged for 14 d at 4℃ had increased desmin and troponin-T degradation compared to aging for 14 at -2 and 0℃ (P &lt; 0.05). Loins aged in 4These data indicate aging at 4℃ increases the rate of proteolysis and subsequent tenderness development and flavor precursor accumulation. However, extended aging at 4℃ resulted in increased microbial counts. Many traits peaked at 42 d of aging.

Beef from Calves Finished with a Diet Based on Concentrate Rich in Agro-Industrial By-Products: Acceptability and Quality Label Preferences in Spanish Meat Consumers

Conjoint analysis was used to estimate the relative importance of some of the main extrinsic attributes and quality labels of beef in three Spanish cities (Córdoba, Marbella, and Santa Pola) in a study performed with 300 individuals. Consumers were segmented according to their frequency of consumption. Willingness to pay for different meats was also calculated from the conjoint analysis results. Consumer liking of beef that had been finished with an alternative concentrate rich in agro-industrial by-products and aged for three different durations as compared to conventionally finished beef was also evaluated using the same consumers. The most important attribute for Spanish consumers was the price (28%), followed by origin (25%), animal welfare certification (19%), protected geographical indication (14%), and organic agriculture certification (14%). Most consumers preferred beef from Spain at the lowest possible price and with the highest number of quality labels. Consumers were willing to pay a premium of 1.49, 3.61, and 5.53 EUR over 14 EUR/kg for organic certification, protected geographical indication, and animal welfare certification, respectively. Sensory analysis revealed that, for regular consumers, beef finished with an alternative concentrate rich in agro-industrial by-products offered several hedonic advantages (color, flavor, and tenderness) when compared to beef finished using a conventional diet, while occasional consumers did not find any difference between the two kinds of meat.

Liquid Chromatography-Tandem Mass Spectrometry for Detecting Myosin Light Chain 3 in Dry-Aged Beef

Liquid chromatography-tandem mass spectrometry (LC/MS/MS) is a more accurate technique for detecting proteins than electrophoresis-based methods such as western blotting. Because of its convenience, western blotting is commonly used for protein analysis in beef. We developed a method for detecting myosin light chain 3 (myl3) in beef samples, particularly dry-aged beef, using LC/MS/MS for quality testing. Musculus longissimus dorsi of Holstein was aged for 0, 2, 4, 5, 9, 11, 17, 20, and 24 weeks and used to measure the myl3 concentration. Because of the high molecular weight of myl3, the limitations of LC/MS/MS were overcome by implementing immunoprecipitation and digestion steps. Ultimately, a tryptic fragment of myl3 (13-mer), generated using immunoprecipitation and digestion by a biotinylated antibody, was detected using LC-MS/MS in positive ion mode through multiple reaction monitoring and analyte separation on a C18 column. Our method showed limits of detection and quantification of less than 0.3 and 0.8 μg/kg, respectively. However, differences in the myl3 concentrations according to the aging time were not significant (p > 0.05). After 12 weeks, myl3 disappeared in tested all samples, thus our analytical method can be used for accurate measurement of muscle protein in beef samples.

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.

Palatability Traits of Sirloin Cap Steaks From Four USDA Quality Grades

Sirloin cap steaks from 4 different USDA quality grades were evaluated to determine the effect of marbling on eating experience. Top sirloin cap steaks (N = 60) of 4 different quality grades (Prime, Top Choice, Low Choice, and Select) were evaluated in the current study. Top sirloin butts were collected, and the biceps femoris was removed, trimmed, and sliced into twelve 2.54-cm-thick steaks. The steaks from each subprimal were aged for 28 d and designated for either trained sensory panels, consumer sensory panels, Warner-Bratzler shear force, or moisture and fat determination. The Prime steaks were rated the highest (P &lt; 0.05) for overall liking and were higher (P &lt; 0.05) for flavor liking than Low Choice and Select steaks within the consumer panels. However, all quality treatments were similar (P &gt; 0.05) in juiciness and tenderness for the consumer panels. Additionally, a similar (P &gt; 0.05) percentage of samples from each treatment were rated acceptable for tenderness, juiciness, flavor liking, and overall liking, with each trait having greater than 70% of samples rated acceptable. Also, Prime steaks were rated the highest (P &lt; 0.05) for sustained juiciness and overall tenderness within the trained sensory panels. Similarly, Prime steaks were rated higher (P &lt;0.05) for initial juiciness than the Low Choice and Select treatments but were similar (P &gt; 0.05) to Top Choice. These results indicate that USDA quality grades impact the eating quality of sirloin cap steaks, especially within the Prime grade, and could provide an opportunity for refined marketing and added economic value for the cut.

Gene Expression and Carcass Traits Are Different between Different Quality Grade Groups in Red-Faced Hereford Steers

Simple Summary

Producing a consistent and positive experience for beef consumers is challenging. The gene expression in muscle at harvest may provide insight into better prediction of United States Department of Agriculture (USDA) quality grade. In this pilot study muscle samples were collected at harvest on sixteen steers with a similar background and identical management. Muscle transcripts were sequenced to determine gene expression. Transcripts related to the extracellular matrix, stem cell differentiation, and focal cell adhesions were differentially expressed in muscle tissue from carcasses with differing USDA quality grades. This confirmed the application of this technique to provide insight into muscle development and fat deposition necessary for better prediction and selection to improve consistency and consumer experience.

Abstract

Fat deposition is important to carcass value and some palatability characteristics. Carcasses with higher USDA quality grades produce more value for producers and processors in the US system and are more likely to have greater eating satisfaction. Using genomics to identify genes impacting marbling deposition provides insight into muscle biochemistry that may lead to ways to better predict fat deposition, especially marbling and thus quality grade. Hereford steers (16) were managed the same from birth through harvest after 270 days on feed. Samples were obtained for tenderness and transcriptome profiling. As expected, steaks from Choice carcasses had a lower shear force value than steaks from Select carcasses; however, steaks from Standard carcasses were not different from steaks from Choice carcasses. A significant number of differentially expressed (DE) genes was observed in the longissimus lumborum between Choice and Standard carcass RNA pools (1257 genes, p < 0.05), but not many DE genes were observed between Choice and Select RNA pools. Exploratory analysis of global muscle tissue transcriptome from Standard and Choice carcasses provided insight into muscle biochemistry, specifically the upregulation of extracellular matrix development and focal adhesion pathways and the downregulation of RNA processing and metabolism in Choice versus Standard. Additional research is needed to explore the function and timing of gene expression changes.

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.

What is the impact of the rearing management applied during the heifers' whole life on the toughness of five raw rib muscles in relation with carcass traits?

The aims of this study were, analysing the effects of rearing managements, carcass traits, and muscle type (M. complexus [CP], M. infraspinatus [IF], M. longissimus [LM], M. rhomboideus [RH], and M. serratus ventralis [SV]) on toughness of raw meat; developing prediction models to act on their toughness. According to our results obtained on the data of 77 heifers, the IF raw muscle was the toughest and appeared the most sensitive to a change in the rearing management. The four other raw muscles had a similar toughness within heifers from the same rearing management. The five raw muscles were less tough when the carcass was heavier and had higher dressing percentage and conformation. The 3 models explained about 40% of the variability observed. Our models showed that it is possible to improve the potential tenderness of raw meat, acting on: age of the heifer's mother, growth rate during the growth and fattening periods, slaughter age, carcass weight and temperature 24 h post-mortem.

Postmortem Aging Time and Marbling Class Effects on Flavor of Three Muscles From Beef Top Loin and Top Sirloin Subprimals

This study evaluated postmortem aging time and marbling class effects on flavor attributes of longissimus lumborum, gluteus medius, and biceps femoris steaks. Carcasses selected to have Lower Small (Small00 to Small49; n = 50) or Upper Slight (Slight50 to Slight99; n = 50) marbling were assigned to aging treatments (14, 21, 28, or 35 d) in an incomplete block arrangement. A trained sensory panel evaluated longissimus lumborum, gluteus medius, and biceps femoris steaks for tenderness, juiciness, and 31 flavor notes. Tenderness increases with aging time were linear (P &lt; 0.001) in longissimus lumborum and gluteus medius steaks and quadratic (P = 0.001) in biceps femoris steaks. Aging response of rancid flavor in longissimus lumborum steaks was cubic (P = 0.01), whereas the aging response of bloody/serumy flavor in biceps femoris steaks was quadratic (P = 0.03). Compared with Upper Slight marbling, carcasses with Lower Small marbling produced longissimus lumborum steaks with greater (P &lt; 0.01) beef flavor and lesser (P = 0.001) bitter flavor, gluteus medius steaks with greater (P = 0.05) brown/roasted flavor, and biceps femoris steaks with greater (P = 0.02) fat-like flavor, although differences were small. Principal component analysis indicated that bloody/serumy, sour, metallic, and bitter flavor attributes were the strongest contributors to a factor explaining 38% of longissimus lumborum flavor variation. Barnyard, bitter, sour, rancid, and bloody/serumy were the greatest contributors to a principal component explaining 41% of gluteus medius flavor. Barnyard, rancid, sour, bloody/serumy, and bitter were contributors to a component explaining 63% of biceps femoris sirloin cap flavor variance. Sample score plots indicated that neither aging time nor marbling class was associated with principal components and identified production lot as contributing to principal components explaining flavor variation in all 3 muscles. Results indicate that, in strip loin and top sirloin subprimals from carcasses with Upper Slight and Lower Small marbling scores, aging time and marbling class had little impact on beef flavor. Thus, increased aging times could be used to enhance tenderness with no adverse effects on other important palatability attributes.

Investigation of Smoked Beef Brisket Palatability from Three USDA Quality Grades

The objective of this study was to investigate differences in smoked beef brisket palatability from 3 USDA quality grades (USDA Prime, average [middle 1/3] Choice, and Select). Briskets (n = 54; 18 per quality grade) were seasoned with a blend of 1:1 coarse salt/black pepper, and then cooked in a smoker to a final internal temperature of 93°C for approximately 6 to 7 h. For sensory analysis, briskets were separated into point (pectoralis superficialis) and flat (pectoralis profundus) portions and then sliced perpendicular to the muscle fibers. Consumer panelists (N = 360) evaluated palatability traits, acceptability of each trait, and willingness to pay (WTP). An interaction between quality grade and muscle was observed (P ≤ 0.03) for all palatability traits, proportion of acceptable samples, and WTP. Consumers could not distinguish among quality grades of the point portions for tenderness, juiciness, flavor liking, and overall liking (P &gt; 0.05). Point samples, regardless of quality grade, were scored greater (P &lt; 0.05) than Prime flat samples for all palatability traits. Choice and Select flat samples were scored lesser (P &lt; 0.05) than all other treatment combinations for tenderness, flavor liking, and overall liking. In alignment with palatability traits, consumers’ WTP was greatest for point portions, regardless of quality grade (P &lt; 0.05), followed by Prime flat portions. Choice and Select flat portions had the lowest WTP (P &lt; 0.05). Consumer acceptability of cooked beef brisket generally followed similar trends as palatability scores. Quality grade had no effect on the eating quality of the point portions of smoked briskets, and point portions received superior palatability scores to flat portions. Prime flat portions had greater eating quality compared to that of Choice and Select flat portions, and consumers had greater WTP for what they perceived as superior eating quality.

Flavor, Tenderness, and Related Chemical Changes of Aged Beef Strip Loins

Varying aging times and methods were evaluated for their effect on flavor, tenderness, and related changes involatile compounds and flavor precursors. Strip loin sections from USDA Choice beef carcasses (n = 38) were randomly assigned to treatments: (1) 3 d wet-aged, (2) 14 d wet-aged, (3) 28 d wet-aged, (4) 35 d wet-aged, (5) 49 d wet-aged, (6) 63 d wet-aged, (7) 21 d dry-aged, and (8) 14 d wet-aged followed by 21 d dry-aged. Samples were analyzed for trained sensory attributes, shear force, volatile compounds, and flavor precursors (fatty acids, free amino acids, and sugars). Discriminant function analysis was used to identify sensory attributes contributing the greatest to treatment differences. Flavor notes were not differentiated in beef aged up to 35 d, regardless of aging method. A shift in flavor occurred between 35 d and 49 d of wet-aging time that was characterized by more intense sour and musty/earthy notes. Both shear force assessment and trained panelists agreed that tenderness was not affected (P &gt; 0.05) by additional aging beyond 28 d. Volatile compound production and liberation of amino acids and sugars increased (P &lt; 0.01) during the progression of aging time, with no change (P &gt; 0.05) in fatty acid composition, which may be a result of metabolic processes like microbial metabolism. Chemical properties shared strong positive relationships (r &gt; 0.50, P &lt; 0.001) with sour, musty/earthy, and overall tenderness. These results substantiate the deteriorative effect of extended aging times of 49 d or greater on flavor of beef strip loins without tenderness improvement.

Effect of the muscle nanostructure changes during post-mortem aging on tenderness of different beef breeds

Objective

Tenderness is a very complex feature, and the process of its formation is very complicated and not fully understood. Its diversification is one of the most important problems of beef production, as a result beef aging is widely used to improve tenderness as it is believed to provide a homogeneous product to consumers. While few studies have evaluated the muscle structure properties in relation to tenderness from early post-mortem, there little to no information available on how the muscle nanostructure of beef carcasses changes during post-mortem ageing to determine the appropriate aging time for acceptable tenderness.

Methods

Muscle nanostructure (myofibril diameter [MYD], myofibril spacing [MYS], muscle fibre diameter [MFD], muscle fibre spacing [MFS], and sarcomere length [SL]), meat tenderness and cooking loss [CL]) were measured on 20 A2 longissimus muscles of Bonsmara, Beefmaster, Hereford, and Simbra at 45_mins, 1, 3, and 7 days post-slaughter. Muscle nanostructure was measured using a scanning electron microscope, while tenderness was measured using Warner Bratzler shear force.

Results

At 45 minutes post-slaughter, breed affected MYD and MYS only, while at 24_hrs it also affected MFD and MFS. On day 3 breed effected MFS and SL, while on day 7 breed effected tenderness only. As the muscles matured, both MYD and MYS decreased while CL increased, and the muscles became tender. There was no uniformity on muscle texture features (surface structure, fibre separation, muscle contraction, and relaxation) throughout the ageing period.

Conclusion

Meat tenderness can be directly linked to breed related myofibril structure changes during aging in particular the MYD, spacing between myofibrils and their interaction; while the MFD, spacing between muscle fibres, SL, and CL explain the non-uniformity in beef tenderness.

Muscle fiber characteristics and postmortem quality of longissimus thoracis, psoas major and semitendinosus from Chinese Simmental bulls

Using Chinese Simmental cattle semitendinosus, psoas major, and longissimus thoracis samples, we assessed muscle fiber characteristics and postmortem quality. The type I, IIA, and IIB fiber diameters were greater in semitendinosus and longissimus thoracis relative to psoas major, with psoas major, semitendinosus, and longissimus thoracis having the highest respective percentages of type I, IIB, and IIA fibers. Psoas major had the highest R 248 and R 250 values and lowest R 258 values at 1- and 6-hr postmortem. Psoas major had the lowest Warner-Bratzler shear force (WBSF), hardness, and chewiness values. The trends of WBSF, hardness, and chewiness changes decreased with increasing aging time. Semitendinosus had higher changes in WBSF than psoas major, and the number % type I fibers was correlated negatively with % changes of WBSF. Therefore, muscles with a high proportion of type IIB fibers and a low proportion of type I had lower tenderness and higher tenderization rate. Further research should be done to seek the optimal composition of muscle fiber type in order to improve beef quality, as muscle fiber type has opposite effect of tenderness background and tenderization rate.

Palatability assessments of beef strip loin steaks portioned by weight or by thickness sourced from various carcass weight/ribeye area size combinations

Beef carcasses (n = 90; U.S. Choice) met a 3 ribeye area (REA - Small, Medium, Large) × 3 carcass weight (CW - Light, Intermediate, Heavy) scheme to assess palatability on steaks cut by portion thickness (PT- 3.18 cm) and weight (PW -340 g). Significant interactions revealed trends for steaks from the Small REA, regardless of CW, to have among the lowest shear-force values. For PT steaks, significant interaction for overall liking revealed no differences for Small and Medium REA across all CW categories, but steaks from Large REA from Light CW differed (P < 0.05) from the other two CW categories. For PT steaks, overall liking and tenderness liking scores were higher (P < 0.05) for Small REA compared to other categories, whereas CW did not influence any palatability trait. REA and CW do impact beef steak palatability, though steaks from all combinations were "very tender" and highly acceptable from a palatability standpoint.

Flavor Characterization of Grass- and Grain-Fed Australian Beef Longissimus Thoracis Aged 35 to 65 Days Postmortem

Our objective was to investigate the effects of extended aging on the flavor characteristics of Australian grass- and grain-fed beef longissimus thoracis. Ribeye rolls from Australian grass- and grain-fed beef carcasses were collected, randomly assigned to one of 4 postmortem aging days (35, 45, 55, and 65), vacuum packaged, and shipped under refrigeration (0°C–2°C) to Texas Tech University (Lubbock, TX). Aged longissimus thoracis were fabricated on their respective aging day into 2.54-cm steaks, vacuum packaged individually, and frozen (−24°C) until further analyses. According to trained flavor panelists, beef flavor identity, fat-like, metallic, umami, bitter, and sweet flavors were not influenced by diet or postmortem aging (P &gt; 0.05). Diet influenced (P &lt; 0.05) liver-like, rancid, grassy, and sour flavors, as well as juiciness. For all flavors except liver-like, grass-fed samples had stronger flavors than grain-fed samples. Postmortem aging influenced (P &lt; 0.05) bloody/serumy, liver-like, rancid, and grassy flavors, along with tenderness and juiciness. Flavor detection typically became stronger for those flavors as postmortem aging increased; however, bloody/serumy, juiciness, and tenderness generally did not follow a linear trend as postmortem aging increased. Content of acetic acid and hexanal were each greater (P &lt; 0.05) in grain-fed beef. The majority of lipid oxidation compounds were most prominent (P &lt; 0.05) in samples aged 45 and 55 d, while content in 35 and 65 d were lower and did not differ (P &gt; 0.05). Aging also influenced content of acetic acid and ethanol (P ≤ 0.04), which increased with aging duration. For 1-octen-3-ol, grain-fed samples aged 65 d had the greatest (P &lt; 0.05) content compared with all other diet and aging combinations. Results indicate that aging up to 65 d had no impact on beef flavor identity and umami, but it led to stronger generation of certain off-flavors such as rancid, grassy, and liver-like.

Flavor Characterization of Grass- and Grain-Fed Australian Beef Longissimus Lumborum Wet-Aged 45 to 135 Days

The study objective was to evaluate the effects of extended postmortem wet aging of Australian beef, cattle diet, and their interaction on objective and subjective measures of beef flavor of the longissimus lumborum. Beef strip loins were collected from grass- and grain-fed cattle (n = 50 total) at a commercial abattoir near Brisbane, Australia. Beef longissimus lumborum were portioned and assigned randomly to one of 3 postmortem aging periods (45, 70, or 135 d). As each section reached its respective postmortem aging designation, that section was fabricated into 2.5-cm steaks, individually vacuum packaged, and frozen (−21°C). Trained panelists evaluated cooked steaks for numerous flavor attributes, tenderness, and juiciness; volatile compounds were also evaluated. Sensory scores differed (P &lt; 0.05) due to diet, whereby grain-fed samples were rated more intense (P &lt; 0.05) for beef flavor identity, fat-like, liver-like, and sweet but grass-fed samples were more intense (P &lt; 0.05) for green-hay and bitter. Juiciness, tenderness, and 4 flavor attributes (bloody/serumy, metallic, umami, and rancid) were similar (P &gt; 0.05) between diets. Extending postmortem aging from 45 to 135 d resulted in decreased beef and umami flavors (P &lt; 0.05), along with concurrent increased detection of off-flavors, such as liver-like, rancid, bitter, and sour (P &lt; 0.05). Volatile flavor compounds were more influenced by postmortem aging than diet. Increased postmortem aging time increased concentration for both lipid oxidation and Maillard-reaction–derived volatiles, resulting in the concentration of negative flavor volatile compounds rather than the absence of positive flavor compounds. Based on these results, differences existed in the flavor profile of longissimus lumborum from grass- and grain-fed beef, regardless of postmortem aging. However, aging beef strip loins 135 d is not recommended based on reduced beef flavor and increased off-flavor detection compared to samples aged 45 or 70 d postmortem.

High-density diet improves growth performance and beef yield but affects negatively on serum metabolism and visceral morphology of Holstein steers

The objective of this study was to evaluate the effect of different dietary densities on growth performance, carcass characteristics, meat quality, serum metabolism, ruminal papillae morphology and liver injuries of steers. For this purpose, a total of eighteen Holstein steers were randomly fed one of the three diets: high energy and protein diet (H), standard energy and protein diet (C), and low energy and protein diet (L) for 11 months fattening with three-step finishing strategy. Steers fed with H diet had higher (p < .05) average daily gain, feed efficiency, hot carcass weight, serum aspartate aminotransferase to alanine aminotransferase ratio, and monounsaturated fatty acids along with continuous low ruminal pH value, severer hepatic steatosis and ruminal papillae parakeratosis. Meanwhile, steers fed L diet increased the proportion of C20:0, C22:6n-3, saturated fatty acids and n-3 polyunsaturated fatty acids along with lower n-6 to n-3 ratio in longissimus dorsi muscle as compared to that of steers fed H diet. Dietary densities did not influence (p > .10) proximate nutrients and sensory characteristics of beef. The present study indicates that Holstein steers could achieve better growth and carcass performance under high-density diet, whereas they are under threat of visceral injuries and metabolic disorders. This study gives comprehensive relationship between productivity and animal health and suggests that a proper diet should be adopted for fattening Holstein steers in consideration of both beef quality and quantity and animal health.

Extending Aging of Beef Longissimus Lumborum From 21 to 84 Days Postmortem Influences Consumer Eating Quality

Our objective was to determine the effect of extending postmortem aging from 21 to 84 days on consumer eating quality of beef longissimus lumborum. Strip loins were collected from 108 carcasses. The longissimus lumborum muscle was isolated from strip loins and assigned to one of ten postmortem aging periods from 21 to 84 days (7-day increments) and balanced within four anatomical positions within the muscle. Consumer evaluations for tenderness, juiciness, flavor, and overall liking were conducted using untrained consumer sensory panels consisting of 1080 individual consumers, in accordance with the Meat Standards Australia protocols. These scores were then used to calculate an overall eating quality (MQ4) score. Postmortem aging had no effect (P > 0.05) on tenderness, but juiciness, flavor liking, overall liking, and MQ4 declined (P < 0.05) as aging period increased. Samples aged 21 to 42 days were most preferred having greater (P < 0.05) overall liking and greater (P < 0.05) MQ4 scores than samples aged 70 to 84 days postmortem. These results suggest that longissimus lumborum samples should not be wet-aged longer than 63 days to prevent potential negative eating experiences for consumers; however, altering storage conditions, specifically reducing temperature, could potentially allow for longer chilled storage without such negative effects on flavor and overall liking.

Evaluation of Beef Top Sirloin Steaks of Four Quality Grades Cooked to Three Degrees of Doneness

The objective of this study was to evaluate the impact of USDA quality grade on beef eating quality of top sirloin steaks when cooked to multiple degrees of doneness (DOD). Beef top sirloin butts (N = 60; 15/quality grade) were collected to equally represent 4 quality grades [Prime, Top Choice (modest00 to moderate100), Low Choice, and Select]. Steaks were assigned to 1 of 3 DOD: rare (60°C), medium (71°C), and well-done (77°C). Steaks were allocated to either consumer sensory analysis, trained sensory analysis, fat and moisture analysis, or Warner-Bratzler shear force (WBSF). There were no interactions (P > 0.05) for all consumer ratings of palatability traits, indicating increases in DOD had the same impact across all quality grades. Prime steaks had greater (P < 0.05) juiciness ratings than all other quality grades, except for Top Choice. As DOD increased, consumer ratings and the percentage of steaks rated acceptable for each palatability trait decreased (P < 0.05; rare > medium > well-done). There was a quality grade × DOD interaction (P < 0.05) for trained sensory panel juiciness scores. When cooked to medium, Prime and Top Choice steaks were rated higher (P < 0.05) for juiciness than Low Choice and Select steaks, while there were no differences at all other DOD. Similar to consumer ratings, trained panel ratings of tenderness decreased (P < 0.05) as DOD increased (rare > medium > well-done). Lastly, there was no quality grade by DOD interaction (P > 0.05) for Warner-Bratzler shear force. These results indicate that regardless of the DOD top sirloin steaks are cooked to, quality grade had minimal impact on palatability. Therefore, it is unnecessary for consumers, retailers, and foodservice to pay premium prices for higher quality top sirloin steaks, as the same eating experience will be provided.

Microbiological, rheological and physical-chemical characteristics of bovine meat subjected to a prolonged ageing period

The aim of this study was to evaluate the effects of a long ageing period on the microbiological, rheological and physicalchemical characteristics of bovine beef. For the trial n. 3 Marchigiana bovine breed (live weight of 760 kg approximately), slaughtered at 34 months were chosen and the loin muscles were undergone to a prolonged ageing process. The analytical determinations performed were: pH and a_w values, texture profile analysis, Warner-Bratzler shear force, colour (CIE L*a*b*), centesimal analysis, total bacterial count, Enterobacteriaceae, Listeria monocytogenes, yeasts and moulds. The results indicate that extended ageing has a negative effect on weight loss but, by the means of the standardization of dry aging parameters, reduce lipid oxidation and improve tenderness.

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.

GROWTH AND DEVELOPMENT SYMPOSIUM: STEM AND PROGENITOR CELLS IN ANIMAL GROWTH: The regulation of beef quality by resident progenitor cells1

The intramuscular adipose tissue deposition in the skeletal muscle of beef cattle is a highly desired trait essential for high-quality beef. In contrast, the excessive accumulation of crosslinked collagen in intramuscular connective tissue contributes to beef toughness. Recent studies revealed that adipose tissue and connective tissue share an embryonic origin in mice and may be derived from a common immediate bipotent precursor in mice and humans. Having the same linkages in the development of adipose tissue and connective tissue in beef, the lineage commitment and differentiation of progenitor cells giving rise to these tissues may directly affect beef quality. It has been shown that these processes are regulated by some key transcription regulators and are subjective to epigenetic modifications such as DNA methylation, histone modifications, and microRNAs. Continued exploration of relevant regulatory pathways is very important for the identification of mechanisms influencing meat quality and the development of proper management strategies for beef quality improvement.

Physicochemical and sensory characteristics of commercial, frozen, dry, and wet-aged Hanwoo sirloins

Objective

The objective of this study was to evaluate the physicochemical, sensory and taste characteristics of commercial, frozen, dry, and wet aged Hanwoo sirloin.

Methods

Grade 2 sirloin from 6 Hanwoo steers (about 30 months old) were obtained after 5 days postmortem. Samples were assigned to four groups which were commercial beef (CON, control group), frozen beef (Hanwoo frozen, HF; 40 days in −18°C freezer), wet-aged beef (Hanwoo wet-aging, HW; 21 days), and dry-aged beef (Hanwoo dry-aging, HD; 40 days). HW and HD were stored in a 80%±5% relative humidity cooler at 1°C.

Results

The HF group showed a significantly higher cooking loss and expressible drip with significantly higher pH compared to other groups. In addition, protein and fat contents in the HD group were higher than those in other groups (p<0.05). The shear forces in the HW and HD groups were significantly lower than those in the CON group. The HD group had significantly higher omega-3 and polyunsaturated fatty acids compared with other groups. Glutamic acid levels in the HD group were significantly higher compared with those in other groups. Electronic tongue analysis revealed that sourness of the HD group was lower than that of other groups, whereas the HD group showed significantly higher umami, richness, and saltiness compared to other groups (p<0.05). Sensory test results revealed that the HW group had significantly higher tenderness, while the HD group had significantly higher chewiness, juiciness, and overall acceptability scores.

Conclusion

These results suggest that both wet- and dry-aging treatments can effectively improve sensory characteristics, and dry-aging was much more useful to enhance umami tastes and meat quality of 2 grade Hanwoo sirloins.

Metabolomic Investigation of Tenderness and Aging Response in Beef Longissimus Steaks

A study was conducted to identify molecular changes reflective of beef tenderness variation and tenderization during postmortem aging. Carcasses (U.S. Select) were selected to represent extremes in tenderness (n = 20; 10 per class). Two pairs of adjacent longissimus lumborum steaks from each strip loin were blocked by location and assigned to each aging time (2, 7, 14, or 28 d postmortem). One steak from each pair was designated for slice shear force determination and the other was used for sarcomere length, western blotting for desmin, and non-targeted LC- and GC–MS metabolite profiling. Tough steaks had higher (P &lt; 0.001) slice shear force values than tender steaks, and increasing aging time decreased (P &lt; 0.001) slice shear force values. Tender steaks had a greater (P &lt; 10–4) proportion of desmin degraded than tough steaks, and increasing aging time increased (P &lt; 10–22) desmin degradation in steaks from both classes. From 2,562 profiled metabolites, 102 metabolites were included in the final analysis after statistical screening. Twenty-eight metabolites could be annotated and loosely categorized into amino acids/peptides (n = 16), metabolism intermediates (n = 7), glycosides (n = 4), and fatty acids and phospholipids (n = 3). Amino acids were primarily associated with desmin degradation. Increased glucose levels were strongly associated to the tender classification and moderately associated to increased proteolysis, while increased glucose-6-phosphate was strongly related to the tender class but was related to decreased proteolysis. Increased malic acid was strongly associated to the tough classification, increased slice shear force, and decreased proteolysis. Increased levels of 3-phosphoglyceric acid and glycerol-3-phosphate was moderately associated with increased slice shear force and decreased proteolysis. These data indicate that accumulation of amino acids during aging is strongly related to postmortem proteolysis and may provide evidence of the fate of proteins degraded postmortem. Measures of glucose, glucose-6-phosphate, and malic acid concentrations may provide a metabolic fingerprint indicative of tenderness differences in beef longissimus.

Retail Display Properties and Consumer Perception of Extended Aged Beef Topically Treated with Ascorbic Acid and Rosemary Extract

Extended aging increases browning and decreases redness in fresh beef. The goal of this study was to test an already proven combination of antioxidants (0.05% ascorbic acid + 0.1% rosemary extract) using a method that could be applied at the retail level to simply and effectively extend the shelf-life of extended aged beef. The specific objective was to analyze the effect of topical application of ascorbic acid and rosemary extract on color, lipid oxidation, microbial growth, and sensory perception of beef longissimus lumborum (LL; n = 12) and semimembranosus (SM; n = 12) muscles wet aged at 0°C for 14, 28, and 42 (extended aging period) days. After aging, steaks were cut, sprayed with 2 mL of a 0.05% ascorbic acid + 0.1% rosemary extract solution (treated) or untreated (control), and subjected to retail display. Antioxidant treated LL steaks had greater (P < 0.05) L* (lightness) values, but lower (P < 0.05) a* (redness) and b* (yellowness) values than control steaks. Furthermore, antioxidant treatment decreased (P < 0.05) browning on d 4 of retail display compared to control steaks. Consumers scored antioxidant treated SM steaks as less tender on d 28, more juicy on d 14 but less juicy on d 18 and 42. Antioxidant treatment did not affect lipid oxidation, microbial growth, or sensory flavor scores. As expected, longer aging periods resulted in less color stability of LL and SM steaks. Although the antioxidant treatment resulted in measurable subjective color improvements, these improvements are likely not detectable by the consumer.

Effects of hormonal growth promotants on beef quality: a meta-analysis

Benefits of hormonal growth promotants (HGPs) include production efficiency, profit, and reduced environmental effects for beef cattle. Questions remain about effects of HGP on beef quality, particularly on measures of toughness such as Warner-Bratzler shear force (WBSF), tenderness, and other taste-panel attributes of beef. The objective of this meta-analysis was to assess the effects of HGP on beef quality using the results of randomized controlled trials identified from 3 searched databases. Thirty-one experiments with 181 treatment comparisons were used to evaluate the effects of HGP on WBSF and sensory measures of beef quality. Experiments varied in design, used many different hormonal treatments and combinations, which were single or repeated, in different breeds and sex groups of cattle, with or without electrical stimulation, and with different lengths of time on feed and beef aging. The effects of multiple treatment comparisons in experiments were evaluated using robust regression models and compared to Knapp-Hartung and permutation meta-analytical methods. Increased WBSF was associated with HGP treatment. Use of multiple HGP implants was associated with an increase in WBSF of 0.248 kg (95% CI = 0.203 to 0.292). Effects of a single implant only increased WBSF by 0.176 kg (95% CI = 0.109 to 0.242). Aging of beef did not alter the association of HGP with increased WBSF (P = 0.105); however, the point direction was toward a reduced effect with aging (standardized mean difference [SMD] = -0.005 per day aged). While aging lowered WBSF, it did not reduce the SMD between HGP treatment and reference groups. Comparisons using trenbolone acetate did not differ in WBSF from those using other implants (P > 0.15). The findings on sensory panel tenderness differ from those using WBSF as HGP treatment was not associated with reduced tenderness (P > 0.3) and multiple HGP treatments improved tenderness (SMD = 0.468) compared to a single implant. Further, juiciness, flavor, and connective tissue were not associated with HGP use, whereas there was a marked 5.5-point decrease in the Meat Standards Australia meat quality 4 score, albeit with limited experiments. In general, the true variance of experiments, tau2 (τ2) was low (<0.1), but heterogeneity, I2 was high (>50%) indicating that much of the variance was due to factors other than measurement error. More targeted studies on the role of HGP in influencing beef quality are needed.

Palatability of beef chuck, loin, and round muscles from three USDA quality grades

The objective of this study was to determine the palatability of various beef cuts from 3 USDA quality grades. Five different beef subprimals from USDA Prime, Choice, and Select (n = 10/quality grade) carcasses were utilized for the study, including: strip loins, inside rounds, bottom rounds, shoulder clods, and chuck rolls. Subprimals were fabricated into 9 retail cuts, which contained the following beef muscles: longissimus lumborum (LL); longissimus thoracis, complexus, and spinalis dorsi (LCS); infraspinatus (IF); serratus ventralis (SV); triceps brachii (TB); teres major (TM); adductor (AD); semimembranosus (SM); and biceps femoris (BF). The pH and percentage of fat, moisture, protein, and collagen was determined for each muscle on a raw basis. Additionally, cooked steak measurements included Warner-Bratzler shear force (WBSF) and slice shear force (SSF). Consumer and trained sensory panelists evaluated palatability traits of each cut and quality grade combination. A quality grade × muscle interaction was determined for trained panelists assessment of overall tenderness (P = 0.03), SSF (P = 0.02), proximate composition (P < 0.01), and pH (P < 0.01). In all objective and subjective measurements of tenderness, the LCS was the most tender (P < 0.05), while cuts from the round (BF, AD, and SM) were among the toughest and least juicy (P < 0.05). Conversely, consumers and trained sensory panelists identified the LCS, IF, and SV to be juicier (P < 0.05) than all others. The TB, TM, and LL were perceived by consumers most often as being everyday quality. The LCS was found by consumers to be the most acceptable (P < 0.05) across all attributes, with the SM being the least (P < 0.05) acceptable muscle. For each muscle, fat percentage was the greatest (P < 0.05) in Prime cuts. Slice shear force determined Prime IF, LL, and SV to be more tender (P < 0.05) than Choice and Select. No SSF differences (P > 0.05) were found among quality grades for the AD, BF, and SM. The WBSF values decreased (P < 0.05) across all muscles, as quality grade increased (Prime < Choice < Select). The results of this study indicate that muscles from the chuck may be utilized to provide consumers with a positive eating experience. Meanwhile, muscles from the round are likely to provide consumers with a lower quality eating experience.

Effects of Marbling and Postmortem Aging on Consumer Assessment of United States Lamb Loin

Consumer sensory analysis was performed to evaluate the effects of three marbling categories [LOW, Intermediate (MED), and HIGH] and 2 postmortem aging categories (21 d and 42 d) on the palatability of lamb loin chops as determined by U.S. consumers and to determine the relationship between marbling, flank streaking, intramuscular fat percentage (IMF), and palatability traits. Marbling and aging did not interact to affect any of the scores for palatability attributes, their acceptances, or the frequency of their overall eating quality classifications (P < 0.05). Consumers rated HIGH treatments (P < 0.05) as more tender, juicier, and with greater flavor liking and overall liking than MED or LOW, which were similar for all traits (P > 0.05). Aging also influenced (P < 0.05) all traits, as consumers scored 21 d samples greater for all palatability traits than their 42 d counterparts. A greater (P < 0.05) percentage of consumers categorized 42 d samples as ‘unsatisfactory’ and fewer as ‘better than everyday’ or ‘premium quality’ than 21 d samples. A larger proportion of consumers categorized HIGH samples as ‘premium quality’ than MED or LOW and fewer called HIGH ‘good everyday quality’ compared to MED (P < 0.05). Flank streaking, marbling score, and IMF were all influenced (P < 0.01) by marbling category in a linear fashion. Increasing marbling score, more so than flank streaking, was positively linked to increasing eating quality scores. Also, tenderness, juiciness and flavor liking are major drivers for consumer sensory scores for overall liking, with flavor liking having the strongest relationship to overall liking of lamb. Overall, consumers preferred HIGH marbling over LOW and MED marbling loin chops, but had difficulty distinguishing between LOW and MED. Furthermore, extending postmortem aging of lamb loin from 21 to 42 d reduced scores for eating quality traits.

Effects of hormonal growth promotants on beef quality: a meta-analysis

Benefits of hormonal growth promotants (HGPs) include production efficiency, profit, and reduced environmental effects for beef cattle. Questions remain about effects of HGP on beef quality, particularly on measures of toughness such as Warner-Bratzler shear force (WBSF), tenderness, and other taste-panel attributes of beef. The objective of this meta-analysis was to assess the effects of HGP on beef quality using the results of randomized controlled trials identified from 3 searched databases. Thirty-one experiments with 181 treatment comparisons were used to evaluate the effects of HGP on WBSF and sensory measures of beef quality. Experiments varied in design, used many different hormonal treatments and combinations, which were single or repeated, in different breeds and sex groups of cattle, with or without electrical stimulation, and with different lengths of time on feed and beef aging. The effects of multiple treatment comparisons in experiments were evaluated using robust regression models and compared to Knapp-Hartung and permutation meta-analytical methods. Increased WBSF was associated with HGP treatment. Use of multiple HGP implants was associated with an increase in WBSF of 0.248 kg (95% CI = 0.203 to 0.292). Effects of a single implant only increased WBSF by 0.176 kg (95% CI = 0.109 to 0.242). Aging of beef did not alter the association of HGP with increased WBSF (P = 0.105); however, the point direction was toward a reduced effect with aging (standardized mean difference [SMD] = -0.005 per day aged). While aging lowered WBSF, it did not reduce the SMD between HGP treatment and reference groups. Comparisons using trenbolone acetate did not differ in WBSF from those using other implants (P > 0.15). The findings on sensory panel tenderness differ from those using WBSF as HGP treatment was not associated with reduced tenderness (P > 0.3) and multiple HGP treatments improved tenderness (SMD = 0.468) compared to a single implant. Further, juiciness, flavor, and connective tissue were not associated with HGP use, whereas there was a marked 5.5-point decrease in the Meat Standards Australia meat quality 4 score, albeit with limited experiments. In general, the true variance of experiments, tau2 (τ2) was low (<0.1), but heterogeneity, I2 was high (>50%) indicating that much of the variance was due to factors other than measurement error. More targeted studies on the role of HGP in influencing beef quality are needed.

Bloom Development of the Beef Semimembranosus and Triceps Brachii as Influenced by Wet-Aging

The semimembranosus (SM) and triceps brachii (TB) from USDA Select beef carcasses were used to test the effect of wet-aging period on bloom development. Inside rounds (IMPS#168) and shoulder clods (IMPS #114) were randomly allocated to 0, 7, 14, 21, 28, and 35 d wet-aging at 2°C (n = 10 subprimal cuts/aging period). Each week, two 2.54-cm-thick, non-adjacent steaks were cut from aged inside rounds and shoulder clods, and instrumental color (L*, a*, and b*) of the SM and TB was measured at 10-min intervals for 2 h after cutting. Steaks from the SM and TB became a more vivid (greater C* values; P < 0.05), redder (greater a* values; P < 0.05), and yellower (greater b* values; P < 0.05) color during the 120-min bloom period. Moreover, the calculated proportion of oxymyoglobin (OMb) in SM and TB steaks increased (linear, P < 0.001) during the first 80 min after cutting but stabilized thereafter. Redness (a* and hue angles), b*, and C* values decreased (linear, P ≤ 0.050) in SM steaks as duration of wet-aging increased from 0 to 35 d, but length of wet-aging had no (P ≥ 0.127) effect on instrumental color measures of TB steaks. Neither the percentage of calculated OMb (P = 0.580) nor OMb asymptotic point (P ≥ 0.214) for SM steaks was affected by duration of wet-aging, and, even though the proportion of OMb in TB steaks was not altered (P = 0.459) by postmortem aging, OMb asymptotic points increased (linear, P = 0.001) in TB steaks with increasing durations of wet-aging. Results of these experiments indicate that 90%, or more, of the change in color was achieved within the first 50 to 60 min after cutting, but duration of wet-aging had little to no impact on bloom development in SM and TB steaks.

Quality Improvement of Pork Loin by Dry Aging

This study aimed to investigate the effects of dry aging on the quality of pork loin. Longissimus lumborum muscles were dissected from the right half of five pork carcasses and were used as the control samples. The left halves of the carcasses were aged at 2±1℃ and a relative humidity of 80% for 40 d. The total aerobic bacteria count was similar between the control and dry-aged pork loin (p>0.05). Lactic-acid bacteria was absent in both the control and dry-aged pork loins. Dry-aged pork loin contained low moisture and high protein and ash compared to the controls (p<0.05). The pH was higher and cooking loss was lower in dry-aged pork loin compared to that in the control (p<0.05). Flavor related compounds, such as total free amino acid, hypoxanthine, and inosine of pork loin were higher in dry-aged pork loin; whereas, inosine 5'-monophosphate and guanosine 5'-monophosphate were low in dry-aged pork loin than control (p<0.05). There was no difference in carnosine and anserine content between dry-aged pork loin and the control (p>0.05). Dry-aged pork loin had lower hardness and shear force and received higher core in sensory evaluation than the control (p<0.05). According to the results, dry aging improved textural and sensorial quality of pork loin.

Instrumental meat quality characteristics associated with aged m. longissimus thoracis from the four Canadian beef quality grades

Canadian beef is quality graded to characterize the potential eating quality of the cooked product. Instrumental meat quality characteristics of 48 m. longissimus thoracis (LT, rib eye) from four Canadian beef grades (Canada A, AA, AAA, and Prime, n = 12) before and after an additional 14-d aging were compared using a split plot design with grade, aging, and their interaction as fixed sources of variation. Mean percentage intramuscular fat was greatest in Canada Prime muscle and least in Canada A and AA muscles (P < 0.0001), whereas mean percentage drip loss was lower in Canada Prime muscle than in muscle from all other grades (P = 0.0348). Canada Prime and AAA muscles were redder and yellower than muscles from other grades even after aging (P < 0.03), which may be associated with increased fat content and indicative of accelerated myoglobin oxidation and increased myoglobin oxygenation. Shear force was not different among the Canada grades, although the differences between Canada AA cooked beef LT and that of Canada Prime and AAA carcasses approached significance (P = 0.0993). Results indicated that Canada quality grades did not differentiate beef on cooked product tenderness, substantiating that muscle compositional characteristics alone define beef grade advantages.

Influence of extended aging on beef quality characteristics and sensory perception of steaks from the biceps femoris and semimembranosus

The objective was to determine the influence of post-fabrication aging (2, 14, 21, 42, and 63days) on beef quality characteristics and consumer sensory perception of biceps femoris (BF) and semimembranosus (SM) steaks. Lipid oxidation and aerobic plate counts increased (P<0.05) with longer aging periods and retail display times. An aging period by day of retail display interaction (P<0.05) was observed for a* and b* values of the BF and SM. Warner-Bratzler shear force values decreased (P<0.05) with longer aging for the SM, while no difference was observed for the BF. Consumer panel results revealed that longer aging periods increased (P<0.05) acceptability of the SM, tenderness of both muscles, and tended to increase (P=0.07) juiciness of the SM. Our results show that extended aging reduces retail color stability yet has positive effects on consumer perception of tenderness of both muscles and overall acceptability of the SM.

Novel approach to aging beef: Vacuum-packaged foodservice steaks versus vacuum-packaged subprimals

This study evaluated quality attributes of beef aged as subprimals versus as steaks. Paired subprimals (n=5 pairs of five subprimal types) were selected and assigned to a treatment: (1) aging as vacuum-packaged steaks (portioned 7 d postmortem), or (2) aging as vacuum-packaged subprimals (portioned into steaks after each aging period: ribeye, 28 d; strip loin, 28 d; top sirloin butt, 35 d; tenderloin, 21 d; and short loin, 28 d). To simulate typical U.S. handling and distribution, all steaks were held an additional 14 d before color, shelf life, Warner-Bratzler shear force (WBSF), and consumer sensory analyses were conducted. Aging subprimals tended to result in a lower WBSF for the strip loin and significantly lower WBSF for top sirloin butts. Although consumer panelists preferred the strip loin aged as steaks, they had no preference for aging method for the other muscles. Overall, findings from this study show the potential for portioning subprimals into steaks before aging.

Aging implications on fresh muscle traits of Certified Angus Beef steaks

Vacuum-packaged Certified Angus Beef (CAB) subprimals ( = 72) that included the longissimus thoracis (LT), longissimus lumborum (LL), gluteus medius (GM), and infraspinatus (IF) muscles were purchased from a major beef packing facility. Subprimals were allocated to 1 of 3 aging periods (14, 28, or 42 d) and aged at 2°C. After aging, 5 steaks were cut from each subprimal and assigned to pH, water-holding capacity, Warner-Bratzler shear force (WBSF), cooked color, cooking yield, cooking loss, and sensory panel analysis. Infraspinatus steaks were more tender ( < 0.05) than all other steaks, and subprimals aged 14 d had greater ( < 0.05) WBSF values than the other 2 aging periods, regardless of muscle. Water-holding capacity and cook yield were greater ( < 0.05) for LL and LT than IF and GM steaks, whereas purge loss was greater ( < 0.05) for IF and GM than LL and LT steaks. Throughout the aging periods, pH declined for all muscle groups, with IF steaks having the greatest ( < 0.05) pH values among all muscles. Among IF steaks, sensory evaluations of all attributes did not ( ≥ 0.26) differ across aging periods; yet among LT steaks, consumers rated those aged 14 d greater ( < 0.05) in overall impression than LT steaks aged 28 and 42 d. Among LT steaks, those aged 14 d received greater ( < 0.05) flavor ratings than LT steaks subjected to longer aging periods, and LT steaks aged 14 d received the greatest ( < 0.05) overall impression, with consumers giving greater ( < 0.05) overall impression scores to LT steaks aged 42 d over those aged 28 d. Aging period had no effect ( ≥ 0.017) on consumer ratings for flavor, tenderness, juiciness, or overall impression of LL steaks. Among GM steaks, consumers rated steaks aged 14 and 28 d more ( < 0.05) flavorful than those aged 42 d, and consumer ratings for overall impression were greater ( < 0.05) for GM steaks aged 28 d than for GM steaks aged 42 d; however, consumers failed ( = 0.035) to note differences in tenderness scores of GM steaks in response to aging period. Furthermore, consumers indicated a greater ( < 0.05) likelihood to purchase LT steaks aged 14 d over LT steaks aged 28 d, LL steaks aged 42 d over LL steaks aged 14 d, and GM steaks aged 14 and 28 d over GM steaks aged 42 d. These results indicate that consumers struggled to identify steak flavor attributes and suggest that the benefit of aging for premium beef products does not offer a tremendous sensory advantage to the consumer.