National beef tenderness survey - 2006: Assessment of Warner-Bratzler shear and sensory panel ratings for beef from US retail and foodservice establishments.

Beef from retail and foodservice establishments in 11 US cities was evaluated using Warner-Bratzler shear (WBS) and consumer evaluation panels. Postmortem aging times ranged from 3 to 83d for retail and 7 to 136d for foodservice with mean aging times of 22.6d and 30.1d, respectively. For retail, the three cuts from the round - top round, bottom round, and eye of round - had the highest (P<0.05) WBS values compared to cuts from the chuck, rib, and loin. Top loin steaks had the lowest (P<0.05) WBS value compared to ribeye and top sirloin foodservice steaks. Retail bone-in top loin, top loin, ribeye, T-bone, and porterhouse received the highest (P<0.05) ratings by consumers for overall like and like tenderness. Quality grade had little or no effect on foodservice sensory evaluations. Improvements in round tenderness are needed to increase consumer acceptability.

Physical, chemical, and histological characteristics of 18 lamb muscles.

Muscles (n=18) were dissected from each side of 20 lamb carcasses to characterize physical, chemical, and histological traits. Muscles from the right sides were used to measure color values, expressible moisture, pH, total collagen content, and sarcomere length. Muscles from the left sides were aged for 7d and used to determine Warner-Bratzler shear (WBS) force values. The M. adductor and M. semimembranosus had the darkest colored lean (lowest L(∗) values), whereas the M. latissimus dorsi and M. tensor fasciae latae had the lightest colored lean (highest L(∗) values). The M. triceps brachii, M. pectoralis profundus, and M. latissimus dorsi had among the lowest numerical expressible moistures whereas the M. adductor and the M. longissimus lumborum had among the highest. The M. infraspinatus was found to have the highest collagen content (9.0mg/g) and the M. psoas major had the longest sarcomere length (3.1µm). Of the muscles sampled, the M. serratus ventralis had one the lowest WBS values (21.8N) and the M. semimembranosus the highest (42.6N). On average, the largest muscles identified were the M. gluteobiceps, M. gluteus medius, M. longissimus lumborum, M. longissimus thoracis, and M. semimembranosus, which would likely be suitable in terms of physical dimensions for used in a variety of individual muscle applications. Other muscles, however, such as the M. teres major and M. tensor fasciae latae, may be too small in size and dimension to be used for individual application.

Retail cutting characteristics for US Choice and US Select beef subprimals.

US Choice (Ch) and US Select (Se) beef subprimals from the rib, chuck, plate, loin, and round were obtained to conduct retail cutting tests. Subprimals were merchandised into bone-in or boneless retail cuts and associated components by experienced retail meat merchandisers. These Se subprimals had less (P<0.05) trimmable fat than their Ch counterparts: ball tip, top sirloin, outside round, inside round, and ribeye. Se inside rounds, outside rounds, eye of rounds, boneless striploins, and ball tips had greater (P<0.05) purge losses than the same cuts from Ch. The only subprimals where grade impacted total saleable yield were the top (inside) rounds (Ch=80.13%, Se=87.34%; P=0.004) and outside rounds cut into roasts, steaks, and cubed steaks (Ch=87.61%, Se=90.28%; P=0.05). Methods to increase retail yields from beef subprimals should consider minimizing purge and increasing cutting efficiencies in addition to reducing fat trim.

Beef hide antimicrobial interventions as a means of reducing bacterial contamination.

This project was designed to evaluate interventions capable of reducing bacterial counts on the hide prior to opening. In Trial I, fresh beef hides (n=12) were cut into sections and assigned to serve as either clipped (hair trimmed) or non-clipped sections. Sections were inoculated with a bovine fecal slurry and sampled following a water wash. Treatments (distilled water, isopropyl alcohol, 3% hydrogen peroxide, 2% l-lactic acid, 10% povidone-iodine, and 1% cetylpyridinium chloride (CPC)) were then applied to each section and the sections were sampled for enumeration of aerobic plate counts (APCs), coliforms, and Escherichia coli. Within clipped samples, 1% CPC and 3% hydrogen peroxide caused the greatest reductions in APCs (4.6 and 4.4 log(10)CFU/100-cm(2), respectively), and 1% CPC, 2% l-lactic acid, and 3% hydrogen peroxide caused the greatest reductions in coliform counts (4.5, 4.1, and 3.9 log(10)CFU/100-cm(2), respectively). In Trial II, beef carcasses with hides on were sampled initially and clipped, and then 2% l-lactic acid, 3% hydrogen peroxide, or 1% CPC were applied before sampling. For APCs, 1% CPC produced the greatest reduction on the hide surface (3.8 log(10)CFU/100-cm(2)). Selective application of these antimicrobials to clipped hide opening sites reduced bacterial counts on hide surfaces, and therefore could reduce final carcass counts in these areas by decreasing the bacterial load before opening.

Factors influencing the variation in tenderness of seven major beef muscles from three Angus and Brahman breed crosses.

Beef carcasses (n=30) from 3/4 Angus (A)×1/4 Brahman (B), 1/4A×3/4B, and 1/2A×1/2B F(1) crosses were used to evaluate breed type, electrical stimulation, and postmortem aging on the M. semimembranosus (SM), M. semitendinosus (ST), M. biceps femoris (BF), M. vastus lateralis (VL), M. gluteus medius (GM), M. longissimus dorsi lumborum (LD), and M. triceps brachii (TB). Shear force values decreased with increased postmortem aging to a greater extent in steaks from 3/4A×1/4B than steaks from the other breed types. Shear force values for steaks from the round (SM, ST, BF, VL) were higher than steaks from the loin (LD, GM) and chuck (TB) for both electrically stimulated and non-electrically stimulated muscles. In the LD muscle, calpastatin activities were similar among breed types. Muscle type played the greatest role in determining tenderness.

In-home consumer evaluations of individual muscles from beef rounds subjected to tenderization treatments.

In-home evaluations of the M. vastus lateralis, M. rectus femoris, M. semimembranosus, and M. adductor (n=266) muscles that were either blade tenderized, enhanced with a salt and phosphate solution, or served as a control (no tenderization or enhancement treatment) were conducted. Consumers (n=261) cooked these steaks and were asked to document cooking method and degree of doneness, and provide palatability ratings for each steak. Enhancing round muscles with a salt and phosphate solution improved most palatability traits compared to blade tenderized or control steaks. For M. semimembranosus and M. vastus lateralis, the enhanced steaks received higher (P<0.05) ratings for all palatability traits. Cooking method and degree of doneness had little influence on consumer palatability ratings, and where differences occurred, they were muscle specific. This may allow limited recommendations for the most appropriate cooking method and degree of doneness for specific beef round muscles.

Influence of animal temperament and stress responsiveness on the carcass quality and beef tenderness of feedlot cattle.

Three groups of steers (A, B, C) were used to study the effect of temperament (Calm, Intermediate, and Excitable) on meat quality. Temperament was based on exit velocity, pen scores, and chute scores. Temperament traits were consistent across evaluations, and values decreased (P<0.05) in magnitude over time. Increasing excitability was associated with higher (P<0.05) serum cortisol concentrations. Carcasses from cattle with calm temperaments had higher (P<0.05) 0.5h postmortem pH values than those from Intermediate and Excitable cattle (0.1 and 0.2 units, respectively). Group C Excitable steers had higher (P<0.05) WBS values than the calmer Group C steers. This trend was observed in Group A steers, although the values were not statistically different. Correlations were highest between temperament values and tenderness after 21d. Temperament influences tenderness, although the mechanism is not clear.

The chilling of carcasses.

Biochemical processes and structural changes that occur in muscle during the first 24h postmortem play a great role in the ultimate quality and palatability of meat and are influenced by the chilling processes that carcasses are subjected to after slaughter. For beef and lamb, employing chilling parameters that minimize cold shortening is of greatest importance and can be best addressed by ensuring that muscle temperatures are not below 10°C before pH reaches 6.2. For pork, because of the impact of high muscle temperatures and low pH on the development of pale, soft, and exudative (PSE) pork, a more rapid chilling process is needed to reduce PSE with the recommended internal muscle temperature of 10°C at 12h and 2-4°C at 24h. Spray chilling, a system whereby chilled water is applied to carcasses during the early part of postmortem cooling, is used to control carcass shrinkage and to improve chilling rates through evaporative cooling. Delayed chilling can be used to reduce or prevent the negative effects of cold shortening; however, production constraints in high-volume facilities and food safety concerns make this method less useful in commercial settings. Electrical stimulation and alternative carcass suspension programs offer processors the opportunity to negate most or all of the effects of cold shortening while still using traditional chilling systems. Rapid or blast chilling can be an effective method to reduce the incidence of PSE in pork but extreme chilling systems may cause quality problems because of the differential between the cold temperatures on the outside of the carcass compared to the warm muscle temperatures within the carcass (i.e., muscles that are darker in color externally and lighter in color internally).

Biochemical and physical factors affecting discoloration characteristics of 19 bovine muscles.

Steaks from muscles (n=19 from nine beef carcasses) were evaluated over the course of retail display (0-, 1-, 2-, 3-, 4- or 5-d) for objective measures of discoloration (metmyoglobin, oxymyoglobin, L*-, a*-, and b*-values), reducing ability (metmyoglobin reductase activity (MRA), resistance to induced metmyoglobin formation (RIMF), and nitric oxide metmyoglobin reducing ability (NORA)), oxygen consumption rate (OCR), oxygen penetration depth, myoglobin content, oxidative rancidity, and pH. Muscles were grouped according to objective color measures of discoloration. M. longissimus lumborum, M. longissimus thoracis, M. semitendinosus, and M. tensor fasciae latae were grouped as "high" color stability muscles, M. semimembranosus, M. rectus femoris, and M. vastus lateralis were grouped as "moderate" color stability muscles, M. trapezius, M. gluteus medius, and M. latissimus dorsi were grouped as "intermediate" color stability muscles, M. triceps brachi - long head, M. biceps femoris, M. pectoralis profundus, M. adductor, M. triceps brachi - lateral head, and M. serratus ventralis were grouped as "low" color stability muscles, and M. supraspinatus, M. infraspinatus, and M. psoas major were grouped as "very low" color stability muscles. Generally, muscles of high color stability had high RIMF, nitric oxide reducing ability, and oxygen penetration depth and possessed low OCRs, myoglobin content, and oxidative rancidity. In contrast, muscles of low color stability had high MRA, OCRs, myoglobin content, and oxidative rancidity and low RIMF, NORA, and oxygen penetration depth. Data indicate that discoloration differences between muscles are related to the amount of reducing activity relative to the OCR.