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

The effects of animal age, feeding regime and a dietary beta-agonist on tenderness of three beef muscles

BACKGROUND

Animal age as determined by number of permanent incisors (p. i.) is used in classification of beef carcasses to describe expected meat tenderness. However, animals differing in age are reared under different production systems (pasture or feedlot). In addition to age, other factors associated with particular production systems may also influence the palatability of meat. Therefore, the effects of age combined with feeding regime and the supplementation of a beta-agonist (zilpaterol) on the tenderness of M. longissimus lumborum (LL), M. semitendinosus (ST) and M. biceps femoris (BF) muscles were investigated.

RESULTS

Tenderness of LL cuts was least affected by age but zilpaterol significantly decreased tenderness and ageing potential. Tenderness of high-collagen cuts (BF and ST) was negatively affected by age due to reduced collagen solubility. The effect of zilpaterol on these cuts was less significant and BF and ST cuts of the grain-fed A-age animals (0 p. i.) supplemented with zilpaterol (AZ) were more tender than the same cuts of grass-fed animals with 1-2 p. i. (AB-age) and grass-fed animals with 3-6 p. i. (B-age) according to Warner-Bratzler shear force (WBSF) and sensory analysis for tenderness.

CONCLUSION

This study indicates that beta-agonists may influence variation in tenderness within an age class more than age or feeding regime. © 2016 Society of Chemical Industry.

Consumer sensory evaluation and chemical composition of beef gluteus medius and triceps brachii steaks from cattle finished on forage or concentrate diets

The objective of this study was to assess the impact of cattle finishing diet and muscle type on meat quality. Consumer sensory response, proximate composition, Warner-Bratzler shear force (WBSF), fatty acid composition, and volatile compounds were assessed from the gluteus medius (GM) and triceps brachii (TB) muscles of cattle ( = 6 per diet) which were grain-finished (USUGrain) on conventional feedlot or 2 forage diets, a perennial legume, birdsfoot trefoil-finished (USUBFT; ), and grass-finished (USUGrass; ). Diet had an interacting effect with muscle for all sensory attributes ( ≤ 0.002), except aroma and flavor ( ≥ 0.078). In forage-finished beef, tenderness, fattiness, overall liking, and WBSF tenderness of GM was greater ( < 0.05) than TB, whereas for USUGrain, the tenderness, fattiness, overall liking, and WBSF tenderness of both muscles were similar ( > 0.05) but the juiciness of TB was more liked than USUGrain GM ( < 0.05). The juiciness of forage-finished beef did not differ ( > 0.05) between GM and TB. Lower ( < 0.05) intramuscular fat (IMF) percent was determined for USUGrass beef in comparison with USUGrain beef. The IMF percent of USUBFT beef was similar ( > 0.05) to both USUGrass and USUGrain beef. However, IMF percent was not impacted by muscle type ( = 0.092). The ratio of -6:-3 fatty acids was affected by muscle dependent on diet ( = 0.016). The ratio of -6:-3 fatty acids was affected by the interaction of muscle × diet ( = 0.016). Between forage diets (USUGrass and USUBFT), -6:-3 ratios were similar ( > 0.05) between GM and TB, whereas within USUGrain, the GM was greater ( < 0.05) than the TB. Cumulative MUFA was greater ( < 0.05) in USUGrain compared with both USUGrass and USUBFT, which were similar ( > 0.05). Strecker aldehydes, ketones, pyrazines, and methional were affected ( ≤ 0.036) by muscle and found to have a greater concentration in GM compared with TB. Overall, consumers determined that USUGrain GM and TB had similar ( > 0.05) quality ratings. However, within forage-finished beef, the GM was perceived more frequently ( < 0.05) to be of premium quality and the forage-finished TB was more frequently ( < 0.05) rated as having unsatisfactory quality. These findings were in agreement with ratings of tenderness and overall liking. Therefore, in the context of our consumer group grilled GM and TB steaks, grain-finished beef provided more uniform quality and eating experience compared with forage-finished beef.

A comparison of intact and degraded desmin in cooked and uncooked pork longissimus thoracis and their relationship to pork quality

The objective was to compare desmin abundance (intact, degraded, and the ratio of intact desmin to degraded desmin) in samples from cooked and uncooked pork and establish its relationship to pork quality traits. Pork chops (2.54-cm thick) from twenty-four pork loins were randomly assigned to treatment (cooked or uncooked). Intact and degraded desmin in cooked and uncooked chops aged 1d were weakly correlated (r<|0.35|) with Warner-Bratzler shear force at 1 and 14d postmortem aging. Intact and degraded desmin in cooked and uncooked chops aged 14d were moderately correlated (|0.35|<r<|0.59|) with Warner-Bratzler shear force at 1 and 14d postmortem aging. Intact:degraded desmin in cooked and uncooked pork aged 1 and 14d was generally weakly correlated (r<|0.35|) with pork quality traits, with only a few exceptions. This research supports previous reports that the same sample can be used for tenderness of cooked pork and the determination of desmin abundance.

Effects of ultrasound, CaCl2 and STPP on the ultrastructure of the milk goat longissimus muscle fiber observed with atomic force microscopy

The aim of this study was to analyze the effects of ultrasound bath intensity, CaCl₂ and sodium tripolyphosphate (STPP) concentration on the ultrastructure of longissimus muscle fiber from milk goats. The sarcomere length was measured by atomic force microscopy. According to the results of AFM images, the sarcomere length is longest when the conditions were an intensity of 100 W ultrasound bath (42.77% increment), a concentration of 300 mM CaCl₂ injection (44.68% increment) or 90 mM STPP injection (19.41% increment). Apart from the sarcomere length, the study put forward a potential index (roughness) to represent tenderness of meat which was treated by ultrasound bath. Among different methods, ultrasound bath was chosen as the preferred tenderization method. SCANNING 38:545-553, 2016. © 2016 Wiley Periodicals, Inc.

The influence of peri-conception and first trimester dietary restriction of protein in cattle on meat quality traits of entire male progeny

Primiparous Santa Gertrudis heifers were used to evaluate the effects of gestational dietary protein content on meat quality traits of 20month old bull progeny (n=40). At -60d before AI, heifers were randomly allocated to HIGH or LOW protein diet (HPERI and LPERI). From 24dpc, half of each treatment group changed to an alternative post-conception HIGH or LOW protein diet (HPOST and LPOST). LPERI and LPOST diets resulted in higher shear force of the semitendinosus muscle than HPERI (P=0.053) and HPOST (P=0.003), respectively. Heat-soluble collagen in the semitendinosus muscle was lower (P=0.019) for LPERI than HPERI. Collagen and tenderness of the longissimus muscle were not affected by dam nutrition (P>0.05). Color, pH, sarcomere length, cooking loss, compression values, desmin and troponin-T degradation, fiber type, intramuscular fat and polyunsaturated fatty acid content were not affected by dam nutrition during the peri-conception and first trimester gestational period (P>0.05).

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.

The influence of diet on collagen content and quality attributes of infraspinatus muscle from Holstein-Friesian young bulls

The aim of the study was to determine effects of feeding intensity on collagen content and eating quality of infraspinatus (INF) muscle. Twenty Polish Holstein-Friesian bulls (11-month-old) were fed either intensively (I, n=10, with triticale meal addition to total mixed ration) or semi-intensively (SI, n=10, without triticale meal) before slaughter at 19months. The animals from I group showed higher body weight at the end of fattening, average daily gain and dressing percentage than SI group. The INF muscle from I treatment had higher fat content and the proportion of water-soluble collagen, whereas lower insoluble collagen content compared with SI treatment. There were no differences in shear force values, cooking loss and eating quality between the treatments. In conclusion, feeding Holstein-Friesian bulls with increased energy value fodder beneficially affected its slaughter value and collagen profile in infraspinatus muscle.

Effect of Aging Time on Physicochemical Meat Quality and Sensory Property of Hanwoo Bull Beef

This study was conducted to investigate the meat quality and sensory properties of 12 major cuts from 10 Hanwoo bulls (25-32 mon of age) after they were aged at 2℃ for 0, 7, 14, and 21 d. Protein content (%) was between 19.17 and 22.50%. Intramuscular fat content ranged from 2.79 to 8.39%. The collagen content of the chuck roll, chuck tender, and short plate muscles was higher (1.97-2.04%) than that of the striploin muscles (1.48%) (p<0.05). CIE lightness (L*) values increased with an increase in aging days for tenderloin, loin, chuck roll, oyster blade, short plate, top sirloin, and eye of round muscles (p<0.05). Most muscles, except the short plate, showed no significant changes in redness CIE (a*) and yellowness (b*) color values during aging. The tenderloin, loin, and striploin showed significantly higher water holding capacity (58.60-62.06%) than that of chuck roll and short plate (53.86-57.07%) muscles (p<0.05). The Warner-Bratzler shear force values of most muscles decreased significantly as the aging period increased (p<0.05), exception the tenderloin. The chuck tender muscles showed the highest cooking loss, whereas tenderloin muscle showed the lowest (p<0.05). The tenderloin muscle had the longest sarcomere length (SL) (3.67-3.86 μm) and the bottom round muscle had the shortest SL (2.21-2.35 μm) (p<0.05). In the sensory evaluation, tenderness and overall-likeness scores of most muscles increased with increase in aging days. The tenderloin and oyster blade showed relatively higher tenderness and overall-likeness values than did the other muscles during the aging period. No significant differences were noted in juiciness and flavor-likeness scores among muscles and aging days.

Do sarcomere length, collagen content, pH, intramuscular fat and desmin degradation explain variation in the tenderness of three ovine muscles?

The longissimus (n=118) (LL), semimembranosus (n=104) (SM) and biceps femoris (n=134) (BF) muscles were collected from lamb and sheep carcases and aged for 5days (LL and SM) and 14days (BF) to study the impact of muscle characteristics on tenderness as assessed by shear force (SF) and sensory evaluation. The impact of gender, animal age, collagen content, sarcomere length (SL), desmin degradation, ultimate pH and intramuscular fat (IMF) on tenderness was examined. The main factors which influenced SF of the LL were IMF, SL and desmin degradation, but for sensory tenderness, IMF, ultimate pH and gender were the main factors. The SF and sensory tenderness of the SM was best predicted by the degree of desmin degradation. For the BF soluble collagen and animal age both influenced SF. Different factors affect tenderness across muscles and not one prediction model applied across all muscles equally well.

Effect of group size and maize silage dietary levels on behaviour, health, carcass and meat quality of Mediterranean buffaloes

The effects of different dietary levels of maize silage (10% v. 36% DM) and group size (7 v. 14 animals) were assessed on growth performance and in vivo digestibility of 28 male fattening buffaloes. In addition, the effects of diet on meat quality and group size on behaviour and immune response were separately evaluated. Animals were weighed and assigned to three groups. The high silage - low size group (HL) was fed a total mixed ration (TMR) containing 36% DM of maize silage and consisted of seven animals (age 12.7±2.6 months; BW 382.2±67.7 kg at the start of the study). The low silage - low size group (LL) was fed a TMR containing 10% DM of maize silage and consisted of seven animals (age 13.0±2.7 months; BW 389.4±72.3 kg). The high silage - high size group (HH) was fed the 36% maize silage DM diet and consisted of 14 animals (age 13.9±3.25 months; BW 416.5±73.9 kg). Total space allowance (3.2 indoor+3.2 outdoor m2/animal) was kept constant in the three groups, as well as the ratio of animals to drinkers (seven animals per water bowl) and the manger space (70 cm per animal). Growth performance, carcass characteristics and digestibility were influenced neither by dietary treatment nor by group size, even if the group fed 36% maize silage diet showed a higher fibre digestibility. No effect of diet was found on meat quality. Group size did not affect the behavioural activities with the exception of drinking (1.04±0.35% v. 2.60±0.35%; P<0.01 for groups HL and HH, respectively) and vigilance (2.58±0.46% v. 1.20±0.46%; P<0.05 for groups HL and HH, respectively). Immune responses were not affected by group size.

Tenderness and sensory attributes of the longissimus lumborum muscles with different quality grades from Chinese fattened yellow crossbred steers

The objectives were to investigate intramuscular fat (IMF) content,Warner–Bratzler shear force(WBSF) and sensory attributes of Chinese fattened yellow crossbred steer beef with different quality grades, and to determine the relationship between WBSF and Chinese consumers' sensory tender. WBSF of grades A1 to A5 decreased from 50.6 N to 33.1 N with IMF % increased from4.26 to 24.55 (P b 0.05). Consumer panelists showed more likeability grades A4 and A5 with no difference between them. Grades A2 and A3 were slightly preferred (P b 0.05). Grade A1 was undesirable. A regression relationship between WBSF and sensory tender was found, which indicated that consumers disliked beef when WBSF N55.43 N and preferred those with WBSF b41.4 N. The range of 41.4 N to 55.43 N was intermediate. Hence, WBSF N55.43 & b41.4 N allow classification of tough and tender for beef tenderness for Chinese consumers, and grade A4 was recommended as suitable top grade.

Beef quality of different portions of the biceps femoris muscle in Bos indicus cattle improved by tumbling with brine

The effect of tumbling with brines on different portions of the biceps femoris muscle was evaluated for the quality of beef from cattle older than 30 mo. Six biceps femoris muscles were divided into portions: origin (OP), insertion 1(IP1), and insertion 2 (IP2). The portions were sliced into steaks and were treated with no tumbling (control), tumbling with brine (BR), and tumbling with brine and hydrolyzed soy protein (BR+HSP). The steaks were vacuum packaged and stored for 1 and 12 d and then analyzed for pH, yield, color, cooking loss, and shear force. The control steaks from the OP had higher (P < 0.05) pH and shear force values and lower (P < 0.05) L* values than the control steaks from IP2. The pH and a* and b* values increased (P < 0.05) and the L* values and cooking loss decreased (P < 0.05) when the steaks were tumbled with BR and BR+HSP. Overall, substantial variation was found for the variables among the different portions of the biceps femoris muscle. Based on the lower lightness (low exudation) and greater yellow and red intensity (less oxidation) of the meat, the tumbling with brines improved the meat quality. However, the hydrolyzed soy protein incorporated into the brine did not increase the effect compared with using the brine alone for most of the variables.

A structural approach to understanding the interactions between colour, water-holding capacity and tenderness

The colour, water-holding capacity (WHC) and tenderness of meat are primary determinants of visual and sensory appeal. Although there are many factors which influence these quality traits, the end-results of their influence is often through key changes to the structure of muscle proteins and their spatial arrangement. Water acts as a plasticiser of muscle proteins and water is lost from the myofibrillar lattice structure as a result of protein denaturation and consequent reductions in the muscle fibre volume with increasing cooking temperature. Changes in the myofilament lattice arrangement also impact the light scattering properties and the perceived paleness of the meat. Causes of variation in the quality traits of raw meat do not generally correspond to variations in cooked meat and the differences observed between the raw muscle and cooked or further processed meat are discussed. The review will also identify the gaps in our knowledge and where further investigation would beneficial.

A consumer sensory study of the influence of rigor temperature on eating quality and ageing potential of beef striploin and rump

Few consumer data are available on the effects of high rigor temperatures on eating quality of different muscles in the beef carcass. The aim of the present study was to investigate the effect of high rigor temperature (heat-toughening) on the consumer and quality traits of two beef muscles. A dataset containing consumer eating-quality scores for 3865 striploins (m. longissimus lumborum) and 734 rumps (gluteus medius) was analysed. Temperature at pH 6 (temp@pH6) was calculated for the striploin and carcasses with a temp@pH6 of >35°C were classified as high rigor temperature (heat-toughened) carcasses. For short ageing periods (1–7 days), high rigor temperature striploins were assessed, by a consumer panel, as being more tender with higher overall liking and higher (more liked) flavour and juiciness, than were striploins entering rigor at a lower temperature. Beyond 14 days of ageing, the high rigor temperature striploins showed minimal improvement in tenderness and the other eating-quality attributes also showed minimal improvements. The consumer scores for tenderness, juiciness, flavour and overall liking for the rump decreased with increasing rigor temperature. High rigor temperature striploins were scored, by trained graders, to have a higher proportion of coarser and softer texture and paler colour. Carcasses defined as ‘high rigor temperature’ will show minimal ageing after extended storage and, at grading, have a higher proportion with pale colour and softer, coarser texture compared to lower rigor temperature carcasses. In conclusion, methods to reduce high rigor temperatures in beef carcasses would improve the acceptability of beef.

Muscle metabolism in sheep and cattle in relation to high rigor temperature – overview and perspective

An increasing number of Australian slaughter plants were found not to meet the Meat Standards Australia (MSA) pH–temperature window, due to high rigor temperatures, particularly at plants where grain-fed animals were slaughtered. Hence, the red meat processing industry in Australia supported a research program focused on resolving this issue, as carcasses that do not meet the MSA pH–temperature window are excluded from MSA grading. This special issue of Animal Production Science describes the outcomes of a major program identifying ante- and post-mortem factors related to heat-induced toughening in both beef and sheep meat through literature reviews and targeted research to find interventions to prevent the impact of high rigor temperature on meat quality, particularly tenderness. This paper provides an overview of the outcomes of the research program, some of which require further research before implementation. It is suggested that an entire supply-chain approach be applied to establish the most efficient and cost-effective way of reducing the incidence of high rigor temperature.

Postmortem proteolysis in three muscles from growing and mature beef cattle

The objective of this study was to determine calpain system activity and postmortem protein degradation in three muscles from growing (n=6, 7.3 ± 0.5 months) and mature (n=6, 106.7 ± 43.1 months) beef cattle. The ratio of μ-calpain:total calpastatin activity tended to be lower in mature animals (P=0.08), suggesting reduced potential for proteolysis. Additionally, muscles from the mature group had greater calpastatin activity compared to calves at 6 days postmortem and had less μ-calpain autolysis and troponin-T and titin degradation during the aging period (P<0.01). Between the longissimus, semimembranosus, and triceps brachii muscles, the triceps brachii had the least postmortem proteolysis, with greater calpastatin activity and less troponin-T and titin degradation compared to other muscles (P<0.01). These data suggest that calpastatin activity in muscle from older animals is more persistent postmortem. This difference may contribute to the decreased protein degradation and increased toughness of beef from mature cattle, even after aging.

Modelling of beef sensory quality for a better prediction of palatability

Despite efforts by the industry to control the eating quality of beef, there remains a high level of variability in palatability, which is one reason for consumer dissatisfaction. In Europe, there is still no reliable on-line tool to predict beef quality and deliver consistent quality beef to consumers. Beef quality traits depend in part on the physical and chemical properties of the muscles. The determination of these properties (known as muscle profiling) will allow for more informed decisions to be made in the selection of individual muscles for the production of value-added products. Therefore, scientists and professional partners of the ProSafeBeef project have brought together all the data they have accumulated over 20 years. The resulting BIF-Beef (Integrated and Functional Biology of Beef) data warehouse contains available data of animal growth, carcass composition, muscle tissue characteristics and beef quality traits. This database is useful to determine the most important muscle characteristics associated with a high tenderness, a high flavour or generally a high quality. Another more consumer driven modelling tool was developed in Australia: the Meat Standards Australia (MSA) grading scheme that predicts beef quality for each individual muscle×specific cooking method combination using various information on the corresponding animals and post-slaughter processing factors. This system has also the potential to detect variability in quality within muscles. The MSA system proved to be effective in predicting beef palatability not only in Australia but also in many other countries. The results of the work conducted in Europe within the ProSafeBeef project indicate that it would be possible to manage a grading system in Europe similar to the MSA system. The combination of the different modelling approaches (namely muscle biochemistry and a MSA-like meat grading system adapted to the European market) is a promising area of research to improve the prediction of beef quality. In both approaches, the volume of data available not only provides statistically sound correlations between various factors and beef quality traits but also a better understanding of the variability of beef quality according to various criteria (breed, age, sex, pH, marbling etc.).

Study of the Warner-Bratzler shear force, sensory analysis and sarcomere length as indicators of the tenderness of sun-dried beef

Sun-dried beef is a frequently consumed and valued product in Brazil, however, there have been no scientific studies on its texture. To assess the tenderness of sun-dried beef, an instrumental analysis (Warner-Bratzler Shear Force; WBSF), a sensory analysis (Quantitative Descriptive Analysis; QDA) and the sarcomere length (SL) were used as indicators. Significant differences were observed among the sun-dried beef samples. Sample 3 (composed of sun-dried meat purchased at three fairs from Region 3 in the city of João Pessoa-PB) was considered the most tender by the assessors, with a score of 6.7, and its WBSF analysis revealed a maximum value of 2.70 kgf. Additionally, this sample exhibited the highest SL value (1.89 µm). Samples 1 and 2 (composed of sun-dried meat purchased at three fairs from Regions 1 and 2, respectively, in the city of João Pessoa) exhibited very similar tenderness values (WBSF and QDA) but differed in their SL values, which suggested that sample 2 was the least tender. In conclusion, these results demonstrate that the studied parameters are complementary and can be used as tenderness indicators for sun-dried beef. However, although the difference was beyond the detection limit of the assessors and the texturometer, the SL analysis appears to have been the most effective.

Relationships between sensory evaluations of beef tenderness, shear force measurements and consumer characteristics

The supply of tender beef is an important challenge for the beef industry. Knowledge about the profile of consumers who are more optimistic or more accurate in their tenderness evaluations is important for product development and beef marketing purposes. Central location tests of beef steaks were performed in Norway and Belgium (n=218). Instrumental and sensorial tenderness of three muscles from Belgian Blue and Norwegian Red cattle was reported. Consumers who are optimistically evaluating tenderness were found to be more often male, less food neophobic, more positive towards beef healthiness, and showed fewer concerns about beef safety. No clear profile emerged for consumers who assessed tenderness similar to shear force measurements, which suggests that tenderness is mainly evaluated subjectively. The results imply a window of opportunities in tenderness improvements, and allow targeting a market segment which is less critical towards beef tenderness.

Comparison of meat quality between eland (Taurotragus oryx) and cattle (Bos taurus) raised under similar conditions

Physical, chemical and sensory characteristics of meat were compared between non-domestic eland (Taurotragus oryx) bulls (n=6) and domestic Fleckvieh (Bos taurus) bulls (n=6) which were finished under controlled conditions of feeding and management. Musculus longissimus lumborum from eland were darker and less yellow in colour, with a higher pH24 and lower contents of intramuscular fat and total collagen, compared to cattle. Contents (mg/100 g muscle tissue) and proportions (g/100 g of FA determined) of SFA and MUFA were higher (P<0.01) in cattle. Although the proportion of total PUFA were higher (P<0.001) in eland, contents of PUFA were similar between species. Meat from cattle was consistently scored higher (P<0.05) for sensory texture characteristics, juiciness, flavour, and overall acceptance. We concluded that bulls of eland provided low-fat meat with a beneficial fatty acid composition from a human nutrition perspective, but with lower sensory scores, compared to bull beef.

Color stability and tenderness variations within the gluteus medius from beef top sirloin butts

Beef top sirloin butts (n=48) from USDA quality grade (QG; upper 2/3 US Choice vs. US Select) and yield grade categories (YG; 1 and 2 vs. 4 and 5) were aged 14 days, GM steaks were cut, with 2 steaks removed from the anterior (ANT), middle (MID) and posterior (POST) sections of the GM. One steak from each section was cut into lateral (LAT), central (CENT) and medial (MED) portions, packaged aerobically, and displayed for 7 days, whereas the second steaks were cooked to 71°C for WBSF. Top Choice-steaks were redder and more yellow (P<0.05) than Select steaks during display. Cooking losses were greatest (P<0.05) in the MED, and least (P<0.05) in the CENT, portions of GM steaks. Neither QG nor YG category affected WBSF, but differences within the GM were found for (P<0.05) WBSF. Results of this experiment indicate tenderness and color stability gradients exist within the GM.

Alternative pre-rigor foreshank positioning can improve beef shoulder muscle tenderness

Thirty beef carcasses were harvested and the foreshank of each side was independently positioned (cranial, natural, parallel, or caudal) 1h post-mortem to determine the effect of foreshank angle at rigor mortis on the sarcomere length and tenderness of six beef shoulder muscles. The infraspinatus (IS), pectoralis profundus (PP), serratus ventralis (SV), supraspinatus (SS), teres major (TM) and triceps brachii (TB) were excised 48 h post-mortem for Warner-Bratzler shear force (WBSF) and sarcomere length evaluations. All muscles except the SS had altered (P<0.05) sarcomere lengths between positions; the cranial position resulted in the longest sarcomeres for the SV and TB muscles whilst the natural position had longer sarcomeres for the PP and TM muscles. The SV from the cranial position had lower (P<0.05) shear than the caudal position and TB from the natural position had lower (P<0.05) shear than the parallel or caudal positions. Sarcomere length was moderately correlated (r=-0.63; P<0.01) to shear force.