Effects of nutritional planes and brees on intramuscular-lipid deposition in M. longissimus dorsi of steers

The influences of nutritional planes and breeds on intramuscular-lipid (IML) deposition in M. longissimus dorsi were investigated by comparing the relationships between intramuscular lipid percentages (IMLP) in the muscle and side-carcass weight (SCW), carcass-fat percentage (CFP), and slaughter age (SA). Japanese Black (JB) and Japanese Shorthorn (JS) steers were fattened under two (medium-high and high) nutritional planes, which were different only in JB and when the adjusted IMLPs were compared on the basis of SCW or CFP. Breed effects on IML deposition were investigated by using three pure breeds and four crossbred-steer groups. The means of IMLPs in the muscle adjusted to three criteria were significantly different among breeds, the IMLPs of JB and their backcrosses being higher than those of JS and Charolais crosses. IML deposition in steers was highly dependent on the genetic potential of the breeds or bulls used.     

Comparison of M. longissimus dorsi pigment concentration from implanted and control Angus and Limousin bulls and steers

M. longissimus dorsi total pigment concentration, visual color score and 24-h pH values were evaluated in a 2(3) factorial design that included bulls versus steers, Zeranol implants versus control and Angus versus Limousin comparisons. Bulls had greater total pigment concentration than steers (3.25 versus 2·90 mg/g; P < 0·01) and darker colored lean (P < 0·01). Twenty-four hour pH values did not differ between bulls and steers. Zeranol implanting and breed had no effect on total pigment concentration or visual color score; however, Limousin had higher (P < 0·05) 24-h pH values than Angus. The initial slaughter group (N = 10; average age = 256 days) had 34% less total pigment than the final slaughter group (N = 48; average age = 458 days). The correlation between visual color score and total pigment concentration was -0·65. These results indicate that the darker colored lean from bulls is due in part to an increase in pigment concentration.     

Manipulation of the pre-rigor glycolytic behaviour of bovine M. longissimus dorsi in order to identify causes of inconsistencies in tenderness

The aim of this study was to monitor the effects of the alteration of the pre-rigor environment of the bovine LD muscle using controlled temperature regimes in order to gain an insight into the early post-mortem pH/temperature/time interactions which are important from the point of view of tenderness and to identify possible reasons for inconsistencies in beef tenderness. LD muscles (n=12) were hot-boned within 90min post-slaughter, cut into three pieces which were randomly placed in polyethylene bags and submerged in water baths pre-set at the following temperatures; 0, 5, 10, 15, 20 and 25°C for 8 h post-mortem then stored at 2°C for up to 14-days post-mortem. The rate of pH decline increased with increasing temperature. Muscles incubated at 0 and 5°C were cold shortened however not all of these muscles were tough as indicated by Warner Bratzler shear force values (WBSF). A pH range of 5.9-6.2 at 3 h post-mortem (pH(3)) produced consistently tender beef where cold-shortening was avoided. Cold shortened muscles showed the greatest variation in tenderness at 14 days post-mortem and underwent the greatest amount of tenderisation (ΔWBSF) and proteolysis between days 2 and 14 post-mortem. Proteolysis of cold shortened muscle may induce variation in tenderness in these muscles.     

Association of polymorphisms in the calpain I, calpain II and growth hormone genes with tenderness in bovine M. longissimus dorsi

The objective of this study was to determine if there is an association between tenderness in bovine M. longisimus dorsi (LD) and polymorphisms in the bovine calpain I (exons 9 & 14), calpain II (regulatory subunit) or growth hormone (intron 3) genes. Genomic DNA was isolated from bovine LD (n = 281) on which quality attributes (Warner Bratzler shear force (WBSF), sarcomere length and composition) were also characterised. DNA polymorphisms were analysed using polymerase chain reaction (PCR) and restriction fragment length polymorphism analysis. Association analyses were performed between genotypes at the four polymorphic loci and day 14 WBSF values. It was found that the calpain 1 exon 9 genotypes had an association with WBSF such that animals with the GA genotype exhibited decreased WBSF and increased tenderness when compared to animals with the GG genotype (P < 0.05). This observation concurs with that of earlier studies, suggesting that this polymorphism is a functional marker for beef tenderness.     

Manipulation of the pre-rigor phase to investigate the significance of proteolysis and sarcomere length in determining the tenderness of bovine M. longissimus dorsi

The objective of this study was to evaluate the importance of proteolysis and sarcomere length in determining the tenderness of bovine M. longissimus dorsi (LD) muscle over a 21-day period. This was done by altering the pre-rigor glycolytic behaviour of hot-boned LD muscles using different early post-mortem temperature regimes. Hot-boned LD muscles (n=8) were cut in two, randomised, placed in polythene bags and submerged in a water bath set at 5°C (rapidly chilled) and 15°C (slowly chilled) for 8h post-mortem. All muscles were then stored at 2°C for up to 21 days post-mortem. The temperature regimes altered the glycolytic behaviour of the muscles in the pre-rigor period. The slowly chilled muscles exhibited a faster (P<0.01) pH fall than rapidly chilled muscles. Cold shortening was induced in rapidly chilled muscles as they had shorter (P<0.01) sarcomere lengths than slowly chilled muscles up to day 21 post-mortem. Warner Bratzler shear force values (WBSF) deemed cold-shortened muscles as tougher than noncold shortened up to day 14 post-mortem. Both cold-shortened and noncold-shortened muscles tenderised over time to an extent where there was no significant difference in WBSF values by day 21 post-mortem. SDS-PAGE protein profiles indicated that the rate of proteolysis was faster in slowly chilled muscles when compared to rapidly chilled muscles. However by day 21 post-mortem it appeared that rapidly and slowly chilled muscles underwent proteolysis to the same extent.     

Muscle fibre orientation and its effect on measurements of tenderness of bovine longissimus dorsi muscle

The muscle fibre orientation within a particular cooked beef steak was found to vary considerably and to be markedly affected by vacuum packaging, freezing and/or cooking. Shear force values, initial-bite tenderness (panel) and cooking loss were highly dependent on, and overall tenderness (panel) was only slightly dependent on muscle fibre orientations. These measures were affected by fibre orientation to a greater extent in tough than in tender meat. At each of three fixed muscle fibre orientation, correlations between tenderness measures were significant (P<0.05), their magnitude depending on the fibre orientation. At a fixed fibre angle correlations of tenderness measures with cooking losses were not significant. However, on a withinanimal basis, cooking loss was related to shear value and to initial-bite tenderness apparently through an effect of fibre orientation. This effect may constitute a major source of variation in the measurement of tenderness and cooking loss.     

Quantifying the extent of variation in the eating quality traits of the M. longissimus dorsi and M. semimembranosus of conventionally processed Irish beef

The aim of this investigation was to quantify the scale of variation in the eating quality of two commercial beef muscles, M. longissimus dorsi (LD) and M. semimembranosus (Sm). Both the LD and Sm were excised from steers (n=81) and heifers (n=81) (classification grade O4H, O4L, R4H, R4L) within 48 h postmortem, vacuum packaged and stored at 4?°C until tested for eating quality at 14 days postmortem. Quality measurements analysed were: pH, Warner Bratzler shear force, sensory attributes, sarcomere length, Hunter L a b muscle and subcutaneous fat colour and chemical composition. Extent of variation in many eating quality measurements, with the exception of most sensory attributes and subcutaneous fat colour, depended on gender, classification grade or a combination of both. The LD was more variable than the Sm for most quality attributes and heifers were more variable than steers. No one carcass grade was more variable over all attributes analysed; with different grades causing higher or lower variances within certain attributes. Knowledge of the current scale of variation in the eating quality of beef is required by the meat industry, and is one that requires further research.     

Colour, composition and quality of M. longissimus dorsi and M. extensor carpi radialis of steers housed on straw or concrete slats or accommodated outdoors on wood-chips

Forty-five Charolais crossbred steers were offered a common diet and accommodated either outside on wood-chips (OWP, 18m(2)/head) or in a naturally-ventilated building in slatted-floor pens (SLA, 2.5m(2)/500kg bodyweight) or in straw-bedded pens (STR, 4m(2)/head) for 132 days. Carcass weight averaged 351, 362, and 372 (sed 6.63)kg (P<0.05), for SLA, STR and OWP, respectively. Accommodation system did not affect the colour, drip loss, shear force or composition of Musculus longissimus dorsi (LD) or Musculus extensor carpi radialis (ECR) muscles or the sensory characteristics of LD. The ultimate pH of ECR was highest (P<0.05) for OWP steers, while their LD was darker at 2 days post-mortem than LD from STR steers. It is concluded that accommodating cattle on OWP had a minor transient effect on beef colour and no impact on beef composition or eating quality.     

The effect of time and type of electrical stimulation on the calpain system and meat tenderness in beef longissimus dorsi muscle

Effects of type and time of electrical stimulation on the calpain system, sensory and objective meat quality in the M. longissimus thoracis et lumborum from 38 pasture-fed carcasses, were investigated under conventional chilling conditions. High voltage stimulation was applied to whole carcasses at 3 min post-mortem (pm) and to sides at either 40 or 60 min pm, whilst low voltage stimulation was applied to whole carcasses at 3 min pm and to sides at 40 min pm. Unstimulated sides served as controls. The levels of extractable μ-calpain and calpastatin decreased during stimulation by 28-44% and 8-17%, respectively. Shear force and adjusted tenderness score showed that stimulation at 3 min, irrespective of type of stimulation, resulted in significantly tougher meat (P<0.05) which was associated with an rapid rate of pH decline, compared to stimulation at 40 min. Higher calpastatin levels soon after stimulation at 3 min (P < 0.05) and lower μ-calpain level at 24 h pm for high voltage stimulation at 3 min (P<0.05) coincided with the tougher meat. On the other hand, high voltage stimulation at 40 and 60 min resulted in similar tenderness and levels of μ-calpain and calpastatin post-stimulation and 24 h pm. Significantly tougher meat from the control sides, with a higher μ-calpain levels at 24 h pm and similar sarcomere length, compared to those from low voltage stimulation at 40 min (P<0.001), appeared to be linked to the later activation of the calpain system. Results from the current study suggest that early application of stimulation may be associated with a very rapid decline in pH and consequently a reduction in meat quality.     

Understanding the influence of PEF treatment on minerals and lipid oxidation of wet- and dry-aged venison M. longissimus dorsi muscle

Pulse electric fields (PEF) treatment can be used to improve meat quality attributes, such as tenderness and mass transfer kinetics of dry ageing of meat. This study investigated the effect of PEF (high-PEF 10 kV, 50 Hz, 20 μs; low-PEF 2.5 kV, 50 Hz, 20 μs) and ageing method (wet- and dry-ageing) on venison mineral profiles, and lipid and conjugated linoleic acid (CLA) oxidative stability. Twelve loins from six red deer were assigned to six groups: no-PEF dry-aged control, no-PEF control, wet-aged Low-PEF, dry-aged Low-PEF, dry-aged High-PEF, wet-aged High-PEF. Secondary oxidation products contents were not affected by PEF treatment (p > 0.05), but were affected by dry ageing (p < 0.05). CLA was stable across PEF treatments and different ageing regimes (p > 0.05). PEF treatments did not have any effect on minerals (p > 0.05). This study validates the safety of using PEF in venison processing with limited detrimental oxidative modifications.Industrial relevance - PEF treatment and the dry-ageing regimes applied to venison in the present study did not produce excessive oxidative by-products that could compromise product quality. The application of both PEF treatments (HPEF 10 kV, 50 Hz, 5 μs; LPEF 2.5 kV, 50 Hz, 5 μs) could potentially improve the drying of venison with a low risk of increasing oxidation.     

Effect of electrical stimulation,delayed chilling and post‐mortem aging on the quality of M. longissimus dorsi and M. biceps femoris of grass‐fed steers

BACKGROUND: Roughage‐based low‐input beef production systems are gaining increasing interest owing to the perceived ecological advantages and potential health benefits associated with the favourable fatty acid composition of such beef. The low plane of nutrition may on the other hand yield less tender beef by affecting growth, carcass weight and fatness and therefore, indirectly, early post‐mortem (p.m.) proteolytic enzyme activity and sarcomere shortening. This study aimed to examine delayed chilling and electrical stimulation as promising techniques to control early p.m. muscle metabolism in a way that improves the tenderness of beef from purely grass‐fed steers in comparison with that from steers receiving a finishing diet with concentrates. RESULTS: Electrical stimulation decreased the pH at 1.5 and 3 h p.m. in the M. longissimus dorsi (LD) and M. biceps femoris (BF) of the treated carcass sides as well as the maximum shear force in the LD, while delayed chilling had no effect on pH or texture. The interactions of carcass fatness with electrical stimulation (P = 0.025) and delayed chilling (P = 0.089) indicated more pronounced effects of the p.m. treatments on beef texture in leaner carcasses. CONCLUSION : Electrical stimulation, but not delayed chilling, could markedly improve pasture beef texture and reduce the aging period needed for proper tenderisation. Copyright © 2008 Society of Chemical Industry     

Relationships between sensory and objective measures of meat tenderness of beef m. longissimus thoracis from bulls and steers

This study assessed whether relationships between sensory and objective measures of beef tenderness were different for beef from bulls and steers. Trained panelists and instruments were used to measure tenderness of m. longissimus thoracis from bulls (n=58) and steers (n=59). Four measures of sensory tenderness (hardness, cohesiveness, toughness and chewiness) were closely correlated with each other, and moderately correlated with mechanical measures using a Warner-Bratzler device, a MIRINZ tenderometer and a compression cell in an Instron device. With increasing values of objective measures, sensory scores increased at a decreasing rate. Use of a general-least-squares model with sensory measures as the dependent variable and objective measures as covariates (linear and quadratic), showed that, after adjustment to a constant objective measure, significant differences between bulls and steers in sensory measures of toughness remained (P<0.001). Adjusted sensory measures also decreased with increasing ultimate pH in some instances. The bull/steer effects on adjusted sensory measures were smaller when regressions were fitted within the two groups. It is concluded that when using a common prediction equation to estimate sensory scores from objective measures, it can be expected that groups or individual samples with higher scores will tend to be under-estimated, and those with lower scores, over-estimated.     

Differential expression of genes associated with lipid metabolism in longissimus dorsi of Korean bulls and steers

The objective of this study was to compare expression of genes associated with lipid deposition and removal between bulls and steers in the longissimus dorsi muscle (LM) tissue of Korean cattle. Castration increased the expression of lipid uptake lipoprotein lipase, fatty acid translocase, and fatty acid transport protein 1 in LM. Castration increased lipogenic gene expression of both acetyl-CoA carboxylase and fatty acid synthase. In contrast, castration downregulated lipolytic gene expression of both adipose triglyceride lipase (ATGL) and monoglyceride lipase. Steers showed higher expression levels of insulin signaling phospho-v-akt murine thymoma viral oncogene homolog 1 than bulls but lower protein levels of nuclear Forkhead box O 1 (FoxO1) than bulls, suggesting that increased insulin signaling following castration decreases nuclear FoxO1 levels, leading to downregulation of ATGL gene expression. These findings suggest that castration contributes to increases in lipid uptake and lipogenesis and a decrease in lipolysis, resulting in improved marbling.     

Colour stability, under simulated retail display conditions, of M. longissimus dorsi and M. semimembranosus from steers given long-term daily exercise and supplemented with vitamin E

The objective was to determine if exercise has a negative impact on the colour stability of beef and if dietary vitamin E (VE) supplementation could counteract any negative effect. Steers were not exercised or were walked 4.41km/day for 18 weeks. Within exercise treatment animals consumed, on average, either 450 or 1050IU/day of VE. Muscle α-tocopherol increased (P=0.004) from 2.35 to 3.15μg/g with VE supplementation. Following ageing M. longissimus dorsi (LD) and M. semimembranosus (SM) steaks were packaged under 80%O(2):20%CO(2) and stored at 4°C. The LD of exercised steers was more red and more saturated (both P<0.05) after 0 and 2 days of storage than LD of unexercised steers. While redness of both muscles decreased over the display period, LD retained a higher redness than SM from day 2 to 7 (P<0.05). Colour shelf-life of LD was extended by 0.75 days, to 3.25 days, due to VE supplementation.     

The interaction between pH and temperature decline early postmortem on the calpain system and objective tenderness in electrically stimulated beef longissimus dorsi muscle

The study investigated the effects of pH and temperature decline early postmortem (pm) on calpains and calpastatin activities and objective tenderness in M. longissimus thoracis et lumborum. A total of 40 sides were used to generate a range of pH and temperature declines, by different stimulation treatments (i.e. low voltage stimulation applied for either 10 or 40 s 3 min pm), and chilling treatments (fast or slow). Both rapid glycolysis, or a slow chilling regime significantly reduced μ-calpain level at 4 h pm (P< 0.001 and P< 0.05, respectively). There were significant interactions between pH and temperature at 1.5 h pm on μ-calpain and calpastatin activities at 24 h pm (P< 0.05). Rapid glycolysis resulted in lower shear force and compression measurements at day 1, although because of low ageing rates, an intermediate pH decline (i.e. pH 5.9-6.2 at 1.5 h pm) resulted in the most tender meat after 14 days ageing. Higher shear forces in the slow glycolysing sides appeared to be associated with the later activation of tenderising process, as well as physical shortening. The optimum pH decline early pm varied with days ageing, with an intermediate pH decline resulting in the lower shear forces for meat aged for 14 days.     

Physico-chemical and processing quality of porcine M. longissimus dorsi frozen at different temperatures

Longissimus dorsi muscle from six pigs (24 h post-mortem) was cut into portions of similar size and shape (c. 700 g) and vacuum-packed in polyfilm. The muscle specimens were divided into three samples, one frozen at -20°C, another at -80°C and the third served as the control (not frozen). The meat sample frozen at -80°C was transferred to the -20°C freezer. After one month, both frozen pork samples were thawed at -2°C and drip loss (%) was measured. Hunter colour, metmyoglobin (MetMb) formation (%), water-holding capacity (WHC), TBA value, transmission value (TM) and myofibril fragmentation were also determined. There was no significant difference in drip loss for the two frozen samples. No MetMb formation could be detected and Hunter values were basically the same for all three samples. WHC, TBA value and TM were essentially the same for all three samples. TBA value was quite low for each frozen sample, indicating that lipid oxidation did not occur during freezing. Histological examination of both frozen samples indicated inter- and intracellular ice crystal formation at -20°C, and intracellular ice at -80°C, the extent being less than at -20°C. At -20°C, ice crystals were larger and muscle fibre diameter smaller than for the control or -80°C sample. Myofibril fragmentation in both frozen samples was significantly higher than in the control. Pork sausage was prepared from all three samples by adding 2% NaCl and 100 ppm NaNO(2). Cooking loss and colour forming ratios were essentially the same. The sausage sample made from the -20°C frozen meat was harder than that of the other two samples according to rheological measurement.     

The estimation of beef carcass muscle using cross-sectional area of M. longissimus dorsi at the fifth rib

The improvements in the accuracy of prediction of side muscle (weight and proportion) using measurements of eye muscle area at the 10th rib (EMA(10)) and eye muscle area at the 5th rib (EMA(5)), were compared in 48 steers, grain-fed for the Japanese market. For side muscle proportion the addition of EMA(10) to hot side weight and a fat thickness measurement did not improve prediction but the addition of EMA(5) did. P8 fat thickness together with hot side weight and EMA(5) (each, P<0·001) predicted side muscle proportion with an SEE of 2·05% and an R(2) of 61%, while the values for 10th rib thickness together with hot side weight and EMA(5) (each, P<0·001) were 2·09% and 68%, respectively. For the prediction of side muscle weight a fat thickness measurement and hot side weight (both, P<0·001) explained 77-84% of variance; the addition of an eye muscle area measurement further improved prediction with the most accurate being P8 fat thickness together with hot side weight and EMA(5).     

Ultrastructural Variation in Beef M. longissimus dorsi as an Explanation of the Variation in Beef Tenderness

ABSTRACT: The objective of this experiment was to quantify variation in bovine M. longissimus dorsi tenderness and determine the extent such variation is explained by variation in the ultrastructure of muscles after different postmortem treatments. Eight muscles were hot-boned and aged for 2 d at 2 °C (T1) to achieve very contracted actomyosin crossover and tough beef. Eight carcass sides were tenderstretched for 10 h at 10 °C and a further 38 h at 2 °C (T2) to achieve lengthened actomyosin crossover and tender beef. Both T1 and T2 were compared with conventionally hung carcasses, which underwent similar chilling regimes, C1 ( n = 8) and C2 ( n = 8), respectively. Measurements of sarcomere length, pH, Warner Bratzler shear force (WBSF), and sensory tenderness were taken, and transmission electron microscopy images analyzed. Variances of attributes were analyzed on Bartlett's test. Variances of the 4 groups were homogenous for all attributes except for pH after 24 h postmortem (with T1 [0.00] having lower variances than C1 = 0.04, T2 = 0.06, and C2 = 0.05) and WBSF after 2 d aging (with T2 [74.33] having lower variances than T1 = 236.76, C1 = 398.82, and C2 = 856.74). The variation in the tenderness of beef was quantified through ultrastructural variation in bovine muscle, with tenderstretched moderately chilled beef having the least variable tenderness as a result of more uniform overlap between actin and myosin filaments. Variation in the eating quality of beef was not reduced by hot-boning with fast chilling or conventional hanging with fast or moderate chilling. The development of the uniformity within filaments of tenderstretched muscle requires further analysis as residual variation remains.