Sorting for beef tenderness using high performance liquid chromatography and capillary electrophoresis: A research note

This study utilized two sampling methods to examine changes in sarcoplasmic proteins during aging of beef and their relation to tenderness. Water-soluble proteins either obtained by manually expressing exudates from the meat (drip) or by an extraction procedure using homogenization and centrifugation (ext) were analyzed for longissimus lumborum muscle using HPLC and capillary electrophoresis (CE) on days 2, 7, 10 and 14 postmortem. A peak that consistently increased with aging was identified using HPLC. Among nine peaks detected in the CE analysis, peak 9 (100kDa) that increased and peak 4 (30kDa) that decreased with aging were correlated (P<0.05) to tenderness as determined by Warner-Bratzler shear force (WBSF). For pooled data of all aging periods, drip sample explained the most variability (49%) in shear force compared to ext sample (25%) using HPLC analyses. At 2 days postmortem, a multiple linear regression model explained 83% of the variation in WBSF using CE-ext or HPLC-drip samples. Sixty percent of the variability in shear force was explained by CE-ext samples for day 7 data. The variability in shear force as explained by either drip or ext sample was less than 51 percent for 10 and 14 days postmortem data. The drip samples were comparable to ext samples in predicting WBSF values for both tough (>46N WBSF on day 2) and tender (<46N WBSF on day 2) strip loins using CE and HPLC procedure. Results suggest that a simple drip sampling may have a potential for use with either HPLC or CE analyses on day 2 postmortem for sorting carcasses into tenderness groups.     

A potential index for assessing the tenderness of hydrodynamic pressure (HDP)-treated beef strip loins

The objective of this research was to obtain physicochemical data that might prove useful in understanding the effect of hydrodynamic pressure (HDP), shock-wave treatment on the structural and functional properties of the HDP-treated beef strip loins. A homogenization protocol that was sufficiently harsh to break-up the tissue yet sufficiently gentle to maintain the integrity of the remaining subcellular structures was therefore developed for HDP-treated beef strip loins. Physicochemical changes resulting from HDP-treatment revealed a relationship between shear resistance value (tenderness level) and protein distribution. The 10,800×g pellet of homogenized HDP-treated strip loins showed a decrease in the protein content associated with a decrease in shear resistance values (increased tenderness). Conversely, the soluble-fraction (post 48,200×g) showed an increase in protein content as the shear resistance value decreased (tenderness increased) from ～11 to 6 kg. The data presented herein indicate that there is a relationship between the tenderness of hydrodynamic pressure (HDP) treated meat and the protein distribution in the HDP-treated samples.     

Measurement of Muscle Exudate Protein Composition as an Indicator of Beef Tenderness

The objective of this study was to determine the relationship between the protein composition of muscle exudates and meat tenderness in beef. Frozen, intact beef strip loins (n = 24) were each divided into 3 equal portions (anterior, middle, and posterior). Steaks were removed from each portion, individually vacuum packaged, thawed at 4 °C, and aged for 0, 7, or 14 d. After the designated aging period, exudate was collected from the packaging and 1 steak from each strip loin portion was utilized for shear force measurements. Muscle exudates were analyzed for protein content (biuret assay) and composition (sodium dodecyl sulfate–polyacrylamide gel electrophoresis). Shear force decreased (P < 0.0001) with aging from 0 to 14 d. The protein concentrations of the muscle exudates were not influenced by the aging period and were not related to the amount of exudate expressed. Electrophoretic analyses of the muscle exudates indicated that with aging the relative abundance of 4 proteins decreased (P < 0.01) and 10 proteins increased (P < 0.05) within the protein profiles of the exudates. The relative abundance of the 167, 97, and 47 kDa proteins in exudates at day 0 were significantly correlated (|r| = 0.57 to 0.77) to shear force at day 14. These data demonstrate that exudate protein composition changes with postmortem aging and beef tenderness.     

Using reflectance spectroscopy to predict beef tenderness

A study was conducted to determine if reflectance measurements made in the near-infrared region of the spectrum were additive to reflectance measurements made in the visible region of the spectrum for predicting Warner–Bratzler shear force (WBSF) values. Eighty seven strip loins were collected following fabrication over 3 d at a commercial beef processing facility from heifer carcasses with Slight or Traces marbling scores. Spectroscopic measurements were made at approximately 50 h postmortem using a Hunter-Lab UltraScan. Subsequently, all strip loins were aged for 14 d, cooked to an internal temperature of 70 °C, and sheared to obtain WBSF values. Reflectance measurements obtained in the near-infrared region of the spectrum were correlated with WBSF values, however, these measurements were not additive to the predictive ability of reflectance measurements (R² values did not differ) made in the visible portion of the spectrum when the use of broad-band wavelength filters were simulated. It was therefore determined, that both the visible and near-infrared spectra measure reflectance and that both methods are acceptable methods of tenderness prediction.     

Aging and Enhancement Effects on Quality Characteristics of Beef Strip Steaks

ABSTRACT: Strip loins were removed 48 h postmortem from beef sides ( n = 20 pairs) to assess the effects of enhancement before or after aging on quality attributes of beef strip steaks. Strip loins were enhanced to 108% of original weight to contain 0.4% alkaline phosphate, 0.3% salt, 0.1% natural flavoring (on a final weight basis), and added water for comparison with non-enhanced samples. Regardless of when enhancement occurred relative to aging, enhanced samples were more tender, juicy, and salty than their non-enhanced counterparts. Enhanced samples were lighter, less red and less yellow, and had lower L *, a *, and b * values than non-enhanced samples; however, they generally had lower hue angles indicating that their color was closer to the true red axis of the color scale. Samples enhanced before aging achieved maximum tenderness after 14 d, whereas those enhanced after aging experienced no tenderness changes. Warner- Bratzler shear values were lower and pH values were higher in enhanced steaks than in controls.     

Microstructure alterations in beef intramuscular connective tissue caused by hydrodynamic pressure processing

Scanning electron microscopy (SEM) was utilized to evaluate microstructural changes in intramuscular connective tissue of beef semimembranosus muscle subjected to hydrodynamic pressure processing (HDP). Samples were HDP treated in a plastic container (HDP-PC) or a steel commercial unit (HDP-CU). Control and HDP samples were obtained immediately post-treatment and after 14 days of aging for SEM and Warner–Bratzler shear force (WBSF) analysis. Immediately post-treatment, HDP treated samples exhibited lower (P < 0.01) WBSF than did controls. After aging, HDP-PC samples had lower (P < 0.01) WBSF than that of aged controls. SEM analysis indicated that HDP-PC treatment disrupted the integrity of the collagen fibril network of the endomysium in both the non-aged and aged samples. Aging effects on the intramuscular connective tissue were observed in the HDP-PC and control samples. Both WBSF and connective tissue changes were greater in the HDP-PC than in the HDP-CU treated samples. Data suggest that shockwave alterations to connective tissue contribute to the meat tenderization of HDP.     

基于支持向量机的牛肉嫩度等级评价模型研究

目的 利用VIS/NIR反射光谱建立基于支持向量机的生鲜牛肉嫩度等级的评价模型。方法 以牛肉背最长肌为研究对象, 选取样本58个, 在牛肉新鲜切口处采集波长范围400~1700 nm的反射光谱信息, 使用肉类嫩度测量仪测量牛肉剪切力值, 应用支持向量机(SVM)模型评价牛肉嫩度等级。结果 应用SVM模型可以较好地实现对牛肉嫩度等级的评价。尤其是经主成分分析降维预处理, 结合径向基核函数SVM, 对牛肉训练集嫩度等级的回判率达到95%, 对样品校正集判别的准确率进一步提高至83.3%。结论 SVM模型对牛肉嫩度等级评价结果较好, 进行主成分分析后, 判别结果有所提高。     

Effect of Hydrodynamic Pressure Processing on the Processing and Quality Characteristics of Moisture-Enhanced Pork Loins

ABSTRACT: The objective of this study was to determine the influence of hydrodynamic pressure processing (HDP) and aging on the processing characteristics and final meat quality of moisture-enhanced pork loins. Boneless pork loins (n = 24) were split into 3 portions and assigned treatments: control (non-HDP treated, brine-injected), HDP treated before brine-injection, or HDP treated after brine-injection. Pork loins were injected with a salt/phosphate/water solution to 110% of original weight on day 0, intermittently tumbled 3 h, and then held overnight. Meat quality and protein characteristics were measured on days 1 and 8. HDP-treated loins had greater (P < 0.05) brine retention after overnight equilibration and a higher (P < 0.05) processing yield than controls. Warner–Bratzler shear force and expressible moisture decreased (P < 0.0001) with aging from days 1 to 8, but were not significantly affected by either HDP treatment. When the drip loss data from HDP treatments were pooled, HDP samples had lower drip loss values than controls. L* and b* measurements exhibited significant HDP by aging interaction effects, but a* was not influenced by either HDP or aging. Myofibrillar protein solubility and gel electrophoresis measurements of protein degradation were influenced by aging treatments. Data from this study suggest that HDP may have beneficial effects on the processing and final product quality of moisture-enhanced pork loins. Practical Application: This study demonstrates that hydrodynamic pressure processing (HDP) is an effective postharvest technology for improving the processing and meat quality characteristics of moisture-enhanced pork loin products, benefiting both meat processors and consumers.     

不同品种牛和部位肌肉在成熟过程中品质差异比较研究

为探究肌肉部位和成熟时间对鲁西黄杂交牛和安秦杂交牛牛肉食用品质的影响,分别选取2种牛宰后的背最长肌、腰大肌和半膜肌3个部位肉,在成熟5、7、14、21?d时测定其嫩度、肌节长度、肉色和蛋白降解程度等指标.结果表明:随着成熟时间的延长,2种牛腰大肌剪切力值较低,肌节长度较长,肉色更好,而背最长肌和半膜肌剪切力更高,肌节长...     

Predictors of Beef Tenderness: Development and Verification

Equations were developed to predict beef longissimus dorsi (LD) tenderness after postmortem refrigerated aging. Warner-Bratzler shear force (WBSF) and myofibril fragmentation indices (MFI) were determined at 1, 3, 7 and 14 days postmortem on LD of Angus-Hereford (AH, n = 8) and 5/8 Brahman crossbred (n = 8) heifer carcasses. Correlation coefficients between WBSF and MFI were ?0.91, ?0.74, ?0.63, and ?0.40 at 1, 3, 7 and 14 days postmortem, respectively. None of the traits measured correlated significantly with 14-day WBSF (P > 0.05). A three-variable prediction equation that included 24-hr calcium-dependent protease (CDP) inhibitor activity, 0-hr CDP-I activity and 24-hr cystatin activity accounted for 63% of the variation in 14-day WBSF.     

Fresh beef tumbling at different post-mortem times to improve tenderness and proteolytic features of M. longissimus lumborum

The aim of this study was to determine the effects of tumbling at different post-mortem times on the proteolytic features and quality attributes of beef loins (M. longissimus lumborum). Loins (n = 12) were cut into 4 sections and assigned to tumbling at 1, 6 or 11 days post-mortem or non-tumbled control. Upon tumbling, additional ageing was applied to a common post-mortem time of 16 days. In general, tumbling had no considerable impacts on water-holding ability of samples. Tumbling resulted in an immediate decrease in shear force values (WBSF) of beef samples. Tumbling at 1 day post-mortem with no ageing had similar WBSF compared to the non-tumbled controls at 16 days (P > 0.05). With ageing, tumbling increased amounts of protein degradation, myofibrillar fragmentation and calpain-1 autolysis of samples. These results suggest that early post-mortem tumbling coupled with ageing can synergistically impact the tenderness development of beef loins and shorten the necessary ageing period.     

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.     

Myosin light chain 1 release from myofibrillar fraction during postmortem aging is a potential indicator of proteolysis and tenderness of beef

The objective of this study was to identify proteins in bovine longissimus dorsi muscle that are related to tenderness. Two dimensional difference in gel electrophoresis (2D-DIGE) was used to compare the sarcoplasmic fractions from steaks that differed in star probe values at 14 days postmortem. The intensity of myosin light chain 1 (MLC1) was greater in the sarcoplasmic fraction prepared from steaks that had lower star probe values. It was hypothesized that μ-calpain catalyzes the release MLC1 into the sarcoplasmic fraction. Myofibrils from beef longissimus dorsi were purified and incubated with μ-calpain and the appropriate buffer controls. μ-Calpain was added at 1.23 μg (0.0875 U) of pure μ-calpain/mg myofibrillar protein. Incubations of one and 120 min had a greater abundance of MLC1 in the supernatants than the control incubations. As a consequence of μ-calpain proteolysis, MLC1 is rapidly released from the myofibril and is a potential indicator of proteolysis and improvement in beef tenderness.     

Establishing tenderness thresholds of Venezuelan beef steaks using consumer and trained sensory panels

The tenderness thresholds for ribeye steaks at 2 d postmortem were found by using sensory trained (n = 734 steaks) and consumers panel data (55 ribeye steaks and 296 consumers). Also, consumers’ perceptions of sensory attributes of beef steaks were assessed to establish their relationships and to determine acceptability levels. The tenderness threshold obtained by regression analysis from trained panelists was 37.98 N (3.87 kg). Customer satisfaction of 81% was obtained when beef steaks had Warner-Bratzler shear force values (WBSF) less than 40.13 N (4.09 kg), suggesting that 40.13 N could be considered as a tenderness threshold to segregate tough from tender steaks, for Venezuelan beef consumers. According to correlation and regression analyses, consumers focused on flavor to assign their overall liking score. Results suggest that consumers are able to detect changes in tenderness of steaks with different WBSF and that flavor drives customer satisfaction when the beef tenderness is acceptable.     

Effects of blade tenderization,aging method and aging time on meat quality characteristics of Longissimus lumborum steaks from cull Holstein cows

The effects of blade tenderization (BT), two aging methods (dry (D) and wet (W)), and aging time (2 and 23 d) on tenderness, color, and sensory properties of Longissimus lumborum muscles from 12 cull Holstein cows were evaluated. Dry-aged loins had higher combined trim and aging losses than control (C) for both D- and W-aging, mostly because of excess trim losses. BT steaks had WBSF of 33.13 N while C steaks had WBSF of 41.46 N (P = 0.09). Aging decreased WBSF. Blade tenderized steaks had higher cook loss than C steaks. Aging, W-aging, and BT × W-aging improved myofibrillar (sensory) tenderness scores. Aging and/or BT improves sensory panel tenderness cull cow Longissimus lumborum steaks. Aging and blade tenderization combined can increase tenderness and value of Longissimus steaks from cull Holstein cows.     

EFFECTS OF DIFFERENT AGING PROCEDURES ON THE PALATABILITY OF BEEF

Ten pairs of beef strip loins were obtained 48 h postmortem from ten good grade beef carcasses. Three steaks (2.5 cm thick) were cut from the loin end of each strip loin and the remaining portion retained as the subprimal. Steaks and subprimals were aged for 7 days at 2°C in the following treatments: polyvinyl chloride overwrapped steaks (PVC-ST), vacuum packaged steaks (VP-ST), vacuum packaged subprimals (VP-SP), and subprimals held in air (Air-SP). After aging of the subprimal, 3 additional steaks were cut for evaluation. The steaks from all treatments were evaluated for palatability and chemical characteristics. Palatability characteristics did not differ significantly (P > 0.05) between treatments with the exception of the off-flavor intensity of PVC-ST which was higher (P < 0.05) than other treatments. Warner-Bratzler shear values were similar for all treatments. No significant differences (P > 0.05) were observed between treatments for percent moisture, percent lipid, pH or TBA number. The results of this study indicate that aging method (air or vacuum) or type of cut (steaks or subprimals) had little effect on the palatability attributes or chemical characteristics of the beef strip loins.     

Relationships of slice shear force and Warner-Bratzler shear force of beef strip loin steaks as related to the tenderness gradient of the strip loin

This study was conducted to investigate the effects of steak location within a strip loin and USDA quality grade on muscle fiber angle, slice shear force (SSF), and Warner-Bratzler shear force (WBSF) and to determine the relationship between SSF and WBSF. Steak location influenced both SSF and WBSF values, as steaks from the anterior portion were typically tenderer than steaks from the posterior end. Although there is some discrepancy between the two shear force methods, both agree that at least the first 5 anterior-most steaks are comparable. Muscle fiber angle was affected by steak position within the strip loin, as the fiber angle shifted between steaks 7 and 8. Quality grade had a significant effect on beef tenderness for both SSF and WBSF. Finally, there was a strong relationship between lateral SSF and average WBSF (r = 0.64), which are currently the most commonly used measurements for instrumental tenderness.     

不同嫩度羊肉肌浆蛋白质磷酸化水平随宰后成熟时间变化的研究

本文研究了不同嫩度羊肉肌浆蛋白磷酸化水平随宰后成熟时间的变化。取40只羊宰后0.5 h、1 h、4 h、12 h、24 h背最长肌样品,根据24 h剪切力和肌原纤维小片化指数分为高嫩度组和低嫩度组。采用SDS-PAGE电泳、荧光染色等方法,分析肌浆蛋白的磷酸化水平。研究结果表明在宰后24 h内肌浆蛋白磷酸化水平在不同嫩度和宰后成熟时间处理组之间差异显著(P0.05),低嫩度组的整体蛋白质磷酸化水平在宰后4 h达到最大,高嫩度组的整体蛋白质磷酸化水平在宰后12 h达到最大。宰后0.5 h、1 h、4 h低嫩度组的肌浆蛋白整体磷酸化水平显著高于高嫩度组(P0.05)。因此,肌浆蛋白磷酸化水平受不同嫩度和宰后成熟时间处理影响显著(P0.05),磷酸化可能通过对宰后肌肉糖酵解的作用影响宰后肌肉僵直进程,进而影响肌肉嫩度。     

电刺激对牛背最长肌中钙激活酶活性及嫩度的影响

通过对中国杂交黄牛(鲁西黄牛×西门塔尔)牛背最长肌中Calpains活性及剪切力值的分析,研究了电刺激对牛背最长肌宰后成熟过程中Calpains活性及牛肉嫩度的影响。结果表明:电刺激显著提高了μ-calpain的活性(P<0.05),降低了calpastatin对μ-calpain的抑制作用,提高了牛背最长肌的嫩度,缩短了牛肉的成熟时间;但电刺激仅在宰后成熟1h,显著提高了m-calpain的活性(P<0.05);宰后成熟24h、3d,与对照组之间差异不显著(P>0.05),试验结果证实,电刺激通过对Calpains体系的影响,改变了牛肉的成熟速度,显著的改善了牛肉的嫩度。     

Evaluation of the Tenderness of Beef Top Sirloin Steaks

Top sirloin butts and strip loins were obtained from both sides of 20 U.S. Choice beef carcasses and cut into six steaks (2.54 cm thick). These steaks were assigned randomly to one of six aging treatments (0, 7, 14, 21, 28 or 35 days). Top sirloin steaks were less tender and more variable in tenderness than top loin steaks. This difference in tenderness appeared to be due to higher amounts of collagen in top sirloin steaks and a tendency toward lower collagen solubility, shorter sarcomere length and higher (less tender) fragmentation index.