Effects of postmortem calcium chloride injection on meat palatability traits of strip loin steaks from cattle supplemented with or without zilpaterol hydrochloride

An experiment was conducted to determine the effects of zilpaterol hydrochloride mM supplementation (ZH; 8.3 mg/kg on a DM basis for 20 d) and calcium chloride injection [CaCl(2), 200 at 5% (wt/wt) at 72 h postmortem] on palatability traits of beef (Bos taurus) strip loin steaks. Select (USDA) strip loins were obtained from control (no ZH = 19) and ZH-supplemented carcasses (n = 20). Right and left sides were selected alternatively to serve as a control (no INJ) or CaCl(2)-injected (INJ) and stored at 4°C. Before injecting the subprimals (72 h postmortem), 2 steaks were cut for proximate, sarcomere length, and myofibrillar fragmentation index (MFI) analyses. At 7 d postmortem each strip loin was portioned into steaks, vacuum packaged, and aged for the appropriate period for Warner-Bratzler shear force (WBSF; 7, 14, 21, and 28 d postmortem), trained sensory analysis (14 and 21 d postmortem), purge loss (7 d), and MFI (3, 7, 14, 21, and 28 d postmortem). Results indicated steaks from both ZH supplementation and INJ had reduced WBSF values as days of postmortem aging increased. The WBSF values of ZH steaks were greater (P < 0.05) than no ZH steaks at each postmortem aging period. The INJ steaks had lower WBSF values (P < 0.05) than non-injected steaks. A greater percentage (91 vs. 71%) of steaks had WBSF values < 4.6 kg from steers with no ZH supplementation at 7 d postmortem, but the percentage did not differ (P > 0.05) due to ZH at 14, 21, or 28 d or due to INJ at any aging period. Trained panelists rated tenderness less in ZH steaks than steaks with no ZH at 14 d and 21 d. However, INJ improved (P < 0.05) the tenderness ratings and flavor intensity of the trained panelists, compared with their non-injected cohorts at 21 d. Zilpaterol hydrochloride supplementation reduced (P < 0.05) MFI values, but INJ resulted in greater (P < 0.05) MFI values compared with no INJ. Subprimals from ZH and INJ showed greater purge loss (P < 0.05). Although no interactions were found with ZH and CaCl(2), injecting USDA Select strip loins from ZH-fed cattle can help reduce the normal WBSF variation as it does in steaks from non-ZH-fed cattle.     

Effect of sire on mu- and m-calpain activity and rate of tenderization as indicated by myofibril fragmentation indices of steaks from Brahman cattle

The objectives of this study were to assess the influence of sire on mu- and m-calpain activities, to evaluate the relationships of activities of these enzymes to other traits related to beef palatability, and to assess the influence of sire on the rate of tenderization (as measured by myofibril fragmentation index [MFI]) in Brahman longissimus muscle. Brahman calves (n = 87), sired by nine bulls, were born, weaned, fed, and slaughtered in central Florida. Traits evaluated were mu- and m-calpain activities and MFI after 1, 7, 14, and 21 d of aging. Other traits were analyzed to determine their associations with mu- and m-calpain activity and MFI, including calpastatin activity, percentage of raw and cooked lipids, Warner-Bratzler shear force (WBSF) values after 7, 14, and 21 d of aging, and sensory panel rating of tenderness, juiciness, and connective tissue amount after 14 d of aging. Data were analyzed using a model with sire, sex, year, and slaughter group (calves of the same sex slaughtered on the same date) as fixed effects, and adjusted to a constant adjusted 12th-rib fat thickness. Sire affected mu-calpain activity (P < 0.04), calpastatin activity (P < 0.01), d-14 MFI (P < 0.02), d-7 WBSF (P < 0.05), d-14 WBSF (P < 0.04), and sensory panel juiciness score (P < 0.01), but not (P < 0.75) m-calpain activity. Measures of tenderness and palatability were generally moderately to strongly correlated (both simple and residual correlations) with calpastatin and m-calpain activity. Myofibril fragmentation index residuals (adjusted for all model components except sire) after all aging periods were fitted using nonlinear regression to the exponential curve (MFI(i) = kappa0 + kappa1 exp[kappa2 t(i)] + epsilon(i), where t(i) represents aging in days, k0 is ultimate MFI after aging, kappa1 is the difference between initial and ultimate MFI, kappa2 is the rate of increase in MFI, and epsilon(i) is the error term associated with the ith observation, assumed to be independent and identically distributed normally). Sires had different estimates and combinations of estimates, which were used to plot MFI change with time. These curves visually differed for sires and suggested that postmortem tenderization extent and rate differ as well. Use of a combination of these estimated parameters in a selection/carcass sorting program represents an alternative consideration for tenderization improvement programs.     

Tenderness, moisture loss and post-mortem metabolism of broiler Pectoralis muscle from electrically stimulated and air chilled carcases

1. This study was to evaluate the effects of post-mortem electrical stimulation (ES) on carcase moisture loss and on tenderness, R-value and pH of breast fillets following air chilling. 2. In each of 4 replications, 8 birds were electrically stimulated and 12 birds were controls. The ES birds were stimulated at the head in a 1% saline bath (450 V, 0.45 A, 2 s on/1 s off for 7 pulses). After evisceration the carcases were air chilled in a cooler at 1 to 2 degrees C with an average relative humidity of 91% and an air speed of 44 m/min. 3. Breast fillets were harvested at 2 and 4 h postmortem from both ES and control carcases and also at 8 h postmortem from control carcases to determine moisture loss pH and R-value. 4. Although there was no significant effect of ES on shear value at 2 h postmortem, the ES fillets had a lower shear value mean than the control fillets at 4 h postmortem. There was no significant difference between the shear value means of the ES 4 h fillets and the control 8 h fillets. 5. ES accelerated the normal post-mortem decline in pH at both 2 and 4 h postmortem. 6. The R-value means for the control and ES samples were similar 2 h but the R-value mean of the ES samples was greater than the control at 4 h postmortem. 7. The results suggest that, when followed by air chilling, ES accelerates postmortem metabolism, reduces ageing by up to 50%, and has no effect upon evaporative moisture loss.     

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

Forty USDA Select and 40 upper two-thirds USDA Choice beef carcasses were used to determine the effects of postmortem aging on tenderness of 17 individual beef muscles. Biceps femoris-long head, complexus, gluteus medius, infraspinatus, longissimus dorsi, psoas major, rectus femoris, semimembranosus, semitendinosus, serratus ventralis, spinalis dorsi, supraspinatus, tensor fasciae latae, teres major, triceps brachii-long head, vastus lateralis, and vastus medialis muscles were removed from each carcass. Seven steaks (2.54-cm thick) were cut from every muscle, and each steak was assigned to one of the following postmortem aging periods: 2, 4, 6, 10, 14, 21, or 28 d postmortem. After completion of the designated aging period, steaks were removed from storage (2 degrees C, never frozen), cooked to a peak internal temperature of 71 degrees C, and evaluated using Warner-Bratzler shear force (WBSF). Analysis of WBSF revealed a 3-way interaction (P = 0.004) among individual muscle, USDA quality grade, and postmortem aging period. With the exception of the Select teres major, WBSF of all muscles (both quality grades) decreased with increasing time of postmortem storage. Nonlinear regression was used to characterize the extent (aging response) and rate of decrease in WBSF from 2 through 28 d postmortem for each muscle within each quality grade. In general, WBSF of upper two-thirds Choice muscles decreased more rapidly from 2 to 10 d postmortem than did corresponding Select muscles. Muscles that had greater aging responses generally had greater 2-d WBSF values. The upper two-thirds Choice psoas major, serratus ventralis, and vastus lateralis muscles required similar aging times to complete a majority of the aging response (< or =0.1 kg of aging response remaining) compared with analogous Select muscles. The upper two-thirds Choice complexus, gluteus medius, semitendinosus, triceps brachii-long head, and vastus medialis muscles required 4 to 6 d less time to complete a majority of the aging response than did comparable Select muscles. Aging times for Select biceps femoris-long head, infraspinatus, longissimus dorsi, rectus femoris, semimembranosus, spinalis dorsi, supraspinatus, and tensor fasciae latae muscles were > or =7 d longer than those for corresponding upper two-thirds Choice muscles. Results from this study suggest that muscle-to-muscle tenderness differences depend on quality grade and aging time and that postmortem aging should be managed with respect to individual muscle and USDA quality grade.     

Chilling and cooking rate effects on some myofibrillar determinants of tenderness of beef

Our objectives were to examine the effects of prerigor excision and rapid chilling vs. conventional carcass chilling of two muscles on proteolysis and tenderness during the postmortem storage, as well as the effects of fast and slow rates of cooking on myofibrillar characteristics and tenderness. The longissimus thoracis (LT) and triceps brachii (TB), long head muscles were removed 45 min after exsanguination from the left side of 12 carcasses and chilled in an ice bath to induce cold shortening (excised, rapidly chilled). At 24 h postmortem, the corresponding muscles were removed from the right side (conventionally chilled). All muscles were cut into 2.54-cm-thick steaks and assigned to one of two postmortem times (1 or 14 d), and to raw and cooking treatments. Steaks were cooked at 260 degrees C (FAST) or 93 degrees C (SLOW) in a forced-air convection oven to an internal temperature of 70 degrees C. Cooking loss, cooking time, and Warner-Bratzler shear force (WBSF) were measured on cooked steaks. Sarcomere length (SL) and the extent of proteolysis of desmin were measured on raw and cooked steaks. As expected, the excised, rapidly chilled muscles had a much more rapid (P < 0.05) temperature decline than those that were conventionally chilled. The excised, rapidly chilled treatment resulted in shorter (P < 0.05) SL, and SL was shorter (P < 0.05) in LT than in TB steaks. Raw steaks had longer (P < 0.05) SL than cooked steaks, regardless of chilling treatment. The FAST cooking resulted in shorter (P < 0.05) SL than SLOW cooking in conventionally chilled steaks, but cooking rate had no effect (P > 0.05) on SL of rapidly chilled steaks. Generally, TB steaks required longer (P < 0.05) cooking times and had higher (P < 0.05) cooking losses than LT steaks, and FAST-cooked steaks had greater (P < 0.05) cooking losses than SLOW-cooked steaks. Rapidly chilled steaks had less (P < 0.05) degradation of desmin than conventionally chilled steaks (31 vs. 41%). Aging for 14 d increased (P < 0.05) desmin degradation. Rapid chilling of muscles resulted in much higher (P < 0.05) WBSF values, whereas aging resulted in lower (P < 0.05) WBSF values. The SLOW-cooked TB steaks were more tender (P < 0.05) than FAST-cooked TB steaks and LT steaks cooked at either rate. Excised, rapidly chilled muscles underwent proteolysis, but it occurred at a slower rate during the first 24 h postmortem than it did in conventionally chilled muscles. Cooking rate did not affect tenderness of LT steaks, but SLOW cooking resulted in more tender TB steaks.     

Effects of ractopamine supplementation and postmortem aging on longissimus muscle palatability of beef steers differing in biological type

Effects of ractopamine hydrochloride (RAC) supplementation and postmortem aging on palatability of beef from steers differing in biological type were evaluated using LM samples from British, Continental crossbred, and Brahman crossbred calf-fed steers (n = 98/type). Equal numbers of steers within each type were assigned to treatments of 0 or 200 mg.steer(-1).d(-1) of RAC fed during the final 28 d of the finishing period. Warner-Bratzler shear force (WBSF) was measured at 3, 7, 14, and 21 d postmortem, and trained sensory panel (TP) evaluation was conducted using LM samples aged for 14 d postmortem. A RAC x type interaction (P = 0.006) was detected for WBSF. Within each type, steers fed RAC produced steaks with greater (P < 0.05) WBSF values than steaks from control steers; however, the magnitude of the effect of RAC on WBSF was more pronounced among Brahman cross-breds (5.53 vs. 4.96 +/- 0.10 kg) than among Continental crossbred (4.16 vs. 3.96 +/- 0.10 kg) and British steers (4.10 vs. 3.75 +/- 0.10 kg). The effect of RAC on WBSF, though diminished slightly by aging (mean WBSF difference: 3 d = 0.49 kg; 21 d = 0.24 kg), was not completely mitigated by 21 d of postmortem storage (P(RAC x AGE) = 0.16). Steers fed RAC produced steaks that received lower (P < 0.05) TP ratings for tenderness (8.09 vs. 8.95 +/- 0.18) and juiciness (7.41 vs. 8.07 +/- 0.16 kg), along with slightly lower (P = 0.06) ratings for beef flavor (6.67 vs. 6.93 +/- 0.10 kg), compared with steaks from unsupplemented steers, regardless of biological type. Among the 3 biological types, Brahman crossbred cattle produced steaks with the greatest (P < 0.05) WBSF values at each aging period; WBSF values for steaks from British and Continental type steers did not differ (P > 0.05) at any aging time. Sensory panel ratings of tenderness, juiciness, and beef flavor were greatest (P < 0.05) for steaks from British steers, and least (P < 0.05) for steaks produced by Brahman-type steers. Results from this study suggest that RAC supplementation slightly decreases LM tenderness (WBSF and TP) of British, Continental crossbred, and Brahman cross-bred steers, and that the effect of RAC on WBSF may be more pronounced in steaks from Brahman crossbred cattle than among stenks from Continental type or British steers.     

Effects of genetic markers and implant strategy on longissimus and gluteus muscle tenderness of calf-fed steers and heifers

Effects of genotype (GEN) and implant program (IMP) on LM and gluteus muscle (GM) tenderization were investigated using crossbred steer (n = 185) and heifer (n = 158) calves. The 3-marker GeneSTAR Tenderness panel [CAST (calpastatin), CAPN1 316 (μ-calpain), and CAPN1 4751 (μ-calpain)] was used to determine the GEN of each animal (reported as total number of favorable alleles, 0 through 6). Calves were randomly assigned to 1 of 2 IMP, conventional (CNV) or delayed. Cattle in the CNV group were implanted at the beginning of the finishing period with Revalor-IS or Revalor-IH (Intervet Inc., Millsboro, DE), and then reimplanted 59 d later with Revalor-S or Revalor-H (Intervet Inc.). Calves in the delayed group received a single terminal implant (Revalor-S or Revalor-H) administered 45 d after initiation of the finishing period. Warner-Bratzler shear force (WBSF) was measured on LM and GM steaks at 3, 7, 14, 21, and 28 d postmortem. No interactions between the main effects of sex, IMP, or GEN were detected (P > 0.05) for WBSF. An IMP × postmortem aging (age) interaction was detected (P < 0.05) for LM and GM WBSF. For both muscles, steaks from CNV cattle had WBSF values that were approximately 0.2 kg greater (P < 0.05) than the values for steaks from delayed animals, but only during the early postmortem period (3 to 7 d). A linear effect of GEN on WBSF was detected (P < 0.05) for LM and GM steaks. Within each muscle, steaks from cattle with 6 favorable alleles had WBSF values 0.33 kg less than the values for steaks from cattle with 1 favorable allele. The GEN × age interaction was not significant for LM (P = 0.14) or GM (P = 0.20), but a numerical trend was observed for the effect of GEN on WBSF to diminish as age increased. To investigate how genetic markers could be interfaced with current beef carcass quality grading, cattle were sorted into 2 gene marker groups (GMG), ≤3 vs. ≥4 favorable alleles. For both muscles, GMG was effective only at identifying tenderness differences within the Select grade. When aged ≤14 d, Select LM steaks from cattle with ≥4 alleles had smaller (P < 0.05) WBSF values than did LM steaks from animals with ≤3 alleles. Preslaughter factors (sex, IMP, and GMG) controlled in the present study each accounted for less than 7% of the explained variation in tenderness of the test population. Results from this study suggest that the 3 GeneSTAR Tenderness markers were associated with small differences (0.33 kg) in WBSF and may be useful for increasing the consistency of Select beef, but these specific markers accounted for only a minor amount of variation in beef tenderness.     

Quantifying the aging response and nutrient composition for muscles of the beef round

The objective of this study was to determine the optimal postmortem aging period and nutrient composition for Beef Value Cuts of the round. Forty USDA Select and 40 Premium USDA Choice beef carcasses were selected from a commercial beef packing plant in Colorado over a 12-wk period. The bottom and inside rounds were collected from both sides of each carcass for further fabrication into the following muscles: adductor, gastrocnemius, gracilis, pectineus, and superficial digital flexor. Each pair of muscles was cut into 7 steaks and randomly assigned to 1 of the following aging periods: 2, 4, 6, 10, 14, 21, and 28 d, and placed in refrigerated storage (2°C, never frozen). Upon completion of the designated aging period, steaks were removed from storage, cooked to a peak internal temperature of 72°C, and evaluated using Warner-Bratzler shear force (WBSF). A 2-way interaction was detected (P < 0.05) between individual muscle and postmortem aging period. The WBSF of all muscles except the superficial digital flexor decreased with increased time of postmortem aging. Quality grade did not affect (P > 0.05) WBSF values for the adductor, gastrocnemius, pectineus, and superficial digital flexor muscles. Exponential decay models were used to predict the change in WBSF from 2 to 28 d postmortem (aging response). The adductor, gastrocnemius, Select gracilis, Premium Choice gracilis, and pectineus required 21, 14, 23, 23, and 25 d, respectively, to complete the majority of the aging response. To determine the nutrient composition of the adductor, gastrocnemius, gracilis, pectineus, semimembranosus, and superficial digital flexor, bottom and inside rounds were collected from 10 USDA Select and 10 Premium USDA Choice carcasses and fabricated into the respective muscles, cut into 2.54-cm cubes, frozen (-20°C), and then homogenized. The adductor, gracilis, pectineus, semimembranosus, and superficial digital flexor were analyzed for DM, moisture, CP, and ash percentages. All muscles were evaluated for total lipid, fatty acid, and cholesterol composition. When quality grades were combined, all muscles fell into the extra lean or lean categories specified by USDA guidelines. Results of this study illustrate the potential for Beef Value Cuts of the round to be sold in food service operations and retail stores with marketing emphasis being placed on the exceptional leanness and acceptable tenderness of these cuts.     

Electrical stimulation effects on tenderness of five muscles from Hampshire x Rambouillet crossbred lambs with the callipyge phenotype

The objective of this study was to determine effects of electrical stimulation (ES) on muscle quality and sensory traits of 12 Hampshire x Rambouillet callipyge lambs. One side of each carcass was randomly assigned to an ES treatment of 550 V and 60 Hz of electricity for 2 s on and 2 s off 15 times. The other side was a nonstimulated control (NES). Heated calpastatin, sarcomere length, myofibrillar fragmentation index (MFI), Warner-Bratzler shear (WBS), and trained sensory panel values were measured on the semitendinosus (ST), semimembranosus (SM), longissimus (ML), supraspinatus (SP), and triceps brachii (TB) muscles. Electrically stimulating the carcass sides induced a more rapid (P = .001) pH decline in the longissimus muscle, and ES sides had a brighter (P = .001) red color of loineye than nonstimulated sides. At d 14 of storage (2 degrees C), the TB had the highest (P < .05) MFI value, indicating more protein degradation, and the ST and ML muscles had the lowest MFI (P = .008). Regardless of ES treatment, SM and ML had the highest (P < .05) WBS values. The ST muscle had higher (P < .05) WBS values than the SP but did not differ (P > .05) from the TB muscle. Electrical stimulation had no effect on WBS or any trained sensory panel values (P > .05). The percentage of loin chops rated slightly tender or better was improved 30 to 34% by electrical stimulation (P < .05). The ML muscle was scored lower (P < .05) in sustained juiciness compared with the SM, SP, and TB but did not differ (P > .05) from the ST muscle. The SM and ML muscles were rated lower (P < .05) in initial and sustained tenderness scores than other muscles. Tenderness scores were higher (P < .05) for the TB than for the SP but did not differ (P > .05) from the ST muscle. Electrically stimulating callipyge carcasses improves the tenderness of loin chops by increasing the percentage of chops rated from slightly tough to slightly tender.     

Vitamin D3 supplementation of cull cows: effects on longissimus and semitendinosus muscle tenderness

Previous studies have shown that supplementation of vitamin D3 to cow diets for 4 to 10 d before slaughter lowers Warner-Bratzler shear force (WBSF) values and increases sensory tenderness scores in beef cuts. The present study was conducted to evaluate the effects of vitamin D3 supplementation on muscle calcium concentration, WBSF values, and sensory tenderness ratings of LM and semitendinosus (ST) muscles from cull, predominately Angus, cows (eight cows per treatment). Treatments included 0 (control), 5 million IU, or 7.5 million IU of vitamin D3 supplemented daily for 7 d preslaughter. Twenty-four hours after slaughter, 2.54-cm-thick LM and ST muscle steaks were cut; aged for either 0, 7, 14, or 21 d (ST steaks aged for 7 d only); and frozen at -20 degrees C for WBFS and sensory analysis. Mean values for LM calcium concentration tended to increase (P = 0.14) with vitamin D3 supplementation (154, 176, and 183 microig/g, fresh basis, for 0, 5, and 7.5 million IU/d, respectively). After 7 d of aging, LM steaks from cows fed 7.5 million IU had lower (P < 0.05) WBSF values than 7-d steaks from controls and cows fed 5.0 million IU/d aged 7 d; however, vitamin D3 supplementation had no (P > 0.05) effect on WBSF values of ST steaks aged 7 d. Vitamin D3 supplementation did not (P > 0.05) affect sensory tenderness ratings for either LM or ST steaks at any aging period. Aging, however, had a linear (P < 0.001) effect on tenderness, with an increase in tenderness as aging time increased from 0 to 21 d. Thus, results from the present study indicate that vitamin D3 supplementation, at these levels and duration before slaughter, provided little benefit to muscle tenderness of beef from cull cows.     

Effect of animal age,postmortem chilling rate,and aging time on meat quality attributes of water buffalo and humped cattle bulls

The study was aimed to investigate the influence of animal age, post‐slaughter chilling rate, and aging time on meat quality of M. longissimus dorsi (LD) of water buffalo (Bubalus bubalis) and humped cattle (Bos taurus indicus) bulls. After slaughtering, one side of carcasses was subjected to rapid chilling (RC) (0 ± 2°C) and other side was hanged in controlled room temperature (25 ± 2°C) for 3 hr, then allowed to the chiller (0 ± 2°C). The meat quality traits were analyzed at 1, 7, and 14 days of storage. It was noted that rapidly chilled carcasses from the younger animals of both species missed the ideal pH/temperature window, which affects the toughness of the meat. Buffalo meat presented higher shear force, color L* values, and lower b* value as compared to the cattle meat. Moreover, meat shear force values decreased while all color coordinates and cooking loss values increased with lengthening the storage time in both age groups of cattle and buffalo. In conclusion, the tenderness of cattle meat was superior to that of buffalo and RC adversely affect the shear force values of young cattle and both age groups of buffalo bulls.     

Effects of electrical stimulation and pre‐rigor conditioning temperature on aging potential of hot‐boned beef M. longissimus lumborum

The objective of this study was to create various pH/temp decline rates in hot‐boned bull beef M. longissimus lumborum (LL) through a combination of electrical stimulation (ES) and pre‐rigor holding temperature. The relationship between the pre‐rigor interventions, the activities of µ‐calpain and small heat shock proteins (sHSP), and the impacts on meat product quality were determined. Paired LL loins from 13 bulls were hot‐boned within 40 min of slaughter, immediately ES and subjected to various holding temperatures (5, 15, 25, and 35°C) for 3 hr. The rate of muscle pH decline, sarcomere length, shear force, and proteolysis of muscle proteins were measured. ES‐25°C had a longer sarcomere length compared to non‐electrical stimulation samples. ES‐25°C and ES‐35°C samples had lower shear force values, higher µ‐calpain activity and higher desmin, troponin‐T, and sHSP degradation. The above findings suggest that pH/temp decline rates created in hot‐boned muscle impacted muscle protein proteolysis by increasing the activity of proteases and degradation of sHSP.     

Online prediction of beef tenderness using a computer vision system equipped with a BeefCam module

Four experiments were conducted in two commercial packing plants to evaluate the effectiveness of a commercial online video image analysis (VIA) system (the Computer Vision System equipped with a BeefCam module [CVS BeefCam]) to predict tenderness of beef steaks using online measurements obtained at chain speeds. Longissimus muscle (LM) samples from the rib (Exp. 1, 2, and 4) or strip loin (Exp. 3) were obtained from each carcass and Warner-Bratzler shear force (WBSF) was measured after 14 d of aging. The CVS BeefCam output variable for LM area, adjusted for carcass weight (cm2/kg), was correlated (P < 0.05) with WBSF values in all experiments. The CVS BeefCam lean color measurements, a* and b*, were effective (P < 0.05) in all experiments for segregating carcasses into groups that produced LM steaks differing in WBSF values. Fat color measurements by CVS BeefCam were usually ineffective for segregating carcasses into groups differing in WBSF values; however, in Exp. 4, fat b* identified a group of carcasses that produced tough LM steaks. Quality grade factors accounted for 3, 18, 21, and 0% of the variation in WBSF among steaks in Exp. 1 (n = 399), 2 (n = 195), 3 (n = 304), and 4 (n = 184), respectively, whereas CVS BeefCam output variables accounted for 17, 30, 19, and 6% of the variation in WBSF among steaks in Exp. 1, 2, 3, and 4, respectively. A multiple linear regression equation developed with data from Exp. 2 accurately classified carcasses in Exp. 1 and 4 and thereby may be useful for decreasing the likelihood that a consumer would encounter a tough (WBSF > 4.5 kg) LM steak in a group classified as "tender" by CVS BeefCam compared with an unsorted population. Online measurements of beef carcasses by use of CVS BeefCam were useful for predicting the tenderness of beef LM steaks, and sorting carcasses using these measurements could aid in producing groups of beef carcasses with more uniform LM steak tenderness.     

Technical note: the effect of freezing on Warner-Bratzler shear force values of beef longissimus steaks across several postmortem aging periods

The objective of this study was to compare fresh and frozen protocol procedures for Warner-Bratzler shear force (WBSF) determination on steaks aged for different periods of time. The fresh protocol consisted of measuring WBSF on steaks cooked on the exact day the aging period ended. The frozen protocol consisted of measuring WBSF on steaks that were aged, frozen (-16 degrees C) for approximately 2 mo, thawed for 24 h, and then cooked. Twenty-two strip loin steaks from each of 20 crossbred heifers and steers were individually vacuum-packaged and assigned to either the fresh or frozen protocol and one of 11 aging periods (1, 2, 3, 4, 5, 6, 7, 10, 14, 21, or 35 d). The frozen protocol resulted in lower (P < 0.05) WBSF values than the fresh protocol for beef longissimus steaks that were aged for 1, 2, 3, 4, 6, 7, 10, 14, or 35 d postmortem. An interaction (P < 0.05) between protocol and postmortem aging resulted from larger differences between protocols at shorter aging periods than at longer aging periods. Correlations and mean differences revealed that frozen protocol WBSF values were not highly indicative of fresh protocol WBSF values at the same period of postmortem aging, but rather suggested that frozen protocol WBSF values at shorter aging times were useful in estimating WBSF values from fresh protocols at longer aging times. Cooking loss was higher (P < 0.05) for frozen vs fresh protocol steaks at all aging periods except for 14, 21, or 35 d. These findings suggest that if research constraints warrant the freezing of samples, shorter aging periods before freezing (6 and 7 d) should be used to estimate WBSF of fresh aged beef (14 to 21 d). In trials in which several postmortem aging periods or very short aging periods are of interest, we recommend that WBSF be assessed using the fresh protocol.     

Mechanical probes can predict tenderness of cooked beef longissimus using uncooked measurements

Two experiments were conducted to determine the effectiveness of using mechanical probes and objective color measurement on beef LM to predict cooked tenderness. In Exp. 1, sharp needle (SN), sharp blade (SB), blunt needle (BN), blunt blade (BB), and plumb bob (PB) probes were used to measure uncooked LM (n = 29) at 2 d postmortem in both a perpendicular and parallel orientation to the long axis of the strip loin. Additionally, instrumental color measurements were measured on uncooked muscle at 2 d postmortem. Steaks for trained sensory panel (TSP) and Warner-Bratzler shear force (WBSF) measurements were aged 14 d postmortem before cooking. Probe measurements taken perpendicular to the long axis of the LM were not correlated (P = 0.22 to 0.82) to TSP tenderness. Probe measurements (BB, BN, SN, SB, and PB) taken parallel to the long axis were correlated to TSP tenderness (r = -0.57, -0.40, -0.77, -0.52, and -0.53, respectively). A regression equation using the SN probe to predict TSP tenderness had a R2 value of 0.74. The SB probe combined with L* accounted for 45% of the variation in TSP tenderness, whereas the PB probe combined with L* accounted for 56% of the variation in TSP tenderness. A second experiment (n = 24) was conducted using the SN, SB, and PB probes on uncooked sections at 2 d and on cooked steaks at 14 d postmortem. Probe measurements on cooked steaks were not correlated to TSP tenderness. New regression equations were calculated using the probe measurements on uncooked steaks from both experiments. Prediction equations formulated with L* values and either SN, SB, or PB probes accounted for 49, 50, and 47% of the variability in TSP tenderness scores, respectively. An equation using WBSF of cooked steaks to predict TSP tenderness had an R2 of 0.58. Of the steaks predicted to be tender (predicted tenderness > 5.0) by the equations using the SN, SB, and PB probes on uncooked steaks and WBSF on cooked steaks, 85, 88, 80, and 84%, respectively, were actually tender (TSP tenderness > 5.0). Mechanical probe measurements of uncooked steaks at 2 d postmortem can potentially classify strip loins into groups based on tenderness, as well as WBSF measurements, which are more costly and time consuming.     

Influence of quality classification, aging period, blade tenderization, and endpoint cooking temperature on cooking characteristics and tenderness of beef gluteus medius steaks

Top sirloin butts (n = 162) were used to investigate the influence of quality classification, aging period, blade tenderization passes, and endpoint cooking temperature on the tenderness of gluteus medius steaks. Top sirloin butts (gluteus medius) from Select (SEL), Choice (CHO), and Certified Angus Beef (CAB) carcasses were obtained, aged for 7, 14, or 21 d, and either not tenderized or blade tenderized one or two times. Three steaks from each top sirloin butt were randomly selected and assigned to a final endpoint cooking temperature of 65.5, 71.0, or 76.6 degrees C. Cooking characteristics and Warner-Bratzler shear force (WBSF) were analyzed as a split-plot with a 3 x 3 x 3 factorial treatment structure of quality classification, aging period, and tenderization passes in the whole plot and endpoint cooking temperature in the subplot. Sensory panel data for CHO steaks cooked to 70 degrees C were analyzed with a 3 x 3 factorial treatment structure of aging period and tenderization passes. Thawing loss was greater (P < 0.05) for steaks aged 7 d than those aged 21 d. Cooking loss was greater (P < 0.05) for steaks aged for 14 and 21 d than those aged 7 d, and increased (P < 0.05) with each increasing endpoint temperature. Each increase in aging period resulted in lower (P < 0.05) WBSF values. In addition, steaks blade tenderized two times had lower (P < 0.05) WBSF values than steaks blade tenderized once or not at all. Within each quality classification, WBSF values increased (P < 0.05) as endpoint cooking temperature increased. When cooked to 71 or 76.6 degrees C, CHO and CAB steaks had lower (P < 0.05) WBSF than SEL steaks. Steaks blade tenderized one or two times received higher (P < 0.05) sensory panel ratings for myofibrillar and overall tenderness than steaks not blade tenderized. Connective tissue amount and overall tenderness ratings were higher (P < 0.05) for steaks aged 21 vs. 7 d. Postmortem aging and blade tenderization of gluteus medius steaks can improve tenderness, as measured by WBSF and sensory panel, without decreasing flavor or juiciness. When cooking to higher endpoint temperatures, higher quality classifications should be selected to minimize toughness due to cooking.     

Calpain activation and proteolysis in postmortem goose muscles

Meat tenderness is considered as the most important criterion for meat quality by consumers and can be improved by the actions of endogenous proteases, mainly calpains, during postmortem storage at 0–5°C. The purpose of this study, therefore, was to examine the postmortem calpain activation and proteolysis in breast (BM) and leg and thigh (LM) muscles of White Roman goose. BM and LM were taken from goose carcasses (n = 15) at 0 (10–15 min postmortem), 1, 3, and 7 days of storage at 5°C. The decrease in postmortem pH, calpain‐1 and ‐11 activities, and contents of the calpain‐1 80 kDa subunit and desmin was more rapid (p < .05) in BM than in LM. Our results show that postmortem proteolysis was more extensive in BM than in LM of White Roman goose, not only because the difference in fiber type composition between two muscles, but because the rate and extent of calpain activation were greater in BM as well. These results may provide useful information to optimize meat processing for different muscles in goose industry.     

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.     

Effect of Chilling Method and Deboning Time on Broiler Breast Fillet Quality

A study was conducted to determine the effects of chilling method and postmortem aging time on broiler breast fillet quality. One hundred fifty eviscerated broiler carcasses were removed from a commercial processing line before chilling and transported to the laboratory. Half of the carcasses were chilled by dry air, whereas the other half were chilled by water immersion. Immersion-chilled (IC) carcasses were divided into 3 groups (0, 1.67, and 24 h) based on postchill fillet aging time on the carcass. Air-chilled (AC) carcasses were divided into 2 groups based on fillet aging time (0 and 24 h postchill). Because AC requires more time to reach the same temperature, fillets removed immediately after chilling (0 h) were the same postmortem age as the 1.67 h IC fillets. Average pH values of IC and AC fillets were similar when fillets were aged for the same length of time postmortem. Method of chilling had no effect on raw breast fillet color; however, postmortem aging time had a slight but significant effect on fillet lightness. Shear values of IC fillets removed 0 and 1.67 h after chilling were similar and corresponded to sensory panel categories of slightly tough to tough (>8 kg/g). Shear values of AC fillets deboned at 0 h (8.4 kg/g) were slightly lower but not significantly different than the shear values for IC fillets (10.3 kg/g) aged for the same length of time (1.67 h). After 24 h of aging, shear values for IC and AC fillets were <8 kg/g and corresponded to sensory panel categories of tender to very tender. Cook yield (%) of AC fillets was significantly higher than cook yield (%) of IC fillets for all deboning times. Results show that air chilling has an accelerating effect on rigor mortis onset, but postchill aging time is required to maximize the proportion of tender meat.