A survey of beef muscle color and pH

The objectives of this study were to define a beef carcass population in terms of muscle color, ultimate pH, and electrical impedance; to determine the relationships among color, pH, and impedance and with other carcasses characteristics; and to determine the effect of packing plant, breed type, and sex class on these variables. One thousand beef carcasses were selected at three packing plants to match the breed type, sex class, marbling score, dark-cutting discount, overall maturity, carcass weight, and yield grade distributions reported for the U.S. beef carcass population by the 1995 National Beef Quality Audit. Data collected on these carcasses included USDA quality and yield grade data and measurements of muscle color (L*, a*, b*), muscle pH, and electrical impedance of the longissimus muscle. About one-half (53.1%) of the carcasses fell within a muscle pH range of 5.40 to 5.49, and 81.3% of the carcasses fell within a longissimus muscle pH range of 5.40 to 5.59. A longissimus muscle pH of 5.87 was the approximate cut-off between normal and dark-cutting carcasses. Frequency distributions indicated that L* values were normally distributed, whereas a* and b* values were abnormally distributed (skewed because of a longer tail for lower values, a tail corresponding with dark-cutting carcasses). Electrical impedance was highly variable among carcasses but was not highly related to any other variable measured. Color measurements (L*, a*, b*) were correlated (P < 0.05) with lean maturity score (-.58, -.31, and -.43, respectively) and with muscle pH (-.40, -.58, and -.56, respectively). In addition, fat thickness was correlated with muscle pH and color (P < 0.05). There was a threshold at approximately .76 cm fat thickness, below which carcasses had higher muscle pH values and lower colorimeter readings. Steer carcasses (L* = 39.62, a* = 25.20, and b* = 11.03) had slightly higher colorimeter readings (P < 0.05) than heifer carcasses (L* = 39.20, a* = 24.78, and b* = 10.80) even though muscle pH was not different between steer and heifer carcasses. Dairy-type carcasses (pH = 5.59, L* = 37.56, a* = 23.40, and b* = 9.68) had higher muscle pH values and lower colorimeter readings than either native-type (pH = 5.50, L* = 39.55, a* = 25.13, and b* = 11.00) or Brahman-type (pH = 5.46, L* = 39.75, a* = 25.17, and b* = 11.05) carcasses (P < 0.05).     

Relationships among glycolytic potential,dark cutting (dark,firm, and dry) beef,and cooked beef palatability

One hundred beef carcasses were selected at three packing plants and were used to determine the relationship between glycolytic potential (GP) and dark, firm, and dry (DFD) beef and to determine the effects of DFD status and GP on cooked beef palatability. Eight individual muscles were excised from one hindquarter of each carcass at d 7 postmortem: longissimus lumborum, psoas major, gluteus medius, tensor fasciae latae, rectus femoris, semimembranosus, biceps femoris, and semitendinosus. Ultimate pH, colorimeter readings, and Warner-Bratzler shear force were determined for all eight muscles at d 7 postmortem. A nine-member trained sensory panel evaluated cooked longissimus lumborum, gluteus medius, and semimembranosus steaks. Traits determined solely for the longissimus lumborum were GP (2 x [glycogen + glucose + glucose-6-phosphate] + lactate) and ether-extractable fat. A curvilinear relationship existed between GP and ultimate pH within the longissimus muscle. There appeared to be a GP threshold at approximately 100 micromol/g, below which lower GP was associated with higher ultimate pH and above which GP had no effect on ultimate pH. The greatest pH and muscle color differences between normal and DFD carcasses were observed in the longissimus lumborum, gluteus medius, semimembranosus, and semitendinosus muscles. Cooked longissimus from DFD carcasses had higher shear force values (46% greater) and more shear force variation (2.3 times greater variation) than those from normal carcasses. Dark cutting carcasses also had higher shear force values for gluteus medius (33% greater) and semimembranosus (36% greater) than normal carcasses. Sensory panel tenderness of longissimus, gluteus medius, and semimembranosus was lower for DFD carcasses than for normal carcasses. Longissimus and gluteus medius flavor desirability scores were lower for DFD than for normal carcasses. Steaks from DFD carcasses had more off-flavor comments than steaks from normal carcasses, specifically more "peanutty," "sour," and "bitter" flavors. The DFD effect of higher shear force values was approximately five times greater (+3.11 kg vs +0.63 kg) for carcasses with "slight" marbling scores than for carcasses with "small" marbling scores. In general, higher GP was associated with increased tenderness, even among normal carcasses. In conclusion, low GP was associated with DFD beef and resulted in substantially less-palatable cooked steaks.     

Measuring muscle color on beef carcasses using the L*a*b* color space.

Because beef muscle color affects consumers' purchasing decisions, is a factor in determining USDA grades, and has been shown to be useful in sorting carcasses according to palatability, this study was conducted to determine the effects of measurement conditions on L*, a*, and b* values, to determine the relationships among USDA quality grading factors, muscle pH, electrical impedance, and colorimeter readings, and to develop a classification system that could be used to sort beef carcasses with respect to muscle color. Data were collected over 2 d from 145 beef carcasses in a commercial packing plant. The exposed longissimus muscle at the 12th/13th rib was used for all muscle pH, electrical impedance, and colorimeter measurements. A Minolta Chroma Meter CR-310 was used to obtain L*, a*, and b* readings. Bloom time, from 0 to 93 min, had a greater effect on a* and b* readings than on L* readings. The L* values stabilized after approximately 30 min bloom time, and a* and b* values stabilized after 78 min bloom time, but relative differences among carcasses in L*, a*, and b* values did not change after 3 to 12 min bloom time. Days postmortem, cut surface (anterior versus posterior), and within-muscle location (medial vs lateral) did not affect L*, a*, and b* readings (P > .05). Blotting the surface moisture from the longissimus muscle resulted in lower a* readings (P < .05), but did not affect L* and b* readings (P > .05). The L*, a*, and b* values were correlated with lean maturity scores (-.67, -.30, and -.40, respectively), dark cutter discount (-.60, -.76, and -.73, respectively), muscle pH (-.57, -.79, and -.78, respectively), and electrical impedance (-.27, -.21, and -.25, respectively). Two muscle color classification systems, nine classes each, are proposed, one system based on L* and one system based on b*. The main advantage of the L* categorization system over the b* system is that the L* value was less sensitive to bloom time, and the main advantage of the b* categorization system over the L* system is that the b* system was slightly more precise at segregating carcasses based upon corresponding differences in muscle pH. This research provides procedural guidelines for measuring beef muscle color and shows that a colorimeter can effectively aid researchers and graders in assessing beef carcass quality.     

Characterization of certified Angus beef steaks from the round, loin, and chuck

Beef carcasses (n = 150) of A-maturity were selected randomly to determine baseline shear force and sensory panel ratings, assess variation in tenderness, and evaluate mean value differences between Certified Angus Beef (CAB), commodity Choice, and Select steaks. Three steaks were removed from the triceps brachii (TB), longissimus lumborum (LL), gluteus medius (GM), semimembranosus (SM), biceps femoris (BF), and quadriceps femoris complex (QF), and assigned to Warner-Bratzler shear (WBSF) and sensory panel analyses. As anticipated, marbling score and measured percentage of i.m. fat were greatest (P < 0.05) for CAB, intermediate (P < 0.05) for Choice, and least (P < 0.05) for Select carcasses. A muscle x quality level interaction (P < 0.05) was observed for WBSF values and sensory panel tenderness ratings. The TB, LL, GM, and BF steaks from CAB carcasses had lower (P < 0.05) WBSF than Select steaks from the same muscles. Even though WBSF values did not differ (P > 0.05) between CAB and Choice QF and TB steaks, the LL and GM steaks from CAB carcasses were more tender (P < 0.05) than Choice-grade LL and GM steaks. The TB from Select carcasses had higher (P < 0.05) WBSF values than TB steaks from CAB or Choice carcasses, but sensory panel ratings indicated that quality level showed little consistency among the GM, SM, BF, and QF. Trained sensory panelists rated CAB LL steaks more tender (P < 0.05) than LL steaks from Choice and Select carcasses, and Choice LL steaks were evaluated as more (P < 0.05) tender than those from Select carcasses. These results demonstrate that the influence of marbling on tenderness was more evident in muscles of middle meats than in end cuts, particularly in muscles of the round.     

Tenderness, sensory, and color attributes of two muscles from the M. quadriceps femoris when fabricated using a modified hot-boning technique

The M. quadriceps femoris from USDA Choice (n = 12) and USDA Select (n = 12) carcasses were fabricated traditionally (COLD) or innovatively (HOT), in which the seams it shares with the top round and bottom round were separated prerigor to evaluate positional and locational effects on Warner-Bratzler shear force (WBSF), sensory attributes, and objective color. At slaughter, paired USDA Choice and USDA Select carcasses were alternately assigned either the HOT or COLD treatment. At 48 h postslaughter, subprimals were removed, vacuum-packaged, and aged for an additional 5 d. After aging, the M. quadriceps femoris was cut into 2.54-cm-thick steaks and allowed to bloom 1 h. For the M. rectus femoris (REC) and M. vastus lateralis (VAL), L* values significantly (P < 0.050) decreased when moving from the proximal to distal position within the muscle. Similarly, a* and b* values decreased in the VAL when moving from the proximal to the distal aspect. After color measurement, steaks were vacuum-packaged and frozen (-26 degrees C) until shear and sensory data were collected. Significant position (proximal to distal) and location effects (cranial to caudal) were noted for both muscles. However, treatment did not affect WBSF of the VAL. Although intramuscular variation existed, WBSF and sensory panel tenderness ratings were acceptable for the REC. Although WBSF values were greater and tenderness ratings were less than the REC, the VAL were not extremely tough and therefore could be used in enhancement applications.     

Benchmarking carcass characteristics and muscles from commercially identified beef and dairy cull cow carcasses for Warner-Bratzler shear force and sensory attributes

The objective of this study was to benchmark carcasses and muscles from commercially identified fed (animals that were perceived to have been fed an increased plane of nutrition before slaughter) and nonfed cull beef and dairy cows and A-maturity, USDA Select steers, so that the muscles could be identified from cull cow carcasses that may be used to fill a void of intermediately priced beef steaks. Carcass characteristics were measured at 24 h postmortem for 75 carcasses from 5 populations consisting of cull beef cows commercially identified as fed (B-F, n = 15); cull beef cows commercially identified as nonfed (B-NF, n = 15); cull dairy cows commercially identified as fed (D-F, n = 15); cull dairy cows commercially identified as nonfed (D-NF, n = 15); and A-maturity, USDA Select grade steers (SEL, n = 15). Nine muscles were excised from each carcass [m. infraspinatus, m. triceps brachii (lateral and long heads), m. teres major, m. longissimus dorsi (also termed LM), m. psoas major, m. gluteus medius, m. rectus femoris, and m. tensor fasciae latae] and subjected to Warner-Bratzler shear force testing and objective sensory panel evaluation after 14 d of postmortem aging. Carcass characteristics differed (P < 0.05) among the 5 commercially identified slaughter groups for the traits of lean maturity, bone maturity, muscle score, HCW, fat color, subjective lean color, marbling, ribeye area, 12th-rib fat thickness, and preliminary yield grade. Carcasses from commercially identified, fed cull cows exhibited more (P < 0.01) weight in carcass lean than did commercially identified, nonfed cull cows. There was a group x muscle interaction (P = 0.02) for Warner-Bratzler shear force. Warner-Bratzler shear force and sensory overall tenderness values demonstrates that muscles from the SEL group were the most tender (P < 0.01), whereas muscles from the B-NF group were the least tender (P < 0.01). Sensory, beef flavor intensity was similar (P > 0.20) among cull cow carcass groups and more intense (P < 0.01) than the SEL carcass group. Muscles from the SEL group exhibited less (P < 0.01) detectable off-flavor than the cull cow carcass groups, whereas the B-NF group exhibited the most (P < 0.01) detectable off-flavor. Although carcass and muscle quality from commercially identified, fed, cull beef and dairy cows was not similar to A-maturity, USDA Select beef, they did show improvements when compared with nonfed, cull, beef and dairy cow carcasses and muscles.     

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.     

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.     

Relative contributions of animal and muscle effects to variation in beef lean color stability

Muscles from beef carcasses (n = 100) were selected from a commercial processor and aged for 14 d. Longissimus lumborum (LL), semimembranosus (SM), biceps femoris (BF), gluteus medius (GM), triceps brachii (TB), rectus femoris, vastus lateralis, adductor, semitendinosus, infraspinatus, teres major, biceps femoris ischiatic head, biceps femoris sirloin cap, and gracillus steaks were placed in display for 9 d. Instrumental color variables [lightness (L*), redness (a*), yellowness (b*), hue angle, chroma, and overall color change from d 0 (E)] were determined on d 0, 1, 3, 6, and 9 of display. Muscle pH and myoglobin content were determined for LL, SM, BF, GM, and TB. Muscles differed (P < 0.05) in initial values of each color variable evaluated, and the extent and timing of changes during display differed across muscles. Relationships between color variables measured in LL steaks and those measured in steaks from other muscles differed across days of display with the strongest relationships being observed earlier in the display period for labile muscles and later in stable muscles. Lightness of LL steaks was correlated with lightness of all of other muscles evaluated, regardless of display day (r = 0.27 to 0.79). For a*, hue angle, chroma, and E values, the strongest relationships between LL values and those of other muscles were detected between d 9 LL values and those of other muscles on d 3, 6, or 9, depending on the relative stability of the muscle. Correlation coefficients between d 9 a*, hue angle, chroma, and E values in LL and those of other muscles were 0.50, 0.65, 0.28, and 0.43 (P < 0.05) or greater, respectively, for the muscles included in the study. Myoglobin content of SM, BF, GM, and TB was highly correlated with that of LL (r = 0.83, 0.82, 0.72, and 0.67, respectively; P < 0.05). Muscle pH of LL was correlated with pH of SM and GM (r = 0.44 and 0.53; P < 0.05), but not (P > 0.05) pH of BF or TB. Muscle effects generally explained more variation in a*, b*, hue angle, chroma, and E than animal effects. However, the relative importance of animal effects increased as display continued. These data indicate that animal effects were consistent across muscles, though muscle effects had greater contribution to color stability variation. Furthermore, strong relationships between LL color stability and the stability of other muscles indicate that strategies developed to manage animal variation in LL color stability would beneficially affect the entire carcass.     

Evaluation of slice shear force as an objective method of assessing beef longissimus tenderness.

Experiments were conducted to develop an optimal protocol for measurement of slice shear force (SSF) and to evaluate SSF as an objective method of assessing beef longissimus tenderness. Whereas six cylindrical, 1.27-cm-diameter cores are typically removed from each steak for Warner-Bratzler shear force (WBSF) determination, a single 1-cm-thick, 5-cm-long slice is removed from the lateral end of each longissimus steak for SSF. For either technique, samples are removed parallel to the muscle fiber orientation and sheared across the fibers. Whereas WBSF uses a V-shaped blade, SSF uses a flat blade with the same thickness (1.016 mm) and degree of bevel (half-round) on the shearing edge. In Exp. 1, longissimus steaks were acquired from 60 beef carcasses to determine the effects of belt grill cooking rate (very rapid vs. rapid) and conditions of SSF measurement (hot vs cold) on the relationship of SSF with trained sensory panel (TSP) tenderness rating. Slice shear force was more strongly correlated with TSP tenderness rating when SSF measurement was conducted immediately after cooking (r = -.74 to -.76) than when steaks were chilled (24 h, 4 degrees C) before SSF measurement (r = -.57 to -.72). When SSF measurement was conducted immediately after cooking, the relationship of SSF with TSP tenderness rating did not differ among the belt grill cooking protocols used to cook the SSF steak. In Exp. 2, longissimus steaks were acquired from 479 beef carcasses to compare the ability of SSF and WBSF of 1.27-cm-diameter cores to predict TSP tenderness ratings. Slice shear force was more strongly correlated with sensory panel tenderness rating than was WBSF (r = -.82 vs -.77). In Exp. 3, longissimus steaks were acquired from 110 beef carcasses to evaluate the repeatability (.91) of SSF over a broad range of tenderness. Slice shear force is a more rapid, more accurate, and technically less difficult technique than WBSF. Use of the SSF technique could facilitate the collection of more accurate data and should allow the detection of treatment differences with reduced numbers of observations and reduced time requirements, thereby reducing research costs.     

Flavor characterization of top-blade, top-sirloin, and tenderloin steaks as affected by pH, maturity, and marbling

Little information is available in the literature on the interrelationships and interactions among pH, aging time, marbling, and maturity on the flavor profile of some beef muscles commonly used for steaks. To investigate these effects on beef flavor, the infraspinatus (top-blade steak) from the chuck clod, the gluteus medius (top-sirloin steak) from the sirloin, and the psoas major (tenderloin steak) from the loin were obtained from A- (n = 80) and B-maturity (n = 60) carcasses with either Slight (n = 68) or Small (n = 72) marbling, and with either normal (< or = 5.7; n = 80) or high (> or = 6.0; n = 60) pH. Muscles were selected from two commercial processing plants at six different sampling times to evaluate factors that affect the flavor profile of cooked beef steaks. Muscles were vacuum-aged for 7, 14, 21, or 35 d, and a highly trained, flavor-profile sensory panel evaluated charbroiled steaks from these muscles. Numerous statistical interactions (P < 0.05) were detected for flavor attributes of the different muscles. In general, muscles from high pH (dark cutting) carcasses had less typical beef flavor identity and less brown-roasted flavor than those from carcasses with normal pH. Aging longer than 21 d generally decreased beef flavor identity. Top-blade steaks generally had less intense beef flavor identity and more intense bloody/serumy flavor than did top-sirloin and tenderloin steaks. Tenderloin and top-sirloin steaks of normal pH generally had the most brown-roasted flavor, especially when aged 21 d or less. Small degree of marbling generally resulted in a more rancid flavor compared with Slight marbling, but marbling had no other appreciable effects on the flavor profile. Aging steaks for 35 d increased (P < 0.05) the metallic flavor compared with aging for only 7 or 14 d. Top-sirloin steaks had a more intense (P < 0.05) sour flavor than did top-blade steaks, and steaks from carcasses with a high pH were more rancid (P < 0.05) than steaks from carcasses with normal pH. Vacuum-aging top-blade, top-sirloin, and tenderloin steaks to 21 or 35 d postmortem generally increased metallic and rancid flavors and increased sour flavor in top-sirloin steaks that were high in pH.     

Relationship between blood hemoglobin, plasma and tissue iron, muscle heme pigment, and carcass color of veal.

In 41 veal calves divided into three groups and fed different levels of dietary iron, blood hemoglobin, plasma iron, liver, spleen, and muscle iron, muscle heme pigment, and carcass muscle color at slaughter were studied. At 45 min postmortem, total carcass color was visually evaluated in the 41 carcasses. In different muscles of the carcasses the color was measured instrumentally using an invasive color measurement method at 45 min postmortem (MCDI score) and a surface color measurement method at 20 h postmortem (Minolta L*, a*, b*, and Chroma scores). Among the three groups, differences (P less than .05) in muscle iron concentrations, muscle heme pigment concentrations, and Minolta a*, b*, and Chroma scores were found. Most striking were the differences in mean iron concentrations in the longissimus thoracis muscles between Groups A (29 micrograms/g DM) and B (44 micrograms/g DM) and in the semimembranosus muscles between Groups A (31 micrograms/g DM) and C (45 micrograms/g DM). The correlations found between Minolta L*, a*, or Chroma score and the iron and heme pigment concentrations in the semimembranosus muscles were high in comparison with those found in the longissimus thoracis and rectus abdominis muscles. Compared with the plasma iron concentration, the blood hemoglobin concentration showed higher correlations with muscle iron and muscle heme pigment concentrations. It can be concluded that different iron concentrations in the milk replacer during the first 7 wk of fattening influence, to some extent, muscle iron and muscle heme pigment at slaughter. However, these differences were not measurable in the overall visual color evaluation of the carcass surface muscles.     

Technical note: use of belt grill cookery and slice shear force for assessment of pork longissimus tenderness

The present experiments were conducted to determine whether improved beef longissimus shear force methodology could be used to assess pork longissimus tenderness. Specifically, three experiments were conducted to: 1) determine the effect of belt grill (BG) cookery on repeatability of pork longissimus Warner-Bratzler shear force (WBSF), 2) compare the correlation of WBSF and slice shear force (SSF) with trained sensory panel tenderness ratings, and 3) estimate the repeatability of pork longissimus SSF for chops cooked with a BG. In Exp. 1 and 2, the longissimus was removed from the left side of each carcass (Exp. 1, n = 25; Exp. 2, n = 23) at 1 d postmortem and immediately frozen to maximize variation in tenderness. In Exp. 1, chops were cooked with either open-hearth electric broilers (OH) or BG, and WBSF was measured. Percentage of cooking loss was lower (P < 0.001) and less variable for chops cooked with a BG (23.2%; SD = 1.7%) vs. OH (27.6%; SD = 3.0%). Estimates of the repeatability of WBSF were similar for chops cooked with OH (0.61) and BG (0.59). Although significant (P < 0.05), differences in WBSF (4.1 vs. 3.9 kg) between cooking methods accounted for less than 5% of the total variation in WBSF. In Exp. 2, the correlation of SSF (r = -0.72; P < 0.001) with trained sensory panel tenderness ratings was slightly stronger than the correlation of WBSF (r = -0.66; P < 0.001) with trained sensory panel tenderness ratings, indicating that the two methods had a similar ability to predict tenderness ratings. In Exp. 3, duplicate samples from 372 carcasses at 2 and 10 d postmortem were obtained, cooked with BG, and SSF was determined. The repeatability of SSF was 0.90, which is comparable to repeatability estimates for beef and lamb. Use of BG cookery and SSF could facilitate the collection of accurate pork longissimus tenderness data. Time and labor savings associated with BG cookery and the SSF technique should help to decrease research costs.     

Effectiveness of the SmartMV prototype BeefCam System to sort beef carcasses into expected palatability groups

This study was conducted to determine the effectiveness of the SmartMV prototype BeefCam Video Imaging System (prototype BeefCam) for classifying beef carcasses into palatability ("certified" or "not certified" as palatable) groups. Carcasses (n = 769) were selected from four beef-packing plants to represent three USDA quality grade groups (Top Choice, TC; Low Choice, LC; and Select, SE). Following chilling, a prototype BeefCam image of the longissimus muscle was obtained for each carcass. Strip loins were collected from the left side of each carcass and aged for 10 d; Warner-Bratzler shear force (WBSF; n = 769) values and consumer panel ratings (hedonic, end-anchored, 9-point ratings for overall like/dislike; n = 500 carcasses) were obtained for cooked steaks. Using information from the images, two regression models were developed to predict the first principal component of WBSF and consumer panel ratings for sorting carcasses based on expected eating quality. Model I used only prototype BeefCam output, whereas Model II used prototype BeefCam output and a coded value for quality grade group. For both models, carcasses with a predicted value of less than 0.0 were certified as producing palatable beef Additional carcasses (n = 292) were evaluated at a fifth and separate packing plant by prototype BeefCam to validate Models I and II. A strip loin was collected from each carcass and WBSF was measured after 14 d of aging. The percentages of validation carcasses that generated tough (WBSF > or = 4.5 kg) steaks were 6.5,5.8,10.7, and 7.9% for, TC, LC, SE, and all carcasses, respectively. Use of Model I certified 51.9, 47.6, 43.8, and 47.3% of TC, LC, SE, and all carcasses, respectively. Of the carcasses certified by use of Model I, 0.0,0.0, 4.1, and 1.4% of TC, LC, SE, and all carcasses, respectively, generated tough steaks. Use of Model II certified 59.7, 47.6, 25.0, and 42.1% of TC, LC, SE, and all carcasses, respectively. Of the carcasses certified by use of Model II, 2.2, 0.0, 3.6, and 1.6% of TC, LC, SE, and all carcasses, respectively, generated tough steaks. For both models, the frequency of carcasses that produced tough steaks in the certified group was lower (P < 0.05) for all validation carcasses sampled compared with that of the original carcass population. Based on the decrease in the frequency of carcasses that produced tough steaks, further development of a commercial BeefCam system is warranted.     

Utilization of beef from different cattle phenotypes to produce a guaranteed tender beef product

Cattle (n = 303) were visually selected from four feed yards to represent six phenotypes (English [EN; n = 50], 3/4 English-1/4 Brahman [ENB; n = 52], 1/2 English-1/2 Exotic [ENEX; n = 56], 1/2 English-1/4 Exotic-1/4 Brahman [ENEXB; n = 47], 3/4 Exotic-1/4 Brahman [EXB; n = 49], and 1/2 Exotic-1/4 English-1/4 Brahman [EXENB; n = 49]). Carcasses were processed at a commercial beef packing facility, and strip loins were collected after 48-h chilling. Strip loins were aged for 14 d at 2 degrees C and frozen at -20 degrees C for 3 to 5 d before three 2.5-cm-thick steaks were cut for Warner-Bratzler shear force (WBSF) determinations and sensory evaluations. Phenotype EN had the highest (P < 0.05) adjusted fat thickness, and EXB had adjusted fat thickness that was lower (P < 0.05) than all other phenotypes except EXENB. Carcasses of EN and ENB had smaller (P < 0.05) longissimus muscle areas than phenotypes ENEX, EXB, and EXENB. Phenotype EN produced carcasses with the highest (P < 0.05) numerical yield grade, whereas carcasses originating from phenotype EXB had lower (P < 0.05) numerical yield grades than all other phenotypes except ENEX. No differences (P > 0.05) were found among phenotypes for mean WBSF values or sensory panel ratings for initial and sustained tenderness, initial and sustained juiciness, beef flavor characteristics, and overall mouthfeel. More than 90% of steaks from carcasses of all phenotypes had WBSF values less than 3.6 kg when cooked to an internal cooked temperature of 70 degrees C. Results from this study indicated that all phenotypes represented in this study could be managed to produce tender beef.     

Subjective and objective evaluation of veal lean color

Because veal lean color continues to be a primary factor that determines veal carcass value and is typically assessed by subjective means, it is important to explore objective methods for color assessment. Objective and subjective evaluations of veal flank and breast lean color were compared as predictors of longissimus lean color at 24 h postmortem. One hundred fifty special-fed Holstein veal calves were Kosher-slaughtered with blood samples collected upon exsanguination and analyzed for hematocrit and hemoglobin content. Lean color was evaluated in the flank and breast at 0, 6, 12, and 24 h postmortem. Color of the longissimus was evaluated at 6 h, when possible, and at 24 h. A panel of three trained individuals used a 5-point color standard developed in the Netherlands to visually evaluate lean color. A Minolta Chromameter CR-300 was used to obtain L*, a*, and b* values. A plant employee assigned packer grades at slaughter. Temperature and pH were also measured at each time period. Hemoglobin was more highly correlated than hematocrit with colorimeter values. Hemoglobin levels correlated well with a* values of the flank at 0 h postmortem (r = 0.52) although the correlation declined at 24 h (r = 0.30). The correlation between packer grades and 24-h visual loin color was r = 0.41. Visual loin color at 24 h postmortem was selected as the predicted variable for regression analysis. Temperature and pH did not contribute significantly to any prediction equations. The equation using breast L*, a*, and b* values at 24 h postmortem to predict 24-h loin color gave a higher prediction coefficient (R2 = 0.44) than the corresponding equation using 0-h breast values (R2 = 0.28). Objective measurement of lean color may be useful in veal carcass grading because it is more precise than subjective methods and would allow for uniformity among processing plants.     

The influence of diets supplemented with conjugated linoleic acid, selenium, and vitamin E, with or without animal protein, on the quality of pork from female pigs

Pork from the LM and semimembranosus muscle (SM) of 59 female Duroc-cross pigs with a mean carcass weight of 80.1 kg (SD = 3.2) were assessed for quality. The pigs were grown on diets containing either animal and plant products (the animal group) or plant products only (the plant group), with or without a supplement (0.31% of the diet) containing extra CLA, selenium, and vitamin E. The 45-min postmortem pH of LM was unaffected by dietary treatment (mean 6.44, SD = 0.21), but the ultimate pH (pHu) was lower for the supplemented animal group for both muscles within the animal group (P < 0.04). Water-holding capacity in terms of drip loss for SM and expressed juice levels for LM, but not cooking loss, was also lower for the supplemented animal group (P < 0.01), but this difference was reduced after adjustment to a constant pHu (P < 0.07). Warner-Bratzler shear force (WBSF) values were greater for the plant group for LM only (P < 0.05), both before and after pHu adjustment. Differences between dietary treatment groups for color (L*, a*, and b*) were small and seldom significant before or after pHu adjustment. Sensory assessment of LM samples (with 5% subcutaneous fat added) from 32 pigs (8 per group) for 8 odor notes and 11 flavor notes by a trained analytical sensory panel of 13 people revealed no differences between the groups, except that the percentage of instances in which a rancid odor was detected was greater for the supplemented plant group compared with the control plant group (25 vs. 12%). Differences (P < 0.001) were shown between the muscles such that, relative to SM, LM had lower pHu values, greater drip losses, greater WBSF values, greater L* values, and lower chroma values, but similar levels of cooking loss. It is concluded that the dietary treatments imposed to improve the nutritional value of pork had some effects on certain meat quality parameters, but that the overall effects on appearance and palatability were small and unlikely to be of practical importance.     

Effects of postexsanguination vascular infusion of carcasses with calcium chloride or a solution of saccharides,sodium chloride,and phosphates on beef display-color stability

Hereford x Angus crossbred steers (n = 36) were stunned, exsanguinated, and infused via the carotid artery either with an aqueous solution containing 98.52% water, 0.97% saccharides, 0.23% sodium chloride, and 0.28% phosphates (MPSC; n = 12) or with 0.3 M CaCl2 (n = 12). The remaining 12 steers served as noninfused controls. At 48 h postmortem, the quadriceps muscles and subcutaneous fat were removed from the carcasses, frozen, and later made into ground beef (18 to 20% fat). The longissimus lumborum (LL), semimembranosus, and psoas major (PM) also were removed, vacuum packaged, aged until 14 d postmortem, and then one steak was sliced from each muscle for visual and instrumental color evaluations. The inside (ISM) and outside (OSM) portions of the SM were evaluated separately. The LL and OSM steaks from MPSC-infused carcasses had a lighter red (P < 0.05) initial appearance than steaks from the other treatments. The LL steaks from noninfused carcasses had the most (P < 0.05) uniform color; the MPSC treatment was intermediate, and the CaCl2 treatment was the most two-toned. Steaks from both infusion treatments had higher (P < 0.05) L* values for the LL, ISM, and OSM muscles compared with noninfused carcasses. In general, the LL from CaCl2-infused carcasses had lower (P < 0.05) a* values, saturation indices, and 630 nm to 580 nm reflectance values, and had larger (P < 0.05) hue angles. Infusion with MPSC increased (P < 0.05) hue angles in the LL and OSM. Display color stability was lowest (P < 0.05) for LL steaks from CaCl2-infused carcasses, whereas steaks from MPSC-infused carcasses were lighter red in initial color, but otherwise had display color stability similar to those from noninfused carcasses. No differences (P > 0.05) due to infusion were found for any color traits for the PM muscle and ground beef. Carotid artery vascular infusion of carcasses with CaCl2 resulted in undesirable meat colors, whereas the MPSC solution lightened loin and inside round color in a desirable way, but the color stability was slightly less compared to muscle from noninfused carcasses. Infusion effects were not consistent among muscles, and further research will be needed to determine what caused these differences.     

Effects of a unique application of electrical stimulation on tenderness, color, and quality attributes of the beef longissimus muscle

This study evaluated effects of four uniquely applied beef carcass electrical stimulation (ES) treatments on USDA grade factors, muscle color, subprimal purge loss, cooked steak weight loss, and cooked steak tenderness. One side of each (n = 284) beef carcass was subjected to ES using one of four treatments (medium voltage for medium duration, MVMD; medium voltage for long duration, MVLD; high voltage for medium duration, HVMD; or high voltage for long duration, HVLD) and was compared to its corresponding non-ES control side. Electrical stimulation of beef sides was applied focusing on middle meats while preventing severe contraction of the round and chuck. From matched (ES and control) sides of 120 carcasses (10 each of Select, low Choice, and upper two-thirds of Choice in each of the four ES treatments), longissimus steaks (2.5 cm thick) were cooked and used for Warner-Bratzler shear force (WBS) analysis. Mean marbling scores (n = 284) for stimulated sides did not differ (P = .923) from those for control sides within ES treatment classes. Mean values for CIE L*, a*, and b* of lean color (n = 284) were higher (P < .05) for MVMD, MVLD, HVMD, and HVLD treated sides than for the respective control sides. When WBS values for steaks were adjusted to an equal visual degree of doneness, WBS values (n = 120) were lower (P < .05) for ES treated sides than for control sides for all four types of ES application treatments. Treatment responses were not influenced by USDA Quality Grade group. For those carcasses for which the control sides had WBS values greater than 4.5 kg, matching sides treated with MVMD, MVLD, HVMD, or HVLD had WBS values less than 4.5 kg 50, 88, 60, and 75% of the time, respectively. Mean cooked steak weight loss (n = 120), adjusted to an equal visual degree of doneness, and mean purge loss (n = 24) did not differ with ES treatment.     

Mechanical measures of uncooked beef longissimus muscle can predict sensory panel tenderness and Warner-Bratzler shear force of cooked steaks

Two experiments were conducted to investigate mechanical measures of tenderness on uncooked USDA Select longissimus muscle as a means to predict Warner-Bratzler shear force (WBSF) and trained sensory panel tenderness (SPT) of cooked steaks. In Exp. 1, strip loins (n = 24) were aged 14 d postmortem and fabricated into steaks (2.54 cm). Medial, center, and lateral locations within uncooked steaks were evaluated by a plumb bob device and correlated with WBSF and SPT of cooked steaks. In Exp. 2, 24 strip loins were used to evaluate how well plumb bob and needle probe devices used on uncooked steaks predicted WBSF and SPT of cooked steaks. At 2 d postmortem, two steaks were fabricated from the anterior end. One uncooked steak (2.54 cm) was assigned to the plumb bob treatment and the other uncooked steak (5.08 cm) was assigned to needle probe treatment. At 14 d postmortem, one uncooked steak (5.08 cm) was assigned to needle probe treatment, a second uncooked steak (2.54 cm) was assigned to plumb bob treatment, whereas the remaining steaks (2.54 cm) were cooked and evaluated by a trained sensory panel and WBSF device. In Exp. 1, average plumb bob values were negatively correlated (P < 0.05) to average SPT scores (r = -0.48). However, correlations between WBSF and plumb bob values for medial, lateral, and average of all sections were not significant (P > 0.05). In Exp. 2, regression models to predict SPT from needle probe and plumb bob measurements individually taken at 2 d postmortem had R2 of 0.54 and 0.51, respectively. Combining needle probe and plumb bob measurements resulted in an R2 of 0.76; when quadratic terms for both variables were in the model, the R2 was 0.80. Regressing needle probe and plumb bob measurements at 2 d postmortem with WBSF produced R2 values of 0.51 and 0.45, respectively. If linear terms of both probes were combined to predict WBSF, the R2 increased to 0.77. An equation to predict WBSF, including both the linear and quadratic terms of needle probe and plumb bob measurements, resulted in an R2 of 0.84. Using plumb bob and needle probe devices on uncooked longissimus muscle at 2 d postmortem can predict cooked WBSF and SPT of USDA Select Grade steaks at 14 d postmortem.