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ANIMAL PRODUCTS |
* Department of Animal Sciences, Colorado State University, Fort Collins 80523; and
Department of Statistics, Colorado State University, Fort Collins 80523
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Abstract |
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 Top Abstract INTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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Key Words: beef • color • pH • value • quality
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INTRODUCTION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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). The color and appearance of fresh product has been characterized as the largest deciding factor as to whether or not a customer will purchase a cut of beef at retail (Dunsing, 1959; Jeremiah et al., 1972; Kropf, 1980). A dark-cutting lean color is an issue during beef carcass grading and is a result of a metabolic condition that is the consequence of elevated pH values of valuable beef cuts, especially the ribeye (Berg and Butterfield, 1976). In value-based cattle pricing systems, carcasses that are considered less desirable with respect to color of the ribeye (i.e., dark cutters) generally do not return full value to producers (USDA, 1997). Discounted prices are detrimental to producers who market cattle using grid-pricing systems, by which approximately 34% of the beef in the United States is marketed (Smith et al., 2005). Smith et al. (2005) reported that the dark-cutting condition is found in 1.5% of the carcasses in the United States; as a result, the dark-cutting condition has potential for a large negative economic effect on the beef industry. By identifying beef muscles that are not affected by ribeye lean color, it may be possible to capture unrealized value of dark-cutting carcasses by aggregating the individual values of acceptable muscles that can be merchandised at full price. This study was conducted to identify ideal ranges of color for various beef muscles and to determine which muscles within a carcass classified by USDA graders as a dark cutter should be valued at full price. |
MATERIALS AND METHODS |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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Carcass Dissection and Muscle Analysis
Between December 2006 and February 2007, alternating sides of beef carcasses classified as having ribeyes exhibiting 1/3, 1/2, or full degree of dark cutting (DEGDC) by USDA graders at chain speeds (USDA, 1997) were purchased from 2 commercial beef packing companies and transported under refrigerated conditions to the Colorado State University Meat Laboratory for fabrication and dissection; carcass chill times were within 36 to 48 h. After weighing to determine the chilled carcass weight, carcass sides were sequentially fabricated into primal cuts [Institutional Meat Purchase Specifications (IMPS) #113 and 117 chuck/shank, IMPS #120 brisket, IMPS #103 rib, IMPS #172 loin, IMPS #158 round, IMPS #121 plate, and IMPS #193 flank] and subprimal cuts (IMPS #114E clod heart-triceps brachii long head, IMPS #114E clod heart-triceps brachii lateral head, IMPS #114D top blade-infraspinatus, IMPS #116B mock tender-supraspinatus, IMPS #114F petite tender-teres major, IMPS #116D chuck eye roll-complexus/longissimus dorsi/spinalis dorsi/multifidus, IMPS #120A brisket flat-pectoralis profundi, IMPS #112 ribeye roll-complexus/longissimus thoracis/spinalis dorsi/multifidus, IMPS #109B lifter meat-latissimus dorsi, IMPS #184E top sirloin butt-gluteus medius/biceps femoris, IMPS #180 1 x 0 strip loin-longissimus lumborum, IMPS #185A flap meat-obliquus abdominis interni, IMPS #185D tri-tip-tensor fasciae latae, IMPS #189A tenderloin-psoas major, IMPS #193 flank steak-rectus abdominis, IMPS #169 top round-semimembranosus/adductor, IMPS #170A bottom round heel out-biceps femoris/semitendinosus, and IMPS #167A knuckle-vastus lateralis/vastus medialis/vastus intermedius/rectus femoris).
Individual weights of subprimal cuts were recorded. Subprimals then were fabricated into individual muscles, weighed, cut at the halfway point of the long axis of the muscle, and the face of each cut was sliced using a meat slicer (Model 2712, Hobart, Troy, OH) to obtain a 0.254-cm-thick sample for pH analysis. After a 20-min bloom time, lean color (L*, a*, and b*) was measured in the face of the remaining muscle half using a portable spectrophotometer with a port size of 1.27 cm, a D-65 illuminant, and calibrated using a black and a white tile (Miniscan XE Model 45/0-L, Hunter Laboratories, Reston, VA). Final color values were the mean of the 3 measurements per muscle. After measuring the lean color, the remaining muscle half was vacuum-packaged, aged for 14 d postmortem, and stored at –20°C to be used for further sensory and tenderness analysis.
Each 0.254-cm sample slice, obtained from the individual muscles, was diluted 10:1 (wt/vol) with double-distilled deionized water and homogenized (Model 1120 Waring Blender, Dynamics Corp., New Hartford, CT). The pH of the homogenate was determined using a pH meter (Orion 2 Star pH Benchtop, Thermo Electron Corp., Waltham, MA).
Steak Preparation
Steaks (2.54-cm thick) for sensory panel evaluation and Warner-Bratzler shear force (WBSF) measurement were cut in the frozen state using a band saw (Model 400, AEW-Thurne, AEW Engineering Co. Ltd., Norwich, UL) under refrigerated conditions (4°C). A representative 14 muscles were evaluated in the study (individual muscles making up the majority of the weight of their respective subprimals) and were further analyzed for WBSF and sensory panel analysis. Beef muscles evaluated for sensory characteristics and WBSF included the following: longissimus lumborum (SLLD), longissimus thoracis (RLD), gluteus medius (GM), infraspinatus (IN), tensor fasciae latae, vastus lateralis (VL), round biceps femoris (RBF), psoas major (PM), semimembranosus (SM), semitendinosus (ST), pectoralis profundi (DP), triceps brachii long head (TBL), latissimus dorsi, and chuck complexus. Steaks from the teres major (TM) were cut for WBSF evaluation only. Steaks were cut such that the first steak from the face was designated for WBSF and the second steak was designated for sensory panel analysis.
Steaks were individually labeled, vacuum-packaged, and stored at –20°C. Steak samples remained frozen during the entire fabrication process and were never subjected to temperature abuse.
Sensory Panel
Panelists were subjected to conditions approved by the Human Use in Research Committee of Colorado State University. Before initiation of sensory panel analysis, panelists were trained by the procedures outlined by Meilgaard et al. (2007), AMSA (1995), and Meisinger (2005). Panelists were screened to ensure that they could identify overall tenderness, overall juiciness, beef flavor intensity, and the following off-flavors: sour, bitter, metallic, liver, serum, and oxidized. Panelist screening was conducted using a modified version of the triangle test. Correct selections of sensory attributes and off-flavors greater than 70% were required for potential panelists to be selected for the actual panel.
Panel sessions were conducted for 5 wk, until all 60 panel sessions were completed. A maximum of 3 sessions per day were conducted, and the panelists were rotated in and out so that 1 panelist would not participate in more than 2 panel sessions in a day. Panels included 8 trained panelists in each session, and panelists evaluated 14 samples per panel session, each sample representing 1 of the 14 muscles chosen for sensory evaluation. Each DEGDC (1/3, 1/2, and full) was represented in each panel session. Every panel session contained 5 steaks from 2 of the DEGDC and 4 steaks from the remaining DEGDC. The random assignment of steaks to panels was conducted in a rotating manner, resulting in each DEGDC being represented by 4 steaks every third session.
Before cooking, steaks for sensory evaluation were tempered for 24 h at 2°C. Steaks were cooked on an electric grill (Salton Clamshell Grill Model No. GR39A, Salton Inc., Lake Forest, IL) to a target internal temperature of 70°C. Initial temperature, peak off-temperature, and cooking loss were recorded for each steak. Initial and cooked temperatures were recorded using a type K thermocouple (Model HH-21 Hand-Held Microprocessor Digital Thermometer, Omega Engineering Inc., Stamford, CT). After cooking, the steaks were cut into cubes (1.3 cm x 1.3 cm x the thickness of the cooked steak), and care was taken to ensure that no large amounts of connective tissue or cooked edges were contained in the sample cubes. Samples were placed in ceramic bowls, covered with foil, and clearly identified with a letter code before being placed in a warming oven at 54°C until presentation to the trained sensory panel; samples did not remain for more than 20 min in the warming oven before panel evaluation.
Panelists used an 8-point, end-anchored rating scale (AMSA, 1995) to evaluate overall tenderness, overall juiciness, and beef flavor intensity (1 = extremely tough, extremely dry, extremely bland; 8 = extremely tender, extremely juicy, extremely intense). A 2-point scale (1 = detectable, 0 = not detectable) was used to determine the prevalence of off-flavors. Panelists were separated by partitions in the sensory evaluation room. Red incandescent lights were used as the lighting source for each panelist. Unsalted crackers (Premium Saltine Crackers, Kraft Foods Global Inc., Northfield, IL) and distilled water (Big K, Inter-American Products Inc., Cincinnati, OH) were used by panelists to cleanse their palettes between samples (minimum of 1 min between samples).
Warner-Bratzler Shear Force
Shear force steaks were randomly assigned to each shear force data collection day so that each muscle and DEGDC (1/3, 1/2, and full) subclass was represented equally. Shear force steaks were tempered at 2°C for 36 h before cooking. Steaks were cooked using the methods described previously for sensory panel evaluation. Initial temperature, peak off-temperature, and cooking loss were recorded for each steak. After cooking, each steak was allowed to equilibrate to room temperature (22°C). Once the steaks cooled to room temperature, 4 (very small steaks only) to 10 cores (1.27-cm diam.) were removed from each steak parallel to the orientation of the muscle fibers. Each core then was sheared once perpendicular to the muscle fiber orientation using an Instron Testing Machine (Model 4443, Instron Corp., Canton, MA) fitted with a Warner-Bratzler shear head (cross speed of 200 mm/min). Peak shear force measurements were recorded and averaged to obtain a single shear force value for each steak (Gruber et al., 2006).
Survey
A combination telephone- and internet-based survey was used to determine the acceptability thresholds for subprimals in relation to fresh beef lean color. Interviewees were subject to conditions approved by the Human Use in Research Committee of Colorado State University. Color swatches were produced from digital images of the face of the individual muscles from which the lean color was measured. Using the principal component procedure (PROC PRINCOMP) of SAS (SAS Institute, 2004), correlations between color scores were assessed in a 3-dimensional analysis, weighted, and then ranked. First principal component (eigenvalue = 2.196) values of L*, a*, and b* (eigen vectors = 0.467, 0.595, and 0.654, respectively) allowed the researchers to select the appropriate incremental color images of muscles to use as a survey for participants to answer questions concerning ideal colors for lean beef muscle. Six color swatches were chosen, and each color swatch was assigned a letter. First principal component values for each color swatch used in the survey are given in Table 1.
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A list of the top 50 retail food outlets was obtained (Staff, 2006), and of those found to sell fresh whole-muscle beef products, the beef merchandisers of those companies were subsequently called and asked to participate in the survey. Additionally, in-person interviews were conducted when available (9 retailers, 6 chefs). Of the 195 individuals contacted representing retail food outlets located around the United States, 34 completed the survey. Similarly, 105 chefs from around the United States who use beef in their cuisine were contacted to participate in the survey; of the chefs, 33 completed the survey.
Salvage Value Analysis
Previous research suggested that a probability of 0.50 or greater, when data are analyzed logistically, is required to attain favorable odds that end users will find a product acceptable (Platter et al., 2005). Muscles that were determined to have lean color first principal component values exceeding 0.50 probability of acceptance for retail meat merchandisers and food service chefs were assigned a monetary value to determine the salvageable value per carcass. Salvageable carcass value was achieved by utilizing the results from the survey; the weights of individual muscles with acceptable color values were aggregated and assigned a monetary value based on a value associated with average boxed beef values of USDA grades (Choice, Select, No Roll) from 2006 (USDA, 2006).
Statistical Analysis
Color attributes (L*, a*, and b*), pH, WBSF, and the 8-point sensory characteristics were compared by DEGDC (1/3, 1/2, and full) and muscle using repeated measures and ANOVA. Computations were performed using PROC MIXED (SAS Institute, 2004). The model included the main effects for DEGDC group and muscle, the DEGDC x muscle interaction, and a random effect for carcass nested within the DEGDC group. For the evaluation of cooked beef traits (e.g., WBSF and sensory scores), peak off-temperature was added to the model as a covariate when significant (P < 0.05). When no interaction was detected (P > 0.05), DEGDC groups were compared averaged over muscles, and muscles were compared averaged over DEGDC. When the interaction was significant, DEGDC groups were compared separately for each muscle, and muscles were compared separately for each DEGDC. For pH and color attributes (e.g., no covariate), comparisons were made using the LSD method (
= 0.05); for the other variables, mean separation was performed using pairwise t-test comparisons of least squares means. Analyses of variance assumptions were evaluated using a combination of residual plots, normal plots, and tests of normality.
Relationships between the lean color of the ribeye and the lean color of the other muscles were evaluated using linear regression. Muscle color from the 3 color attributes (L*, a*, and b*) was summarized by its first principal component. The ribeye first principal component was the independent variable in the regression. Computations were performed using PROC PRIN-COMP and PROC REG of SAS.
Sensory panel data (off-flavor detection) were analyzed using a repeated measures logistic model. Computations were performed using PROC GLIMMIX of SAS. Effects included in the model, as well as comparisons of main effect and interaction least squares means, were performed in the same manner as in the repeated measures ANOVA model. For variables with very a low frequency of yes responses (i.e., bitter, sour, and oxidized off-flavors), the DBLDOG option was used to aid the convergence.
Acceptability (yes/no) of color swatches of beef lean, evaluated by food service chefs and retail meat merchandisers, was modeled as a function of the first principal component of the color attributes using quadratic logistic regression. The fitted model was used to estimate the first principal component value at which the probability of acceptance exceeds 0.50. Computations were performed using PROC GLIMMIX of SAS.
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RESULTS AND DISCUSSION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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A muscle x DEGDC interaction (P < 0.001) was detected for L*, a*, b*, and pH. The least squares means of pH for the muscle x DEGDC interaction are presented in Table 2. Mean pH values for 1/3, 1/2, and full DEGDC RLD were 5.72, 5.76, and 6.06, respectively. Within DEGDC category, pH for RLD and SLLD muscles did not differ (P > 0.05). Previous research has demonstrated that normal ultimate pH of LM is within the range of 5.40 to 5.79 (Lawrie, 1958; Tarrant and Mothersill, 1977; Zhang et al., 2005). More recent research has shown that a reasonable approximate threshold pH for dark cutting carcasses was 5.87 in the LM (Page et al., 2001). In the present study, regardless of DEGDC category, no muscles had mean pH values of less than 5.60.
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; Page et al., 2001). Consistent with expectations, the mean 1/3 DEGDC GM pH value was less than the mean 1/2 DEGDC GM pH value (P < 0.05; Table 2
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Within a muscle, 1/2 DEGDC pH differed (P < 0.05) from full DEGDC pH for 13 of the 29 muscles (adductor, chuck spinalis dorsi, rectus abdominis, obliquus abdominus interni, IN, rectus femoris, RLD, SLLD, SM, serratus ventralis, and TM). As expected, mean pH values for several muscles (adductor, chuck spinalis dorsi, rectus abdominis, obliquus abdominis interni, IN, rectus femoris, RLD, SLLD, SM, serratus ventralis, and TM) removed from the 1/2 DEGDC carcasses were lower than that for corresponding muscles removed from full DEGDC carcasses (Table 2). Across all muscle and DEGDC categories, 24% of the muscle x DEGDC subclasses had mean pH values lower (P < 0.05) than a 5.87 threshold (Page et al., 2001) for dark-cutting carcasses. Several of the LM mean pH samples from the strip loin and the ribeye roll, in addition to all of the mean LM pH samples from the chuck eye roll, were less than pH 5.87 (Table 2).
A total of 7 muscles (adductor, latissimus dorsi, RLD, sirloin biceps femoris, ST, triceps brachii lateral head, and TBL) from carcasses classified by USDA graders as 1/3 DEGDC, 10 muscles (adductor, DP, RBF, rectus femoris, rib spinalis dorsi, sirloin biceps femoris, SM, supraspinatus, ST, and VL) from the carcasses classified by USDA graders as 1/2 DEGDC, and 5 muscles (GM, RBF, triceps brachii lateral head, TBL, and VL) from the carcasses classified by USDA graders as full DEGDC would have fallen within a calculated 95% confidence limits of the pH values considered normal for those respective muscles (NCBA, 2000); calculations not shown. Variation in pH values among and within muscles can be explained by previous literature due to the presence of nonhomogeneously stored glycogen residues throughout the animal (Howard and Lawrie, 1956). A study conducted by Tarrant and Sherington (1980) found that pH is most frequently affected in the LM compared with 13 other muscles. If pH is associated with color (Egbert and Cornforth, 1986; Wulf et al., 1997, 2002; Wulf and Wise, 1999; Page et al., 2001), then the color should be more frequently affected in the LM as well, when compared with other muscles. This logic helps explain why there was so much variation within and between muscle color values of dark-cutting carcasses; the most variable muscle (LM) was the muscle used to classify (i.e., grade) the carcass, thereby inadvertently adding variation to the color results of the remaining muscles within the carcass. This indicated that LM is not the best muscle to use when predicting the condition of all of the remaining muscles in a carcass.
Beef lean color least squares means for the muscle x DEGDC interaction subclasses are reported in Table 3. The L*, a*, and b* values of beef lean color for dark-cutting carcass muscles by DEGDC were numerically lower than the color values reported for the same muscles from normal carcasses of a previous study (NCBA, 2000). The high amount of color variation in muscles dissected from dark-cutting carcasses was demonstrated to be much greater than the amount of variation in color from the same muscles that were considered normally colored in a previous study (NCBA, 2000). Wulf and Wise (1999) discovered a greater relationship of b* values to dark cutters than L*. Additionally, several studies demonstrated high correlation between a* and b* values (Wulf and Wise, 1999; Page et al., 2001), thus explaining drastic differences due to the dark-cutting condition in a* values compared with normal carcass a* values of a previous study (NCBA, 2000). Furthermore, the larger size of the spectrophotometer port used in the previous NCBA (2000) study on normal carcass lean (2.54-cm vs. 1.27-cm diam.) may have allowed normal carcass lean color reflectance values to be greater as a result of the larger opening, compared with the current study, which would have included flecks of marbling causing color scores to be greater.
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) can be explained by the subjectivity in visual evaluation of a color (i.e., the subjective determination of degree of dark-cutting of a ribeye). Previous studies have noted changes and variation between visual panels when attempting to assess color differences between beef muscles (Okerman and Cahill, 1969; AMSA, 1991). Therefore, a result of the subjectivity of the USDA graders’ evaluation of ribeye color may have resulted in even greater variation of the remaining muscles within each respective carcass. Moreover, Hood (1980) described how muscles can vary in color within animal and within muscle; therefore, color variation may have been dependent upon whether or not the location of the color measurement was a location that happened to be inadvertently more dark than the rest of that particular muscle.
The 3-dimensionality of color (AMSA, 1991; Morgan et al., 1997) prompted the use of principal component analysis. By using the first principal component (explains the greatest amount of variability orthogonally in space) of each muscle, a single value could be assigned to each muscle that was representative of all 3 color values (L*, a*, and b*) concomitantly (Table 4; SAS Institute, 2004). The relationship between the first principal component of the ribeye lean color and the principal component of color measures for various other muscles was investigated using linear regression (Table 5). Results of linear regression showed that the first principal component values for lean L*, a*, and b* of 18 of the 29 muscles (DP, chuck complexus, chuck longissimus dorsi, chuck spinalis dorsi, IN, PM, rectus femoris, rib complexus, rib spinalis dorsi, sirloin biceps femoris, serratus ventralis, TBL, triceps brachii lateral head, tensor fasciae latae, supraspinatus, vastus intermedius, VL, and vastus medialis) were not related (P > 0.05) to the first principal component values for lean color of the ribeye face, once again indicating that color of the carcass ribeye is not an accurate indicator of lean colors for all remaining muscles within a carcass.
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To determine the probability of acceptance of beef lean color, a survey was developed for evaluation by retail meat merchandisers and food service chefs. First principal component values were utilized to develop color swatches (Table 1) to be included in the survey. The probability of acceptance of the first principal component of lean color measures associated with the survey color swatches evaluated by food service chefs and retail meat merchandisers are presented in Figure 1. First principal component values corresponding to a 
0.50 probability of acceptance were between 0.2047 to 2.0981 and 0.7713 to 2.9839 for food service chefs and retail meat merchandisers, respectively. The range of principal component values evaluated in the survey was 3.681 (from –0.0129 to 3.552), where the colors were representative of fully discounted dark cutting-like beef (low numbers) to pale pink veal-like lean (high numbers). The quality grade and associated value of a carcass can only be decreased as a result of the ribeye being too dark, not too light (USDA, 1997; AMSA, 2001); therefore, acceptability of lean color ultimately was determined from the lower acceptable first principal component value thresholds and up.
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) of muscles at a 0.50 probability of acceptance for lean color are stratified by end user (food service chef, retail meat merchandiser), quality grade (Choice, Select), and DEGDC (1/3, 1/2, and full) in Table 6 and represent the difference between the aggregate value of muscles with acceptable color values (probability 0.50) and the same muscles at ungraded commodity boxed beef prices (common pricing scheme for dark-cutting beef carcasses). Salvage value for both Choice and Select grades for chefs did not differ among DEGDC subclasses, although probabilities approached significance. Regardless of quality grade, responses from chefs showed that salvage amounts were numerically greater for 1/3 DEGDC carcasses than 1/2 and full DEGDC carcasses; salvage dollar amounts for 1/2 DEGDC were numerically greater than for full DEGDC. Survey responses collected from merchandisers indicated that Choice and Select salvage amounts were larger (P < 0.05) for 1/3 DEGDC than for full DEGDC carcasses. In general, as the DEGDC increased from 1/3 to full, there were fewer muscles with acceptable color values (data not shown), which resulted in decreased mean salvage values. Nonetheless, all but 6 of the 60 carcasses had at least 1 muscle that was salvageable with regard to acceptable color.
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0.50 probability of acceptance for meat merchandisers and food service chefs was 0.7714 and 0.2205, respectively. The number of muscles with acceptable mean first principal component color values (first principal component values greater than the 0.7714 and 0.2205 thresholds) for retail meat merchandisers and food service chefs was 4 (TBL, RLD, triceps brachii lateral head, and the rib complexus) and 12 (TBL, RLD, triceps brachii lateral head, rib complexus, SM, ST, rib spinalis, TM, serratus ventralis, IN, GM, and the PM) of the 29 muscles evaluated, respectively. WBSF and Sensory Panel Evaluation
No muscle x DEGDC interaction was detected for WBSF (P = 0.213); the main effect of DEGDC was not significant (P = 0.233), but muscle served as a significant source of variation (P < 0.001). Least squares means and percentage of CV for WBSF of individual muscles are presented in Table 7. Ranking of muscles by tenderness was in general agreement with previous reports (Gruber et al., 2006); the PM and IN were among the most tender, whereas the SM and RBF were among the least tender. Previous research suggests that high LM ultimate pH results in more tender WBSF values (Purchas, 1990). Muscles dissected from the dark-cutting carcasses compared with muscles dissected from carcasses considered normal (NCBA, 2000) were found to be numerically slightly more tender, with the exception of the RBF, SM, and TFL; Dransfield (1981) confirms this, stating that, on average, dark-cutting beef was determined to be only marginally more tender than normal beef. Comparable amounts of variation were associated with the means from both the dark-cutting carcasses and those considered normal (NCBA, 2000).
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). Previous studies also have reported differences in sensory attributes between different beef muscles (Dransfield, 1981; Wulf et al., 2002; Meisinger et al., 2005). Findings for tenderness and flavor intensities of dark-cutting muscles in the present study were similar to sensory attributes for muscles from carcasses with normally colored lean analyzed in previous studies (NCBA, 2000; Jones et al., 2004).
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). No differences between DEGDC were reported for any off-flavors (P > 0.05); no interaction was detected for any off-flavors (P > 0.05). Off-flavors detected were similar to those found within the TM, VL, IN, rectus femoris, and triceps brachii previously investigated on normal beef carcasses (Meisinger, 2005). Detectable off-flavors can be attributed to the individual muscles themselves containing off-flavors that will be present regardless of whether or not the carcass is a dark cutter. Therefore, off-flavors detected should not cause any decrease in carcass value, because they would likely be detected in normal carcasses as well. A sensory evaluation of muscles from dark cutters and muscles from normal carcasses, however, should be conducted in the future to further verify this suggestion.
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Footnotes |
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2 Corresponding author: Keith.Belk{at}Colostate.edu
Received for publication October 26, 2007. Accepted for publication March 5, 2008.
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LITERATURE CITED |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
) and food service chefs (•). Regression equation for retail meat merchandisers (•••): {Pi = exp[–3.6573 + (5.9671 x PC)] + [–1.5890 x PC2]/1 + exp[–3.6573 + (5.9671 x PC)] + [–1.5890 x PC2]}. Regression equation for chefs (——); {Pi = exp[–0.9907 + (5.5303 x PC)] + [–3.4955 x PC2] + [0.5171 x PC3]/1 + exp[–0.9907 + (5.5303 x PC)] + [–3.4955 x PC2] + [0.5171 x PC3]}. Fit statistics of 
2/degrees of freedom for chef and merchandiser lines are 1.03 and 1.08, respectively (values close to 1.00 are a closer fit). Principle components take into account L*, a*, and b* values; eights are assigned to each value and then ranked; colors from this ranking range from fully discounted dark-cutting-like beef (low values) to pale pink veal-like (high values) lean color.