Effects of marbling and shear force on consumers' willingness to pay for beef strip loin steaks

Experimental economic procedures were used to measure the effects of changes in marbling score and Warner-Bratzler shear force (WBSF) value on consumer purchasing behavior and willingness to pay for beef strip loin steaks (n = 541). Consumers were more likely to bid on a steak during the experimental auction if the steak had a high marbling score or low WBSF value. Averaging across all consumers in the study (n = 489), the predicted odds that consumers would submit a nonzero bid were favorable for steaks with a marbling score greater than Modest(50) or a WBSF value less than 3.9 kg. Bid prices for steaks were analyzed with respect to changes in steak marbling score, WBSF value, quality grade marketing category classification (Select, Low Choice, Premium Choice, and Prime), and WBSF marketing category classification (very tender, 5.40 kg). The percentage of bids that were zero was highest (P < 0.05) for Select steaks, intermediate (P < 0.05) for Low Choice steaks, and lower (P <0.05) for Premium Choice or Prime steaks. Steaks in the very tender category had the lowest (P < 0.05) percentage of zero bids, and steaks in the slightly tough and very tough categories had the highest (P < 0.05) percentage of zero bids submitted from "buyers" in the auction. Premium Choice and Prime steaks were valued higher (P < 0.05) than Select steaks by consumers. On average, Premium Choice steaks received a 0.89 dollars/kg premium, and Prime steaks received a 2.47 dollars/kg premium over the mean bid price for Select steaks. Predicted mean bid prices for steaks decreased by 1.02 dollars/kg for each 1 kg increase in WBSF value. On average, steaks in the very tender marketing category received a higher (P < 0.05) bid price than the bid price for steaks in the slightly tender, slightly tough, and very tough categories (+0.83 dollars/kg, +2.09 dollars/kg, and +2.55 dollars/kg, respectively). Mean bid prices for steaks from the slightly tough and very tough categories did not differ (P = 0.184). Compared with the mean bid price for steaks in the slightly tender category, steaks from the slightly tough and very tough categories were discounted (P < 0.05) by 1.26 dollars/kg and 1.72 dollars/kg, respectively. Results suggest that marbling score and WBSF influence both the probability that consumers will purchase and the price they are willing to pay for strip loin steaks.     

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.     

Consumer acceptance of calcium chloride-marinated top loin steaks

In this study, a multi-city, retail consumer survey was used to determine whether marinating in calcium chloride at 72 h postmortem improves consumer and trained sensory panel evaluations of beef loin steaks, Warner-Bratzler shear force (WBSF) values, and the value of CaCl2 marinades to improve tenderness in a national consumer market. Boneless strip loin subprimals (n = 8) were obtained from eight, not electrically stimulated, USDA Standard-grade carcasses, halved, and alternating ends were marinated with 200 mM CaCl2 at 5% (wt/wt) or not injected (controls). Strip loins were then aged for 7 d in vacuum packages at 2 degrees C before WBSF, trained or consumer evaluations. Four trained research teams traveled on the same 7-d period to collect the consumer data. Consumers (n = 393; minimum of 10 consumers/panel, three panels/store, three stores/city, and four cities) varying widely in income level, education, and gender evaluated the steaks for tenderness, beef flavor, juiciness, and overall quality in each of three supermarkets in major cities (Los Angeles, CA; Baltimore, MD; Chicago, IL; and Dallas, TX). The average improvement (P < 0.05) in WBSF for steaks marinated with CaCl2 was 1.39 kg. Trained panelists scored marinated steaks higher (P < 0.05) than control steaks in sustained juiciness (6.00 vs. 5.09), beef flavor (6.31 vs. 5.64), and overall mouth-feel (5.98 vs. 4.93). Consumers also rated marinated steaks higher (P < 0.05) than control steaks in juiciness (5.98 vs. 5.45), beef flavor (6.70 vs. 6.05), tenderness (6.75 vs. 5.89), and overall quality (6.68 vs. 6.20). Consumers in this study would pay dollar 0.95/kg more for steaks marinated with CaCl2, adding dollar 21.64 to the value of a loin from tough carcasses. These results indicate that consumers can differentiate tenderness levels and are willing to pay a premium for calcium chloride marinating to effectively improve the quality of beef loin steaks.     

Evaluation of the Tendertec beef grading instrument to predict the tenderness of steaks from beef carcasses

Four experiments were conducted, using carcasses from cattle identified for anticipated variability in tenderness (Exp. 1, 2, and 3) and carcasses selected for variability in physiological maturity and marbling score (Exp. 4), to evaluate the ability of the Tendertec Mark III Beef Grading Probe (Tendertec) to predict tenderness of steaks from beef carcasses. In Exp. 1, 2, and 3, longissimus steaks were aged for different periods of time, cooked to a medium degree of doneness (70 degrees C), and evaluated for Warner-Bratzler shear force (WBS) and trained sensory panel ratings. In Exp. 4, longissimus steaks were aged 14 d and cooked to 60, 65, 70, 75, or 80 degrees C for WBS tests and to 65 or 75 degrees C for sensory panel evaluations. Tendertec output variables were not correlated with 1) 24-h calpastatin activity, steak WBS (following 1, 4, 7, 14, 21, or 35 d of aging), or d-14 sensory panel tenderness ratings in Exp. 1 (n = 467 carcasses) or 2) 14-d WBS in Exp. 2 (n = 202 carcasses). However, in Exp. 3 (n = 29 carcasses), Tendertec output variables were correlated (P < 0.05) with tenderness of steaks aged 1, 21, 28, or 35 d, and we were able to separate carcasses into groups yielding tough, acceptable, and tender steaks. In Exp. 4 (n = 70), Tendertec output variables were correlated (P < 0.05) with steak WBS at 60 degrees C and with steak ratings for muscle fiber tenderness, connective tissue amount, and overall tenderness at 65 degrees C, but these relationships weakened (P > 0.05) as degree of doneness increased. Consequently, Tendertec output variables only were effective for stratifying carcasses according to tenderness when steaks from those carcasses in Exp. 4 were cooked to a rare or medium-rare degree of doneness. Although Tendertec was able to sort carcasses of older, mature cattle based on tenderness of steaks at some cooked end points, it failed to detect tenderness differences in steaks derived from youthful carcasses consistently, and was thus of limited value as an instrument for use in improving the quality, consistency, and uniformity of the U.S. fed-beef supply.     

Using the near-infrared system to sort various beef middle and end muscle cuts into tenderness categories

The objectives of this study were to determine the effectiveness of a visible-near-infrared (VIS-NIR) system to predict the ultimate tenderness rating of various beef muscles and conclude if a relationship exists between predicted LM shear force and tenderness of other subprimal cuts. Carcasses (n = 768) were scanned with the VIS-NIR system in 2 commercial beef-processing facilities. Carcasses were categorized based on their predicted 14-d LM slice shear force value. After carcass scanning, 100 carcasses were randomly selected based on their tenderness classification, and subprimals (ribeye rolls, clods, knuckles, top sirloins, inside rounds, and eye of rounds) were removed, vacuum-packaged, and transported to the Oklahoma State University Food and Agricultural Products Research Center, where 2.54-cm steaks (n = 6) were fabricated and stored in refrigerated conditions (1 degrees C +/- 1) and aged for 14 d. The center steak from right-side subprimals was designated for slice shear force (LM) or Warner-Bratzler shear force (all other subprimals) analysis. The remaining steaks were categorized based on predicted tenderness taken at 2 d postmortem with the VIS-NIR spectrophotometer and used in a consumer taste study. The test population of carcasses (n = 100) scanned in-plant predicted 27 carcasses as tender, 45 carcasses as intermediate, and 28 carcasses as tough. The VIS-NIR system correctly classified 26 of the 28 (92.9% accuracy) tough carcasses. Overall consumer satisfaction was greatest (P < 0.05) for steaks classified as tender and was intermediate compared with the steaks classified as tough. It was concluded that in-plant VIS-NIR scanning can properly identify and sort carcasses into tenderness groups, which may lead to the development of certified not-tough programs.     

Relationships of consumer sensory ratings, marbling score, and shear force value to consumer acceptance of beef strip loin steaks

Logistic regression was used to quantify and characterize the effects of changes in marbling score, Warner-Bratzler shear force (WBSF), and consumer panel sensory ratings for tenderness, juiciness, or flavor on the probability of overall consumer acceptance of strip loin steaks from beef carcasses (n = 550). Consumers (n = 489) evaluated steaks for tenderness, juiciness, and flavor using nine-point hedonic scales (1 = like extremely and 9 = dislike extremely) and for overall steak acceptance (satisfied or not satisfied). Predicted acceptance of steaks by consumers was high (> 85%) when the mean consumer sensory rating for tenderness,juiciness, or flavor for a steak was 3 or lower on the hedonic scale. Conversely, predicted consumer acceptance of steaks was low (< or = 10%) when the mean consumer rating for tenderness, juiciness, or flavor for a steak was 5 or higher on the hedonic scale. As mean consumer sensory ratings for tenderness, juiciness, or flavor decreased from 3 to 5, the probability of acceptance of steaks by consumers diminished rapidly in a linear fashion. These results suggest that small changes in consumer sensory ratings for these sensory traits have dramatic effects on the probability of acceptance of steaks by consumers. Marbling score displayed a weak (adjusted R2 = 0.053), yet significant (P < 0.01), relationship to acceptance of steaks by consumers, and the shape of the predicted probability curve for steak acceptance was approximately linear over the entire range of marbling scores (Traces67 to Slightly Abundant97), suggesting that the likelihood of consumer acceptance of steaks increases approximately 10% for each full marbling score increase between Slight to Slightly Abundant. The predicted probability curve for consumer acceptance of steaks was sigmoidal for the WBSF model, with a steep decline in predicted probability of acceptance as WBSF values increased from 3.0 to 5.5 kg. Changes in WBSF within the high (> 5.5 kg) or low (< 3.0 kg) portions of the range of WBSF values had little effect on the probability of consumer acceptance of steaks.     

Consumer sensory acceptance and value of wet-aged and dry-aged beef steaks

To determine sensory preference and value of fresh beef steak differing in aging technique, strip steaks were evaluated by consumers in Denver (n = 132 consumers) and Chicago (n = 141 consumers). Wet-aged Choice strip loins were matched with dry-aged Choice strip loins, whereas wet-aged Prime strip loins were matched with dry-aged Prime strip loins. Dry-aged strip loins were commercially aged in air in a controlled environment for 30 d and vacuum-aged for 7 d during shipping and storage. Wet-aged strip loins were vacuum-packaged and aged for 37 d in a 1 degrees C cooler. Pairs of strip loins were matched to similar Warner-Bratzler shear force values and marbling scores. Twelve sensory evaluation panels (of 12 scheduled panelists each) were conducted over a 3-d period in each city. Individual samples from a pair of steaks were evaluated by the panelists for sensory traits. Bids were placed on the samples after sensory traits were obtained utilizing a variation of the Vickery auction with silent, sealed bids. No significant differences for sensory traits of flavor, juiciness, tenderness, or overall acceptability were detected between wet-aged Choice samples and dry-aged Choice samples. Although wet-aged Choice samples were numerically superior for all sensory traits, consumers placed similar bid values (P = 0.12) on wet- and dry-aged Choice samples ($3.82 per 0.45 kg and $3.57 per 0.45 kg, respectively). Wet-aged Prime samples were rated more desirable (P < 0.001) for flavor, tenderness, and overall acceptability than dry-aged Prime samples. Wet-aged Prime samples were valued at $4.02 per 0.45 kg, whereas dry-aged Prime samples brought $3.58 per 0.45 kg (P = 0.008). Consumers (29.3%) who preferred the dry-aged Choice samples over the wet-aged Choice samples were willing to pay $1.99/0.45 kg more (P < 0.001) for dry-aged samples. The consumers who preferred the wet-aged Choice over the dry-aged Choice samples (39.2%) were willing to pay $1.77/0.45 kg more (P < 0.0001). Consumers who preferred wet-aged Prime over dry-aged Prime samples (45.8%) paid $1.92/0.45 kg more (P < 0.0001). Consumers who preferred dry-aged Prime samples (27.5%) were willing to pay $1.92/0.45 kg more than for the wet-aged Prime samples. Although more consumers preferred wet-aged samples, markets do exist for dry-aged beef, and consumers are willing to pay a premium for this product.     

Consumer sensory acceptance and value of domestic, Canadian, and Australian grass-fed beef steaks

To determine US consumer acceptance and value of beef from various countries, 24 taste panels of consumers (n = 273 consumers) were conducted in Denver and Chicago. Two pairs of strip steaks were evaluated for flavor, juiciness, tenderness, and overall acceptability on eight-point hedonic scales. One pair consisted of an Australian grass-fed strip steak and a domestic strip steak, whereas the other pair included Canadian and domestic strip steaks. The pairs were matched to similar Warner-Bratzler shear values and marbling scores to decrease variation associated with tenderness and juiciness. A variation of the Vickery auction was used to obtain silent, sealed bids on steaks (0.45 kg) from the same strip loins sampled in the taste panel. Consumers gave higher (P < 0.001) scores for flavor, juiciness, tenderness, and overall acceptability for domestic steaks compared with Australian grass-fed steaks. Domestic steaks averaged 3.68/0.45 dollars kg, whereas consumers placed an average value of 2.48/0.45 dollars kg on Australian grass-fed steaks (P < 0.001). Consumers rated Canadian steaks numerically lower for juiciness (P = 0.09) and lower (P < 0.005) for flavor, tenderness, and overall acceptability than domestic samples. Consumers placed an average value of 3.95/0.45 dollars kg for domestic steaks and 3.57/0.45 dollars kg for Canadian steaks (P < 0.01). Consumers (19.0%) who preferred Australian grass-fed steaks over domestic steaks paid 1.38/0.45 dollars kg more (P < 0.001), whereas consumers (29.3%) who favored the Canadian steaks over the domestic steaks paid 1.37/0.45 dollars kg more (P < 0.001) for the Canadian steaks. A majority of US consumers seem to be accustomed to the taste of domestic beef and prefer domestic steaks to beef from Australia grass-fed and Canadian beef.     

Technical note: validation of a model for online classification of US Select beef carcasses for longissimus tenderness using visible and near-infrared reflectance spectroscopy

The present experiment was conducted to provide a validation of a previously developed model for online classification of US Select carcasses for LM tenderness based on visible and near-infrared (VISNIR) spectroscopy and to determine if the accuracy of VISNIR-based tenderness classification could be enhanced by making measurements after postmortem aging. Spectroscopy was conducted online, during carcass grading, at a large-scale commercial fed beef-processing facility, and the strip loin was obtained from the left side of US Select carcasses (n = 467). Slice shear force (SSF) was measured on fresh steaks at 2 and 14 d postmortem. Online VISNIR tenderness classes differed in mean SSF values at both 2 d (29.4 vs. 33.6 kg) and 14 d (18.0 vs. 21.2 kg) postmortem (P < 10(-7)). Online VISNIR tenderness classes differed in both the percentage of carcasses with LM SSF values greater than 40 kg at 2 d postmortem (5.1 vs. 21.0%; P < 10(-6)) and the percentage of carcasses with LM SSF values greater than 25 kg at 14 d postmortem (6.8 vs. 23.2%; P < 10(-5)). Whereas 15.0% of the carcasses sampled for this experiment had LM SSF values greater than 25 kg at 14 d postmortem, only 6.8% of the carcasses classified as tender by VISNIR had LM SSF values greater than 25 kg. All the carcasses sampled that had LM SSF values greater than 35 kg at 14 d postmortem were accurately classified as tough by VISNIR. Before measurement of SSF on d 14, VISNIR spectroscopy was conducted on the SSF steak. Tenderness classes based on d 14 VISNIR spectra differed both in mean SSF value at 14 d postmortem (17.7 vs. 21.6 kg; P < 10(-11)) and the percentage of carcasses with LM SSF values greater than 25 kg at 14 d postmortem (7.3 vs. 22.7%; P < 10(-5)). These data support our previous work showing that VISNIR spectroscopy can be used to classify US Select carcasses noninvasively for LM tenderness, and the results establish that this technology could also be applied to aged US Select strip loins. This technology would allow packing companies and other segments of the beef marketing chain to identify US Select carcasses or strip loins that excel in LM tenderness for use in branded beef programs.     

Predicting beef tenderness using near-infrared spectroscopy

The objective of this multiple-phase study was to determine the accuracy of an on-line near-infrared (NIR) spectral reflectance system to predict 14-d-aged cooked beef tenderness. In phase I, 292 carcasses (140 US Select, 152 US Choice) were selected (d 2) from 2 commercial beef processing facilities. After carcass selection, longissimus lumborum (LL) muscle sections (ribs 9 to 12) were individually identified, vacuum-packaged, and transported to the Oklahoma State University Meats Laboratory, where a 2.54-cm-thick steak (n = 1) was fabricated and stored in refrigerated conditions (1 degrees C +/- 1). Following a 30-min oxygenation period, a NIR spectral scan was obtained on the 12th-rib LL steak. Steaks (d 3) were individually vacuum-packaged and aged at 4 degrees C for a total of 14 d before cooking slice shear force (SSF) analysis. In phases II and III, 476 carcasses (258 US Select, 218 US Choice) were immediately NIR scanned after carcass presentation to in-plant USDA grading personnel. In a similar fashion, all LL steaks were aged (1 degrees C +/- 1) for 14 d before cooking (70 degrees C) and conducting SSF. Of the phase I and II samples, 39 (6.77%) were categorized as being tough (i.e., >/= 25 kg of SSF after the 14-d postmortem aging period). Of these 39 tough samples, 20 (3.7% error rate) were correctly placed in the 90% certification level. Another 10 tough samples were placed in the 80% certification level (2.0% error rate). The overall NIR certified tender group was 1.67 kg more tender (P < 0.05) than LL samples from the noncertified samples. When the NIR predicted samples to be tough, 10% of the samples were eliminated from the phase I and II LL populations at 90% certification. The population SSF mean improved in excess of 6.5 kg. For phase III, SSF evaluation by an independent third party indicated the NIR system was able to successfully sort tough from tender LL samples to 70% certification levels. It was concluded that NIR scanning offers an in-plant opportunity to sort carcasses into tenderness outcome groups for guaranteed-tender branded beef programs.     

National Beef Tenderness Survey-1998

Fifty-six retail stores representing 15 retail chains and 14 foodservice facilities in eight U.S. cities were sampled to determine the tenderness of beef steaks at retail and foodservice levels based on Warner-Bratzler shear (WBS) values and consumer evaluation panels. Retail consumer panels were conducted at five universities. Each retail and foodservice steak was evaluated using 10-point scales. Steaks were divided into the following quality groups for statistical analysis: Prime, Top Choice, Choice, Select, and Lean or No Roll. Quality group had no effect on WBS values of retail clod, chuck roll, top round, bottom round, eye of round, top loin, top sirloin, or ribeye steaks but did (P < .05) affect values for the T-bone/porterhouse. The percentages of retail top round, eye of round, and bottom round steaks with a WBS force > 3.9 kg were 39.6, 55.9, and 68.0, respectively. Foodservice ribeye, top loin, and top sirloin steaks had WBS values less than 3.4 kg for all quality groups, with Prime ribeye steaks having lower (P < .05) WBS values than ribeyes from the other quality groups. With the exception of the retail ribeye steak, quality group did not affect consumer sensory ratings of retail and foodservice steaks. Average postfabrication aging times were 32 d for foodservice subprimals and 19 d for retail cut subprimals. These data indicate that improvements in the tenderness of retail cuts from the round are needed. Finally, quality group had little or no effect on consumer sensory evaluations and WBS values of retail and foodservice steaks used in this study.     

Effects of repetitive use of hormonal implants on beef carcass quality,tenderness, and consumer ratings of beef palatability

Effects of repetitive use of anabolic implants on beef carcass quality, tenderness, and consumer ratings for palatability were investigated using crossbred steer calves (n = 550). Steers from five ranches were randomly allocated to one of 10 different lifetime implant strategies or to a nonimplanted control group. Cattle were implanted at some or all of five phases of production (branding, weaning, backgrounding, feedlot entry, or reimplant time). Carcasses from the control group had higher (P < 0.05) marbling scores than carcasses from steers in all other treatment groups. Implanting steers at branding, weaning, or backgrounding vs. not implanting steers at these production stages did not affect (P > 0.05) marbling scores. Steers implanted twice during their lifetime produced carcasses with higher (P < 0.05) marbling scores than did steers receiving a total of four or five implants. Steaks obtained from carcasses in the control group had lower (P < 0.05) shear force values and were rated by consumers as more desirable (P < 0.05) for tenderness like/dislike than steaks obtained from carcasses in all other treatment groups. Implanting steers at branding or weaning production stages did not affect (P > 0.05) steak shear force values, consumer ratings for like/dislike of steak tenderness, or percentage of consumers rating overall eating quality of steaks as satisfactory. Implanting steers at backgrounding vs. not implanting steers at this production stage increased (P < 0.05) steak shear force values, but did not influence (P > 0.05) consumer ratings for like/dislike of steak tenderness or percentage of consumers rating overall eating quality of steaks as satisfactory. Steaks from nonimplanted steers were rated as more desirable (P < 0.05) for overall eating quality than steaks from steers implanted two, three, four, or five times. Use of implants increased (P < 0.05) average daily gain by 11.8 to 20.5% from weaning to harvest compared with nonimplanted controls. Implant strategies increased (P < 0.05) hot carcass weight of steers by 8.9 to 13.8% compared with the control group. Use of implants also increased (P < 0.05) longissimus muscle area and decreased (P < 0.05) estimated percentages of kidney/pelvic/heart fat, but did not affect (P > 0.05) dressing percentage or adjusted fat thickness. Our findings suggest that beef quality, palatability, and production characteristics are influenced by lifetime implant protocols.     

Implant strategies during feeding: impact on carcass grades and consumer acceptability

Anabolic growth promotants influence beef grade factors and Warner-Bratzler shear force of steaks. No study has assessed the consumer acceptability of beef derived from implanted cattle. This study determined beef carcass grades and consumer acceptability for cooked beef from unimplanted (control) cattle and from cattle implanted with one of seven different implant strategies (initial implant/implant at 59 d = Encore & Component T-S/no implant, Ralgro/Synovex Plus, Ralgro/Revalor-S, Revalor-S/Revalor-S, Revalor-S/no implant, no implant/Synovex Plus, and Synovex Plus/no implant). British crossbred steers (n = 448) were allocated randomly into one of eight pens for each of the control and seven treatment groups. Carcass quality and yield grade (n = 403) and Warner-Bratzler shear force (n = 298) data were collected by trained personnel. Twenty steaks per control or treatment group were selected randomly for use in consumer sensory evaluation. Steaks were evaluated by consumers for overall like, tenderness like, tenderness level, flavor like, flavor intensity, and juiciness level using 9-point, end-anchored hedonic scales. Control carcasses had smaller (P < .05) longissimus muscle areas than carcasses in all treatment groups except those receiving Encore & Component T S/no implant, Ralgro/Synovex Plus, or Revalor S/no implant. Control carcasses had higher (P < .05) marbling scores than carcasses in all treatment groups except those receiving Ralgro/Revalor-S or Encore & Component T-S/no implant. Steaks from control steers had lower (P < .05) Warner-Bratzler shear force values than steaks from steers given Revalor-S/no implant. Consumer ratings for tenderness like and tenderness level were influenced (P < .05) by implant strategy. Effects of implant strategy on overall like, flavor like, and flavor intensity approached significance (P = .07 to .09). Consumers rated steaks from unimplanted steers as more tender (tenderness level; P < .05) than steaks from all treatment groups except that involving Encore & Component T-S/no implant. Consumers rated steaks from unimplanted steers as more desirable (P < .05) for tenderness like than steaks from all treatments except those involving Encore & Component T-S/no implant or Revalor-S/no implant. Although use of implants in this study resulted in heavier hot carcass weights and larger ribeyes, some of the implant strategies reduced consumer preference of tenderness of steaks.     

Field testing of a system for online classification of beef carcasses for longissimus tenderness using visible and near-infrared reflectance spectroscopy

The present experiments were conducted to field test a system optimized for online prediction of beef LM tenderness based on visible and near-infrared (VISNIR) spectroscopy and to develop and validate a model for prediction of tenderness that would be unbiased by normal variation in bloom time before application of VISNIR. For both Exp. 1 and 2, slice shear force (SSF) was measured on fresh (never frozen) steaks at 14 d postmortem. Carcasses with VISNIR-predicted SSF ≤15 kg were classified as VISNIR predicted tender and carcasses with VISNIR-predicted SSF >15 kg were classified as VISNIR not predicted tender. In Exp. 1, spectroscopy was conducted online, during carcass grading, at 3 large-scale commercial fed-beef processing facilities. Each carcass (n = 1,155) was evaluated immediately after ribbing and again when the carcass was graded. For model development and validation, carcasses were blocked by plant and observed SSF. One-half of the carcasses (n = 579) were assigned to a calibration data set, which was used to develop regression equations, and one-half of the carcasses (n = 576) were assigned to a prediction data set, which was used to validate the regression equations. Carcasses predicted tender by VISNIR spectroscopy had smaller (P < 10(-19)) mean LM SSF values at 14 d postmortem in the calibration (13.9 vs. 16.5 kg) and prediction (13.8 vs. 16.4 kg) data sets than did carcasses not predicted tender by VISNIR spectroscopy. Relative to carcasses not predicted tender by VISNIR, a decreased percentage of carcasses predicted tender by VISNIR had LM SSF >25 kg in the calibration (2.0 vs. 7.8%) and prediction (0.8 vs. 8.0%) data sets. In Exp. 2, carcasses (n = 4,204) were evaluated with VISNIR online at 6 commercial fed-beef processing facilities on 38 production days. The carcasses predicted tender by VISNIR spectroscopy had decreased mean LM SSF values at 14 d postmortem (16.3 vs. 19.9 kg; P < 10(-87)), longer sarcomere lengths (1.77 vs. 1.72 μm; P < 10(-10)), and a greater percentage of desmin degraded (42 vs. 34%; P < 10(-5)) by 14 d postmortem. Relative to carcasses not predicted tender by VISNIR, a decreased percentage of carcasses predicted tender by VISNIR had LM SSF >25 kg (4.9 vs. 21.3%). The present experiments resulted in development and independent validation of a robust method to noninvasively predict LM tenderness of grain-fed beef carcasses. This technology could facilitate tenderness-based beef merchandising systems.     

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.     

Effect of vitamin D3 supplementation level on the postmortem tenderization of beef from steers

The objective of this experiment was to determine the effect of different doses of vitamin D3 (VITD) on beef feedlot performance, plasma and muscle Ca2+, tissue residues, and improvement of Warner-Bratzler shear force (WBS) and panel tenderness. A total of 167 steers were fed one of six levels of VITD. The VITD treatments (28 steers/treatment) were 0, 0.5 x 10(6), 1 x 10(6), 2.5 x 10(6), 5 x 10(6), and 7.5 x 10(6) IU/steer daily of VITD fed nine consecutive days before slaughter. Feedlot performance and plasma Ca2+ were measured during the last 21 days on feed. Warner-Bratzler shear force was measured on strip loin and top round steaks at 7, 10, 14, and 21 d postmortem. The VITD treatments of 5 and 7.5 x 10(6) IU/steer daily decreased (P < 0.05) ADG, and VITD supplementation of 2.5, 5, and 7.5 x 10(6) IU/steer daily decreased average dry matter feed intake (P < 0.05) at the end of the feeding trial. Plasma Ca2+ increased linearly with VITD treatment (P < 0.01). Calpastatin and calpain activity were not influenced by treatment (P > 0.05), but muscle Ca2+ was increased (P < 0.05) by VITD treatments of 1, 2.5, 5, and 7.5 10(6) IU/steer daily. Feeding VITD did not influence (P > 0.05) carcass quality or yield traits. Supplementing VITD at levels of 1, 2.5, 5, and 7.5 10(6) IU/steer daily increased (P < 0.05) VITD concentrations in strip loin and liver samples. Cooking liver decreased VITD concentrations 10 to 28%. Vitamin D3 treatments of 0.5 and 7.5 x 10(6) IU/d reduced strip loin steak WBS at d 7 (P < 0.05), but VITD treatments did not decrease strip loin steak WBS at any other time postmortem. The VITD treatments of 0.5, 1, and 5 x 10(6) IU/steer daily decreased top round steak WBS at 7 d, and all VITD treatments decreased 10-d top round steak WBS (P < 0.05). Supplementing steers with 0.5 x 10(6) IU/steer daily of VITD also decreased (P < 0.05) top round steak WBS at 21 d postmortem compared with controls. Sensory tenderness at 7 d postmortem was increased (P < 0.05) by all VITD treatments in top round steaks, yet strip loin tenderness scores were not affected (P > 0.05) by VITD treatment. Treatment with VITD quadratically decreased (P < 0.05) round WBS. Thus, VITD treatment will effectively improve tenderness when cattle tend to be tough and have no impact on cattle that produce tender beef. Feeding steers 0.5 x 10(6) IU of VITD daily for 9 d improved tenderness in two muscles without negatively affecting feedlot performance or tissue residues.