Flavor relationships among muscles from the beef chuck and round

This research compared off-flavor notes and the relationship of pH and heme-iron content to off-flavor for different beef muscles. After grading, knuckles and shoulder clods were removed from 16 USDA Choice and 14 USDA Select beef carcasses, vacuum-packaged, and aged for 7 d. The rectus femoris (REC), vastus medalis (VAM), vastus lateralis (VAL), teres major (TER), infraspinatus (INF), and triceps brachii-long head (TRI) were separated, cut into steaks, and frozen (-16 degrees C). Sensory analysis was conducted using a trained taste panel, with steaks grilled to an internal temperature of 65 degrees C. Heme-iron concentration and pH were determined. The INF had lower (P < 0.05) off-flavor intensity ratings and less frequent sour flavor than the other muscles, and the VAL had the most intense (P < 0.05) off-flavor ratings and among the greatest frequency of sour, charred, and oxidized flavors. The frequencies of liver-like, bloody, and rancid flavors were not affected by muscle type. Heme-iron concentration did not differ among muscles. Three USDA Select carcasses had intense off-flavor in the muscles. Liver-like flavor was highly negatively correlated with off-flavor intensity for each of the muscles tested. Muscles rated a 5 or below (on an 8-point rating scale, where 1 = extremely intense off-flavor and 8 = no off-flavor) in off-flavor intensity and identified as liver-like by 30% or more of the panelists were grouped together and compared to normal muscles. Those in the liver-flavored group were less frequently identified as charred, probably because the liver-like flavor was so intense. There were no differences between the 2 groups for sour, metallic, bloody, oxidized, or fatty off-flavor notes. Regression equations containing the linear and quadratic functions of heme-iron concentration, muscle pH, and their interaction were established for the frequency of off-flavor notes within each muscle. The REC, TER, VAL, and VAM showed a relationship between pH, heme iron, and off-flavor intensity (P < 0.05). Liver-like flavor was explained partially by pH and heme iron in the REC, VAM, and VAL (R2 = 0.45 to 0.55; P < 0.05). Few other significant relationships were found. Heme iron and pH were unrelated to metallic, oxidized, or rancid flavors for any of the muscles tested. These data suggest that liver-like off-flavors are specific to individual animals, and that pH and heme iron are not strongly related to off-flavor notes.     

Enhancement of beef chuck and loin muscles with ammonium hydroxide and salt

The objective of this study was to evaluate the tenderness of beef chuck and round muscles when enhanced with ammonium hydroxide and salt at different pump levels. A randomized, complete block design of 4 treatments and 3 muscles with 3 replications was used, with a total of 15 subprimals per treatment. Treatments included a 0% (CON), 15% (T15), 22.5% (T22), and 30% (T30) target pump. The triceps brachii (TB), biceps femoris (BF), and rectus femoris (RF) muscles were studied. Muscles were injected with a solution of ammonium hydroxide and sodium chloride (patent-pending technology from Freezing Machines Inc., Dakota Dunes, SD). Individual steaks were cut to a thickness of 2.54 cm, vacuum-packaged in trays, and frozen. Warner-Bratzler shear force, pH, and sensory evaluations were determined. Shear force decreased as the target pump percentage increased for all muscles (P < 0.050): TB = 39.9, 35.1, 32.1, and 27.0 N; BF = 39.4, 26.2, 23.3, and 19.3 N; RF = 42.7, 32.9, 30.7, and 28.9 N for CON, T15, T22, and T30, respectively. In all cases, there were no shear force differences between T15 and T22 (P > 0.050). As percentage pump increased, pH increased. The ultimate pH was moderately strongly to strongly related to shear force (r = 0.55, 0.70, and 0.80 for RF, TB, and BF, respectively). Trained taste panel ratings revealed an increase in tenderness, decrease in connective tissue, and an increase in juiciness as pump level increased for all muscles. In all cases but one (juiciness of the RF), the CON had the least desirable ratings and shear force values (P < 0.050). There were no major differences between T15 and T22, and T30 steaks tended to have an uncharacteristic soft and mushy texture. For this reason a 20% target pump level was determined to be the optimum pump level. These data suggest that adjusting pH in beef with ammonium hydroxide and salt can increase tenderness in muscles from the beef chuck and round. Any level of treatment was beneficial, with the greatest shear force benefit occurring in muscle pumped to 30%.     

Fiber-type composition of muscles of the beef chuck and round

Thirty-eight muscles of the beef chuck and round were histochemically stained to characterize fiber-type composition in order to facilitate optimal muscle use in value-added products. Select-grade chucks and rounds (n = 4 each) were chosen to represent two carcass weight classes (250 to 295 kg and 363 to 410 kg) and two yield grades (1 and 3). Muscles were sectioned and stained with a procedure that included a succinate dehydrogenase and an adenosine triphosphatase staining technique. Number and diameter of beta-red, alpha-red, and alpha-white muscle fibers were used to determine muscle fiber percentage, muscle fiber area, and percent area in each muscle. Weight did not significantly (P > 0.05) affect these muscle fiber-type characteristics, probably because of limited sample numbers. Muscles containing greater than 40% beta-red fibers were classified as red; greater than 40% alpha-white fibers were classified as white. All other muscles were classified as intermediate. Nine of 12 round muscles were white, including semitendinosus, biceps femoris, rectus femoris, adductor, and semimembranosus. The chuck muscles were red (10 of 26), intermediate (9 of 26), and white (7 of 26). These data indicate variable fiber-type composition of most of the muscles of the beef chuck and round. Functional and biochemical traits of each muscle fiber class would be expected to create different processing characteristics, which would influence optimal muscle use in value-added products.     

Consumer assessment of beef strip loin steaks of varying fat levels

A consumer study was conducted in Lubbock, Texas, to determine the effects of fat level of beef strip steaks on the palatability traits of tenderness, juiciness, flavor liking, and overall liking, while further investigating the window of acceptability for fat content of beef. Thirty beef strip loins were selected by trained personnel to equally represent USDA Prime, High Choice (upper 1/3 Choice), Low Choice (lower 1/3 Choice), Select, and Standard. Proximate analysis was conducted on all strip loins to determine percentage fat, moisture, protein, and collagen. Three strip loins from each quality grade were selected based on fat percentages from proximate analysis to best represent each USDA quality grade for use in the consumer evaluations. Strip loins were fabricated into 2.5-cm steaks, and further processed into 5 × 5 cm pieces. In addition to the US-sourced product, beef LM pieces from 6 Australian Wagyu steers (Wagyu) and 6 Australian grain finished steers (Australian) were used in the consumer evaluations. Consumers (n = 120) were served 7 samples: a warm-up sample, 1 sample from each USDA quality grade treatment, and either a Wagyu or Australian sample, in a balanced order in accordance with a 6 × 6 Latin square. Consumers rated each steak sample for tenderness, juiciness, flavor, and overall liking and rated each palatability trait as either acceptable or unacceptable. Moreover, consumers rated each sample as unsatisfactory, good everyday quality, better than everyday quality, or premium quality. Tenderness, juiciness, flavor liking, and overall liking increased with increasing fat content (P < 0.05). However, Wagyu and Australian samples did not follow this trend for flavor and overall liking. A decrease in consumer acceptability of each palatability trait was observed as fat level decreased (P < 0.05). Consumer overall liking was correlated (P < 0.05) with consumer tenderness (r = 0.76) and juiciness ratings (r = 0.73), but most highly correlated with flavor liking (r = 0.88). Results of this study indicated that increased fat level in beef strip steaks positively affected tenderness, juiciness, flavor liking, and overall liking of beef strip steaks. Moreover, flavor liking was the most highly correlated palatability trait with overall liking. In US-sourced samples, fat level had a large effect on the flavor liking of beef as determined by consumers.     

Calcium-activated tenderization of strip loin, top sirloin, and top round steaks in diverse genotypes of cattle

Steers of known percentage Brahman (B) and Angus (A) breeding (100% A, n = 6; F1 B x A, n = 6; and 100% B, n = 6) were used to determine the effect of calcium chloride injection on the calpain proteinase system and meat tenderness. The steers were slaughtered in six replications (at either 9 or 14 mm of backfat, determined ultrasonically), with each breed type represented. Calpains and calpastatin activities were measured on fresh, prerigor longissimus muscle samples. Carcass data were collected after a 24-h chill, and the short loin (IMPS #180), top sirloin (IMPS #184), and top round (IMPS #168) were removed from both sides of each carcass. The cuts from the right side were then injected at 5% (wt/wt) with CaCl2 solution (2.2%). Longissimus muscle calpain and calpastatin activities were also measured at 48 h postmortem from the injected and control sides of each carcass. Warner-Bratzler shear force was measured on steaks from the three subprimals aged 1, 2, 5, 15, or 31 d. Marbling scores and USDA quality grades were higher (P<.05) in A than in F1 B x A and B carcasses. Calpastatin activity was higher (P<.05) in muscle from B than in muscle from A and F1 B x A steers, and postmortem storage (O vs 48 h) and CaCl2 injection reduced (P<.05) the activity of the calpains and calpastatin. Strip loin and top sirloin steaks from A and F1 B x A steers were more tender (P<.05) than steaks from B steers; however, top round steak tenderness did not differ (P>.05) across breed type. Calcium injection improved strip loin and top sirloin steak tenderness, but it did not affect top round steak tenderness. Collectively, these data show that CaC12 injection can be used to improve meat tenderness, with similar responses shown in cattle containing 0, 50, and 100% B inheritance. However, even with CaCl2 injection, B steaks are less tender than their A and F1 B x A counterparts.     

Effects of aging on beef chuck and loin muscles enhanced with ammonium hydroxide and salt

The objective of this study was to determine whether aging would alter the beneficial effects (tenderness, juiciness, and flavor) of enhancing beef chuck and round steaks with a 20% solution of water, ammonium hydroxide, salt, and carbon monoxide. A randomized, complete block design was used, with 2 treatments [0% (control) and 20% (pump)], 3 aging periods (1, 2, and 3 wk), 3 muscles (M. triceps brachii from the clod heart, M. biceps femoris from the sirloin cap, and M. rectus femoris from the knuckle), and 3 replications. There were a total of 12 subprimals per treatment per aging period (n = 72 each). Individual steaks were cut to a thickness of 2.54 cm and packaged in a high-oxygen modified-atmosphere package (80% oxygen, 20% carbon dioxide). At the end of the aging period, steaks were vacuum packaged and frozen. Steaks were used to determine Warner-Bratzler shear force (WBS) and consumer sensory ratings. For all muscles, WBS values were lower for pump steaks than control at every aging period (P < 0.050). In addition, as aging period increased, WBS values for all steaks increased. Consumer taste panels revealed more desirability for tenderness, juiciness, flavor, and overall acceptability for pump steaks than control steaks. In addition, steaks aged for 1 d were more desirable than steaks aged for 7 and 14 d (P < 0.050). These data indicate that aging does not decrease the benefits (tenderness, juiciness, and flavor) of enhancement.     

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.     

A comparison of consumer sensory acceptance and value of domestic beef steaks and steaks from a branded, Argentine beef program

To determine consumer sensory acceptance and value of branded, Argentine (grass-finished, aged 30+ d) and domestic (U.S. grain-finished beef, aged 9 d) strip loins were paired based on similar Warner-Bratzler shear force values (P = 0.34) and similar marbling levels (P = 0.82). Consumers in Chicago, IL, and San Francisco, CA (n = 124 per city), evaluated one pair of Argentine and domestic steaks, and had the opportunity to participate in a silent, sealed-bid auction to purchase steaks matching the taste panel samples. Consumers were categorized into three groups based on overall acceptability ratings: 1) those who found Argentine steaks more acceptable, 2) those who found domestic steaks more acceptable, and 3) those who were indifferent. Consumers rated domestic steaks higher (P < 0.05) in juiciness, tenderness, flavor, and overall acceptability. Consumers in both Chicago and San Francisco were willing to pay more (P < 0.05) for domestic steaks (0.86 dollars and 0.52 dollars per 0.45 kg, respectively). In both cities, consumers who found Argentine samples more acceptable were willing to pay more (P < 0.05) for Argentine steaks (0.74 dollars per 0.45 kg in Chicago and 1.82 dollars per 0.45 kg in San Francisco), and consumers who found domestic samples more acceptable were willing to pay more (P < 0.05) for domestic steaks (1.66 dollars per 0.45 kg in Chicago and 1.34 dollars per 0.45 kg in San Francisco). Consumers who were indifferent were willing to pay similar (P = 0.99) amounts for Argentine and domestic steaks. Although some consumers found Argentine beef more acceptable than domestic beef (19.7 and 16.5% in Chicago and San Francisco, respectively) and were willing to pay more for it, most consumers found domestic beef to be more acceptable (59.0% in Chicago and 61.5% in San Francisco) and were willing to pay more to obtain a more acceptable product.     

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.     

Retail yields from beef chuck and round subprimals from two grade groups when merchandised as single muscle cuts

Beef subprimals from two different grade groups were obtained from two beef processors to assist in updating the Beef Computer Assisted Retail Decision Support (CARDS) program with new fabrication styles. The grade groups consisted of Top Choice (containing subprimals from carcasses with a Modest or Moderate degree of marbling) and Select (containing subprimals from carcasses with a Slight degree of marbling). Subprimals (shoulder clod; top blade, roast; arm roast; knuckle, peeled; outside round, flat) were separated into individual muscles and fabricated into retail cuts by professional retail meat cutters. Mean retail cutting yields and labor requirements were calculated from observed weights (kilograms) and processing times (seconds). Data were analyzed to determine means and standard errors of percentage yield and processing times for subprimals in each grade group, and comparisons were made between grade groups. Generally, there were few differences in processing times between Top Choice and Select subprimals, and the trimming phase required the most time to complete for each subprimal. Differences (P < 0.05) were observed in saleable yield between Top Choice and Select subprimals for the shoulder clod (Top Choice = 73.89%; Select = 78.49%), top blade, roast (Top Choice = 84.36%; Select = 86.70%), and outside round, flat (Top Choice = 85.99%; Select = 91.34%). Trimmable fat differed (P < 0.05) between Top Choice and Select subprimals: shoulder clod (Top Choice = 25.30%; Select = 20.85%), top blade, roast (Top Choice = 14.88%; Select = 12.59%), arm roast (Top Choice = 8.35%; Select = 7.47%), knuckle (Top Choice = 5.72%; Select = 2.73%), and outside round, flat (Top Choice = 13.82%; Select = 7.26%). Most of the differences in saleable yields were related to less trimmable fat for Select subprimals, which also required less trimming time than Top Choice subprimals. These data will serve to update the Beef CARDS program and will provide retailers and foodservice operators with third-party cutting yield and time allocation information.     

Comparison of steaks from Holstein and Simmental x Angus steers.

Boneless rib eye steaks from 32 Holstein and 32 Simmental x Angus steers were evaluated by 55 supermarket meat managers. Within breed, steers were divided into light or heavy initial weights. Within initial weight groups, steers were either implanted with Revalor or not implanted. Steers were slaughtered commercially when they reached a small degree of marbling, and rib eye steaks were cut from the carcass and stored at -20 degrees C until the day before evaluation. After thawing overnight in a 0 to 4 degrees C cooler, uncooked steaks were randomly assigned to positions on paper plates. Each of the 55 evaluators was then told to record whether each steak was from a Holstein or a traditional beef breed. The percentage identified correctly was 50.9 +/- .96, which was not different from being random. Steaks were later assigned to blocks of eight treatments and cooked to an internal temperature of 68 degrees C before six or seven participants evaluated steaks from each block. Sensory attributes were acceptable for all steaks. Steaks from Holstein steers generally were superior to those from Simmental x Angus steers. Steaks from steers with heavy initial weights generally were superior to steaks from steers with light initial weights. Steaks from steers implanted with Revalor were slightly less acceptable than steaks from unimplanted steers for several sensory attributes, but the difference in overall acceptability was minor and nonsignificant. All the differences were small, and may have limited commercial relevance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of high-oil corn on feedlot performance, carcass characteristics, fatty acid profiles, beef palatability, and retail case life traits of beef top loin steaks

Our objective was to compare the effects of feeding steam-flaked, high-oil corn with normal steam-flaked corn to which yellow grease was added to equalize dietary fat on performance and carcass characteristics of finishing beef steers, and palatability, retail case life, and fatty acid composition of strip loins. Angus steers (n = 120; initial BW = 288 kg) were allotted to dietary treatments consisting of 1) normal mill-run, steam-flaked corn plus added fat (NMR) or 2) high-oil, steam-flaked corn (HOC) and assigned randomly to pens (12 pens/treatment with 5 steers/pen). Performance (ADG, DMI, and G:F) was measured over time, and cattle were shipped to a commercial abattoir for collection of carcass data after 165 d on feed. Carcass data were collected at 48 h postmortem on all carcasses, and 2 carcasses from each pen were selected randomly for collection of strip loins (IMPS #180A). At 14 d postmortem, 4 steaks (2.54 cm thick) were removed for retail display, trained sensory panel analysis, Warner-Bratzler shear force determination, and fatty acid analysis. Daily BW gain was greater (P = 0.03) and G:F was increased 8.4% (P = 0.01) for steers fed NMR compared with HOC, but DMI was not affected (P > 0.10) by treatment. No treatment differences were observed (P > 0.10) for HCW, 12th-rib fat, KPH, and yield grade. Marbling scores were greater (P = 0.01) for NMR than for HOC, and LM area tended (P = 0.07) to be greater in NMR than in HOC carcasses. The proportion of carcasses grading USDA Choice did not differ (P = 0.77) between treatments, but a greater (P = 0.04) proportion of carcasses graded in the upper two-thirds of Choice for NMR vs. HOC. Trained sensory panel traits and Warner-Bratzler shear force values did not differ between treatments (P > 0.10), and no differences (P > 0.10) were detected for purge loss or fatty acid composition. Overall, ADG and G:F were less and marbling score was decreased, but there were no differences between treatments in beef palatability, retail case life, or concentrations of fatty acids in strip loins.     

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.     

Evaluating consumer acceptability of various muscles from the beef chuck and rib

One hundred thirty-eight consumers evaluated steaks from the complexus (CX), infraspinatus (IF), serratus ventralis (SV), supraspinatus (SS), and triceps brachii (TB) from the wholesale beef chuck; the deep pectoral (DP) from the wholesale brisket; and the longissimus thoracis (LT) from the wholesale rib. The LT was used as a reference for comparison to the other muscles. Ten USDA Choice and ten USDA Select boneless boxed beef subprimals were used for each muscle. Subprimals were aged 14 d from box date, frozen, and cut into 2.5-cm-thick steaks. Consumers rated the IF highest (P < 0.05) for overall like, tenderness, juiciness, and flavor, and assigned it the highest (P < 0.05) price/0.45 kg. The TB also was rated higher (P < 0.05) than the LT for overall like, tenderness, juiciness, flavor, and price/0.45 kg. The SV and CX were rated as being similar (P < 0.05) to the LT for overall like, tenderness, juiciness, flavor, and price/0.45 kg. Consumers rated the SS lower (P < 0.05) than the LT for tenderness, juiciness, flavor, and price. The DP was rated as the toughest, driest, and blandest (P < 0.05), resulting in assignment of the lowest (P < 0.05) price/0.45 kg. Differences in palatability ratings due to quality grade were found for several muscles; USDA Choice SV and SS were rated higher (P < 0.05) for overall like, tenderness, and juiciness than USDA Select SV and SS. For the IF, USDA Choice was rated higher (P < 0.05) for tenderness and juiciness than USDA Select. The USDA Choice TB was rated higher (P < 0.05) for juiciness, and the USDA Choice DP was rated higher (P < 0.05) for overall like, than their USDA Select counterparts. Tenderness, juiciness, and flavor ratings were correlated with overall like ratings (r = 0.84, 0.77, and 0.76, respectively) and with price (r = 0.73, 0.70, and 0.68, respectively). These results indicate the IF, TB, SV, and CX were acceptable, whereas and the SS and DP were unacceptable as steaks.     

Effects of dark storage and retail display on beef chuck and round muscles enhanced with ammonium hydroxide, salt, and carbon monoxide

The objective of this study was to determine the retail shelf stability of beef chuck and round muscles enhanced with ammonium hydroxide, salt, and carbon monoxide. A split plot design was used for each of 3 muscles [triceps brachii (TB), biceps femoris (BF), and rectus femoris (RF)] with 2 treatments (0 and 20% pump), 3 dark storage periods (1, 2, and 3 wk), and 3 replications in the whole plot and retail display period as the split plot. There were a total of 12 subprimals per treatment per dark storage period (n = 72 each). Individual steaks were cut to a thickness of 2.54 cm and packaged in a modified-atmosphere package (MAP). The TB was packaged in a high-oxygen MAP (80% oxygen, 20% carbon dioxide). The BF and RF were packaged in a low-oxygen MAP (100% carbon dioxide). At the completion of each dark storage period, steaks were subjected to 7 d of simulated retail display. Steaks were used for objective and subjective color measurements, total plate counts, and determination of retail purge and oxidation. For all muscles, total plate counts were always numerically greater in injected steaks. Triceps brachii steaks held in dark storage for 3 wk and displayed at retail for 4 or more days all exceeded 10(7) log of cfu/cm(2) for aerobic plate count. Biceps femoris and RF steaks packaged in a low-oxygen MAP had much lower bacterial counts, with levels below 4.2 log of cfu/cm(2), even after 7 d of retail display. Oxidation values for the TB were extremely high (ranging from 12.3 to 26.6), whereas the BF and RF had values that were much lower (< or =1.0 mg of malonaldehyde/kg of muscle), likely due to the oxidation occurring in a high-oxygen MAP for the TB. Enhanced TB steaks proved to have greater color stability (less discoloration) than nonenhanced TB steaks. In addition, the BF and RF (low-oxygen MAP) steaks had better color stability (more stable redness values) than TB (high-oxygen MAP) steaks, although TB steaks initially exhibited a brighter red color. Retail display life was enhanced by packaging in 100% carbon dioxide, and enhanced steaks exhibited greater color stability in retail display than control 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.     

Evaluating the point of separation, during carcass fabrication, between the beef wholesale rib and the beef wholesale chuck

This study determined whether there is a logical point of value change, related to either tenderness or consumer acceptance, at which to separate the beef carcass within the rib/chuck region. Rib/chuck rolls (RCR); (n = 30) consisting of the ribeye roll and chuck eye roll subprimals (2nd through 12th rib locations) were cut into 22 steaks each (two steaks per rib location), and Warner-Bratzler shear force and consumer purchase preference were evaluated for steaks at each rib location. Steaks from different locations of the RCR were composed of differing proportions of several muscles: longissimus muscle (LM), spinalis dorsi and multifidus dorsi (SM), and complexus (CO). The LM (4th to 12th rib) contained three tenderness regions: 7th through 12th rib, 5th and 6th ribs, and 4th rib regions (lowest, intermediate, and highest shear force values, respectively; P < 0.01). Shear force differed (P < 0.05) among rib locations for the SM (2nd to 9th rib), but no logical pattern was evident. The CO (2nd to 7th rib) was more tender toward the anterior end (P < 0.05). The region of the RCR represented by the 4th through 6th rib locations had steaks with higher weighted-average shear force (average shear force of each steak, weighted for surface area of each muscle) values than the remainder of the RCR (P < 0.05). Animal-to-animal variation in shear force was 36% greater than rib-to-rib variation in shear force; thus, statistically significant differences in tenderness among rib locations may be undetectable by consumers. Steaks (n = 330) were offered for sale at a retail supermarket and case time was monitored on each steak to determine consumer purchase preference. Steaks from the 2nd through 4th rib locations required more time to sell (P < 0.01) than steaks from the 5th through 12th rib locations. Two alternative locations for the rib/chuck separation point could be between the 6th and 7th ribs, yielding a ribeye subprimal useful in marketing a "premium quality" product, or between the 4th and 5th ribs, which would yield four more 2.5-cm ribeye steaks per carcass.     

Intramuscular tenderness variation within four muscles of the beef chuck

The i.m. tenderness variation was examined within four beef chuck muscles, the infraspinatus (IF), supraspinatus (SS), triceps brachii (TB), and serratus ventralis (SV). The IF, SS, TB, and SV muscles were cut into 2.5 cm thick steaks perpendicular to the long axis of the muscle. An identification tag was placed on each steak, consisting of a muscle identification number, steak number, and orientation of the steak. Steaks were vacuum-packaged and stored at -22 degrees C until subsequent analysis. Steaks were thawed at 1 degrees C and cooked on electric broilers to an internal temperature of 71 degrees C. One core was removed from each 2.5-cm x 2.5-cm section parallel to the muscle fiber and sheared once to determine Warner-Bratzler shear force (WBSF). The SS had an overall WBSF mean of 5.43 kg (SD = 2.20 kg) with no tenderness difference (P = 0.43) among steak locations. The IF had an overall WBSF mean of 3.16 kg (SD = 1.01 kg) with no tenderness difference (P = 0.51) among steak locations. The SV had a mean WBSF value of 4.37 kg (SD = 1.27 kg) with tenderness variation (P < 0.05) among steak locations; however, tenderness variations were not dispersed in a discernible pattern. The TB had a mean WBSF value of 4.12 kg (SD = 1.26 kg) with lower (P < 0.05) shear force in the middle region of the TB, and the distal and proximal ends were tougher (P < 0.05). Results of this study provided a reasonably detailed mapping of the tenderness regions within the IF, SS, TB, and SV muscles, and this information could be used to add value to the beef chuck by cutting and marketing consistently tender regions.