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°C until subsequent analysis. Steaks were thawed at 1°C and cooked on electric broilers to an internal temperature of 71°C. One core was removed from each 2.5-cm × 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 \u3c 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 \u3c 0.05) shear force in the middle region of the TB, and the distal and proximal ends were tougher (P \u3c 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

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 \u3c 0.05) for overall like, tenderness, juiciness, and flavor, and assigned it the highest (P \u3c 0.05) price/0.45 kg. The TB also was rated higher (P \u3c 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 \u3c 0.05) to the LT for overall like, tenderness, juiciness, flavor, and price/0.45 kg. Consumers rated the SS lower (P \u3c 0.05) than the LT for tenderness, juiciness, flavor, and price. The DP was rated as the toughest, driest, and blandest (P \u3c 0.05), resulting in assignment of the lowest (P \u3c 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 \u3c 0.05) for overall like, tenderness, and juiciness than USDA Select SV and SS. For the IF, USDA Choice was rated higher (P \u3c 0.05) for tenderness and juiciness than USDA Select. The USDA Choice TB was rated higher (P \u3c 0.05) for juiciness, and the USDA Choice DP was rated higher (P \u3c 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

Technical note: The Effect of Freezing on Warner-Bratzler Shear Force Values of Beef Longissimus Steaks Across Several Postmortem Aging Periods

The objective of this study was to compare fresh and frozen protocol procedures for Warner- Bratzler shear force (WBSF) determination on steaks aged for different periods of time. The fresh protocol consisted of measuring WBSF on steaks cooked on the exact day the aging period ended. The frozen protocol consisted of measuring WBSF on steaks that were aged, frozen (−16°C) for approximately 2 mo, thawed for 24 h, and then cooked. Twenty-two strip loin steaks from each of 20 crossbred heifers and steers were individually vacuum-packaged and assigned to either the fresh or frozen protocol and one of 11 aging periods (1, 2, 3, 4, 5, 6, 7, 10, 14, 21, or 35 d). The frozen protocol resulted in lower (P \u3c 0.05) WBSF values than the fresh protocol for beef longissimus steaks that were aged for 1, 2, 3, 4, 6, 7, 10, 14, or 35 d postmortem. An interaction (P \u3c 0.05) between protocol and postmortem aging resulted from larger differences between protocols at shorter aging periods than at longer aging periods. Correlations and mean differences revealed that frozen protocol WBSF values were not highly indicative of fresh protocol WBSF values at the same period of postmortem aging, but rather suggested that frozen protocol WBSF values at shorter aging times were useful in estimating WBSF values from fresh protocols at longer aging times. Cooking loss was higher (P \u3c 0.05) for frozen vs fresh protocol steaks at all aging periods except for 14, 21, or 35 d. These findings suggest that if research constraints warrant the freezing of samples, shorter aging periods before freezing (6 and 7 d) should be used to estimate WBSF of fresh aged beef (14 to 21 d). In trials in which several postmortem aging periods or very short aging periods are of interest, we recommend that WBSF be assessed using the fresh protocol

Glimepiride, a novel sulfonylurea, does not abolish myocardial protection afforded by either ischemic preconditioning or diazoxide

Background: The sulfonylurea glibenclamide (Glib) abolishes the cardioprotective effect of ischemic preconditioning (IP), presumably by inhibiting mitochondrial KATP channel opening in myocytes. Glimepiride (Glim) is a new sulfonylurea reported to affect nonpancreatic KATP channels less than does Glib. We examined the effects of Glim on IP and on the protection afforded by diazoxide (Diaz), an opener of mitochondrial KATP channels. Methods and results: Rat hearts were Langendorff-perfused, subjected to 35 minutes of regional ischemia and 120 minutes of reperfusion, and assigned to 1 of the following treatment groups: (1) control; (2) IP of 2x 5 minutes each of global ischemia before lethal ischemia; or pretreatment with (3) 30 µmol/L Diaz, (4) 10 µmol/L Glim, (5) 10 µmol/L Glib, (6) IP+Glim, (7) IP+Glib, (8) Diaz+Glim, or (9) Diaz+Glib. IP limited infarct size (18.5±1% vs 43.7±3% in control, P<0.01) as did Diaz (22.2±4.7%, P<0.01). The protective actions of IP or Diaz were not abolished by Glim (18.5±3% in IP+Glim, 22.3±3% in Diaz+Glim; P<0.01 vs control). However, Glib abolished the infarct-limiting effects of IP and Diaz. Patch-clamp studies in isolated rat ventricular myocytes confirmed that both Glim and Glib (each at 1 µmol/L) blocked sarcolemmal KATP currents. However, in isolated cardiac mitochondria, Glim (10 µmol/L) failed to block the effects of KATP opening by GTP, in contrast to the blockade caused by Glib. Conclusions: Although it blocks sarcolemmal currents in rat cardiac myocytes, Glim does not block the beneficial effects of mitochondrial KATP channel opening in the isolated rat heart. These data may have significant implications for the treatment of type 2 diabetes in patients with ongoing ischemic heart disease

Mapping Intramuscular Tenderness Variation in Four Major Muscles of the Beef Round

The objective of this study was to quantify intramuscular tenderness variation within four muscles from the beef round: biceps femoris (BF), semitendinosus (ST), semimembranosus (SM), and adductor (AD). At 48 h postmortem, the BF, ST, SM, and AD were dissected from either the left or right side of ten carcasses, vacuum packaged, and aged for an additional 8 d. Each muscle was then frozen and cut into 2.54- cm-thick steaks perpendicular to the long axis of the muscle. Steaks were broiled on electric broilers to an internal temperature of 71°C. Location-specific cores were obtained from each cooked steak, and Warner- Bratzler shear force was evaluated. Definable intramuscular shear force variation (SD = 0.56 kg) was almost twice as large as between-animal shear force variation (SD = 0.29 kg) and 2.8 times as large as between muscle variation (SD = 0.20 kg). The ranking of muscles from greatest to least definable intramuscular shear force variation was BF, SM, ST, and AD (SD = 1.09, 0.72, 0.29, and 0.15 kg, respectively). The BF had its lowest shear force values at the origin (sirloin end), intermediate shear force values at the insertion, and its highest shear force values in a middle region 7 to 10 cm posterior to the sirloin-round break point (P \u3c 0.05). The BF had lower shear force values toward the ST side than toward the vastus lateralis side (P \u3c 0.05). The ST had its lowest shear force values in a 10-cm region in the middle, and its highest shear force values toward each end (P \u3c 0.05). The SM had its lowest shear force values in the first 10-cm from the ischial end (origin), and its highest shear force values in a 13- cm region at the insertion end (P \u3c 0.05). Generally, shear force was lower toward the superficial (medial) side than toward the deep side of the SM (P \u3c 0.05). There were no intramuscular differences in shear force values within the AD (P \u3e 0.05). These data indicate that definable intramuscular tenderness variation is substantial and could be used to develop alternative fabrication and(or) merchandising methods for beef round muscles

Effects of Fasting and Transportation on Pork Quality Development and Extent of Postmortem Metabolism

One hundred seventy-seven pigs were used to determine the interaction effects of fasting and length of transport prior to harvest on pork muscle quality. The study design was a 2 × 2 × 3 factorial, which involved two genetic sources, fasting (F) or no fasting (N) of pigs 48-h prior to harvest, and three transport times (0.5, 2.5, or 8.0 h) on a semitrailer to the packing plant. Genetic source was a significant source of variation (P \u3c 0.05) for most composition and muscle quality variables. Fasting reduced hot carcass weight 3.6% (P \u3c 0.05), but length of transport did not affect hot carcass weight (P \u3e 0.05). There were no differences (P \u3e 0.05) in percent lean among fasting and transport treatments. Fasted pigs had higher longissimus dorsi (LD) ultimate pH (pHu), darker lean color, higher marbling score and lower 7-d purge loss, 24-h drip loss, and cooking loss (P \u3c 0.05) than nonfasted pigs. Meat from pigs that were transported 8.0 h had lower glycolytic potential (GP), higher LD and semimembranosus (SM) pHu, darker lean color, and lower L*, 7-d purge loss, 24-h drip loss, cooking loss, and shear force values than meat from pigs transported 0.5 h (P \u3c 0.05). Meat from pigs transported 2.5 h had higher LD and SM pHu and lower L*, 7-d purge loss, 24-h drip loss, and cooking loss than meat from pigs transported 0.5 h (P \u3c 0.05). Meat from pigs transported 8.0 h had higher LD pHu and color scores and lower L* and cooking loss than meat from pigs transported 2.5 h (P \u3c 0.05). The fasting × transport interaction was significant for SM pHu, L*, color score, and drip loss. Fasting improved SM pHu, L*, color score, and drip loss for pigs that were transported 0.5 h (P \u3c 0.05), but when pigs were transported for 2.5 h or 8.0 h, fasting had little or no effect on these muscle quality traits. Fasting lowered GP and increased LD pHu for pigs from the genetic source with the higher initial pork quality (P \u3c 0.05), while fasting had no effect on pork quality for pigs from the genetic source with the lower initial pork quality (P \u3e 0.05). Longer transport times resulted in lower GP and higher LD pHu regardless of genetic source. Fasting and length of transport each had positive effects on pork quality, but length of transport effects was greater in magnitude. When pigs were transported for 0.5 h, fasting for 48 h prior to harvest improved pork quality, but when pigs were transported 2.5 or 8.0 h, fasting had little effect on pork quality

Determining the Optimum Beef Longissimus Muscle Size for Retail Consumers

Research was conducted in two phases to determine the optimum beef LM size for retail consumers. In Phase I, 50 USDA Choice beef carcass sides were selected at a commercial packing plant and assigned to five different categories (10 sides per category) based on LM size: 61 to 68 cm2 (A), 70 to 78 cm2 (B), 80 to 90 cm2 (C), 92 to 103 cm2 (D), and 105 to 119 cm2 (E). Ribeye rolls were retrieved from all carcass sides. Steaks (2.5-cm thick; 14 per ribeye roll) were cut as needed and transported in groups of 35 steaks (seven per LM size category) to a retail grocery store in Brookings, SD, where they were placed into a designated section of the retail meat case. Steaks were tallied every 4 h on weekdays and every 2 h on weekends and holidays to determine the number of monitoring periods that each steak remained in the retail case. Steaks that did not sell within an allotted time were removed from the case and termed “pulled.” Time in case and percentage of steaks pulled from the case did not differ among LM size categories (P \u3e 0.16). Quadratic regression indicated that larger LM steaks sold faster (P \u3c 0.05) than average and small LM steaks. Steaks from rib locations 6 and 7 spent more (P \u3c 0.05) time in the case than steaks from rib locations 8 through 12. Steaks from the 7th rib location were more (P \u3c 0.05) likely to be pulled than steaks from the 8th through 12th rib locations. In Phase II, 15 USDA Choice ribeye rolls were selected from a commercial packing plant to represent two LM size categories: 80 to 90 cm2 (AVG; n = 5); and 105 to 119 cm2 (LARGE; n = 10) and cut into 2.5-cm-thick steaks. A portion of the LARGE steaks was subsequently cut in half (HALF). Four display steaks represented each treatment group in each of five random nth price auctions. Seventy-five people were recruited from the Brookings, SD area to participate in the auctions to determine their willingness to pay for the three different types of ribeye steak. Consumers were willing to pay a premium of $1.50/kg for LARGE ribeye steaks over AVG ribeye steaks (P \u3c 0.05). Consumers discounted HALF ribeye steaks by$1.01/kg compared with AVG ribeye steaks (P \u3c 0.05). In conclusion, no optimum LM size existed for beef retail consumers; however, a trend existed toward greater demand for larger LM sizes over smaller LM sizes

Evaluating Consumer Acceptability and Willingness to Pay for Various Beef Chuck Muscles

In-home consumer steak evaluations, followed by centralized laboratory-setting auctions, were used to determine consumer (n = 74 consumers) acceptability and willingness to pay for various beef chuck muscles. The infraspinatus (IF), serratus ventralis (SV), supraspinatus (SS), and triceps brachii (TB) from the beef chuck were evaluated against LM steaks from the rib to determine price and trait differentials. Muscles from USDA Choice, boneless, boxed-beef subprimals were aged 14 d, frozen, and cut into 2.5-cmthick steaks. Consumers received two steaks from each muscle for in-home evaluations of uncooked steak appearance and cooked steak palatability. After in-home evaluation of steaks, consumers participated in a random nth price auction session to determine willingness to pay for those steaks. Muscles differed (P \u3c 0.05) for overall like of appearance, like of size, like of shape, and like of leanness; LM generally rated the highest. Steaks from the LM rated highest (P \u3c 0.05) for overall like, and steaks from the SS and SV were lowest (P \u3c 0.05) for overall like. Juiciness and beef flavor intensity scores were highest (P \u3c 0.05) for steaks from the LM and IF, whereas SS steaks received the lowest (P \u3c 0.05) juiciness scores, and SS and SV steaks were rated lowest (P \u3c 0.05) for beef flavor intensity. Average auction price differentials differed (P \u3c 0.05) from the LM, and were $−0.71,$−0.79, $−1.75, and$−2.44/0.45 kg for the TB, IF, SS, and SV, respectively. Average appearance trait differentials and average palatability trait differentials were correlated significantly with average price differentials. Results indicate the IF and TB were acceptable to consumers as steaks but only at prices lower than the LM

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 \u3c 0.01). Shear force differed (P \u3c 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 \u3c 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 \u3c 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 \u3c 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

Increasing Tenderness of Beef Round and Sirloin Muscles Through Prerigor Skeletal Separations

Crossbred steers (n = 30) were used to explore and compare tenderness improvements in beef round and sirloin muscles resulting from various methods of pre-rigor skeletal separations. Animals were slaughtered according to industry procedures, and at 60 min postmortem one of six treatments was applied to each side: A) control, B) saw pelvis at the sirloin round junction, C) separate the pelvic-femur joint, D) saw femur at mid-point, E) combination of B and C, and F) combination of B and D. After 48 h, the following muscles were excised from each side: semi-membranosus, biceps femoris, semi-tendinosus, and adductor from the round; vastus lateralis and rectus femoris from the knuckle; and gluteus medius, biceps femoris and psoas major from the sirloin. Following a 10-d aging period, samples were removed from each muscle to determine the effect of treatment on sarcomere length and Warner-Bratzler shear force. Most skeletal separation treatments resulted in longer sarcomeres than controls for semi-membranosus, adductor, semi-tendinosus, and gluteus medius muscles. All skeletal separation treatments yielded shorter sarcomeres for the psoas major as compared with controls. Warner-Bratzler shear force differed among treatments for rectus femoris, semi-tendinosus, and psoas major. For rectus femoris, treatments C, D, E, and F resulted in lower (P \u3c 0.05) shear values than for controls. Treatments B, D, and F increased shear force of the semi-tendinosus relative to controls (P \u3c 0.05) within muscle. Treatment F resulted in higher shear force values for the PM than controls (P \u3c 0.05). Correlations between sarcomere length and shear force were found to be low and quite variable among muscles. In general, treatments increased sarcomere length of several muscles from the sirloin/round region, but had mixed effects on shear force values