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.     

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.     

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 degrees 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 < 0.05). The BF had lower shear force values toward the ST side than toward the vastus lateralis side (P < 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 < 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 < 0.05). Generally, shear force was lower toward the superficial (medial) side than toward the deep side of the SM (P < 0.05). There were no intramuscular differences in shear force values within the AD (P > 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.     

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 prerigor 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: semimembranosus, biceps femoris, semitendinosus, 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 semimembranosus, adductor, semitendinosus, 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, semitendinosus, and psoas major. For rectus femoris, treatments C, D, E, and F resulted in lower (P < 0.05) shear values than for controls. Treatments B, D, and F increased shear force of the semitendinosus relative to controls (P < 0.05) within muscle. Treatment F resulted in higher shear force values for the PM than controls (P < 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.     

Relationship between longissimus composition and the composition of other major muscles of the beef carcass

Left sides from 18 beef carcasses (9 steers and 9 heifers), selected to represent a wide range of marbling scores, were evaluated to determine the relationship between longissimus composition and the composition of other major muscles. The adductor (A), biceps femoris (BF), deep pectoral (DP) gluteal group (GL), infraspinatus (I), longissimus (L), psoas major (PM), rectus abdominis (RA), rectus femoris (RF), semimembranosus (SM), semitendinosus (ST), serratus ventralis (SV), spinalis (SP), supraspinatus (SU) and triceps brachii (TB) were removed, trimmed of external fat, weighed and ground for proximate analysis. Fat content of all muscles was related linearly (P less than .001) to L fat content (R2 values ranged from .67 to .84). The ST had the lowest mean fat content (4.4%) and SP had the highest mean percentage of fat (16.1%). The L ranged from 3.59% to 15.42% fat with a mean of 8.61%. Longissimus fat percentage can be used to predict the fat content of the other major muscles of the beef carcass.     

Effects of conventional and grass-feeding systems on the nutrient composition of beef

The objectives of this study were to determine the nutrient composition of grass-fed beef in the United States for inclusion in the USDA National Nutrient Database for Standard Reference, and to compare the fatty acid composition of grass-fed and conventionally fed (control) beef. Ground beef (GB) and strip steaks (SS) were collected on 3 separate occasions from 15 grass-fed beef producers that represented 13 different states, whereas control beef samples were collected from 3 regions (Ohio, South Dakota, and Texas) of the United States on 3 separate occasions. Concentrations of minerals, choline, vitamin B(12), and thiamine were determined for grass-fed beef samples. Grass-fed GB samples had less Mg, P, and K (P < 0.05), and more Na, Zn, and vitamin B(12) (P < 0.05) than SS samples. Fat color, marbling, and pH were assessed for grass-fed and control SS. Subjective evaluation of the SS indicated that grass-fed beef had fat that was more yellow in color than control beef. Percentages of total fat, total cholesterol, and fatty acids along with trans fatty acids and CLA were determined for grass-fed and control SS and GB. Grass-fed SS had less total fat than control SS (P = 0.001), but both grass-fed and control SS were considered lean, because their total fat content was 4.3% or less. For both GB and SS, grass-fed beef had significantly less (P = 0.001 and P = 0.023, respectively) content of MUFA and a greater content of SFA, n-3 fatty acids, CLA, and trans-vaccenic acid than did the control samples. Concentrations of PUFA, trans fatty acids, n-6 fatty acids, and cholesterol did not differ between grass-fed and control ground beef. Trans-vaccenic acid (trans-11 18:1) made up the greatest concentration of the total trans fats in grass-fed beef, whereas CLA accounted for approximately 15% of the total trans fats. Although the fatty acid composition of grass-fed and conventionally fed beef was different, conclusions on the possible effects of these differences on human health cannot be made without further investigation.     

Beef quadriceps hot boning and modified-atmosphere packaging influence properties of injection-enhanced beef round muscles

Two experiments were conducted to examine the effects of hot boning, modified atmosphere packaging, and injection enhancement on the oxidative and sensory properties of beef round muscles. The beef knuckle (quadriceps muscles) was partially hot boned within 1.5 h postmortem from one randomly selected side of each beef carcass (n = 14), whereas the quadriceps on the opposite side remained intact throughout a 48-h chilling period. At 5 d postmortem, biceps femoris, semimembranosus, vastus lateralis, and rectus femoris muscles from both hot- and cold-boned sides were injected with an enhancement solution consisting of water, salt, phosphate, and natural flavorings (rosemary) at either 6 (Exp. 1) or 10% (Exp. 2) of fresh muscle weight. Enhanced muscles were then processed into 2.54-cm-thick steaks, which were allotted randomly to high-oxygen (HiOx; 80% O2:20% CO2) or ultra-low oxygen (LoOx; 80% N2:20% CO2) modified atmosphere packaging. Regardless of hot boning or enhancement, steaks packaged in LoOx had lower thiobarbituric acid-reactive substances values (P < 0.05), more beef flavor intensity (P < 0.05), fewer off flavors (P < 0.05), and were more tender (P < 0.05) than steaks packaged in HiOx. Hot boning the knuckle had no effect on oxidative (P > or = 0.99) and sensory properties (P > or = 0.85). Increasing the level of injection enhancement from 6 to 10% introduced more rosemary and phosphate into the muscles, thereby decreasing the extent of oxidation, but also imparting a nontypical beef flavor. Packaging in LoOx atmosphere offered the optimal result of decreased oxidation and improved tenderness, without detriment to flavor. Injection enhancement (both 6 and 10%) created off-flavors attributable to the enhancement solution; however, the 10% injection seemed to offer more resistance to lipid oxidation.     

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.     

肉牛日粮的营养供给量

1960～1998年间,美国所有各种肉类的人均年消费量增加了29％(折合成无骨肉计是从140lb增至180 lb),然而,此后38年间牛肉的人均消费量变化情况却与此不同,它从60 lb增至1976年的89 lb,又降至1998年的62 lb。在市场上,禽肉的竞争力愈来愈强劲。为了使牛肉在消费者选择肉类面前变得具有竞争力,就必须在从肉牛受孕起到牛肉放进陈列柜内止的全过程对营养、管理和市场销售服务予以密切关注。我们每年一度发表以此为题的文章,其目的就是为了提供最     

肉牛的日粮营养供给量

衰1生长和肥育肉牛的,养,要.动‘体重仙.).J口654刀NEm留豁*7.52371长谢回阂肠﹄代钙礴平1 .272.724一245 .817 .420.340.660.971271 .570.290.540.770.991 .2011 2 3 45 ..…,且2 3 459 1725犯3814 2739犯641 .12.23.34.45.5························……日维持需要t························……4.84 5.55 6.23 6.89 239 274 307 340 8 9 11 12 6 7 8 10.....············……旧增重所需净能伽cal)·········,········……1 .50 1.72 1.93 2.14 3 .21 3.6…     

Warner-Bratzler and slice shear force measurements of 3 beef muscles in response to various aging periods after trenbolone acetate and estradiol implants and zilpaterol hydrochloride supplementation of finishing beef steers

Our objectives were to determine the effects of zilpaterol hydrochloride (ZH) and the release rate of trenbolone acetate and estradiol-17β on the Warner-Bratzler shear force (WBSF) and slice shear force (SSF) of longissimus lumborum (LL) and the WBSF of gluteus medius (GM) and psoas major (PM) in response to various aging periods. British × Continental steers (n = 168) were assigned to treatments in a 3 × 2 factorial. The main effects of treatment were implant (no implant, Revalor-S, Revalor-XS, Intervet/Schering Plough Animal Health, De Soto, KS) and ZH (0 or 8.3 mg/kg of DM for 20 d). Slaughter group was included as a random effect to account for the variation in days on feed (153 or 174 d). Loins (n = 96) were fabricated to obtain strip loin, top sirloin butt, and tenderloin subprimals. Five 2.54-cm steaks were cut from each subprimal and assigned to 1 of 5 aging periods (7, 14, 21, 28, or 35 d postmortem). Feeding ZH increased (P ≤ 0.01) LL WBSF and SSF values at each aging period compared with controls. Implanting increased (P < 0.05) LL WBSF values at 14 and 21 d, but did not affect LL SSF values (P > 0.05). Only Revalor-S increased (P ≤ 0.05) WBSF values at 28 and 35 d compared with no implant or Revalor-XS. The percentage of LL steaks with a WBSF value below 4.6 kg did not differ (P > 0.05) between ZH supplementation or implant strategy at any aging period, and by d 28, more than 99% of LL steaks registered WBSF values below 4.6 kg. Feeding ZH increased (P < 0.05) GM WBSF values only on d 21. Implant had no effect (P > 0.05) on GM WBSF values. The percentage of GM steaks with a WBSF value below 4.6 kg did not differ (P > 0.05) between ZH supplementation or implant strategy at any aging period. Neither ZH nor implant strategy affected PM WBSF values (P > 0.05). All PM WBSF values were below 4.6 kg on d 7. The results of this study indicated that feeding ZH increased WBSF and SSF of LL steaks, regardless of the aging period; however, the percentage of steaks with WBSF below 4.6 kg did not differ because of ZH or implant. Implanting increased LL WBSF values, but not SSF values. These results showed that although differences existed between implanting, as well as ZH supplementation of British × Continental steers, 99% of LL steaks were classified as tender based on WBSF values by extending aging to 28 d postmortem. It should be noted that 21.2% of 7-d, 13.8% of 14-d, and 17.3% of 21-d ZH steaks had WBSF values greater than 4.6 kg, but 0% of nonsupplemented steaks were greater than 4.6 kg at these aging periods. However, because ZH and implants can increase retail yield of valuable subprimals, such as the tenderloin, considerable value could be captured through ZH supplementation with anabolic implants because shear force was not affected in PM steaks.     

Effects of postmortem aging and USDA quality grade on Warner-Bratzler shear force values of seventeen individual beef muscles

Forty USDA Select and 40 upper two-thirds USDA Choice beef carcasses were used to determine the effects of postmortem aging on tenderness of 17 individual beef muscles. Biceps femoris-long head, complexus, gluteus medius, infraspinatus, longissimus dorsi, psoas major, rectus femoris, semimembranosus, semitendinosus, serratus ventralis, spinalis dorsi, supraspinatus, tensor fasciae latae, teres major, triceps brachii-long head, vastus lateralis, and vastus medialis muscles were removed from each carcass. Seven steaks (2.54-cm thick) were cut from every muscle, and each steak was assigned to one of the following postmortem aging periods: 2, 4, 6, 10, 14, 21, or 28 d postmortem. After completion of the designated aging period, steaks were removed from storage (2 degrees C, never frozen), cooked to a peak internal temperature of 71 degrees C, and evaluated using Warner-Bratzler shear force (WBSF). Analysis of WBSF revealed a 3-way interaction (P = 0.004) among individual muscle, USDA quality grade, and postmortem aging period. With the exception of the Select teres major, WBSF of all muscles (both quality grades) decreased with increasing time of postmortem storage. Nonlinear regression was used to characterize the extent (aging response) and rate of decrease in WBSF from 2 through 28 d postmortem for each muscle within each quality grade. In general, WBSF of upper two-thirds Choice muscles decreased more rapidly from 2 to 10 d postmortem than did corresponding Select muscles. Muscles that had greater aging responses generally had greater 2-d WBSF values. The upper two-thirds Choice psoas major, serratus ventralis, and vastus lateralis muscles required similar aging times to complete a majority of the aging response (< or =0.1 kg of aging response remaining) compared with analogous Select muscles. The upper two-thirds Choice complexus, gluteus medius, semitendinosus, triceps brachii-long head, and vastus medialis muscles required 4 to 6 d less time to complete a majority of the aging response than did comparable Select muscles. Aging times for Select biceps femoris-long head, infraspinatus, longissimus dorsi, rectus femoris, semimembranosus, spinalis dorsi, supraspinatus, and tensor fasciae latae muscles were > or =7 d longer than those for corresponding upper two-thirds Choice muscles. Results from this study suggest that muscle-to-muscle tenderness differences depend on quality grade and aging time and that postmortem aging should be managed with respect to individual muscle and USDA quality grade.     

肉牛日粮的养分供给量（续）

矿物质 动物体总的矿物质或灰分含量,在整个干物质含量中所占的百分数很微小。一位作者曾经这样来描述一头牛(在非常粗略的基础上减去肠胃道内容物):水约占73％,蛋白质约为22％,而灰分则占5.3％,再加上少量的碳水化合物。Missoun大学的研究人员分析了若干头已繁殖过的动物体后,发现各种矿物质所占的量值比例为:钙1.3％、磷0.74％、钠0.16％、钾     

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.     

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 sub-primals were aged 14 d, frozen, and cut into 2.5-cm-thick 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 < 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 < 0.05) for overall like, and steaks from the SS and SV were lowest (P < 0.05) for overall like. Juiciness and beef flavor intensity scores were highest (P < 0.05) for steaks from the LM and IF, whereas SS steaks received the lowest (P < 0.05) juiciness scores, and SS and SV steaks were rated lowest (P < 0.05) for beef flavor intensity. Average auction price differentials differed (P < 0.05) from the LM, and were -0.71 dollars, -0.79 dollars, -1.75 dollars, and -2.44 dollars/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.     

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.     

Use of 25-hydroxyvitamin D3 and dietary calcium to improve tenderness of beef from the round of beef cows

The objective of this trial was to determine how 25-hydroxyvitamin D(3) (25-OH D(3)) supplementation, altering supplemental dietary calcium, or their combination influence postmortem biochemical and tenderness changes in muscles from the round of mature cows. Twenty-seven Angus cows (3 to 7 yr old) were allotted randomly to 9 pens with 3 cows per pen. Treatments were arranged in a 3 x 3 factorial design with 3 dosages of 25-OH D(3) (0, 250, or 500 mg of 25-OH D(3) administered as a 1-time oral bolus 7 d before slaughter) and 3 percentages of supplemental limestone (0.5, 0.75, and 1.0%) replenished in the diet for 3 d before slaughter and after a 2-wk limestone withdrawal. Plasma samples were obtained during the feeding period. Upon slaughter, adductor, gracilus, pectineus, sartorius, semimembranosus, vastus intermedius, and vastus lateralis muscles were obtained and aged for 1, 3, or 7 d. Calcium concentrations were increased in plasma when 250 or 500 mg of 25-OH D(3) were administered (P 相似文献   

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.     

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

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

半胱胺对肉牛生产性能及养分消化率影响的研究

选用西门塔尔杂交公牛64头,采用随机分组的设计方式,随机分为4组,每组16头,每组添加不同剂量半胱胺,分别为5、10、20、0g/头·d。结果表明:试验期间各组生长无不良状况,淘汰率为0;采食量正常,且各组间采食量无明显差异。试验期试验1、2、3、对照组平均日增重分别为1065g、1025g、1217g、1052g,其中试验3组显著高于其它3组(P<0.05),试验1组比对照组略高,试验2组比对照组略低,但均差异不显著(P>0.05)。各组粗料料肉比分别为12.37、13.42、11.21、12.63,精料料肉比分别为3.09、3.24、2.28、3.13,第3组明显低于其它各组(P<0.01),第1组显著低于2、对照组(P<0.05),2、对照组差异不显著。粗蛋白消化率试验3组高于对照组且差异显著(P<0.05),粗脂肪消化率极显著高于对照组(P<0.01);中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)消化率各组差异不显著(P>0.05)。对照组获利润2.55元,第3组获利润3.47元,比对照组净增36%,是对照组的1.36倍,经济效益明显增加。