Effects of potential antimicrobial ingredients used to control Listeriamonocytogenes on quality of natural casing frankfurters.

Listeriosis concerns have led to increased antimicrobial use; reformulation may affect quality. The objective was to determine the effects of potential antimicrobials on quality of natural casing frankfurters. Eleven treatments were used: no antimicrobials (control); 3.0% sodium lactate and sodium diacetate blend (SL+SD); 1.0%, 2.5%, and 3.5% buffered sodium citrate (SC); 1.0%, 2.5%, and 3.5% buffered sodium citrate and sodium diacetate blend (SC+SD); and 1.0%, 2.5%, and 5.0% whey protein peptides (WP). Trained and consumer panelists analyzed sensory characteristics. Cooking yield was unaffected by treatment (P>0.05). Addition of SC and SC+SD decreased pH (P<0.05). Texture profile analysis was conducted. Hunter color values and growth of aerobic bacteria and lactic acid bacteria were monitored over 15 weeks of storage. No samples reached spoilage. SL+SD 3% caused few changes; WP caused changes perceived as negative; and SC and SC+SD caused changes often perceived as positive.

Measuring muscle color on beef carcasses using the L*a*b* color space.

Because beef muscle color affects consumers' purchasing decisions, is a factor in determining USDA grades, and has been shown to be useful in sorting carcasses according to palatability, this study was conducted to determine the effects of measurement conditions on L*, a*, and b* values, to determine the relationships among USDA quality grading factors, muscle pH, electrical impedance, and colorimeter readings, and to develop a classification system that could be used to sort beef carcasses with respect to muscle color. Data were collected over 2 d from 145 beef carcasses in a commercial packing plant. The exposed longissimus muscle at the 12th/13th rib was used for all muscle pH, electrical impedance, and colorimeter measurements. A Minolta Chroma Meter CR-310 was used to obtain L*, a*, and b* readings. Bloom time, from 0 to 93 min, had a greater effect on a* and b* readings than on L* readings. The L* values stabilized after approximately 30 min bloom time, and a* and b* values stabilized after 78 min bloom time, but relative differences among carcasses in L*, a*, and b* values did not change after 3 to 12 min bloom time. Days postmortem, cut surface (anterior versus posterior), and within-muscle location (medial vs lateral) did not affect L*, a*, and b* readings (P > .05). Blotting the surface moisture from the longissimus muscle resulted in lower a* readings (P < .05), but did not affect L* and b* readings (P > .05). The L*, a*, and b* values were correlated with lean maturity scores (-.67, -.30, and -.40, respectively), dark cutter discount (-.60, -.76, and -.73, respectively), muscle pH (-.57, -.79, and -.78, respectively), and electrical impedance (-.27, -.21, and -.25, respectively). Two muscle color classification systems, nine classes each, are proposed, one system based on L* and one system based on b*. The main advantage of the L* categorization system over the b* system is that the L* value was less sensitive to bloom time, and the main advantage of the b* categorization system over the L* system is that the b* system was slightly more precise at segregating carcasses based upon corresponding differences in muscle pH. This research provides procedural guidelines for measuring beef muscle color and shows that a colorimeter can effectively aid researchers and graders in assessing beef carcass quality.

Using measurements of muscle color, pH, and electrical impedance to augment the current USDA beef quality grading standards and improve the accuracy and precision of sorting carcasses into palatability groups.

This research was conducted to determine whether objective measures of muscle color, muscle pH, and(or) electrical impedance are useful in segregating palatable beef from unpalatable beef, and to determine whether the current USDA quality grading standards for beef carcasses could be revised to improve their effectiveness at distinguishing palatable from unpalatable beef. One hundred beef carcasses were selected from packing plants in Texas, Illinois, and Ohio to represent the full range of muscle color observed in the U.S. beef carcass population. Steaks from these 100 carcasses were used to determine shear force on eight cooked beef muscles and taste panel ratings on three cooked beef muscles. It was discovered that the darkest-colored 20 to 25% of the beef carcasses sampled were less palatable and considerably less consistent than the other 75 to 80% sampled. Marbling score, by itself, explained 12% of the variation in beef palatability; hump height, by itself, explained 8% of the variation in beef palatability; measures of muscle color or pH, by themselves, explained 15 to 23% of the variation in beef palatability. When combined together, marbling score, hump height, and some measure of muscle color or pH explained 36 to 46% of the variation in beef palatability. Alternative quality grading systems were proposed to improve the accuracy and precision of sorting carcasses into palatability groups. The two proposed grading systems decreased palatability variation by 29% and 39%, respectively, within the Choice grade and decreased palatability variation by 37% and 12%, respectively, within the Select grade, when compared with current USDA standards. The percentage of unpalatable Choice carcasses was reduced from 14% under the current USDA grading standards to 4% and 1%, respectively, for the two proposed systems. The percentage of unpalatable Select carcasses was reduced from 36% under the current USDA standards to 7% and 29%, respectively, for the proposed systems. These grading systems, which included requirements for maturity, marbling, hump height, and colorimeter readings, could be implemented into the current USDA beef quality grading standards and improve the accuracy and precision of sorting beef carcasses into palatability groups. At the least, measurements of muscle color or pH could be used in a branded-beef program to increase the palatability consistency of its beef products.

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 degrees 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 < 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 < 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 < 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.

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.

Current merchandising practices and characteristics of beef wholesale rib usage in three U.S. cities.

Packers/processors, supermarket meat managers, and restaurant meat purchasers were surveyed to determine industry utilization of the beef wholesale rib. Nine packer/processors representing > 52% of the U.S. steer-heifer slaughter reported that more than two-thirds (68.5%) of the ribs were wholesaled as ribeye, lip-on (IMPS 112A) subprimals and that its predominance in the market makes it the standard for pricing. For merchandising variations of this cut (e.g., ribeye, lip-off), packer prices are adjusted to lip-on bases according to the relative yield. Excess fat was the most common complaint about ribeye steaks, reported by 78% of the packer/processors. In particular, 71% of them reported the "kernel" fat near the center of a ribeye steak between the longissimus and spinalis dorsi muscles is quite difficult to trim out and represents the greatest problem in merchandising. Forty-two percent of supermarket meat managers and 58% of restaurant meat purchasers thought the fat content of beef ribeyes discouraged consumers from purchasing all beef. Kernel fat was specifically cited by 36% of the restaurateurs. Alternative merchandising strategies should be employed to minimize the negative value effects of kernel fat. Even with excess fat being a concern to approximately half of the beef rib buyers, most still bought lip-on ribeyes and trimmed excess fat away. Apparently, they made this choice of lower price per weight, even though price per trimmed serving might be similar to lip-off ribeyes. Excess fat is being transported from packer/processor to buyers in the form of lip-on ribeyes because of the price relationships.(ABSTRACT TRUNCATED AT 250 WORDS)

Composition of the beef wholesale rib.

Wholesale ribs (n = 40) were dissected to determine composition from anterior to posterior end. There were much greater differences in tissue amounts from different anatomical locations within the wholesale rib than between wholesale ribs from carcasses of different USDA yield grades. Kernel fat (seam fat between the longissimus and spinalis dorsi muscles) was found in considerably higher amounts in the 7th, 8th, and 9th rib bone sections. Removal of the lip from IMPS 112A decreased the separable fat content of ribeyes by approximately 46%. This large decrease in fat could make the ribeye more appealing to today's consumer.

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 x 2 x 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 < 0.05) for most composition and muscle quality variables. Fasting reduced hot carcass weight 3.6% (P < 0.05), but length of transport did not affect hot carcass weight (P > 0.05). There were no differences (P > 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 < 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 < 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 < 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 < 0.05). The fasting x 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 < 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 < 0.05), while fasting had no effect on pork quality for pigs from the genetic source with the lower initial pork quality (P > 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.

A survey of beef muscle color and pH.

The objectives of this study were to define a beef carcass population in terms of muscle color, ultimate pH, and electrical impedance; to determine the relationships among color, pH, and impedance and with other carcasses characteristics; and to determine the effect of packing plant, breed type, and sex class on these variables. One thousand beef carcasses were selected at three packing plants to match the breed type, sex class, marbling score, dark-cutting discount, overall maturity, carcass weight, and yield grade distributions reported for the U.S. beef carcass population by the 1995 National Beef Quality Audit. Data collected on these carcasses included USDA quality and yield grade data and measurements of muscle color (L*, a*, b*), muscle pH, and electrical impedance of the longissimus muscle. About one-half (53.1%) of the carcasses fell within a muscle pH range of 5.40 to 5.49, and 81.3% of the carcasses fell within a longissimus muscle pH range of 5.40 to 5.59. A longissimus muscle pH of 5.87 was the approximate cut-off between normal and dark-cutting carcasses. Frequency distributions indicated that L* values were normally distributed, whereas a* and b* values were abnormally distributed (skewed because of a longer tail for lower values, a tail corresponding with dark-cutting carcasses). Electrical impedance was highly variable among carcasses but was not highly related to any other variable measured. Color measurements (L*, a*, b*) were correlated (P < 0.05) with lean maturity score (-.58, -.31, and -.43, respectively) and with muscle pH (-.40, -.58, and -.56, respectively). In addition, fat thickness was correlated with muscle pH and color (P < 0.05). There was a threshold at approximately .76 cm fat thickness, below which carcasses had higher muscle pH values and lower colorimeter readings. Steer carcasses (L* = 39.62, a* = 25.20, and b* = 11.03) had slightly higher colorimeter readings (P < 0.05) than heifer carcasses (L* = 39.20, a* = 24.78, and b* = 10.80) even though muscle pH was not different between steer and heifer carcasses. Dairy-type carcasses (pH = 5.59, L* = 37.56, a* = 23.40, and b* = 9.68) had higher muscle pH values and lower colorimeter readings than either native-type (pH = 5.50, L* = 39.55, a* = 25.13, and b* = 11.00) or Brahman-type (pH = 5.46, L* = 39.75, a* = 25.17, and b* = 11.05) carcasses (P < 0.05).

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.

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.

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.

Effects of high-protein/low-carbohydrate swine diets during the final finishing phase on pork muscle quality.

The aim of this study was to lower the glycogen stores in pork muscle in order to improve pork muscle quality by feeding an ultra-high-protein/low-carbohydrate (HIPRO) diet. Forty-eight barrows (average live weight = 92 kg) were assigned across five treatments and two replications (four or five pigs per treatment by replication combination). All barrows were fed a control diet (13.1% CP) until their assigned treatment began. A treatment was the number of days the barrows were fed the HIPRO diet prior to slaughter (0, 2, 4, 7, or 14 d). The HIPRO diet (35.9% CP) was 97% extruded soybeans. Daily feed intake and weekly live weights were recorded for all barrows. At-death blood glucose levels were determined. Muscle pH, temperature, and electrical impedance were measured in the longissmus lumborum and semimembranosus muscles at 45 min, 3 h, and 24 h postmortem. Glycolytic potential; Minolta L*a*b* values; visual scores for color, firmness, and marbling; water-holding capacity traits (drip loss, purge loss, and cooking loss); and Warner-Bratzler shear force values were determined in the longissmus thoracis et lumborum. Weight gain per day decreased the longer the pigs were fed the HIPRO diet (P < 0.05). Daily feed intake decreased during the 1st wk on the HIPRO diet but returned to near-control levels during the 2nd wk, which when coupled with the continued decreases in daily gain resulted in substantial decreases in feed efficiency during the 2nd wk on the HIPRO diet (P < 0.05). Blood glucose levels and glycolytic potentials were not lowered by feeding the HIPRO diet (P > 0.05); therefore, no differences in rate of pH decline or ultimate pH among dietary treatments were found (P > 0.05). Likewise, there were no differences among dietary treatments in any of the measured meat quality attributes (P > 0.05). Feeding barrows the HIPRO diet for a time period prior to slaughter decreased feed intake, rate of gain, and feed efficiency and was not effective at lowering glycolytic potential or improving pork muscle quality.

Relationships among glycolytic potential, dark cutting (dark, firm, and dry) beef, and cooked beef palatability.

One hundred beef carcasses were selected at three packing plants and were used to determine the relationship between glycolytic potential (GP) and dark, firm, and dry (DFD) beef and to determine the effects of DFD status and GP on cooked beef palatability. Eight individual muscles were excised from one hindquarter of each carcass at d 7 postmortem: longissimus lumborum, psoas major, gluteus medius, tensor fasciae latae, rectus femoris, semimembranosus, biceps femoris, and semitendinosus. Ultimate pH, colorimeter readings, and Warner-Bratzler shear force were determined for all eight muscles at d 7 postmortem. A nine-member trained sensory panel evaluated cooked longissimus lumborum, gluteus medius, and semimembranosus steaks. Traits determined solely for the longissimus lumborum were GP (2 x [glycogen + glucose + glucose-6-phosphate] + lactate) and ether-extractable fat. A curvilinear relationship existed between GP and ultimate pH within the longissimus muscle. There appeared to be a GP threshold at approximately 100 micromol/g, below which lower GP was associated with higher ultimate pH and above which GP had no effect on ultimate pH. The greatest pH and muscle color differences between normal and DFD carcasses were observed in the longissimus lumborum, gluteus medius, semimembranosus, and semitendinosus muscles. Cooked longissimus from DFD carcasses had higher shear force values (46% greater) and more shear force variation (2.3 times greater variation) than those from normal carcasses. Dark cutting carcasses also had higher shear force values for gluteus medius (33% greater) and semimembranosus (36% greater) than normal carcasses. Sensory panel tenderness of longissimus, gluteus medius, and semimembranosus was lower for DFD carcasses than for normal carcasses. Longissimus and gluteus medius flavor desirability scores were lower for DFD than for normal carcasses. Steaks from DFD carcasses had more off-flavor comments than steaks from normal carcasses, specifically more "peanutty," "sour," and "bitter" flavors. The DFD effect of higher shear force values was approximately five times greater (+3.11 kg vs +0.63 kg) for carcasses with "slight" marbling scores than for carcasses with "small" marbling scores. In general, higher GP was associated with increased tenderness, even among normal carcasses. In conclusion, low GP was associated with DFD beef and resulted in substantially less-palatable cooked steaks.

Effects of ground flaxseed in swine diets on pig performance and on physical and sensory characteristics and omega-3 fatty acid content of pork: I. Dietary level of flaxseed.

Forty-eight barrows and gilts were fed diets containing 0 (CO), 5, 10, or 15% ground flaxseed (FS) for the final 25 d before slaughter. Flaxseed treatments did not affect any production or carcass traits (P > .10). No pork processing problems due to lack of firmness were encountered. Amounts (milligrams/gram of tissue) of alpha-linolenic acid (ALA [18:3n-3]) and eicosapentaenoic acid (EPA [20:5n-3]) increased (P < .01) in both backfat layers and ALA increased (P < .01) in kidney (leaf) fat after FS. Alpha-linolenic acid and EPA increased (P < .001) in the raw belly in response to FS; the effect was maintained throughout processing (P < .01) to microwaved bacon. Alpha-linolenic acid and EPA increased (P < .01, P < .05, respectively) with amount of FS in longissimus thoracis and liver. In the brain, DHA decreased (P < .05) with amount of FS. Trained panelists in triangle tests were able to identify bacon from pigs fed 10 and 15% flaxseed. Panelists could not identify various treatments in the loin tests.

Effects of ground flaxseed in swine diets on pig performance and on physical and sensory characteristics and omega-3 fatty acid content of pork: II. Duration of 15% dietary flaxseed.

Four barrows and four gilts were assigned to each of five dietary treatments: a control (CO) diet or a 15% flaxseed (FS) diet fed for 7, 14, 21, or 28 d prior to slaughter. Flaxseed treatments did not affect any production or carcass traits (P > .10). No pork processing problems due to lack of firmness were encountered. Amounts (milligrams/gram of tissue) and percentages of alpha-linolenic acid (ALA [18: 3n-3]), arachidonic acid (AA [20:4n-6]), and eicosapentaenoic acid (EPA [20:5n-3]) increased (P < .001) in both backfat layers and in kidney (leaf) fat and docosahexaenoic acid (DHA [22:6n-3]) increased (P < .006) in the middle/inner backfat layer after FS. The effects of dietary FS on fatty acid profiles were maintained in lard and pastry. Alpha-linolenic acid, AA, and EPA increased (P < .001) and DHA increased (P < .021) in the raw belly in response to FS; the effect was maintained throughout processing to microwaved bacon. Percentage of oleic acid (OA [18:1n-9]) decreased (P < .016) in raw bellies after FS. Alpha-linolenic acid and EPA increased (P < .001) with duration of FS in longissimus thoracis and liver neutral lipids, polar lipids, and combined lipid fractions, but DHA increased (P < .004) only in longissimus thoracis polar and combined lipid fractions. Arachidonic acid decreased in the longissimus thoracis polar lipid fractions (P < .037) and in liver neutral (P < .01) and combined lipid fractions (P < .006) with FS. All ALA:AA and EPA:AA ratios increased (P < .001 to P < .048) with increased duration of FS (except ALA:AA in pastry [P = .56]). Processing of bellies into bacon and storing at -18 degrees C for 6 wk did not cause thiobarbituric acid (TBA) values to exceed a value of 1.0 after either the CO or FS diets. After microwaving bacon when TBA values approached 2.0, there was no FS dietary effect on TBA values. Trained panelists rated FS bacon more flavor-intense than CO bacon and recorded more flavor defects for FS bacon. A 105-member consumer group showed a higher frequency of "dislikes" for FS bacon than for CO bacon.

Genetic effects on beef tenderness in Bos indicus composite and Bos taurus cattle.

Bos indicus composite and Bos taurus cattle, originating from diverse production environments, were used to quantify genetic variation in marbling, 24-h calpastatin activity, and beef tenderness and to identify strategies for prevention of beef tenderness problems in Bos indicus composite cattle. Comparisons among 3/8 Bos indicus breeds (Braford, Red Brangus, Simbrah) revealed significant differences in marbling and 24-h calpastatin activity, but not in tenderness. Compared with Bos taurus cattle, 3/ 8 Bos indicus cattle had similar marbling scores but higher 24-h calpastatin activities. Also, beef from 3/8 Bos indicus composites aged more slowly from 1 to 7 d and was less tender at 4, 7, 14, 21, and 35 d postmortem than beef from Bos taurus cattle. However, beef from 3/8 Bos indicus cattle was relatively tender if it was aged for a sufficient period of time (21 d). The delayed response to aging and greater toughness of beef from 3/8 Bos indicus cattle was associated with Brahman breed effects and was not related to the Bos taurus germplasm source. Marbling was moderately heritable (.52 +/- .21) but exhibited positive genetic correlations with shear force at d 1 through 14 of aging, suggesting that, in these cattle, selection for increased marbling would have an unfavorable effect on beef tenderness. A low heritability estimate for 24-h calpastatin activity (.15 +/- .15), coupled with low genetic correlations between calpastatin activity and shear force at 7, 14, and 35 d, suggested that selection for low calpastatin activity would have little effect on aged beef tenderness. Panel tenderness and shear force at 7, 14, and 21 d were moderately heritable (.27 to .47), indicating that aged beef tenderness could be improved by direct selection (via progeny testing). Comparisons among Simbrah, Senegus x Simbrah, and Red Angus x Simmental steers showed that inclusion of a tropically adapted Bos taurus breed (Senepol) could be an effective strategy for preventing beef tenderness problems in heat-tolerant cattle.

Using objective measures of muscle color to predict beef longissimus tenderness.

This research was conducted to determine whether objective measures of muscle color could be used to classify beef carcasses with respect to tenderness. Bos taurus (161 steers) and Bos indicus cross (101 steers, 55 heifers) cattle were fed a high-concentrate diet and slaughtered in seven groups when ultrasound scans indicated approximately 1.1 cm fat thickness. Following low-voltage electrical stimulation and a 24-h chill, all routine carcass data, USDA grade data, and colorimeter readings (luminance, L*; redness, a*; yellowness, b*) of the exposed longissimus muscle were obtained. The longissimus lumborum was sampled for ultimate pH (pHU) measurement, shear force at 1, 4, 7, 14, 21, and 35 d postmortem, and taste panel assessment at 14 d postmortem. The pHU was correlated (P < .05) with L*, a*, and b* values (r = -.48, -.52, and -.60, respectively). Correlations of color measurements with tenderness measurements were higher than correlations of marbling score with tenderness measurements. Of the three color measurements, b* value showed the highest correlation with shear force value (r = -.38) and taste panel tenderness rating (r = .37). A classification system (lowest 25%, middle 50%, highest 25%) based on marbling score resulted in classes of beef that were 9, 3, and 4% tough, respectively. A classification system (darkest/bluest 25%, middle 50%, lightest/yellowest 25%) based on colorimeter readings resulted in classes of beef that were 15, 3, and 0% tough, respectively. Bos taurus cattle had lower shear force values, higher panel tenderness ratings, higher L* values, and lower a* values (P < .05) than Bos indicus cross cattle.

Effects of animal age, marbling score, calpastatin activity, subprimal cut, calcium injection, and degree of doneness on the palatability of steaks from limousin steers.

Strip loin (longissimus lumborum), sirloin (gluteus medius) and round (semimembranosus) subprimals from 114 purebred and crossbred Limousin steers were used to identify main effects and interactions of animal age, marbling score, calpastatin activity, subprimal cut, calcium injection (5% wt/wt with a 200 mM CaCl2 solution at 48 h postmortem), and degree of doneness on the palatability of cooked beef steaks. Steaks were aged for 14 d, frozen, thawed, cooked to different internal temperature end points, visually scored for degree of doneness, sheared on a Warner-Bratzler shear machine, and evaluated by a trained taste panel. Raw and cooked steaks from carcasses of higher USDA quality grades had higher fat and lower moisture percentages (P < .05). Higher degrees of doneness resulted in lower moisture percentages (P < .05). Lower shear force values were associated with less variation in shear force. Younger slaughter age and lower calpastatin activity both resulted in greater tenderness (P < .05). Shear force was lowest between "medium rare" and "medium" and increased toward both ends of the degree of doneness scale for round and sirloin steaks; however, shear force increased linearly with degree of doneness in strip loin steaks (P < .05). Subprimal cut had the largest effect on taste panel tenderness ratings, and degree of doneness had the largest effect on taste panel juiciness ratings. The improvement in shear force due to CaCl2 injection was greater for strip loin and sirloin steaks than for round steaks (P < .05 for the interaction). Injection with CaCl2 improved all taste panel attributes. In addition, CaCl2 injection reduced the toughening effects of cooking (P < .05).

Effects of dietary supplementation of vitamin E on storage and caselife properties of lamb retail cuts.

Thirty wether lambs were randomly assigned to three treatments consisting of a control (C) and two vitamin E-supplemented treatments (VE), one fed 500 IU of vitamin E.lamb-1.d-1 (E500) and the other fed 1,000 IU of vitamin E.lamb-1.d-1 (E1000). After a 56-d feeding period, lambs were slaughtered and carcass traits were evaluated. Wholesale legs and loins were vacuum-packaged, stored at 4 degrees C for 7, 14, 21, or 28 d, fabricated into retail cuts, and packaged and displayed to simulate retail industry conditions. The E1000 lambs gained less (P < .05) (kg/d; total gain) and had lower (P < .05) carcass weights than the E500 lambs. Alpha-tocopherol levels in the longissimus lumborum were higher (P < .05) (5.79 vs 3.50 micrograms/g of tissue) for VE than for C; however, there was no difference in alpha-tocopherol level in longissimus lumborum between E500 and E1000. Leg retail cuts experienced greater (P < .05) lipid oxidation and received lower (P < .05) lean color scores than did loin retail cuts. Less (P < .05) lipid oxidation occurred from 1 to 7 d of display in VE retail cuts than in C retail cuts. Longer storage periods before retail display resulted in greater (P < .05) lipid oxidation at both 1 and 7 d of display and a higher (P < .05) rate of lipid oxidation during the display period. Supplementing vitamin E had the greatest effect in reducing lipid oxidation when cuts were stored for longer periods before retail display.(ABSTRACT TRUNCATED AT 250 WORDS)