Differences In Shear Values Research Articles

A novel way to dynamize a spatial frame and optimize fracture healing

BackgroundFracture site motion creates mechanical strains on the healing tissues which influences bone formation. Axial micro-motion maximizes dilatational strains, whereas shearing motions maximize deviatoric strains on the healing tissues. Dilatational strains optimize bone healing, deviatoric strains retard bone healing. Dynamization of external fixation using either an Ilizarov or Spatial Frame platform is used to increase loading on the limb which increases the mechanical stress and strain on the tissues to improve healing. The scientific literature does not address how dynamization of the spatial frame effects fracture site motion. The purpose of this study is to assess the effect of modified shoulder bolts incorporated into a spatial frame during dynamic loading. MethodsFive identical two-ring spatial frame constructed were mounted on Sawbones tibias with an osteotomy performed distal to the tibial tubercle. Sinusoidal load was applied at a rate of 0.25 Hz. Axial force and displacement, in addition to motion of the proximal and distal tibia segments were recorded. Eight constructs were tested: 1) All struts of the Spatial Frame rigid, 2) Strut #1 loose, 3) Struts #1 and #3 loose, 4) Struts #1, #3 and #5 loose, 5) All struts loose, 6) All struts rigid with dynamization bolts on the proximal end, 7) All struts rigid with dynamization bolts on alternating sides, 8) Threaded rods between the rings with two millimeters of dynamization. ResultsNo difference in vertical displacement was observed between the Ilizarov and all struts locked. No significant difference in shear values between all struts locked and modified shoulder bolt struts was observed. Increase in vertical movement with the modified shoulder bolts was an average of 1.83 mm. Significant shear forces at the fracture site were observed with unlocking single or multiple struts of the spatial frame. ConclusionModified shoulder bolts can be used for spatial frame dynamization without increasing shear motion.

The influence of postmortem electrical stimulation on rigor mortis development, calpastatin activity, and tenderness in broiler and duck pectoralis

This study was conducted to evaluate the effects of electrical stimulation (ES) on rigor mortis development, calpastatin activity, and tenderness in anatomically similar avian muscles composed primarily of either red or white muscle fibers. A total of 72 broilers and 72 White Pekin ducks were either treated with postmortem (PM) ES (450 mA) at the neck in a 1% NaCl solution for 2 s on and 1 s off for a total of 15 s or were used as nonstimulated controls. Both pectoralis muscles were harvested from the carcasses after 0.25, 1.25, and 24 h PM and analyzed for pH, inosine:adenosine ratio (R-value), sarcomere length, gravimetric fragmentation index, calpastatin activity, shear value, and cook loss. All data were analyzed within species for the effects of ES. Electrically stimulated ducks had a lower muscle pH at 0.25 and 1.25 h PM and higher R-values at 0.25 h PM compared with controls. Electrically stimulated broilers had a lower muscle pH at 1.25 h and higher R-values at 0.25 and 1.25 h PM compared with controls. Muscles of electrically stimulated broilers exhibited increased myofibrillar fragmentation at 0.25 and 1.25 h PM, whereas there was no such difference over PM time in the duck muscle. Electrical stimulation did not affect calpastatin activity in either broilers or ducks; however, the calpastatin activity of the broilers did decrease over the aging time period, whereas that of the ducks did not. Electrical stimulation decreased shear values in broilers at 1.25 h PM compared with controls; however, there was no difference in shear values of duck muscle due to ES at any sampling time. Cook loss was lower for electrically stimulated broilers at 0.25 and 1.25 h PM compared with the controls, but had no effect in the ducks. These results suggest that the red fibers of the duck pectoralis have less potential for rigor mortis acceleration and tenderization due to ES than do the white fibers of the broiler pectoralis.

Measurement of Broiler Breast Meat Shear Values

Consideration of factors affecting instrument measurement of chicken meat tenderness is important in experimental design. To determine what factors affect measurement of tenderness, this study used an instrument that measures the force required to shear the tissue with a multi-blade Kramer shear cell. The force was expressed as shear values (kg/g).Varying shear rates caused differences in shear values in 9-cm2 samples. In samples with smaller (4 cm2) and larger (16cm2) surface areas, shear rate did not affect shear value. Samples 9 or 16 cm2 had shear values 25 to 46% lower than samples 4 cm2. Dividing peak force by sample weight did not correct for all differences in surface area and weight. Sample shape (circle, rectangle, and square) and sample temperature (4, 26, and 46°C) had little affect on shear values. No statistical differences attributable to load cell size (100 vs. 1000 kg) occurred. Shear values calculated with peak force had a smaller variation than those calculated with yield force. Using peak force and yield force, however, resulted in similar trends in shear values for different sample sizes, sample shapes, and shear rates.

The Effects of Electric Stimulation and Extended Chilling Times on the Biochemical Reactions and Texture of Cooked Broiler Breast Meat

Electric stimulation has been shown to affect functional and biochemical properties of the Pectoralis major muscle. In this study the effects of stimulating broilers with a pulsed electric current of 200 V alternating current (VAC) 2 s on, 1 s off, during exsanguination on biochemical reactions and objective texture of the meat deboned after 1, 2, or 3 h in the chiller were determined. Broilers (three replications, 18 birds per replication) were either stunned (50 VAC, 10 s) simulating commercial conditions, or stunned and stimulated during exsanguination, processed, and placed in 1 C ice baths. Carcasses were removed after 1, 2, or 3 h and the P. major excised. The R value and pH samples were taken and the deboned muscles were vacuum-bagged and held overnight at 2 C prior to cooking in 85 C water for 30 min. Shear values were determined using a Warner-Bratzler shear. Stimulation and static chilling for 2 and 3 h resulted in significantly higher R values and lower shear values than stunning and static chilling. The largest difference in shear values was noted after the 2 h chill; 7.12 kg for the stunned vs 3.42 kg for the stimulated group.

Effects of cooking and shearing methodology on variation in Warner-Bratzler shear force values in beef2

Longissimus lumborum between the 13th rib and the 4th lumbar vertebra from 57 steers was obtained at 48 h postmortem, stored at 2 degrees C, and frozen after 7 d postmortem. Consecutive 2.54-cm-thick, paired steaks were used to make the following comparisons: Protocol A) steaks were broiled to 70 degrees C, chilled 24 h at 3 degrees C, cored parallel to fiber orientation, and sheared with a Warner-Bratzler attachment to the Instron and Protocol B) steaks were modified-oven-broiled to 65 degrees C, cooled 30 min at 23 degrees C, cored perpendicular to the steak surface, and sheared with a Warner-Bratzler shear machine. Each of the four differences in protocol was subsequently compared one at a time with paired steaks. Protocol A resulted in higher (P < .05) shear force values than Protocol B (6.29 vs 3.60 kg). Neither shearing instrument nor cooling condition contributed to the difference (P > .05) in shear values. However, parallel vs perpendicular core orientation (6.31 vs 4.51 kg, respectively) and broil to 70 degrees C vs modified-oven broil to 65 degrees C cooking method (6.37 vs 5.31 kg, respectively) increased (P < .05) shear force values. Total variance (6.2 vs 1.2 kg2) and the proportion of variance in shear value attributed among animals was greater (P < .05) for Protocol A than for Protocol B (70.0 vs 44.5%). These data indicate that Protocol A resulted in greater animal differences in shear values, and thus was more discriminating than Protocol B.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of Storage Times After Cooking on Warner‐Bratzler Shear Values of Beef Roasts

ABSTRACTFifty longissimus and 49 biceps femoris roasts were cut from five Choice‐grade steer carcasses and used to evaluate differences in Warner‐Bratzler shear values at different times after cooking. Five longissimus roasts and four or five biceps femoris roasts were cut from both sides of each carcass. Roasts were cooked to an internal temperature of 71°C then wrapped in aluminum foil and chilled (4°C) for 2, 24, 48, 72 or 168 hr prior to shear analysis. No differences in shear values by carcass side or by length of chill after cooking existed for biceps femoris roasts. Longissimus roasts were more tender when taken from the left side and when chilled for 2 hr vs longer chill periods. Roasts chilled for 24, 48, 72 or 168 hr had similar shear values. Cores taken from the medial portion of the longissimus roasts had lower shear values than cores taken from the central or lateral portions. Longissimus roasts were always more tender than roasts from the biceps femoris muscle and they were less variable in tenderness.

The Effect of Water Soaking, Brining and Cooking Procedure on Tenderness of Broilers

Experiments were conducted to determine the effects of salt brining time, water soaking, and cooking procedures on the tenderness of broilers. In all experiments there were no significant differences in shear values of meat from birds that were either smoked or oven-roasted. Meat from birds that were soaked in salt brine 16 or 32 hours before either smoking or oven-roasting had significantly lower shear force values than meat from unbrined birds. There were no significant differences in shear values between light and dark meat from birds brined for either 16 or 32 hours while shear values for light meat were significantly higher than dark meat from unbrined birds. When broilers were either unbrined or soaked for 32 hours in brine or tap water, the meat from water soaked birds had numerically higher shear force values than meat from unbrined birds. Meat from both water soaked and unbrined birds had significantly higher shear force values than meat from brined birds. Microbiological examination of broilers after smoking showed low levels of total aerobes and an absence of coliforms.

Effect of Salt Brining and Cooking Procedure on Tenderness and Microbiology of Smoked Cornish Game Hens

Two trials were conducted to determine the effects of cooking procedure and salt brining on the tenderness and microbiology of Cornish hens. Shear values were significantly lower for both light and dark meat from brined Cornish hens. Meat from birds slow-cooked with smoke gave significantly lower shear force values than meat from birds which were oven-roasted. Shear values obtained from light meat were significantly higher than those obtained for dark meat. Brining increased the tenderness of light meat significantly more than it did of dark meat. There was no significant difference in shear values of light and dark meat from brined Cornish hens. No significant difference in shear values was observed for dark meat from birds cooked by any of the three methods; however, light meat from birds cooked slowly with smoke had significantly lower shear values than those from birds which were cooked slowly without smoke or which were oven-roasted. Coliform and total counts were numerically lower on birds brined and slow-cooked with smoke.

COMPARISON OF DIFFERENT POSTMORTEM TEMPERATURES AND DISSECTION PROCEDURES ON SHEAR VALUES OF UNAGED AND AGED AVIAN AND OVINE MUSCLES

ABSTRACTPre‐rigor dissected turkey muscles when heated in the rigor state had higher shear values than similarly heated rigor dissected controls. This difference was eliminated by aging. There was no difference in shear values between unaged and aged muscles which were dissected after rigor mortis. Chilling or freezing‐thawing either pre‐rigor or rigor dissected turkey muscles caused no increase in shear values. Aging these muscles produced no significant change in shear values. Turkey semi‐tendinosus muscle which entered rigor after pre‐rigor dissection had significantly higher shear values than the contralateral muscles which entered rigor in a stretched position. Aging for 7 days removed these differences in shear values. Shear values increased on heating unaged or aged (3 days) turkey pectoralis muscle between 50 and 100°C. The appearance of the curves for the unaged and aged muscles was similar. The effect of aging ovine muscles did not produce the same pronounced change in shear values that was obtained on the turkey muscles.

Chemical Composition, Carcass Yield and Tenderness of Broilers as Influenced by Rearing Methods and Genetic Strains

Experiments were conducted to determine the influence of cage and floor rearing and strains as well as the rearing of sexes separately or in equal numbers on chemical composition, yield and tenderness. The sexed birds were processed at 6, 7 and 8 weeks of age with measurements made at these ages.The shear values from the iliotibialis of the males were higher than those of the same muscle from the female. This difference in shear values was the only one noted. The second slice of the pectoralis muscle from birds reared in cages produced lower shear values than the corresponding slice from floor reared birds. The shear values from the broilers reared separately by sex or combined were influenced by both the sex of the individual bird as well as rearing method. Shear values from males grown separately were lower than those obtained from the females or those values from birds grown with equal numbers of sexes per pen. Shear values from the 8 week old broilers were lower than either 6 or 7 week old birds. The highest values were obtained from the 7 week old broilers.Females had a higher percentage of total meat as well as a greater meat-to-bone ratio for light meat, but no statistical difference was found between sexes for the dark meat portions. Yield of the sex separated birds increased as they increased in age.

TENDERNESS VARIATION IN OVINE LONGISSIMUS MUSCLE

31 lamb carcasses were split after slaughter and one side of each had pre‐rigor tension applied to the longissimus muscle by weighted or mechanical methods. Warner‐Bratzler shear values were obtained on each of three core positions within rib and within loin chop samples from each nontensioned and tensioned side. Differences in shear values between cores were significant (P &lt; 0.001), and the interactions of muscle location, tension treatment and core were also significant (P &lt; 0.001). The lateral position was the least tender in rib chops while the dorsal position was least tender in loin chops of the nontensioned sides. Pre‐rigor tension made core positions more uniform in tenderness in the rib chops, while considerable tenderness variation persisted in tensioned loin chops.

Eating Quality of Two Basic Breeds of Broiler Chickens and their Crosses

Relative eating quality of male and female chicken broilers from pure lines of White Rock and Cornish breeds and their reciprocal crosses was assessed. Flavor and tenderness were evaluated using the paired comparisons method. Shear force was measured by the modified Warner-Bratzler shearing device.The panel preferred the flavor of the males and found them more tender than the females. No flavor differences were detected among the four crosses. The Cornish male on White Rock female cross and the pure White Rock breed were rated more tender than the White Rock male on Cornish female cross.There were no differences in shear values between sexes or among crosses.The Cornish x White Rock cross used in this study was found superior to the other combinations in flavor and tenderness.

The Effect of Time and Temperature of Cooking on Quality of Freeze-Dehydrated Chicken

HEATING is known to produce pronounced changes in meat proteins. Such changes include increase in pH (Bard and Tischer, 1951; Wierbicki et al., 1957), transformation of collagen to gelatin (Hamm, 1960), changes in tenderness (Tischer et al., 1953; Tuomy et al., 1963; Tuomy and Lechnir, 1964) and structural changes (Sosebee et al., 1964b). There is some disagreement as to the effect of different cooking methods on tenderness of poultry. Goodwin et al. (1962) found no significant differences in tenderness of turkey cooked by several methods but did find a difference in shear values when the turkey was cooked to different end-point temperatures. Mickelberry and Stadelman (1960) found differences in shear values among birds cooked by deep fat frying (least tender), birds baked in aluminum foil wrapping (most tender) and other methods of cooking.This study was designed to determine the effect of different times and temperatures of cooking on the…

Cottage Cheese Texture

The firmness of cottage cheese was determined with the Kramer shear press and results reported as maximum force required to shear a 100g sample. Reproducibility of the method was satisfactory. Products from 4 plants were analyzed and significant differences in shear values and water contents between plants were observed. There was also a lack of uniformity of the products from individual plants. Shear value and water content showed a highly significant correlation (r=−.87). In spite of this the extreme variability observed makes prediction of water content from shear value impossible. The product from the plant producing cottage cheese of low shear value had a greater percentage of larger particles than the product from the plant producing cottage cheese of high shear value.

Effect of Coring Methods on Shear Values Determined by Warner‐Bratzler Sheara

SUMMARYShear‐force values were determined with the Warner‐Bratzler shear machine on cores obtained by two methods from steaks from longissimus dorsi (LD) and biceps femoris (BF) muscles cooked to 61 and 80°C. One‐half‐inch cores were cut either parallel with the muscle fibers or perpendicular to the cut surface of the steak without regard to orientation of the fibers. The LD and BF muscles did not react in the same manner to changes in coring method. Method of coring made a large difference in shear values in LD at 80°C. With one exception shear values of paired steaks from the same muscle with cores cut parallel were more closely related than shear values of cores from within the same steak cut differently.