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Biochemical post-mortem changes between red and white avian muscle were determined using duckling and chicken Pectoralis muscles, respectively. Six live Pekin ducklings and six live broiler chickens, in each of two trials, were obtained from commercial plants and processed at a pilot facility. After evisceration, carcasses were held at 4 C, then Pectoralis muscles were removed at .25, 1, 4, and 24 h post-mortem, and sampled for pH, lactate, adenosine triphosphate (ATP) content, and R-value (inosine to adenine ratio). Duckling Pectoralis pH significantly (P less than .05) decreased from 6.25 to 5.66 from .25 to 24 h post-mortem, respectively, as compared with that of the chicken, which decreased from 6.41 to 5.62 for the same times. Duckling lactate values, from .25 to 24 h, increased from 15.86 to 28.86 mumol/g, respectively, and chicken lactate values increased from 27.62 to 53.51 mumol/g. The ATP content of the duckling Pectoralis muscle decreased from 1.59 to .14 mumol/g and chicken Pectoralis decreased from 3.42 to .21 mumol/g from .25 to 24h, respectively. The R-values of duckling and chicken Pectoralis significantly increased from .25 to 24 h (.98 to 1.37 and .80 to 1.51, respectively). Duckling and chicken biochemical measurements were significantly different at all post-mortem sampling times, except for 24-h values of pH (5.66 versus 5.62, respectively) and 24-h contents of ATP (.14 versus .21 mumol/g, respectively). The different post-mortem biochemical measurements between duckling and chicken Pectoralis muscle is evidence that different rates of post-mortem metabolism and rigor development exist between these red and white avian breast muscles.

An experimental carcass cleaning machine was designed and constructed in a pilot setting, then installed and field-tested on a commercial broiler processing (i.e., picking) line operating at 160 birds per min. Powered brushes and water sprays provided the means for removal of dirt and fecal material from the thighs, vent and breast areas of the carcass. With a brush length of 2.4 m, each carcass was scrubbed for approximately 6 s. The powered brushes rotated at 65 rpm and provided a constant downward cleaning force on the carcasses. With brushes 25.4 cm in diameter, commercial, on-line testing produced a machine effluent of 1754 mg total solids/L. Increasing the brush diameter to 35.6 cm and using larger diameter, hence stiffer bristles, increased the total solids content of the effluent water to 2135 mg/L. Machine operation also significantly reduced the total solids content of scalder water. Furthermore, visual appearance of the skin was not adversely affected by the use of the larger brushes and stiffer bristles.

A physical treatment was applied to broiler carcasses during commercial processing to evaluate its effectiveness in shortening the postmortem time necessary to achieve tenderness in cooked Pectoralis major (P. major) meat. Pectoralis major muscles were stretched by using cable ties to position the wings behind the back of the carcass. The restraints were removed from the carcasses at two postchill times: within 15 min (WR) and after 1 h (WR + 1). Treated carcasses were compared with a control group of carcasses. Pectoralis major muscles were removed from control carcasses and WR carcasses between 10 and 15 min postchill. Muscles were held at 2 C until the next day, when they were cooked. Two 1.9-cm-wide strips, noted as anterior and medial, were removed from each sample and objective texture determined. The experiment was replicated five times with a total of 82, 80, and 79 carcasses evaluated for the control, WR, and WR + 1 groups, respectively. There were significant differences in objective texture due to the physical treatment and location in the muscle. The lowest shear value (5.5 kg) was noted for the WR + 1 group at the anterior location. Significantly lower shear values were noted for the anterior strip compared with the medial strip. Physically restraining the P. major muscles during processing and holding for 1 h postchill resulted in a significant reduction in force to shear broiler breast meat.

The tremendous increase in volume of new products containing broiler breast meat has caused many processors to abbreviate the traditional postmortem aging period necessary to ensure ultimate tenderness in the cooked meat. Differences in the tenderness of broiler breast muscle were examined by varying the time prior to deboning breast muscle (0, 1, or 24 hours postchill) and by holding the deboned muscles at refrigerated temperature for various times prior to freezing (0, 12, or 24 hours). Removing breast muscles immediately postchill resulted in the toughest meat. Muscles left on the carcass for 1 hour postchill were less tough than the muscles removed immediately postchill, and the muscles removed after 24 hours were the most tender.

Twenty-eight live Pekin ducklings and 28 broiler chickens were obtained at 49 days of age from commercial processing facilities for each of two trials to determine processing yields and breast meat tenderness. Birds were withdrawn from feed for 8 h and then processed. Breast halves, without skin, were removed from four birds of each species at .25, .5, 1, 2, 4, 6, and 24 h post-mortem. One side of each breast was cooked immediately after deboning (0-h aging) and the other half held 24 h at 4 C before cooking (24-h aging). Tenderness of the cooked breast meat was evaluated by Allo-Kramer shear. Duckling live, dry shell without giblets (WOG), and breast weights were significantly greater (P

The objective of the present study was to compare the effects of sodium, calcium, magnesium, and manganese ions on some biochemical and functional properties of chicken breast fillets prepared from pre- and postrigor muscles. Pre- and postrigor Pectoralis major muscles were treated with isoionic solutions of CaCl2, MgCl2, MnCl2, or NaCl and then cooked. Biochemical, textural, and yield parameters were observed. Upon cooking, pH of the prerigor muscles treated with divalent cations increased .028 units but those treated with NaCl increased .157 units. The pH of postrigor muscles increased .291 units but the change was unaffected by the treatment. Calcium ions and manganese ions increased the ratio of inosine to adenine nucleotides (R values) in the prerigor fillets but the other ions did not. Moisture absorption and cooking losses were greater for the prerigor fillets treated with divalent cations than for those treated with sodium ions. Calcium chloride reduced and MgCl2 increased Warner-Bratzler shear values of prerigor fillets but none of the treatments affected shear values of postrigor fillets. The data indicate that treatment of breast fillets with certain divalent cations, especially calcium ions, can significantly affect fillet quality.

The effects of various feed withdrawal times on yields, pH, and shear values of breast meat deboned 4 h post-mortem (PM) were determined. A total of 144 commercially reared female broilers was obtained from the holding area of a local processor, and housed for 5 days in floor pens to recover from the stress associated with transport to the plant. After 5 days, the birds were placed in one of two finishing batteries for 48 h prior to feed withdrawal treatments. Feed withdrawal times were 0, 8, 16, or 24 h prior to slaughter. Measurements included live shrink, prechill and postchill carcass yields, breast meat yield, pH at 2 and 4 h PM, and shear values. There was a progressive loss in body weight as feed withdrawal time increased. The 0-h withdrawal treatment resulted in the lowest prechill yield. Quadratic effect of feed withdrawal on shear values was significant. Breast meat from the 0-h withdrawal treatment required more force to shear, 7.09 kg, than did the meat from the 8 and 16 h treatments, 5.84 and 5.78 kg, respectively, meat from the 24-h treatment required 6.01 kg. The results indicate that feed withdrawal schedules can affect not only the carcass yields but also the objective texture of broiler meat deboned 4 h PM.

The purpose of the study was to evaluate the effect of feed withdrawal on the amount and condition of lower gut contents in broiler chickens. A total of 168 birds was used; there were seven treatments of feed withdrawal before slaughter. Data were combined into the following periods (hours of withdrawal) for statistical analysis: Period 1 = 0 and 4 h; Period 2 = 8 and 12 h; and Period 3 = 16, 20, and 24 h. Birds were killed by ether inhalation. Results indicated an increased production of excreta DM and greater loss of BW for birds subjected to the longer periods of withdrawal. The amounts of gross contents in the small intestine, ceca, colon, and cloaca were greater for Period 1 than for Periods 2 and 3. Percentages of moisture in the contents of these segments differed, as follows: in the small intestine, no differences were detected among periods; in the colon and cloaca, moisture content was lower for Period 1 than for Period 3, and no difference was detected between Periods 2 and 3; in the ceca, moisture content was higher for Period 1 than for Period 3, but, again, no difference was detected between Periods 2 and 3. Cecal material was observed in the colon only 15 times, and the numbers in each period were about equal. Ether inhalation almost entirely eliminated peri-mortem excretion. In conclusion, the scheduling of feed withdrawal to occur within Period 2 (withdrawal 8 and 12 h before slaughter) seemed adequate for minimizing the potential of fecal contamination during preslaughter handling.

Sixty ready-to-cook broiler carcasses obtained from several local supermarkets were tested for the presence of Yersinia enterocolitica and other Yersinia species. In the present study, the authors used two enrichment broths, yeast-extract/rosebengal-bile oxalate sorbose (YER-BOS) and phosphate-buffered saline with a postenrichment KOH treatment (PBS-KOH), and two plating media, cefsulodin-irgasan-novobiocin (CIN) and pectin agar. Yersinia organisms were found on 34 of 60 carcasses (56.7%) and Y. enterocolitica, on 16 of 60 carcasses (26.7%). There was no significant difference between CIN and pectin agar; however, PBS-KOH yielded a significantly higher (P≤.05) detection rate than YER-BOS, regardless of the plating media used. In addition to Y. enterocolitica, Y. frederiksenii and Y. intermedia were also isolated from the market broilers. None of the Y. enterocolitica isolates were found to be presumptively virulent.

Two experiments were conducted to determine the effect of mutual opposition of breast muscles during rigor development on ultimate tenderness of the cooked meat. In each experiment, 32 broilers were conventionally processed. Immediately after evisceration, the supracoracoideus tendon was cut at the humeral insertion on one wing (treatment) and the opposite wing was sham-operated with the tendon exposed but not cut (control). The tendon of insertion for the Pectoralis minor muscle was cut to prevent the opposition of breast muscles during rigor, while avoiding confounding effects caused by making cuts on the muscles, as would occur during typical deboning. Cutting the tendon significantly (P < 0.05) increased Warner-Bratzler shear values after cooking for both the Pectoralis major and P. minor. Deboning at 2 h post-mortem resulted in shear values for the P. major of 7.22 kg for controls and 9.08 kg for treated carcasses; P. minor shear values were 2.98 kg for controls and 4.04 kg for treated carcasses. Deboning at 24 h post-mortem produced P. major shear values of 4.68 kg for controls and 5.68 kg for treated carcasses. On whole carcasses, breast muscle opposition during rigor contributes to the tenderness of the cooked meat.

The objective of the present study was to compare the effectiveness of a microscopy method with a laser diffraction method for measuring sarcomere lengths of chicken pectoralis major (p. major) muscle fibers exhibiting various contraction states. Chicken p. major muscles were excised from the animals at death. Samples of each muscle were treated with pH-buffered (5.0 and 7.5) isoionic CaCl2, KCI, or ethylene glycol bis-(b-aminoethyl ether) N,N,N′,N′-tetraacetic acid (EGTA) solutions in order to produce variability in the degree of fiber contraction. Sarcomere lengths (SL) of the fibers were observed using light microscopy and a laser diffraction method. The methods gave comparable results for sarcomere lengths greater than 1.6 μm. However, for SL less than 1.6 μm, sarcomere contraction was not accurately assessed by the laser diffraction method.

Two experiments were conducted to evaluate the effects of wing restraint during rigor development on the physical properties of broiler breast meat. Four trials were conducted in the first experiment, using a total of 150 birds. Restraining treatments were applied post-mortem and consisted of an elbow (wing) fixing behind the carcass, lateral extension of the wings and attachment to a bar, and secure binding of the wings together behind the carcass. Results for the first two post-mortem restraints did not indicate significantly different shear values of the meat in comparison with that of the control. However, binding the wings securely behind the carcass toughened (P The second experiment was conducted to evaluate the effect of ante-mortem wing restraint using treatments of lateral extension of the wings and a modified wing tie that appeared to reduce the severity of treatment on the live bird. In 2 trials using 60 birds, the results indicated longer (P

Treatments of wing restraint (WR) were applied to broiler carcasses immediately after picking in an attempt to increase tension in the pectoralis (p.) major and restrict muscle shortening during rigor development. In the course of the study, the time allowed for aging prior to deboning of the breast meat was decreased from 4 h to 2 h post-mortem, and the effect on tenderness was determined. Results of deboning at 4 h indicated significantly longer sarcomere lengths for the p. major of wing-restrained carcasses, but shear values of the meat were not decreased. A second experiment tested a modification of the WR, combining a 3-h tie with a “release” interval of 1 h. This treatment combination resulted in higher lactate contents at 4 h, longer sarcomeres, and lower shear values than those of earlydeboned muscles without WR. A modified-WR in abbreviated schemes of deboning at 3 h and 2 h, respectively, resulted in a slight acceleration of post-mortem metabolism in p. major muscles of the WR treatment, a significant increase in sarcomere lengths, and a reduction in the meat toughening associated with early post-mortem deboning. In all of the experiments, WR resulted in significantly reduced sarcomere lengths and toughened meat in the p. minor muscle, consistent with the expected effect of treatment on opposing muscle.

Four marigold products, a bixin product, and two synthetic xanthophylls, canthaxanthin and β-apo-8′-carotenal, were evaluated for their effects on xanthophyll utilization and coloring capability in egg yolks. The selected sources, obtained as commercially available products, were added to a yellow corn basal diet containing 11 mg total xanthophyll/kg diet, and all except bixin were formulated to supply an additional 13 mg total xanthophyll/kg of test diet. Laying hens were fed control and test diets for a 21-day repletion period prior to egg collection for yolk xanthophyll and color analyses. Yolk xanthophyll content was determined by the same procedure used for feed xanthophyll analysis, and yolk color determined using the Roche color fan (RCF) and reflectance colorimetry. Canthaxanthin and β-apo-8′-carotenal resulted in the largest increases in coloring capability and the highest and lowest xanthophyll utilizations, respectively. Within the group of marigold products, there was no difference in xanthophyll utilization. The bixin product, when used alone or in combination with a marigold concentrate, produced no effect on xanthophyll utilization or yolk color.

Six trials were conducted to determine the effect of sodium pentobarbital (SP) anesthesia on broiler muscle pH, sarcomere length, and Allo-Kramer shear values. Birds were divided into six groups, three of which were anesthetized with SP prior to slaughter. Birds from both the anesthetized and nonanesthetized groups were subjected to one of three processing treatments: 1) muscles hot boned as soon as possible after death and immediately analyzed (HB/0); 2) muscles hot boned and aged 24 h in ice/water slush (HB/24); and 3) muscles left on carcass (conventional process) and aged 24 h in ice/water slush (CP/24) before deboning. The SP/HB/0 group was found to have significantly higher (P less than .05) pH values and longer sarcomere lengths than those of the other five treatment groups. No significant differences were observed for pH among the four 24-h aged groups. Sarcomere lengths were found to be shortest in the SP/HB/24 and HB/24 groups followed by SP/CP/24, HB/0, and CP/24 groups. The CP/24 and SP/CP/24 groups had the lowest shear values, with the HB/0, HB/24, and SP/HB/24 groups exhibiting three-fold higher shear values. These results indicate that SP can delay the effects of ante-mortem stress on early rigor processes; however, no such effects were apparent following 24-h aging.

In three experiments using a total of 102 broilers, effects were evaluated of post-mortem aging temperatures between 0 C and 40 C on chicken breast muscles, pectoralis (p.) major and p. minor. The first experiments analyzed the effects of temperature on muscles excised immediately post-mortem. Results of Experiment 1 suggested maximum sarcomere lengths at aging temperatures of 16 C for both muscles. However, differences between lengths observed at 0 C and 4 C were not significant for p. major, and at 0, 4, and 23 C for p. minor. Experiment 2 analyzed effects of 4 and 16-C aging temperatures and indicated that the rates of increase of R values (ratio of inosine to adenine nucleotides) were nearly equal at 4 C and 16 C when compared across each of the locations of p. major. Decreases in sarcomere lengths slowed at 16 C in anterior and middle sections of p. major, relative to lengths at 4 C. For the p. minor muscle, the increase of R values was more rapid at 16 C, whereas sarcomere shortening was slower in comparison with that observed at 4 C. In Experiment 3, an attempt was made to apply 4 C and 16-C aging temperatures to schemes of early deboning at 3 h and 4 h post-mortem. No significant effects were observed of these temperature conditionings on sarcomere lengths of the raw muscles or on shear values of the cooked meat. Furthermore, neither scheme resulted in values of p. major meat tenderness comparable with those resulting from aging the muscle intact on the carcass for 24 h.

Three experiments were conducted to examine the effects of sodium pentobarbital (SP), iodoacetate (IO), tubocurarine (TC), and surgical denervation (DN) on early rigor development in broiler breast muscle. In Experiment 1, birds were either anesthetized or not with SP before receiving an injection of IO or TC or maintained as noninjected controls. Experiment 2 was identical except that a treatment of denervation of the breast muscle was added. Experiment 3 was conducted to contrast birds at 1 day (DN1) and 3 days (DN3) denervation prior to slaughter to nonoperated controls. Measurements of muscle lactate, ATP, R value (ratio of inosine to adenine nucleotides), pH, sarcomere lengths, and shear were used to evaluate treatment effects. Results for Experiment 1 showed no significant differences among treatment and control groups for ATP and lactate contents, R values, or sarcomere lengths; however, significantly lower pH and higher shear values were observed for control birds. In Experiment 2, no significant differences were observed among the treatment groups for ATP, R values, or sarcomere lengths. However, lactate and shear values were significantly lower, and pH higher, for the DN and SP treated birds. Experiment 3 resulted in lower lactate and higher pH values for the DN3 treatment in comparison with both DN1 and control groups. Results of these studies indicate that the use of SP and DN can be used to alter the early profiles of rigor development.

Two experiments were conducted to compare the broiler skin coloring capabilities of a saponified and nonsaponified marigold concentrate. In both experiments, 260 male broiler chicks, 1 day of age, were randomly assigned to eight pens, each pen receiving one of two test diets formulated to contain the same total xanthophyll from either a saponified or nonsaponified marigold extract. In Experiment 1, a white corn basal diet was utilized so that dietary xanthophyll was entirely supplied by the test products. In Experiment 2, the diets were formulated identically to Experiment 1, except that yellow corn was substituted for white corn, and the added xanthophyll from the marigold products reduced accordingly. The broilers were processed at 49 days of age. Carcass skin and shank color were evaluated by reflectance colorimetry. Shank color was also evaluated by visual scoring with the Roche Color Fan (RCF). Saponification of the marigold concentrate resulted in significantly (P

The study was conducted to investigate a method of reducing the potential for fecal contamination during slaughter of broiler chickens. Birds were withdrawn from feed for 4, 8, 12, or 16 h before slaughter, then subjected to an electrical treatment of either stunning at 50 V, stunning plus pulsed stimulation at 50 V, or electrocution at 200 V. Peri-mortem defecatory responses were characterized, and postmortem examinations of the lower gut contents were made. Results indicated significant increases for the following variables when analyzed as linear functions on time of feed withdrawal: 1) loss of body weight (expressed as shrink); 2) amount of excreta collected during withdrawal; and 3) frequency and amount of perimortem excretions. Cecal material was observed in the colon most often for the group withdrawn 4 h from feed. Among electrical treatments, electrocution resulted in the lowest frequency of excretion, the smallest amount of excreta, and a greater tendency toward more urinous excreta; however, these results were significantly different from only the treatment of stimulation. There were no significant differences detected among electrical treatment for contents of the various segments of the lower gut. Potential for the use of electrocution to reduce fecal loads during commercial slaughtering conditions was not conclusively demonstrated.

The pectoralis muscles of broilers were either excised immediately after picking (hot-boned) or after 24 h of aging on the carcass. Gross muscle shortening along selected lengths, muscle area loss, and sarcomere shortening were calculated for the raw and cooked muscles of both treatments. Cooked meat tenderness was also evaluated at selected intramuscular locations. For hot-boned muscles, shortening after excision was about 10% along a shorter length confined and parallel to the region of clavicular origin, compared with 2% along a longer length parallel to the tendinous partition between the medial belly and lateral portion, and 16% when expressed as muscle area loss. After 24-h chill, hot-boned muscles had shortened 21% along the shorter length, 8% along the longer length, and 20% as area loss. After cooking, in the same comparison, the shortenings averaged 32% and 24%, and area loss 42%, respectively. The linear shortenings of the hot-boned muscles were related to area loss in an empirical model. Shear and texture values of the cooked meat indicated a difference due to location, which seemed consistent with the model of complex muscle shortening for this group. For muscles aged on the carcass, postchill (postexcision) and postcook shortenings, respectively, averaged 9 and 22% along the shorter length, 1 and 20% along the longer length, and 10 and 36% as area loss. Postcook decreases in sarcomere length averaged 6% for hot-boned muscles and 32% for those aged on the carcass.

A study was conducted to determine the influence of electrical stimulation (50, 200, or 350 V ac) on biochemical and textural changes in broiler breast muscle. Sixty-four broilers were stunned (50 V ac) prior to kill, and all but a control group were pulse stimulated during bleeding. After processing, carcasses were held in 10-C water for 1 h, then in 2-C ice/water slush for 1 h prior to muscle removal at 2 h post-mortem (PM). Bagged samples were held at 2 C for 24 h, then cooked. The pH, R value (ratio of adenine nucleotides to inosine nucleotides), cook yield, fluids and solids lost (F&S), and objective texture were measured. In addition, 16 broilers processed in the same manner were used in producing a profile of sarcoplasmic protein/enzyme changes in the breast muscle by cation exchange fast protein-liquid chromatography at 10 min, 2, and 24 h PM. The R values and soluble protein were also determined. Stimulation at 200 and 350 V accelerated the onset of rigor noted by lower pH values at 10 min and 1 h PM, and higher R values at 2 h PM. Muscle stimulated at 350 V exhibited the lowest cook yield and highest percentage of F&S lost, suggesting both the loss of functional properties and muscle integrity due to this treatment. All control and stimulated samples exhibited shear values in excess of what would be considered tender. Hardness and chewiness values increased as stimulation voltage levels increased. Only one of the seven principal chromatographic peaks decreased in response to increased electrical stimulation. Additional separation of the peak suggested that the component was a one active sulfhydryl site monomer of a four subunit lactate dehydrogenase enzyme.