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Most current research on Campylobacter has focused on preharvest or processing plant cross-contamination. Little is known about the effect of storage environment on the survival of Campylobacter on raw poultry. We evaluated the effects of modified storage atmosphere and freezing on the survival of naturally occurring Campylobacter on raw poultry. Broiler carcasses (n = 560) were collected as they exited the chiller in 2 commercial processing plants and were sampled for the detection of Campylobacter, Escherichia coli, psychrophiles, and total aerobes at 0 and 14 d of refrigerated (2°C) storage. Gases evaluated were air, 100% O(2), 100% CO(2), and a standard poultry modified atmosphere packaging mixture (5% O(2) + 10% CO(2) + 85% N). Freezing was included as a control group. All carcasses were sampled by the whole-carcass rinse method. The rinse fluid was recovered and pooled from 5 individual rinses, and serial dilutions were made for examination of Campylobacter (42°C, 48 h), E. coli (37°C, 24 h), psychrophiles (plate count agar, 4°C, 7 d), and total aerobic bacterial populations (plate count agar, 37°C, 24 h). Campylobacter counts for all treatments were reduced during the 14-d storage period but the 100% O(2) treatment caused a significantly (P < 0.05) greater reduction than the other gas treatments. For the psychrophiles, storage in air resulted in the greatest growth after 14 d, with reduced psychrophilic growth allowed by either O(2) or the modified atmosphere packaging mixture (not different from each other). Of the treatments evaluated, CO(2) allowed the least growth of psychrophiles. Proliferation of E. coli and aerobes was the greatest when packaged in air after 14 d, whereas CO(2) packaging resulted in the least growth. These data suggest that storage under O(2) may reduce Campylobacter recovery and slow psychrophile and aerobe recovery following storage.

Lipid oxidation is known to occur rather rapidly in cooked chicken meat containing relatively high amounts of polyunsaturated fatty acids. To assess the lipid oxidation stability of sous vide chicken meat enriched with n-3 and conjugated linoleic acid (CLA) fatty acids, 624 Cobb × Ross broilers were raised during a 6-wk feeding period. The birds were fed diets containing CLA (50% cis-9, trans-11 and 50% trans-10, cis-12 isomers), flaxseed oil (FSO), or menhaden fish oil (MFO), each supplemented with 42 or 200 mg/kg of vitamin E (dl-α-tocopheryl acetate). Breast or thigh meat was vacuum-packed, cooked (74°C), cooled in ice water, and stored at 4.4°C for 0, 5, 10, 15, and 30 d. The lipid oxidation development of the meat was estimated by quantification of malonaldehyde (MDA) values, using the 2-thiobarbituric acid reactive substances analysis. Fatty acid, nonheme iron, moisture, and fat analyses were performed as well. Results showed that dietary CLA induced deposition of cis-9, trans-11 and trans-10, cis-12 CLA isomers, increased the proportion of saturated fatty acids, and decreased the proportions of monounsaturated and polyunsaturated fatty acids. Flaxseed oil induced higher deposition of C18:1, C18:2, C18:3, and C20:4 fatty acids, whereas MFO induced higher deposition of n-3 fatty acids, eicosapentaenoic acid (C20:5), and docosahexaenoic acid (C22:6; P < 0.05). Meat lipid oxidation stability was affected by the interaction of either dietary oil or vitamin E with storage day. Lower (P < 0.05) MDA values were found in the CLA treatment than in the MFO and FSO treatments. Lower (P < 0.05) MDA values were detected in meat samples from the 200 mg/kg of vitamin E than in meat samples from the 42 mg/kg of vitamin E. Nonheme iron values did not affect (P > 0.05) lipid oxidation development. In conclusion, dietary CLA, FSO, and MFO influenced the fatty acid composition of chicken muscle and the lipid oxidation stability of meat over the storage time. Supranutritional supplementation of vitamin E enhanced the lipid oxidation stability of sous vide chicken meat.

The fatty acid composition of chicken muscle may affect the lipid oxidation stability of the meat, particularly when subjecting the meat to thermal processing and storage. The objective of this study was to evaluate the diet effect on lipid oxidation stability of fresh and cooked chicken meat. Six hundred broilers were raised for a 6-wk feeding period and were assigned to 8 treatments with 3 repetitions. Broilers were fed a basal corn-soybean meal diet, including 5% of either animal-vegetable, lard, palm kernel, or soybean (SB) oil, each supplemented with a low (33 mg/kg) or high (200 to 400 mg/kg) level of vitamin E. Fresh breast and thigh meat and skin were packaged and refrigerated (4°C) for 15 d. Breast and thigh meat were frozen (-20°C) and stored for ~6 mo and then thawed, deboned, ground, and formed into patties of 150 g each. Patties were cooked (74°C), cooled, packaged, and stored in refrigeration for 6 d. The lipid oxidation development of the products was determined using the TBA reactive substances analysis. The results showed that the lipid oxidation development, in both fresh chicken parts and cooked meat patties, was influenced by the interaction of either dietary lipid source or vitamin E level with storage time. Fresh breast meat showed no susceptibility to lipid oxidation, but thigh meat and skin presented higher (P < 0.05) malonaldehyde values in the SB oil treatment, starting at d 10 of storage. In cooked patties, during the entire storage time, the SB oil showed the highest (P < 0.05) lipid oxidation development compared with the other treatments. Regarding vitamin E, in both fresh parts and cooked meat patties, in most sampling days the high supplemented level showed lower (P < 0.05) malonaldehyde values than the control treatment. In conclusion, the lipid oxidation stability of chicken meat is influenced by the lipid source and vitamin E level included in the diet upon storage time and processing of the meat.

There is an increasing demand in precooked chicken meat products for restaurants and catering services. Because cooked chicken meat develops lipid oxidation relatively fast, sous vide chicken meat was studied to assess its shelf-life. Six hundred Cobb x Ross broilers were fed for 6 wk with a basal corn-soybean meal diet including soybean, palm kernel, or animal-vegetable oil, each supplemented with 33 or 200 mg/kg of dl-alpha-tocopheryl acetate. Broilers were randomly assigned into 6 treatments and 4 repetitions with 25 birds each. Boneless breast or thigh muscle pieces were dissected into 5 x 5 x 5 cm cubes, vacuum-packed, cooked in water bath (until 74 degrees C internal temperature), chilled, and stored at 4 degrees C for 1, 5, 10, 25, and 40 d. For each storage day, each pouch contained 3 pieces of meat, either breast or thigh. Thiobarbituric acid reactive substances analysis, to quantify malonaldehyde (MDA) values, was conducted to estimate the lipid oxidation development. Nonheme iron values of cooked meat were analyzed. Fatty acid methyl esters analysis was performed in chicken muscle to determine its fatty acid composition. There was no interaction between dietary fat and vitamin E level in all of the variables studied except in nonheme iron. Dietary fat significantly influenced the fatty acid composition of the muscle (P < 0.01), but it did not affect the MDA values, regardless of differences in the muscle fatty acid composition between treatments. Supplementation of the high level of vitamin E significantly reduced the MDA values in both breast and thigh meat (P < 0.01). The maximum MDA values were observed at d 40 of storage in thigh and breast meat in animal-vegetable and soybean oil treatments with the low levels of vitamin E, 0.91 and 0.70 mg/kg, respectively. Nonheme iron values in thigh meat differed between treatments at 1 or 25 d of storage but not in breast meat. In conclusion, refrigerated sous vide chicken meat has a prolonged shelf-life, which is enhanced by dietary supranutritional supplementation of vitamin E.

Pale, soft, and exudative (PSE) refers to meat that is pale in color, forms soft gels, and has poor water-holding ability. Most frequently used in reference to pork, this defective meat is being seen with increasing frequency in turkey and broiler processing plants. It has been estimated that this PSE-type meat represents 5 to 40% of meat that is produced in the poultry industry. With the increased production of further-processed products, this PSE problem has become more apparent in the turkey industry. It has been estimated that due to the high incidence, a single turkey processing plant could be losing $2 to 4 million per year, resulting in a loss in excess of $200 million dollars by the turkey industry alone.

Beef carcasses (n=30) from 3/4 Angus (A)×1/4 Brahman (B), 1/4A×3/4B, and 1/2A×1/2B F(1) crosses were used to evaluate breed type, electrical stimulation, and postmortem aging on the M. semimembranosus (SM), M. semitendinosus (ST), M. biceps femoris (BF), M. vastus lateralis (VL), M. gluteus medius (GM), M. longissimus dorsi lumborum (LD), and M. triceps brachii (TB). Shear force values decreased with increased postmortem aging to a greater extent in steaks from 3/4A×1/4B than steaks from the other breed types. Shear force values for steaks from the round (SM, ST, BF, VL) were higher than steaks from the loin (LD, GM) and chuck (TB) for both electrically stimulated and non-electrically stimulated muscles. In the LD muscle, calpastatin activities were similar among breed types. Muscle type played the greatest role in determining tenderness.

Beef and pork longissimus dorsi (LD) and semimembranosus (SM) and chicken breast (B) and thigh (T) muscles excised 24 h postmortem were ground by muscle/species group, formed into patties, pan-fried, refrigerated for 0, 3 or 6 days, and evaluated by a trained sensory panel for intensity of specific flavors. The rate of decline in species-specific natural meat flavor intensity and the rate of increase in "cardboard" (CBD) flavor intensity during the first half of the 6-day storage were fastest for beef, while such decline and increase during the entire storage period were slowest for chicken B. Overall trends of natural meat flavor and CBD intensity changes for chicken T appeared more like those for the red meats than chicken B. It was concluded that, while flavor deterioration can occur in cooked-stored meats from all the species, quantitative or the magnitude of differences between species would depend on muscle types and sensory terms/method used.

Broiler carcasses are often trimmed during evisceration to remove damaged areas of the carcass. Because deboning before rigor mortis development can toughen meat, trimming during evisceration may toughen the meat. This study evaluated the effects of trimming on the tenderness of broiler breast meat. To evaluate the effect of wing removal on tenderness, breast halves from 2 flocks were collected after chilling at a commercial plant. One-third were untrimmed controls, one-third had small amounts of breast meat removed with wing (WMin), and one-third had large amounts of breast meat removed with wing (Wmax). Salvage fillets from the 2 flocks were also collected from the salvage table of the plant. Carcasses were also processed to evaluate the effect of breast blister trimming that removed a superficial amount of muscle tissue, half of which had breast blister trims, and half did not. All front halves or carcasses were aged until 24 h postmortem and deboned. Salvage fillets were held refrigerated until 24 h postmortem. Fillets were cooked and then sheared in 2 locations on the fillet, upper and lower, to determine if tenderness was more affected at areas close to the trim. Carcasses with wing trims had significantly higher shear values compared with the control, and shear values from the upper portion of the fillets from the WMax and WMin (nearer the trim) were significantly greater than for the lower portion. Location, however, did not affect shear values in the control carcasses. This finding indicated that tenderness of the areas nearest the trim might be affected more by the trim process. Salvage table deboning significantly increased shear values throughout the fillet. There was no significant difference in shear value due to breast blister trimming. The results of this study suggest that trimming carcasses by wing or breast fillet removal results in decreased meat tenderness.

Postmortem electrical stimulation (ES) tenderizes meat by acceleration of adenosine triphosphate (ATP) depletion, pH decline, and physical disruption of muscle fibers. It has been demonstrated that rigor development at elevated temperatures, as with slow chilling, can cause meat to develop pale color and poor water-holding capacity. The objective of this study was to compare the functionality of broiler breast meat from control and electrically stimulated carcasses with and without normal rapid chilling. Broilers were either electrically stimulated (450 mA, 450 V, 2 s on, 2 s off for 7 pulses) immediately after bleeding or used as nonstimulated controls. The ES birds were either chilled immediately (ES2) or had chilling delayed for 2 h at room temperature (ESD2). All ES breast fillets were harvested at 2 h postmortem. The control carcasses were chilled immediately and had fillets harvested at 2 h postmortem (C2) or at 8 h postmortem (C8). Electrical stimulation accelerated pH decline and prevented toughening when breast meat was deboned at 2 h postmortem, regardless of chilling rate. The water released from the gels during cooking was higher for the ESD2 than the ES2 group, which was not different from the C2 group, suggesting that ES followed by slow chilling reduced water-holding capacity compared with the ES2 and C2 groups. There were no differences in expressible moisture, gel strength, or lightness among the ES2, ESD2, and C2 treatments. These results indicated that high voltage ES followed by normal chilling did not impair protein functionality or cause pale, soft, exudative meat. However, there was some evidence that slow chilling after ES may negatively affect some water-holding properties of the meat.

Broiler carcass skin color is important in the United States and Mexico. This study evaluated the use of natural and synthetic pigments in broiler diets at commercial levels. Birds were fed natural or synthetic pigments at low or high levels, simulating US and Mexican commercial practices. Skin color was measured during live production (3 to 7 wk of age) and after slaughter and chilling. The natural pigments had consistently greater skin b* values (yellowness) than the synthetic pigments. The high levels produced greater skin b* values than the low levels, regardless of source. The synthetic pigments had a slower increase in skin b* but reached the same level as the natural low by 7 wk. There was no difference in skin a* values (redness) due to pigment source or level or the age of the bird. By 7 wk, all pigment sources approached plateau levels in the blood, but the synthetic pigment diet produced higher blood levels of yellow and red pigments than the natural pigment diets. Processing intensified skin yellowness and reduced skin redness. These data suggest that although synthetic pigments might have been absorbed better than natural ones, natural pigments were more efficient at increasing skin yellowness and there were only small differences between high and low levels for each pigment source. This finding may allow reduction in pigment use and feed cost to achieve the same skin acceptance by the consumer.

Several processors use inline injection and tumble marination practices to decrease labor costs and product handling. However, the stimulation of this early postmortem (PM) muscle may cause increased toughness. Therefore, the objective of this study was to compare marination of early PM meat by using injection, vacuum tumbling, or both to determine their effects on tenderness of broiler breast fillets. Breast fillets from 45 broilers were deboned at 3 h PM and injected, tumbled (30 min, 635 mmHg, 14 rpm), or injected + tumbled with a 10% solution of 0.54%. NaCl + 0.42% sodium tripoly phosphate (STPP). Nonmarinated controls deboned at 3 and 6 h PM were also included. Shear value, sarcomere length, and cook loss were determined on each of the fillets. The control and tumbled fillets had the highest shear value compared with the remaining 3-h treatments. The injected + tumbled and tumbled fillets had the highest cook loss followed by 3-h control and injected treatments. Tumble marination at 3 h PM produced significantly tougher meat then the injection treatment. Experiment 2 was conducted to test marinade penetration through the fillets because penetration could have affected the results of the previous study. Broiler breast fillets were deboned from 60 broilers at 3 h PM and were vacuum tumbled (30 min, 635 mmHg, 14 rpm) with a 15% solution of 0.54% NaCl and 0.42% STPP. We determined shear value and cooked meat moisture of the fillets and sodium ion migration into the fillets. Although there were no significant differences in shear value between control and tumbled fillets, the cooked meat moisture was significantly higher in tumbled fillets when compared with the controls. Sodium ion concentration was significantly higher on the surface (especially the lateral surface) of the fillets when compared with the center, which suggested some uneven distribution.

Pale, soft, exudative (PSE) turkey meat is a growing problem for the industry of further processed poultry meat. The low pH condition due to rapid glycolysis while the body temperature is still high leads to protein denaturation, causing pale color and reduced water-holding capacity. This condition impacts product yield and quality. These studies were designed to estimate the incidence of PSE broiler meat in a commercial plant and to use response surface methodology to characterize the relationship between pH and lightness (at deboning and at 24 h postmortem), expressible moisture, drip loss, and cook loss. Pale fillets had significantly lower pH, greater L* values at 3 and 24 h postmortem, and higher expressible moisture, drip loss, and cook loss. The lower water-holding capacity of the pale fillets was characteristic of PSE meat. Additionally, L* values were measured on 3,554 boneless broiler breast fillets in a commercial processing line. By using the L* value range (>54) from the pale group of fillets as an indication of paleness, approximately 47% of the 3,554 fillets were pale and could potentially exhibit poor water-holding capacity. These results may not represent the entire industry but indicate that PSE chicken can represent a substantial proportion of commercially processed broiler meat.

Pale, soft, exudative (PSE) meat is a growing problem in the poultry industry and is characterized by rapid postmortem pH decline. The low pH condition while the body temperature has not yet chilled leads to protein denaturation, causing pale color and reduced water-holding properties. The water loss and the protein damage from the PSE condition may impact the ability of the muscle to uptake or retain marinade solution. This study was conducted to determine if a marination with salt and alkaline phosphates could rectify the protein functionality losses imparted by the PSE condition and to determine if marinade pH affects pale and normal fillets in the same manner. Pale (n = 175) and normal-colored (n = 160) fillets were collected from deboning lines at two commercial processing plants based on subjective color evaluation alone. The fillets were then characterized by L* value, pH, and expressible moisture. They were then tumbled with a solution containing salt and sodium tripolyphosphate at 4 C for 30 min. Marinade uptake, drip loss, and cook loss were all measured. As expected, the pale fillets had higher L* values and lower pH values than the normal fillets. For the pH 9 marinade, uptake and drip losses were similar in pale and normal fillets, but cook loss from pale fillets was greater than that of the normal fillets. Marinade solution at pH 11 showed no difference in pH or cook loss between pale and normal fillets. These results indicate that the PSE condition cannot be reversed by the marination treatments used in this study.

Rigor mortis development in turkey breast muscle and the effect of electrical stunning on this process are not well characterized. Some electrical stunning procedures have been known to inhibit postmortem (PM) biochemical reactions, thereby delaying the onset of rigor mortis in broilers. Therefore, this study was designed to characterize rigor mortis development in stunned and unstunned turkeys. A total of 154 turkey toms in two trials were conventionally processed at 20 to 22 wk of age. Turkeys were either stunned with a pulsed direct current (500 Hz, 50% duty cycle) at 35 mA (40 V) in a saline bath for 12 seconds or left unstunned as controls. At 15 min and 1, 2, 4, 8, 12, and 24 h PM, pectoralis samples were collected to determine pH, R-value, L* value, sarcomere length, and shear value. In Trial 1, the samples obtained for pH, R-value, and sarcomere length were divided into surface and interior samples. There were no significant differences between the surface and interior samples among any parameters measured. Muscle pH significantly decreased over time in stunned and unstunned birds through 2 h PM. The R-values increased to 8 h PM in unstunned birds and 24 h PM in stunned birds. The L* values increased over time, with no significant differences after 1 h PM for the controls and 2 h PM for the stunned birds. Sarcomere length increased through 2 h PM in the controls and 12 h PM in the stunned fillets. Cooked meat shear values decreased through the 1 h PM deboning time in the control fillets and 2 h PM in the stunned fillets. These results suggest that stunning delayed the development of rigor mortis through 2 h PM, but had no significant effect on the measured parameters at later time points, and that deboning turkey breasts at 2 h PM or later will not significantly impair meat tenderness.

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.

Broilers were stunned with carbon dioxide or electricity prior to slaughter to evaluate feather release force (FRF) following scalding with conventional or abbreviated scald methods. Broilers (n = 72) were stunned using an electrical saline stunner (35 mA, 60 Hz AC, 7 s) or shackle-line CO2 gas stunning tunnel (15 to 40% CO2 gradient for 90 s). After bleeding for 90 s, the broilers were then scalded with a soft scald (53 C for 120 s) or a softer scald (53 C for 90 s). Within 2 min after scalding, feathers from the right femoral feather tract were removed perpendicularly using a force gauge to evaluate FRF. The FRF for the soft scald was higher than that for the softer scald. The FRF results indicated that there were no significant differences between the two stunning treatments (CO2 and electrical) for either scalding treatment.

Previous research has indicated that antemortem stress factors can influence the development of pale, soft, and exudative (PSE) meat in swine as well as in turkeys. Such antemortem factors can include environmental temperatures, relative humidity, preslaughter handling practices, and transportation. However, the effect of transportation on meat quality of turkeys has not been extensively studied. Eighty Nicholas male turkeys (21 wk of age) were divided into two groups and were either transported in coops on a flatbed trailer for 3 h immediately prior to processing or processed without transportation. Breast muscle samples were collected for pH (0, 2, 24 h), L* value (2, 24 h), drip loss, and cook loss. Additionally, breast fillets were marinated and cooked to determine marination uptake, retention, and cook loss. The breast muscles from transported turkeys had significantly higher muscle pH at 0, 2, and 24 h; significantly lower L* values at 2 and 24 h; significantly higher marination retention (i.e., lower drip loss after marination); and significantly lower cook loss in the marinated fillets compared with fillets of the nontransported turkeys. There were no significant differences in drip loss and cook loss of the nonmarinated fillets or the marination uptake percentage between the transported and nontransported turkeys. These results suggest that transporting turkeys immediately before processing does not induce PSE meat and may actually improve water-holding properties.

Pale, soft, exudative (PSE) turkey meat is a growing problem for industry and has been associated with rapid postmortem pH decline and loss of protein functionality, similar to PSE pork. This study was designed to estimate the incidence of PSE meat in a commercial plant and use response surface methodology to characterize the relationship between pH, lightness (L* value), and water-holding capacity (WHC). One hundred thirty-four turkey breast fillets were selected from the processing line so that 67 had normal color (lightness), and the other 67 were more pale than normal. Fillets were analyzed at time of deboning (1.5 h postmortem) and at 24 h postmortem for color (L* value), pH, drip loss, expressible moisture, and temperature. Additionally, L* values were measured on 2,995 turkey breasts from the processing line to determine the commercial incidence of PSE meat based on color. The pale fillets had significantly lower pH, greater L* value, and less WHC but equal temperature when compared with the fillets with normal color. The L* value and pH were correlated with WHC as measured by expressible moisture, but L* value seems to have more predictive value. By using the L* value range (>53) from the pale-selected fillets as an indication of paleness, approximately 40% of the 2,995 fillets would exhibit poor WHC. These results suggest that PSE meat can represent a significant portion of commercially processed turkey breast meat and that the L* value measurement could be used to sort turkey meat so that PSE type meat could be used in specialized formulations.

Previous research has indicated that seasonal-type heat stress (HS) can contribute to the development of pale, soft, exudative (PSE) meat in fast-growing turkeys and that halothane exposure may identify stress-susceptible animals. This study evaluated the ability of halothane screening to identify stress-susceptible birds prone to developing pale, exudative meat when reared to market age. Two lines of turkeys (n = 292), one selected for rapid overall growth (BODY) and the other for large breast muscle yield (BREAST), were exposed to 3% halothane for 5 min at 2 to 4 wk of age and were raised together until 16 wk of age. Approximately 10% of both BODY and BREAST birds were sensitive to halothane. Between 16 and 20 wk, all of the halothane sensitive (HAL+) and half of the halothane nonresponders (HAL-) were exposed to an HS environment of 30 to 36 C (night/day), whereas the other half of the HAL- birds were kept at an ambient temperature of 13 to 21 C (night/day). All birds were slaughtered at 20 wk of age, and samples were collected for pH, L* value, drip loss, cooking loss, and shear value. The BREAST strain had 5% greater breast percentage than the BODY strain, and there were no differences in ready-to-cook yields between any treatments. The HAL+ HS birds had significantly lower muscle pH (0 h) and significantly higher L* values at 2 h postmortem compared with HAL- HS birds in the BREAST strain; however, there was no difference in L* value at 24 h postmortem. The HAL- HS birds had significantly lower muscle pH (0 h and 2 h) and significantly higher L* values at 2 h postmortem compared with HAL- controls in the BODY strain. The HAL- HS BREAST birds had significantly higher drip loss than HAL- controls. No differences in shear value were found among any treatments. The incidence of PSE (2-h L* values >52) was significantly higher in HAL+ HS birds (34.7%) compared with HAL- HS birds (13.4%). These results suggest that halothane sensitivity early in life is associated with HS susceptibility and the development of pale meat when birds are slaughtered at market age. These results also suggest that halothane screening may be better at predicting the development of PSE meat during HS in the strain selected for large breast yield rather than rapid overall growth.

1. This study was to evaluate the effects of post-mortem electrical stimulation (ES) on carcase moisture loss and on tenderness, R-value and pH of breast fillets following air chilling. 2. In each of 4 replications, 8 birds were electrically stimulated and 12 birds were controls. The ES birds were stimulated at the head in a 1% saline bath (450 V, 0.45 A, 2 s on/1 s off for 7 pulses). After evisceration the carcases were air chilled in a cooler at 1 to 2 degrees C with an average relative humidity of 91% and an air speed of 44 m/min. 3. Breast fillets were harvested at 2 and 4 h postmortem from both ES and control carcases and also at 8 h postmortem from control carcases to determine moisture loss pH and R-value. 4. Although there was no significant effect of ES on shear value at 2 h postmortem, the ES fillets had a lower shear value mean than the control fillets at 4 h postmortem. There was no significant difference between the shear value means of the ES 4 h fillets and the control 8 h fillets. 5. ES accelerated the normal post-mortem decline in pH at both 2 and 4 h postmortem. 6. The R-value means for the control and ES samples were similar 2 h but the R-value mean of the ES samples was greater than the control at 4 h postmortem. 7. The results suggest that, when followed by air chilling, ES accelerates postmortem metabolism, reduces ageing by up to 50%, and has no effect upon evaporative moisture loss.

The turkey industry suffers from pale, soft, and exudative meat (PSE) that is unsuitable for further processing because of excessive color variation, poor meat binding, and depressed water holding ability. This condition is caused by accelerated postmortem muscle metabolism and is thought to be related to a similarly inherited condition in swine. A quick, nondestructive method of screening animals is needed to avoid further propagation of PSE in breeding flocks. In this study, a halothane test used with swine was evaluated as a possible detection method for PSE-susceptible turkeys. In Experiment 1, a commercial strain of 4-wk-old male turkeys (n = 116) was exposed to 3% halothane gas for 3 min (6 L/min) and examined for leg muscle rigidity. Experiment 2 followed similar testing measures, using two strains of growth-selected turkeys (n = 504). Measurements of pH, R-value (ratio of inosine:adenosine), color, and expressible moisture content were made from each bird's breast fillet to determine whether the muscles of the responding birds would develop PSE characteristics. Five percent of tested birds in the first experiment and 2% in the second experiment exhibited rigid legs, indicating some of the discriminating power of this test. However, the data indicated that the characteristics of muscles from these birds did not differ from those of the nonresponding birds (P < 0.05). Possibly, the birds may need to be screened or slaughtered at a different age or using different methods.

This experiment was conducted to evaluate the effects of electrical stimulation (ES) on breast fillets harvested at 1 h post-mortem and individually quick frozen (IQF) or aged on ice (ICE). Twelve birds were electrically stimulated (450 V, 750 mA, 2 s on/1 s off for 15 s) at the neck in a saline bath. Twenty-four unstimulated birds were used as controls. Breast fillets were harvested at 1 h post-mortem from ES and control carcasses or at 4 h post-mortem from control carcasses and were either IQF or ICE until 24 h post-mortem. Fillets were then analyzed for shear value, pH, R value, and color. Electrical stimulation significantly reduced shear values compared to the 1 h controls for both IQF and ICE treatments. The ICE fillets deboned at 1 h from ES-treated carcasses had shear values similar to those of ICE fillets deboned from the 4 h controls. Electrical stimulation increased the percentage of shear values at or below 8 kg/g for the fillets from ES-treated carcasses compared to the 1 h controls. Electrical stimulation accelerated the normal post-mortem decline in pH and increase in R value. There was no significant difference in L* or a* values between the fillets held for 1 or 24 h. The results suggest that by electrically stimulating carcasses at the neck using a saline bath, the aging period could be eliminated by removing fillets immediately after chilling at 1 h, decreasing the costs associated with aging whole carcasses or front halves.

Rapid post-mortem metabolism concomitant with the early onset of rigor mortis can lead to the development of pale, soft, and exudative (PSE) meat. However, a reliable, nonlethal method for induction of this syndrome for the ante-mortem identification of abnormal turkeys has not been identified. The present study was conducted to evaluate the potential use of succinylcholine for inducing PSE meat in susceptible turkeys. Four-week-old Nicholas toms were either uninjected (controls) (n = 44) or injected with succinylcholine and butorphanol (n = 76) in combination. Post-mortem tissue samples were taken from the Pectoralis at 15 min, 2 h, and 4 h, for pH and R-value (the ratio of inosine to adenosine) determination. L*values were evaluated at 4 and 24 h post-mortem and drip loss and cook loss were determined. Means for pH, R-value, L*value, drip loss, and cook loss did not differ due to injection treatment. When Pectoralis were grouped as normal (L* < 53) or pale (L* > 53), pale fillets had lower pH and higher R-values than normal birds by 15 min post-mortem. Decreased water-holding properties were evident as drip loss and cook loss were increased in the pale group. The observed frequency of pale birds was 21.6% in the population, and the occurrence of pale birds was highest in the butorphanol-treated group. These findings suggest that although butorphanol did not affect overall treatment means for the test parameters, more turkeys in the treated group exhibited PSE meat.

Development of rigor mortis at elevated post-mortem temperatures may contribute to turkey meat characteristics that are similar to those found in pale, soft, exudative pork. To evaluate this effect, 36 Nicholas tom turkeys were processed at 19 wk of age and placed in water at 40, 20, and 0 C immediately after evisceration. Pectoralis muscle samples were taken at 15 min, 30 min, 1 h, 2 h, and 4 h post-mortem and analyzed for R-value (an indirect measure of adenosine triphosphate), glycogen, pH, color, and sarcomere length. At 4 h, the remaining intact Pectoralis muscle was harvested, and aged on ice 23 h, and analyzed for drip loss, cook loss, shear values, and sarcomere length. By 15 min post-mortem, the 40 C treatment had higher R-values, which persisted through 4 h. By 1 h, the 40 C treatment pH and glycogen levels were lower than the 0 C treatment; however, they did not differ from those of the 20 C treatment. Increased L* values indicated that color became more pale by 2 h post-mortem in the 40 C treatment when compared to the 20 and 0 C treatments. Drip loss, cook loss, and shear value were increased whereas sarcomere lengths were decreased as a result of the 40 C treatment. These findings suggested that elevated post-mortem temperatures during processing resulted in acceleration of rigor mortis and biochemical changes in the muscle that produced pale, exudative meat characteristics in turkey.

Heat stress is one of the prominent ante-mortem stressors that elicits pale, soft, and exudative meat characteristics in stress-susceptible pigs. Industry reports of exudative turkey meat increase in the early summer with the onset of prolonged high temperatures. To study the effect of seasonal heat exposure on turkeys, 122 17-wk-old Nicholas tom turkeys were subjected in January either to growth temperatures of 16/24 C (night/day) (control) or to elevated temperatures of 32/38 C (night/day) (heat-stressed, HS). Turkeys were processed at 21 wk of age in a manner simulating commercial conditions. Pectoralis muscle samples were taken at 15 min (prechill), 2 h (postchill), and 24 h and analyzed for R-value, pH, and color. At 2 h, the remaining intact Pectoralis muscle was harvested, aged on ice for 23 h, and analyzed for drip loss and cook loss. Percentage mortality and carcass weights were not significantly different between treatments. By 15 min post-mortem, the HS birds exhibited a faster pH decline and had higher R-values that persisted through 24 h. The HS birds were also paler in color and exhibited increased drip loss and cook loss when compared to controls; however, expressible moisture was not different between treatments. In addition, the HS birds had a higher frequency of abnormal birds than controls when birds were grouped as normal (L* < 53) or abnormal (L* > 53).

In this study, different methods of 0.2 M or 0.3 M CaCl2 delivery into hot-boned spent Leghorn breast fillets followed by tumbling were evaluated. The CaCl2 was delivered by adding 10% (wt/wt) solution into the tumbler, injection 10% (wt/wt) into the fillet, or soaking at room temperature for 15 min followed by soaking at 2 C for 45 min. All these treatments were subjected to either tumbling at room temperature for 1 h or no tumbling. Water injected and untreated samples served as controls. All fillets were baked and sheared with an Allo-Kramer cell. Introduction of 0.2 M CaCl2 through different delivery methods was not sufficient to improve spent fowl meat tenderness, even when followed by tumbling. When 0.3 M CaCl2 injection was followed by tumbling, the mean shear value of the hot-boned spent hen fillets was reduced to near the tenderness level acceptable to consumers. However, when tumbling was performed on the fillets treated with calcium introduced by methods other than injection, the shear values were higher than samples using the calcium injection method. Therefore, tumbling in combination with injection of 0.3 M CaCl2 is essential for maximal tenderization of spent fowl meat.

Biochemical characteristics of spent fowl meat injected with calcium chloride or sodium chloride were evaluated. Hot-boned breast fillets were injected to 10% (wt/wt) with 0.3 M CaCl2 or 0.6 M NaCl, tumbled, and aged 24 h. Tumbling was conducted at 20 C, -635 mm Hg, 20 rpm for 1 h. Hot-boned and cold-boned (24 h) fillets were used as controls. One fillet from each carcass was baked and sheared with an Allo-Kramer cell, whereas the other fillet was used for biochemical analysis. Shear values indicated that both CaCl2- and NaCl-treated samples had significantly (P < 0.05) lower shear values than hot-boned controls but were similar (P > 0.05) to cold-boned samples. The CaCl2 injection treatment significantly elevated (P < 0.05) the tissue calcium content compared to all other treatments. There was no significant difference in heat-stable collagen content (P > 0.05) among all treatments, which indicated that CaCl2 or NaCl did not contribute to meat tenderness through degradative changes in collagen. Calpain data indicated that mu-calpain had disappeared by 24 h aging in all treatments. The m-calpain activity was significantly lower (P < 0.05) in samples treated with CaCl2 than in the other samples. The NaCl-treated samples had m-calpain activity similar (P > 0.05) to that of hot-boned controls. Sarcomeres of CaCl2-treated samples were significantly shorter (P < 0.05) than those of cold-boned controls, were similar (P > 0.05) to those of hot-boned controls, and were shorter than those of NaCl-treated muscles. The sarcomere length and calpain data suggest that CaCl2 tenderized fillets by ionic strength and calcium-specific effects (possibly a proteolytic action), whereas the NaCl solution tenderized by ionic strength effect at a similar conductivity level to that of the CaCl2 solution.

Solutions of 0.6 M NaCl and 0.3 M CaCl2 having similar conductivities were used to evaluate the ionic strength effects on spent fowl meat tenderness. Breast fillets were deboned immediately after bleeding (hot-boned) and NaCl or CaCl2 was injected into them at two different times (< 30 min post-mortem and after 24 h storage) followed by tumbling and solution replenishment to evaluate the effects of delayed application. Hot-boned and cold-boned (24 h) were used as controls. All tumbling was conducted at -635 mm Hg, 20 C, 20 rpm for 1 h. All fillets were baked and then sheared with an Allo-Kramer cell. The results indicated that CaCl2 and NaCl reduced the shear values similarly, suggesting that elevated ionic strength at a similar conductivity to NaCl may play a major role in spent fowl meat tenderization with CaCl2. Replenishing muscle at 24 h post-mortem with 0.3 M calcium solution to 10% (wt/wt) after tumbling did not exert further tenderization, indicating that injecting a 10% level of 0.3 M calcium solution into spent hen fillets was sufficient to cause maximum tenderization. The delayed application of both CaCl2 and NaCl solutions resulted in a tenderizing effect, perhaps by eliminating the toughening effect of the prerigor physical stimulation effect of the earlier injection process. The additional tenderizing effects of calcium or sodium solutions injected at 24 h post-mortem may allow poultry processors to tenderize their spent fowl meat without the time constraints present in the prerigor state.

High voltage post-mortem electrical stimulation (ES) and muscle tensioning during chilling (MT) were applied to broiler carcasses to determine the effect of this combined treatment on absorbance ratio (R- value), sarcomere shortening, and myofibrillar fragmentation in muscles of differing fiber type composition. The ES + MT treatment resulted in a greater effect on these three parameters in the posterior Latissimus dorsi (predominantly twitch-glycolytic) than in the anterior L. dorsi (predominantly tonic-oxidative). The differing responses of these two muscles to the ES + MT treatment combination may be useful in explaining the effects of rigor-accelerating treatments such as ES + MT in avian and mammalian muscles.

Aminoguanidine (AG) is a nucleophilic compound that inhibits nonenzymatic, glucose-derived collagen cross-linking in animal tissues. Whether AG can attenuate the accumulation of collagen cross-links in the Biceps femoris muscle of 64-wk-old broiler breeder hens as well as improve meat quality, was investigated. Eighty-four broiler breeder hens (30-wk-old) were divided into four equal groups. Each group was assigned randomly to diets supplemented with 0. 200, 400, or 800 ppm AG, respectively. Birds were fed individually, 150 g diet/d. After feeding AG for 34 wk, six birds from each group were killed and samples from the leg muscle were analyzed for changes in collagen content. Aminoguanidine decreased (P < 0.05) glucose-derived collagen cross-links in skeletal muscle as measured by fluorescence and collagen solubility. Insoluble collagen fraction decreased with increasing AG dosage, whereas acid-soluble and pepsin-soluble fractions increased with increasing AG dosage. Aminoguanidine did not affect shear force. In agreement with studies on animals with diabetes, AG is a potent inhibitor of glucose-derived cross-linking in chickens although the results from the measurements of shear force do not support its used for improving carcass quality in spent hens.

A single anion-exchange column resolved two peaks of calcium-activated neutral protease activity, corresponding to the two calpain forms chicken skeletal muscle. Multiple columns have previously been needed to resolve the two isoforms from avian tissue. Calcium requirement assays confirmed one form to require approximately 100 microM Ca2+ for half-maximal activity, while the other required approximately 500 microM Ca2+. Electrophoresis revealed that the enzymes were not purified to homogeneity.

Two 72-bird trials were conducted to determine the effects of 15 s electrical stimulation (ES) (440 V, 2 s on and 1 s off) and prechill muscle tensioning (MT) on fragmentation, tenderness, and post-mortem metabolism of early-harvested (1 h post-mortem) broiler breast fillets. Compared with controls, all treatments increased sarcomere length and decreased shear value. Electrical stimulation reduced muscle pH values. Histological examination of samples from fillets harvested early and then aged 24 h revealed that all treatments increased fiber disruption compared with controls. Both fragmentation and excessive sarcomere shortening prevention were important to the improvement in fillet tenderness associated with the ES and MT treatments.

A staining procedure used for simultaneously determining three different fiber types in single sections of bovine, porcine, or ovine skeletal muscle was modified for use with broiler skeletal muscle. The modification involved acid-preincubation of muscle sections at a pH of 4.15 followed by staining for reduced nicotinamide adenine dinucleotide (NADH) tetrazolium reductase enzyme and for acid-stable myosin-adenosine triphosphatase enzyme activity, respectively. Four broiler muscles were selected for fiber-type determination of fast (alpha), slow (beta), red, aerobic (R), or white, anaerobic (W) properties. The anterior latissimus dorsi muscle was composed almost entirely of beta-R fibers while the pectoralis superficialis muscle was composed almost entirely of alpha-W fibers. The sartorius and posterior latissimus dorsi muscles were much more heterogeneous in fiber-type distribution, exhibiting all three types of fibers (alpha-W, alpha-R, and beta-R).

Scabs and scratches in the hip region of chicken carcasses have become the single most common cause of downgrading and required trimming at processing in some areas of the United States. Repeatable correlations with microbiological agents, environment, and nutrition have not been observed. The present report provides evidence that scabs and scratches, present at processing, are the result of injuries inflicted by toenails of birds as they climb on one another. Onychectomy (removal of approximately two-thirds of the distal phalanx) of all four digits of each foot prior to chick placement resulted in 3.7 and 4.8-fold reduction in subjective lesion scores and 7 to 10-fold increases in the percentage of USDA Grade A carcasses at a commercial processing plant.

The use of acetylenic acid analogs differing in chain length or position of the triple bonds permitted the systemic study of structure activity relationships for the arachidonate metabolizing enzymes (i.e, cyclo-oxygenase and lipoxygenase) in platelets and the relationship of these enzymes to aggregation. We were able to demonstrate analogs that were differentially selective in altering platelet arachidonic acid metabolism. We found analogs that preferentially: (a) inhibited cyclo-oxygenase only, (b) inhibited the 12-lipoxygenase only, (c) inhibited the cyclo-oxygenase and lipoxygenase, and (d) inhibited neither enzyme in platelets. There was a direct correlation between the rank order of potency of the acetylenic analogs to inhibit platelet cyclo-oxygenase and to suppress aggregation. Certain structural features of the triynoic acetylenic analogs were critical in influencing platelet function; thus the presence of a triple bond at position 14 as well as the lack of triple bond at position 5 resulted in analogs which inhibited both cyclo-oxygenase and platelet aggregation. On the other hand, analogs that inhibited only platelet 12-lipoxygenase were very weak inhibitors of platelet aggregation. These inhibitors provide potentially powerful tools for dissociating the two arachidonate metabolic pathways. If other tissues are are readily manipulated as platelets, the analogs may be especially useful for gaining insight into the contribution of lipoxygenase products to biological function.

Utilizing a variety of fatty acids, differing in chain length, degree and position of unsaturation, we investigated the substrate specificity for the enzymatic production of biologically active slow reacting substances (SRS) and of the other leukotrienes. A cell-free enzyme system obtained from RBL-1 cells was used in this study. The primary structural requirement observed for the conversion by this lipoxygenase enzyme system was a delta 5,8,11 unsaturation in a polyenoic fatty acid. Such fatty acids as 20:4 (5,8,11,14) 20:5 (5,8,11,14,17), 20:3 (5,8,11), 19:4 (5,8,11,14) and 18:4 (5,8,11,14) were readily converted to compounds that comigrated with 5-HETE and 5,12-DiHETE and to biologically active SRS. Chain length did not have an influence on the formatin of these hydroxyacids. Fatty acids with the initial unsaturation at delta 4, delta 6, delta 7, or delta 8 were a poor substrate for the leukotriene enzyme system. Therefore, this lipoxygenase pathway in leukocytes is quite different from the lipoxygenase in platelets which does not exhibit this specificity.