Effect of selected modified atmosphere packaging on Campylobacter survival in raw poultry.

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 stability of omega-3- and conjugated linoleic acid-enriched sous vide chicken meat.

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.

Dietary lipid source and vitamin E effect on lipid oxidation stability of refrigerated fresh and cooked 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.

Soybean, palm kernel, and animal-vegetable oils and vitamin E supplementation effect on lipid oxidation stability of sous vide chicken 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.

Research developments in pale, soft, and exudative turkey meat in North America.

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.

Factors influencing the variation in tenderness of seven major beef muscles from three Angus and Brahman breed crosses.

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.

Early postmortem carcass trim effects on the tenderness of broiler breast fillets.

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.

Research note: Functionality of electrically stimulated broiler breast meat.

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.

Skin pigmentation evaluation in broilers fed natural and synthetic pigments.

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.

Comparison of flavor changes in cooked-refrigerated beef, pork and chicken meat patties.

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.

Early postmortem injection and tumble marination effects on broiler breast meat tenderness.

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.

Turkey carcass chilling and protein denaturation in the development of pale, soft, and exudative meat.

Pale, soft, and exudative (PSE) meat is a growing problem in the turkey industry and has been associated with processing conditions such as slow carcass chilling. The development of PSE meat is caused by protein denaturation resulting from a rapid rate of pH decline early postmortem (PM) while carcass temperatures are still elevated. This research was conducted to determine the relationship of slow chilling to protein denaturation and PSE development. A total of 48 toms were conventionally processed in 2 trials at 22.5 wk of age, and chilled at 0, 10, 20, or 30 degrees C for either 45 or 90 min before deboning (at 60 or 105 min PM). Temperature and pH of the breast muscle was recorded at 15 min PM, at the time of deboning (60 or 90 min PM), and at 24 h PM. Color was determined at deboning and again at 24 h PM. Gel strength, cook loss, expressible moisture, total protein solubility, and bound phosphorylase quantities were determined on the fillets at 24 h PM. There was no difference in carcass temperature at 15 min PM, but by 105 min PM each temperature treatment was significantly different, with the carcasses chilled at 0 and 10 degrees C having the lowest temperature, the 30 degrees C-chilled birds having the highest temperature, and the 20 degrees C-chilled carcasses being intermediate but significantly different from either extreme. The carcass temperature differences at 105 min PM indicated that the carcass experienced differing chilling rates. To varying degrees, slower rates of chilling resulted in lower pH, greater degree of lightness (L* value), greater cook loss, and reduced gel strength. However, chilling rate had no effect on total protein solubility or myofibrillar phosphorylase for any of the treatments. Chilling rate seems to contribute to PSE turkey meat characteristics but by a mechanism independent of total protein solubility or myofibrillar phosphorylase.

Injection marination strategies for remediation of pale, exudative broiler breast meat.

Pale, soft, and exudative (PSE) breast meat is caused by a rapid postmortem pH decline while carcass temperatures are still warm. The resulting protein denaturation leads to a pale color and a decrease in water-holding capacity, causing excessive yield losses to producers. If some of this protein damage could be prevented or reversed, and water-holding capacity increased, these excessive yield losses could be avoided. Therefore, this study evaluated the use of prerigor injection of broiler breast fillets with sodium phosphates (STPP) and sodium bicarbonate to determine the effects on PSE and normal meat. A total of 200 prerigor broiler breast fillets were collected at 2 h postmortem (PM) at a commercial processing plant and were classified by L* value as pale (L* >54) or normal (L*<51). The fillets were then injected (about or less than 3 h postmortem) with 7% (wt/wt) of 0.54% NaCl + 0.42% PO4 (pH 9), 0.54% NaCl + 0.42% PO4 (pH 11), 0.30 M sodium bicarbonate (pH 12), or left as noninjected controls. The pH and L* value at 2 and 24 h postmortem, marinade uptake, water-holding capacity, and expressible moisture were evaluated. As expected, the pale fillets had lower pH and higher L* values at 2 h postmortem and lower water-holding capacity than the normal fillets. Prerigor marination with NaCl and STPP (pH 9) reduced cook loss in breast fillets. The pH 11 marinade increased 24 h pH of pale fillets compared to that of normal fillets and reduced cook loss. Sodium bicarbonate increased pH at 24 h PM of pale fillets but not to that of normal fillets. These results indicate that marinating prerigor PSE meat with the high-pH phosphate marinade used in this study can improve PSE meat quality.

Evaluation of physical dimension changes as nondestructive measurements for monitoring rigor mortis development in broiler muscles.

Studies were conducted to develop a non-destructive method for monitoring the rate of rigor mortis development in poultry and to evaluate the effectiveness of electrical stimulation (ES). In the first study, 36 male broilers in each of two trials were processed at 7 wk of age. After being bled, half of the birds received electrical stimulation (400 to 450 V, 400 to 450 mA, for seven pulses of 2 s on and 1 s off), and the other half were designated as controls. At 0.25 and 1.5 h postmortem (PM), carcasses were evaluated for the angles of the shoulder, elbow, and wing tip and the distance between the elbows. Breast fillets were harvested at 1.5 h PM (after chilling) from all carcasses. Fillet samples were excised and frozen for later measurement of pH and R-value, and the remainder of each fillet was held on ice until 24 h postmortem. Shear value and pH means were significantly lower, but R-value means were higher (P < 0.05) for the ES fillets compared to the controls, suggesting acceleration of rigor mortis by ES. The physical dimensions of the shoulder and elbow changed (P < 0.05) during rigor mortis development and with ES. These results indicate that physical measurements of the wings maybe useful as a nondestructive indicator of rigor development and for monitoring the effectiveness of ES. In the second study, 60 male broilers in each of two trials were processed at 7 wk of age. At 0.25, 1.5, 3.0, and 6.0 h PM, carcasses were evaluated for the distance between the elbows. At each time point, breast fillets were harvested from each carcass. Fillet samples were excised and frozen for later measurement of pH and sacromere length, whereas the remainder of each fillet was held on ice until 24 h PM. Shear value and pH means (P < 0.05) decreased, whereas sarcomere length means (P < 0.05) increased over time, indicating rigor mortis development. Elbow distance decreased (P < 0.05) with rigor development and was correlated (P < 0.01) with shear value (r = 0.2581), sarcomere length (r = -0.3079), and pH (r = 0.6303). These results suggest that elbow distance could be used in conjunction with other detection methods for optically automating measurement of rigor mortis development in broiler carcasses.

The role of carcass chilling rate in the development of pale, exudative turkey pectoralis.

Pale, soft, and exudative meat is a growing problem in the turkey industry that has been associated with processing conditions such as improper chilling. This condition is caused by accelerated postmortem glycolysis while carcass temperatures are still elevated, resulting in protein denaturation and poor meat quality. To evaluate the involvement of chilling rate, 48 toms were conventionally processed at 17.5 wk of age and chilled at 0,10, 20, or 30 C for 45 or 90 min and deboned. Temperature and pH of the breast fillet were recorded at 15 min, deboning time, and at 24 h postmortem (PM). Drip loss, L* value, expressible moisture, gel strength, and cook loss were determined on the fillets at 24 h PM. At 15 min PM, there were no temperature differences among treatments. At deboning, the carcasses chilled at 30 C had the highest fillet temperature and had significantly lower pH values when compared to those chilled at 0 and 10 C. L* value was significantly higher in carcasses chilled at 30 C and deboned at 60 min PM when compared to 0 and 10 C chilled carcasses. There were no significant differences in L* values at 105 min and 24 h PM among any treatment group. Drip loss and cook loss were significantly higher in carcasses chilled at 30 C compared to the remaining treatments. There were no differences in expressible moisture at 60 or 105 min PM or gel strength at 60 min PM in any of the treatments. However, at 105 min PM, carcasses chiled at 0 C had higher gel strength when compared to the remaining treatments. These results indicate that there is a relationship between chilling rates and meat quality with slower chilling producing PSE-like characteristics.

The characterization and incidence of pale, soft, and exudative broiler meat in a commercial processing plant.

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.

Marination performance of pale broiler breast 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.

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.

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.

The influence of transportation on turkey meat quality.

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.