Insights into the Identification of the Specific Spoilage Organisms in Chicken Meat

Poultry meat deterioration is caused by environmental conditions, as well as proliferation of different bacterial groups, and their interactions. It has been proposed that meat spoilage involves two bacterial groups: one group that initiates the deterioration process, known as specific spoilage organisms (SSOs), and the other known as spoilage associated organisms (SAOs) which represents all bacteria groups recovered from meat samples before, during, and after the spoilage process. Numerous studies have characterized the diversity of chicken meat SAOs; nonetheless, the identification of the SSOs remains a long-standing question. Based on recent genomic studies, it is suggested that the SSOs should possess an extensive genome size to survive and proliferate in raw meat, a cold, complex, and hostile environment. To evaluate this hypothesis, we performed comparative genomic analyses in members of the meat microbiota to identify microorganisms with extensive genome size and ability to cause chicken meat spoilage. Our studies show that members of the Pseudomonadaceae family have evolved numerous biological features such as large genomic size, slow-growing potential, low 16S rRNA copy number, psychrotrophic, and oligotrophic metabolism to initiate the spoilage of poultry meat. Moreover, inoculation experiments corroborated that these biological traits are associated with the potential to cause chicken meat deterioration. Together, these results provide new insights into the identification of SSO. Further studies are in progress to elucidate the impact of the SSO on meat quality and microbiota diversity.

Sanitization of Chicken Frames by a Combination of Hydrogen Peroxide and UV Light To Reduce Contamination of Derived Edible Products

Chicken carcass frames are used to obtain mechanically separated chicken (MSC) for use in other further processed food products. Previous foodborne disease outbreaks involving Salmonella-contaminated MSC have demonstrated the potential for the human pathogen to be transmitted to consumers via MSC. The current study evaluated the efficacy of multiple treatments applied to the surfaces of chicken carcass frames to reduce microbial loads on noninoculated frames and frames inoculated with a cocktail of Salmonella enterica serovar Enteritidis and Salmonella enterica serovar Typhimurium. Inoculated or noninoculated frames were left untreated (control) or were subjected to treatment using a prototype sanitization apparatus. Treatments consisted of (i) a sterile water rinse, (ii) a water rinse followed by 5 s of UV-C light application, or (iii) an advanced oxidation process (AOP) combining 5 or 7% (v/v) hydrogen peroxide (H₂O₂) with UV-C light. Treatment with 7% H₂O₂ and UV-C light reduced numbers of aerobic bacteria by up to 1.5 log CFU per frame (P < 0.05); reductions in aerobic bacteria subjected to other treatments did not statistically differ from one another (initial mean load on nontreated frames: 3.6 ± 0.1 log CFU per frame). Salmonella numbers (mean load on inoculated, nontreated control was 5.6 ± 0.2 log CFU per frame) were maximally reduced by AOP application in comparison with other treatments. No difference in Salmonella reductions obtained by 5% H₂O₂ (1.1 log CFU per frame) was detected compared with that obtained following 7% H₂O₂ use (1.0 log CFU per frame). The AOP treatment for sanitization of chicken carcass frames reduces microbial contamination on chicken carcass frames that are subsequently used for manufacture of MSC.

Descriptive sensory and instrumental texture profile analysis of woody breast in marinated chicken

The broiler industry is currently experiencing a muscle anomaly referred to as "woody breast," and the effect of different cooking methods on the marination properties of severe woody breast (SWB) has not yet been reported. This study compared the texture attributes of marinated (injected) normal (NOR) and SWB using a convection oven and a flat-top grill. The objectives were 1) to develop and validate a descriptive texture attribute panel with 6 trained panelists using a 16-point scale and 2) to evaluate the instrumental texture profile analysis (TPA) using a texture analyzer. Sixty-four NOR and SWB were obtained from a commercial facility. Fillet color (L*, a*, b*) and pH were measured before marination. In each of 2 trials, the breast muscles were injected in bulk with 15% brine (0.48 STPP, 0.55% NaCl, final concentration), and marinade retention was determined after 20 minutes. The meat was vacuum packaged, stored at -20°C (7 d sensory; 29 d TPA) and then thawed (4°C, 24 h). Fillets were cooked to 73°C on a flat-top grill (176°C) or in an oven (176°C), and cook loss % was determined. Panelist samples (2 × 2 cm) and TPA samples (4 × 2 cm) were cut into 3 pieces. Color and pH were higher for SWB than NOR fillets (P < 0.05). Marinade retention was 83.21% for NOR meat and 59.23% for SWB meat. The flat-top grill method resulted in higher cook loss than oven (P < 0.05). SWB had higher cook loss when compared to NOR (P < 0.05). Sensory texture descriptors springiness, hardness, denseness, cohesiveness, fracturability, fibrousness, crunchiness, and chewiness were higher for SWB than NOR fillets (P < 0.05). TPA attributes also showed higher values for SWB compared to NOR (P < 0.05). No differences in texture were found between the grill and oven for sensory and TPA attributes. In summary, marinated SWB has significant texture differences when compared to NOR, regardless of cooking method.

Utilizing original XPC™ in feed to reduce stress susceptibility of broilers

Reduction of stress is an important factor in improving poultry welfare, especially during periods of heat stress. A study was conducted to evaluate the effects of feeding the functional metabolites of Diamond V Original XPCTM to broilers reared under ambient or heat stress temperatures. Dietary treatments included: control feed (CON) and Original XPC fed continuously at 1.25 kg/MT (XPC). Half the birds in each dietary treatment were subjected to either no heat stress (24°C constant) or heat stress (35°C:24°C for 18:6 h daily) from 28 to 42 d. At the end of the heat stress period, blood was collected from 40 birds/treatment. Blood was analyzed for plasma corticosterone (CORT), plasma HSP70 (HSP70), and heterophil/lymphocyte ratios (H/L). At 42 d, bilateral metatarsal traits were also measured in 40 birds/treatment to assess physical asymmetry. Birds fed XPC had significantly lower CORT levels than CON (P < 0.001; 5,129 ± 617 vs. 8,433 ± 730, respectively). Physical asymmetry scores were also significantly higher in CON compared to XPC fed broilers (P < 0.001; 1.50 ± 0.13 vs. 0.54 ± 0.05, respectively). H/L ratios were significantly greater in CON than for XPC birds (P = 0.01; 0.81 ± 0.05 mm vs. 0.62 ± 0.05 mm, respectively). No differences were observed between CON and XPC fed broilers in HSP70. However, heat stress did increase (P < 0.0001) HSP70 compared to no heat stress birds (5.65 ± 0.12 vs. 4.78 ± 0.11 pg/mL, for heat stress and no heat stress, respectively). Feeding XPC to broiler chickens improved animal welfare via reduced stress indicators while under heat stress or no heat stress conditions. These results indicate that feeding XPC may improve poultry welfare by reducing heat stress susceptibility.

Comparative evaluation of texture wheat ingredients and soy proteins in the quality and acceptability of emulsified chicken nuggets

Chicken nuggets are commonly made with varying levels of textured vegetable proteins, such as soy and wheat, for their ability to bind water and their meat like conformation. This project compared textured wheat proteins and soy proteins at 10%, 20%, 30%, and 40% in emulsified chicken nuggets. A total of 3,024 chicken nuggets were evaluated in replications for batter breader pickup (%), par fry yield (%), cook loss (%), L*, a*, b* color value, texture profile analysis, and sensory analysis. The analysis was conducted for all 4 concentrations of wheat and soy treatments then compared to each other and an all white meat chicken nugget control. All data were analyzed with an α < 0.05 using SAS with PROC GLM and Duncan's MRT, except for sensory data, which were analyzed as a complete randomized block design using analysis of variance with a α < 0.05 and was analyzed using SAS with PROC GLM. Chicken nuggets prepared with increasing levels of textured soy and wheat proteins exhibited generally similar properties in terms of yields, color, and objective texture. Trained panel sensory analysis indicated an increased detection of soy flavors over wheat flavors at higher inclusion percentages (30% and 40%); however, these results do not have any implication of consumer acceptance.

Validation of Thermal Lethality against Salmonella enterica in Poultry Offal during Rendering

Recent outbreaks of human disease following contact with companion animal foods cross-contaminated with enteric pathogens, such as Salmonella enterica, have resulted in increased concern regarding the microbiological safety of animal foods. Additionally, the U.S. Food and Drug Administration Food Safety Modernization Act and its implementing rules have stipulated the implementation of current good manufacturing practices and food safety preventive controls for livestock and companion animal foods. Animal foods and feeds are sometimes formulated to include thermally rendered animal by-product meals. The objective of this research was to determine the thermal inactivation of S. enterica in poultry offal during rendering at differing temperatures. Raw poultry offal was obtained from a commercial renderer and inoculated with a mixture of Salmonella serovars Senftenberg, Enteritidis, and Gallinarum (an avian pathogen) prior to being subjected to heating at 150, 155, or 160°F (65.5, 68.3, or 71.1°C) for up to 15 min. Following heat application, surviving Salmonella bacteria were enumerated. Mean D-values for the Salmonella cocktail at 150, 155, and 160°F were 0.254 ± 0.045, 0.172 ± 0.012, and 0.086 ± 0.004 min, respectively, indicative of increasing susceptibility to increased application of heat during processing. The mean thermal process constant (z-value) was 21.948 ± 3.87°F. Results indicate that a 7.0-log-cycle inactivation of Salmonella may be obtained from the cumulative lethality encountered during the heating come-up period and subsequent rendering of raw poultry offal at temperatures not less than 150°F. Current poultry rendering procedures are anticipated to be effective for achieving necessary pathogen control when completed under sanitary conditions.

Transport Mechanisms and Quality Changes During Frying of Chicken Nuggets--Hybrid Mixture Theory Based Modeling and Experimental Verification

Hybrid mixture theory (HMT) based 2-scale fluid transport relations of Takhar coupled with a multiphase heat transfer equation were solved to model water, oil and gas movement during frying of chicken nuggets. A chicken nugget was treated as a heterogeneous material consisting of meat core with wheat-based coating. The coupled heat and fluid transfer equations were solved using the finite element method. Numerical simulations resulted in data on spatial and temporal profiles for moisture, rate of evaporation, temperature, oil, pore pressure, pressure in various phases, and coefficient of elasticity. Results showed that most of the oil stayed in the outer 1.5 mm of the coating region. Temperature values greater than 100 °C were observed in the coating after 30 s of frying. Negative gage-pore pressure (p(w) < p(g)) magnitudes were observed in simulations, which is in agreement with experimental observations of Sandhu and others. It is hypothesized that high water-phase capillary pressure (p(c) > p(g)) in the hydrophilic matrix causes p(w) < p(g), which further results in negative pore pressure. The coefficient of elasticity was the highest at the surface (2.5 × 10(5) Pa) for coating and the interface of coating and core (6 × 10(5) Pa). Kinetics equation for color change obtained from experiments was coupled with the HMT based model to predict the color (L, a, and b) as a function of frying time.

Controlling Listeria monocytogenes Scott A on Surfaces of Fully Cooked Turkey Deli Product Using Organic Acid-Containing Marinades as Postlethality Dips

This study evaluated the efficacy of organic acids applied singly or in combination as postlethality dips to sliced uncured turkey deli loaves to inhibit the growth of Listeria monocytogenes (Lm) Scott A. Treatments consisted of sodium lactate (SL; 3.6%), potassium lactate (PL; 3.6%), sodium citrate (SC; 0.75%), a combination of SL and sodium diacetate (SDA; 0.25%), and a combination of SL/PL/SDA, alongside appropriate negative and positive controls. Products were inoculated with 10(4)-10(5) CFU/mL streptomycin-resistant (1500 μg/mL) Lm Scott A prior to treatment. Products were then stored at ~4°C and sampled at 0, 7, 14, 21, 28, 42, and 56 d. The SL/SDA combination applied to turkey slices extended the lag phase through 21 days of refrigerated storage. Numbers of Lm Scott A rose by 0.7 log10 CFU/g through the 56 d storage period. The application of the SL/PL/SDA treatment to turkey product surfaces extended the lag phase through 42 d, with pathogen numbers declining after 21 d. Combination organic acid dips prolonged the lag phase for 2 to 6 wk on turkey product surfaces and can be useful as antimicrobial agents for Lm control on postlethality exposed sliced deli products.

SavorPhos as an all-natural phosphate replacer in water- and oil-based marinades for rotisserie birds and boneless-skinless breast

As consumer demand for all-natural marinades increases, the need to replace phosphate with a natural product that can produce equivalent or improved yield in products such as but not limited to rotisserie chickens (whole birds without giblets) and boneless/skinless breast (BSB) is a challenge for processors. The objective of this study was to determine if using an all-natural nonphosphate blend (SavorPhos-200, SP) in water-based (WB) and oil-based (OB) marinades would perform better than a commercial phosphate blend (PB). The treatments included WB+PB (water, 0.4% phosphate, 0.7% salt), WB+SP (water, 0.5% SavorPhos-200, 0.7% salt), OB+PB (water, 3% oil, 0.4% phosphate, 0.7% salt), and OB+SP (water, 3% oil, 0.5% SavorPhos-200, 0.7% salt). The rotisserie chickens and BSB were injected with a multineedle injector to 20% (wt/wt) pickup at a constant pressure (103-138 kPa). The parameters measured were marinade pickup %, 20-min and 24-h marinade retention %, and cook loss %. Color, tenderness, total moisture, and sensory test were conducted on BSB. Data were analyzed within marinade type (WB and OB). Rotisserie birds picked up and retained the same yield in WB marinades. In OB marinades, SP had higher yields postinjection and lower cook loss % than the PB, while retaining the same yield over 24 h. For BSB, the cook loss was lower in SP than the PB in WB marinades. Higher yields postinjection were achieved with OB, but had the same retention 20 min and 24 h postinjection and cook loss % as the PB. No differences were observed for total moisture or L* (lightness) within marinade type and treatment. Texture was lower, indicating increased tenderness (P < 0.05) on SP samples in both marinades. However, consumers were not able to distinguish between treatments in sensory analyses. Therefore, SavorPhos-200 can be used as a natural nonphosphate blend in WB marinades with no detriment to yield. In addition, SavorPhos-200 can be used as a natural nonphosphate blend in OB marinades with yield improvements.

Marination and packaging impact on textural properties of home-frozen broiler breast fillets

Different packaging is available to consumers, and marination is widely applied. However, their effects on the quality of broiler breast fillets during home freezing are not well known to consumers. Therefore, the objective of this study was to evaluate the effect of packaging materials on the quality of chicken breast fillets after 1, 3, and 6 wk storage at -18°C. A total of 256 fillet were randomly placed in tray packs, freezer bags, butcher paper, and nonpackaged controls. Samples were analyzed for raw pH, color, percent moisture content, and TBA reactive substances (TBARS) at d 0 (only nonpackaged controls), wk 1, 3, and 6, and cooked texture and sensory attributes at wk 1 and 6. There were differences (P < 0.05) in pH, color, percent moisture content, and texture among the treatments by wk 6, but no differences (P < 0.05) in TBARS values and the sensory evaluation (tenderness, juiciness, and overall flavor) were seen. Consumers were not able to detect quality differences (P < 0.05) among treatments despite analytical differences. Experiment 2 was conducted to evaluate the effects of marination on the quality of chicken breast fillets after 2 wk of storage in a home freezer (-18°C). A total of 240 fillets were used in the treatments: nonmarinated fresh nonfrozen, nonmarinated frozen, marinated fresh nonfrozen, and marinated frozen. Fillets were vacuum-tumbled in a 10% solution yielding a final concentration of 0.45% sodium tripolyphosphate and 0.65% salt in the meat. Raw samples were evaluated for color, TBARS, and thaw loss. Cooked samples after 2 wk of storage were analyzed for cook loss, texture, moisture, and sensory evaluation (color, juiciness, tenderness, overall flavor, and preference). Both marinated samples showed better (P < 0.05) quality in terms of L* value, TBARS, cook loss, texture, moisture content, and better sensory attributes (except color) than nonmarinated samples. Quality of marinated samples was not negatively affected by home freezing after 2 wk.

Utilization of pork collagen for functionality improvement of boneless cured ham manufactured from pale, soft, and exudative pork

This study was designed to determine the effect of raw material and the inclusion of pork collagen on the protein functionality of boneless cured pork manufactured from 100% pale, soft, and exudative (PSE), 50% PSE, and 0% PSE with either 3 or 0% collagen. A Randomized Complete Block Design with six replications was utilized as the experimental design. Inclusion of collagen decreased (P<0.05) expressible moisture and increased (P<0.05) CIE b* value. Differences (P<0.05) revealed that collagen inclusion caused the 0% PSE treatments to have a lower cooking loss for 100% PSE treatments with and without collagen and a higher protein-protein bind value for 100% PSE treatments without collagen. Utilization of pork collagen in boneless cured pork that incorporates PSE meat increases water holding capacity and has the potential to improve protein functionality characteristics of the product.

Attachment of Salmonella serovars and Listeria monocytogenes to stainless steel and plastic conveyor belts

In poultry industry, cross-contamination due to processing equipment and contact surfaces is very common. This study examined the extent of bacterial attachment to 6 different types and design of conveyor belts: stainless steel-single loop, stainless steel-balance weave, polyurethane with mono-polyester fabric, acetal, polypropylene mesh top, and polypropylene. Clean conveyor belts were immersed separately in either a cocktail of Salmonella serovars (Salmonella Typhimurium and Salmonella Enteritidis) or Listeria monocytogenes strains (Scott A, Brie 1, ATCC 6744) for 1 h at room temperature. Soiled conveyor chips were dipped in poultry rinses contaminated with Salmonella or Listeria cocktail and incubated at 10°C for 48 h. The polyurethane with mono-polyester fabric conveyor belt and chip exhibited a higher (P<0.05) mean number of attached Salmonella serovars (clean: 1.6 to 3.6 cfu/cm2; soiled: 0.8 to 2.4 cfu/cm2) and L. monocytogenes (clean: 4.0 to 4.3 cfu/cm2; soiled: 0.3 to 2.1 cfu/cm2) in both clean and soiled conditions. The stainless steel conveyor belt attached a lower (P<0.05) number of Salmonella serovars (clean: 0 to 2.6 cfu/cm2; soiled: 0.4 to 1.3 cfu/cm2) and L. monocytogenes (clean: 0.4 to 2.9 cfu/cm2; soiled: 0 to 0.7 cfu/cm2) than the polymeric materials, indicating weaker adhesion properties. Plastic conveyor belts exhibited stronger bacterial adhesion compared with stainless steel. The result suggests the importance of selecting the design and finishes of conveyor belt materials that are most resistant to bacterial attachment.

Control of Listeria monocytogenes in turkey deli loaves using organic acids as formulation ingredients

The growth of Listeria monocytogenes in further-processed meat products has become a major concern and an important food safety issue. The meat and poultry industries have incorporated interventions such as organic acids in marinades to inhibit the growth of L. monocytogenes. In this study, organic acids were utilized in the raw product and as a postcook dip to determine their inhibitory effect on the growth of L. monocytogenes in turkey deli loaves. The turkey deli loaves were processed, cooked, cooled, inoculated with streptomycin-resistant L. monocytogenes, and then dipped. Treatments were potassium lactate (PL) in the raw product with sodium lactate (SL), sodium diacetate (SD) dip, PL with SL/PL/SD dip, SL with SL/SD dip, and SL with SL/PL/SD dip. There was also a positive (inoculated) and negative (noninoculated) control, which was dipped in distilled water. Days 0, 7, 14, 21, 28, 42, and 56 were sampled for L. monocytogenes. There were no differences (P>0.05) among the organic acid treatments in the turkey deli loaves at any time points; therefore, all of the treatments increased the lag phase of L. monocytogenes, extending the shelf-life of the product. However, there was a difference between the treatments and the positive control at d 7, 14, 21, 28, 42, and 56. The growth of L. monocytogenes increased immediately in the positive control, whereas the negative control appeared to have no growth. These organic acids can provide meat processors with a useful method for extending the lag phase of L. monocytogenes in ready-to-eat meat and poultry products.

Validation of a lactic acid- and citric acid-based antimicrobial product for the reduction of Escherichia coli O157: H7 and Salmonella on beef tips and whole chicken carcasses

The objectives of this study were to determine the effects of a lactic acid- and citric acid-based antimicrobial product on the reduction of Salmonella on whole broiler carcasses during processing and the reduction of Salmonella and Escherichia coli O157:H7 on beef trim. Freshly harvested broiler carcasses were inoculated with an inoculum of Salmonella strains to yield a 10(5) CFU/ml pathogen load on the surface of the carcass. The beef tips were inoculated as well with an inoculum of either E. coli O157:H7 or Salmonella to yield 10(4) CFU/100 cm(2). After 30 min for attachment, the broiler carcasses were treated with Chicxide applied for 5 s via a spray or immersed in Chicxide for 5, 10, or 20 s. Broiler carcasses were rinsed in poultry rinse bags with 400 ml of Butterfield's phosphate buffer in which Salmonella was enumerated from the diluents and Butterfield's phosphate. Chicxide significantly reduced Salmonella by 1.3 log CFU/ml with spray treatment and 2.3 log CFU/ml for all dip treatments. Following 30 min of attachment, the beef tips were placed into a spray cabinet with either Beefxide or sterilized water (control) and sprayed at 1 ft/2.5 s chain speed at 40 lb/in(2). The external surface of each beef tip was swabbed (100 cm(2)) to determine pathogen loads. Beefxide significantly reduced E. coli O157:H7 by 1.4 log CFU/100 cm(2) and Salmonella by 1.1 log CFU/100 cm(2) (P < 0.05) compared with the control samples.

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.

Comparison of quality attributes of shell eggs subjected to directional microwave technology

Microwaves have been shown to cause thermal as well as nonthermal destruction of pathogens such as Salmonella, which can be found in shell eggs. The objective of this study was to determine if using microwave technology would cause detrimental quality effects in shell eggs. Treatments included control (no treatment) and microwave-treated (20 s) shell eggs. There were no differences in mineral content, fatty acid profile, Haugh units, broken-out score, yolk index, emulsion stability, pH of whole egg, and foaming capacity between 2 treatments (P >or= 0.05). At 0 and 30 d, there were no noticeable differences in H(2)O activity between 2 treatments. The foaming stability and albumen thermocoagulation of microwave-treated eggs were significantly higher than control eggs (P <or= 0.05). The control eggs had significantly higher emulsion capacity and lower vitelline membrane strength than the microwave-treated eggs (P <or= 0.05). Poached eggs were evaluated by sensory testing for hardness, yolk color, and albumen color, and there are no noticeable differences at 0, 15, or 30 d. At 0 d, the color of control albumen was more yellow than the microwave-treated albumen, and the chalazae of the microwave-treated eggs was more attached than the control eggs (P <or= 0.05). The TBA reactive substances were similar for 2 treatments at 0, 15, and 30 d. Peroxide values were significantly higher in the microwave-treated eggs at d 0 (P <or= 0.05), but at 15 and 30 d, no prominent differences in peroxide values were noted (P >or= 0.05). Therefore, microwave technology can be applied to shell eggs without causing detrimental effects to quality.

Use of UV light for the inactivation of Listeria monocytogenes and lactic acid bacteria species in recirculated chill brines

Ready-to-eat meat products have been implicated in several foodborne listeriosis outbreaks. Microbial contamination of these products can occur after thermal processing when products are chilled in salt brines. The objective of this study was to evaluate UV radiation on the inactivation of Listeria monocytogenes and lactic acid bacteria in a model brine chiller system. Two concentrations of brine (7.9% [wt/wt] or 13.2% [wt/wt]) were inoculated with a approximately 6.0 log CFU/ml cocktail of L. monocytogenes or lactic acid bacteria and passed through a UV treatment system for 60 min. Three replications of each bacteria-and-brine combination were performed and resulted in at least a 4.5-log reduction in microbial numbers in all treated brines after exposure to UV light. Bacterial populations were significantly reduced after 5 min of exposure to UV light in the model brine chiller compared with the control, which received no UV light exposure (P < 0.05). The maximum rate of inactivation for both microorganisms in treated brines occurred between minutes 1 and 15 of UV exposure. Results indicate that in-line treatment of chill brines with UV light reduces the number of L. monocytogenes and lactic acid bacteria.

The effect of blood removal on oxidation and shelf life of broiler breast meat

Blood components, especially hemoglobin, are powerful promoters of lipid oxidation and may decrease the shelf life of meat products. Therefore, this study examined different slaughter techniques to determine their effects on pH (24 h), color (L*a*b* values at 24 h), lipid oxidation, residual hemoglobin concentration (24 h), and sensory evaluation (d 1 and 4 postmortem; PM) in broiler breast fillets. The treatments included 1) CO(2) slaughter and not bled, 2) no stunning and bled, 3) electrical stunning (ES) and bled, 4) CO(2) stunning and bled, and 5) ES and decapitation. The birds were conventionally processed, and analyses were performed at 24 h PM except residual hemoglobin for which the samples were frozen (-80 degrees C) until analyses ( < 2 mo). There were no significant differences in pH or b* values at 24 h PM among any of the treatments. L* values were significantly higher, indicating lighter fillets in the ES and decapitated birds compared with the darker fillets from the CO(2) stunned and bled birds. The CO(2) slaughter and not bled birds had significantly higher a* values, indicating more red color, when compared with the ES and bled and decapitated birds. There were no significant differences in the residual hemoglobin contents in the broiler breast muscle when comparing all of the treatments except CO(2) slaughter and not bled, which was significantly (around 15%) greater. Overall TBA-reactive substances (TBARS; raw, cooked at 24 h, and cooked at 72 h PM) indicated that ES and bled birds had the lowest TBARS when compared with the remaining treatments. Consumer panels detected increased aroma (chicken meaty and warmed-over aromas) and flavor (chicken meaty and warmed-over flavors) in not bled samples at 24 h PM. By 72 h PM, however, there were no significant differences in aroma or flavor. Therefore, different slaughter and bleeding method may affect color and sensory properties of the broiler breast fillets, and the ES and decapitation method had the most favorable results for sensory quality.

Marination of Turkey Breast Fillets to Control the Growth of Listeria monocytogenes and Improve Meat Quality in Deli Loaves

Turkey deli loaves were evaluated using organic marinades in the raw product to control the growth of Listeria monocytogenes (LM) and improve meat quality in the cooked product. Treatments included sodium tripolyphosphate (STP; 0.45%, control), sodium lactate (3%), sodium diacetate (0.25%), sodium citrate (0.75%), and sodium lactate (3%)/sodium diacetate (0.25%) combination, all containing 1.5% salt. Data collected in the 2 trials included pH; lightness, redness, and yellowness; bind ability; cooked meat moisture; oxidation (thiobarbituric acid reactive substances); aerobic plate count (d 0 to 80); and sensory evaluation. Also, thirty-two slices from each loaf were inoculated with a 10(3) cfu/ mL surface inoculum streptomycin-resistant LM cocktail and analyzed for LM levels (d 0 to 77). The sodium lactate treatment was lower in pH (5.84) postmarination. Lactate, citrate, and the combination treatments had significantly lower lightness values; lactate, diacetate, and citrate had higher redness values; and lactate had lower yellowness values postmarination compared with premarination. Cook loss, moisture, and bind ability were higher in the STP treatment. Citrate and the combination treatments had lower thiobarbituric acid reactive substances on d 3, but there were no differences by d 15. Cohesiveness was significantly higher in the STP, lactate, and diacetate treatments, and turkey flavor was more intense in the combination treatment. The STP loaves had >10(6) cfu/cm(2) aerobic plate count by 14 d, lactate by 20 d, citrate by 40 d, diacetate by 70 d, and lactate/diacetate by 74 d. Sodium diacetate, citrate, and lactate/diacetate all extended the lag phase of LM. Therefore, acidic marinades applied in the raw product do have a negative effect on some cooked product quality attributes but do improve shelf life and decrease LM growth by extending the lag phase through 21 d postmortem.

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.

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.

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.

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.

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.