Proteome basis of pale, soft, and exudative-like (PSE-like) broiler breast (Pectoralis major) meat.

Pale, Soft, and Exudative (PSE) broiler breast meat has poor protein functionality, which leads to quality problems and economic loss in the poultry industry. Proteomics has been applied to characterize the biochemical mechanisms governing tenderness, color, and water-holding capacity in meat. However, the proteome basis of PSE has not yet been characterized for broiler breast meat. Therefore, this study was conducted to determine the differences in meat quality (cooking loss and shear force), descriptive sensory characteristics, consumer acceptance, and whole muscle proteome between normal and PSE-like broiler breast meat. Male Hubbard × Cobb 500 birds (n = 1,050) were raised in commercial houses. Prior to harvest, a sample of the broilers (n = 900) were subjected to short-term stress (38°C for 2 h), and the remaining broilers (n = 150) were maintained at control conditions (21°C for 2 h). Broiler breast (Pectoralis major) meat was collected and characterized by pH24 and L*24 as normal (pH24 5.8 to 6.2, L*24 45 to 55) or PSE-like (pH24 5.4 to 5.7, L*24 55 to 65) samples. Normal broiler breast meat had lower shear force values than PSE-like meat (P < 0.05). Based on sensory descriptive analysis, normal cooked chicken breast meat was more tender and juicier than PSE-like breast meat (P < 0.05). Consumer sensory analysis results indicated that 81% of consumer panelists liked normal breast meat whereas 62% of the panelists liked PSE-like breast meat. Whole muscle proteome profiling identified fifteen differentially abundant proteins in normal and PSE-like broiler breast samples. Actin alpha, myosin heavy chain, phosphoglycerate kinase, creatine kinase M type, beta-enolase, carbonic anhydrase 2, proteasome subunit alpha, pyruvate kinase, and malate dehydrogenase were over-abundant (P < 0.05) in PSE-like broiler breast whereas phosphoglycerate mutase-1, alpha-enolase, ATP-dependent 6-phosphofructokinase, and fructose 1,6-bisphosphatase were over-abundant (P < 0.05) in normal meat. Thus, results indicated that differences in proteome abundance could be related to the meat quality differences between normal and PSE-like broiler breast meat.

Utilization of buffered vinegar to increase the shelf life of chicken retail cuts packaged in carbon dioxide.

Poultry processors commonly place whole parts of broilers in plastic packages and seal them in an atmosphere of 100% carbon dioxide before shipping them to food service and retail customers. This practice extends the shelf life of retail cuts to approximately 12 d under refrigerated conditions. The objective of this study was to determine the antimicrobial efficacy of vinegar for growth inhibition of mesophilic and lactic acid bacterial counts and enhancement of shelf life in CO2-packaged refrigerated chicken thigh samples. Meat quality, sensory differences, and microbial enumeration were evaluated for chicken thighs that were sprayed with 0, 0.5, or 1.0% vinegar. No differences were observed (P > 0.05) among treatments (control vs. 0.5 and 1.0% vinegar-treated chicken thighs) with respect to pH and Commission Internationale d'Eclairage L*a*b*for both chicken skin and the meat tissue. The difference from the control test indicated that trained panelists were not able to detect a difference (P > 0.05) in flavor between the chicken thigh treatments. The mesophilic and Lactobacillus bacterial counts were enumerated after 0, 4, 8, 12, 16, and 20 d of storage. The mesophilic bacterial load for the 1.0% vinegar treatment was less than all other treatments after 8, 12, 16, and 20 d of storage, whereas the 0.5% vinegar treatment had lower bacterial counts at d 12 than both controls and had an approximate shelf life of 16 d. For lactic acid bacteria, the vinegar 1.0% treatment had lower counts than the control treatments at d 12 and 16. The results from the study indicate that a combination of 1.0% vinegar with CO2 packaging can extend the shelf life from 12 to 20 d for chicken retail cuts without negatively affecting the quality and sensory properties of the broiler meat.

Reduction of Listeria monocytogenes biofilms on stainless steel and polystyrene surfaces by essential oils.

Plant-derived essential oils were tested for their ability to eliminate biofilms of Listeria monocytogenes on polystyrene and stainless steel surfaces. Various concentrations of essential oils were tested with different contact times on biofilms of various ages. Preliminarily screening of nine essential oils and related phenolic compounds in a disk diffusion assay revealed that thyme oil, oregano oil, and carvacrol had the highest antimicrobial activity. Further screening of these three compounds against 21 L. monocytogenes strains representing all 13 serotypes indicated some strain-specific variations in antimicrobial activity. For 1-day-old biofilms of mixed L. monocytogenes strains produced at 22°C on polystyrene microtiter plates, only 0.1% concentrations of thyme oil, oregano oil, and carvacrol were needed to eliminate 7 log CFU per well. On the stainless steel coupons, a 0.5% concentration of these compounds was adequate to completely eliminate 4-day-old biofilms at 7 log CFU per coupon. Our findings indicate that these compounds are potential candidates for elimination of L. monocytogenes biofilms on stainless steel and polystyrene surfaces.

Reduction of Listeria monocytogenes in raw catfish fillets by essential oils and phenolic constituent carvacrol.

The antimicrobial activity of various essential oils and carvacrol was determined on fresh raw catfish fillets against a 4-strain Listeria monocytogenes mixture representing serotypes 1/2b, 3b, 4b, and 4c that were predominantly isolated from catfish processing environments. Thyme oil, oregano oil and carvacrol exhibited concentration and time dependent responses in broth against L. monocytogenes; for example 0.5% concentrations resulted in 4 log CFU/mL reduction within 30 min whereas 0.1% concentrations required more than 24 h for the same level of reduction. Lemon, orange, and tangerine oils, at 0.5% showed listeriostatic effect in which 4 log CFU/mL of the initial L. monocytogenes load was unchanged at 4 °C in 10 d whereas 1% concentrations were listericidal in a time dependent manner. Apart from carvacrol, efficacy of tested essential oils in reducing L. monocytogenes and total microbial load from catfish fillet was very limited. Dipping treatment of catfish fillets in 2% carvacrol solution for 30 min at 4 °C reduced L. monocytogenes to an undetectable level from their initial load of 5 log CFU/g and reduced total microbial load from catfish fillets by approximately 5 log CFU/g. In sensory analysis trained panelist preferred control samples over 2% carvacrol treated samples implying potential limitation in applicability of carvacrol for fillet treatments.