Physicochemical and biochemical parameters of chicken breast meat influenced by stunning methods

Synergistic Effect of Combined Treatment with Allicin and Antioxidant of Bamboo Leaves and Preservation of Bullfrogs (Lithobates catesbeiana) during Refrigeration Storage

The effects of allicin and antioxidant of bamboo leaves (AOB) on the quality of bullfrogs (Lithobates catesbeiana) during refrigerated storage (4 °C) were investigated. The quality changes in samples treated with deionized water (CK), allicin solution (All), antioxidant of bamboo leaves (AOB), and allicin solution combined with AOB solution (AA) in microbiological, physicochemical, and sensory evaluation were analyzed, respectively. The results demonstrated that combination treatment inhibited the increase in total viable counts, delayed the decrease in amino acid content, and retarded the sensory deterioration. Preservative treatment has an inhibitory effect on the early storage of PBC, which can reduce PBC by about 1.0 log CFU/g. The reduction in thiobarbituric acid (TBA) content and total volatile basic nitrogen (TVB-N) content indicated that combination treatment could better restrain the lipid oxidation and degradation of protein than the CK group and single-treatment group. In addition, the TVB-N content in the AA group still did not exceed the threshold on the 14th day. As a consequence, combination treatment prolonged the shelf life of bullfrogs for another six days. Therefore, allicin and AOB with excellent antioxidant and antimicrobial activity could be an effective approach to delay the biochemical reaction of refrigerated bullfrogs. This study has provided a potential approach for increasing the shelf life of bullfrogs and preserving their quality during refrigerated storage.

Underlying formation mechanisms of ultrasound-assisted brined porcine meat: The role of physicochemical modification, myofiber fragmentation and histological organization

Ultrasound treatment has been a good hurdle technique for meat curing processing, where both physical and chemical consequences can be involved towards final quality of obtained products. However, the specific correlation between ultrasound parameters and muscle fiber fragmentation and myofibrillar microstructural changes during curing deserve further evaluation. In present study, we comparatively studied the effect of ultrasound-assisted brining (UAB) and static brining (SB) on the muscle proteolysis events and microstructural/morphological variation of porcine meat as well as the physicochemical indices and histological characteristics. The results showed that UAB (20 kHz, 315 W for 1 h) could markedly enhance the muscle proteolysis with higher free-/peptide-bound alpha-amino-nitrogen (α-NH2-N) content (P < 0.05) than SB treatment and greatly improved the fragmentation of muscle fiber tissues of cured meat. Meanwhile, UAB processing favored more opening structures of myofibrillar proteins with more hydrophobic groups being exposed. The quantitative histological analysis revealed that, compared with SB treatment, UAB could significantly increase the gap between muscle fibers and the swelling of the perimysium (P < 0.01), proving an efficient curing process with better textural and water holding properties.

Longissimus dorsi Muscle's Chemical Composition, Fatty Acid Pattern, and Oxidative Stability in Korean Hanwoo Finishing Cattle Following Slaughtering and Stunning with or without Brain Disruption and State of Consciousness

Handling during pre- and post-slaughter conditions can affect the quality and safety of meat. An experiment was conducted to compare slaughtering with or without a state of consciousness on Longissimus dorsi muscle's proximate composition, cholesterol content, fatty acid profile, and storage quality (pH, microbiology, and thiobarbituric acid reactive substances (TBARS) value) in Korean Hanwoo finishing cattle (KHFC). Twenty-four KHFC (three replications of four animals per replicate) were slaughtered following two methods: (1) SSUC: slaughtering by applying captive bolt stunning, brain disruption, and neck cutting with the animal in an unconscious state; and (2) SSCS: slaughtering by applying captive bolt stunning, without brain disruption, and neck cutting with the animal in a conscious state. General carcass traits, proximate composition (exempting higher ash content), and cholesterol content of the Longissimus dorsi muscle did not differ between slaughter treatments (SSCS vs. SSUS) (p > 0.05). The total SFA, UFA, PUFA, and MUFA values did not change for those subjected to different slaughtering types; however, some particular SFA values, namely lauric, myristic, and myristoleic acid, were diminished for the SSCS method as compared with the SSUC method (p < 0.05). The Longissimus dorsi muscle's pH value was elevated (p < 0.05), the microbial population tended to be diminished (p < 0.10), and the TBARS value was suppressed for the SSCS method relative to that of the SSUC method during 2 weeks of storage (p < 0.05). Thus, compared with the SSUC method, the SSCS method ensured splendid storage quality with some positive influence on the proximate composition (total ash content) and fatty acid profile (some specific saturated fatty acids) of the Longissimus dorsi muscle of KHFC.

Effects of quercetin on tenderness, apoptotic and autophagy signalling in chickens during post-mortem ageing

The effect of quercetin on chicken breast muscle tenderness and the associated mechanism were investigated. The results indicated that quercetin significantly decreased the shear force and increased the myofibril fragmentation index (MFI). Haematoxylin-eosin-stained images showed that the internal structure of myofibril bundles in the quercetin-treated group was obviously degraded. Transmission electron microscopy showed that the myofibril structure, especially the M-line and A-band, was seriously degraded after quercetin treatment. Furthermore, quercetin treatment increased caspase-3 activity and the Bax/Bcl-2 ratio. The intensity of BiP, XBP1 and p-IRE1/IRE1 ratio increased significantly, and caspase-12 was activated. In addition, quercetin induced the transition from LC3I to LC3II and increased the expression of ATG7 and Beclin-1. The PI3K/Akt/mTOR signalling pathway was involved in the induction of autophagy and apoptosis by quercetin. These results indicated quercetin can promote meat tenderization, and activate apoptosis and autophagy pathways during post-mortem ageing.

Innovative Characterization Based on Stress Relaxation and Creep to Reveal the Tenderizing Effect of Ultrasound on Wooden Breast

In order to explore a new strategy to characterize the texture of raw meat, based on the ultrasonic tenderized wooden breast (WB), this study proposed stress relaxation and creep to determine the rheological properties. Results showed that hardness was significantly decreased from 3625.61 g to 2643.64 g, and elasticity increased, after 600 W ultrasound treatment at 20 kHz for 20 min (on-time 2 s and off-time 3 s) at 4 °C. In addition, based on the transformation of creep data, a new indicator, slope ε'(t), was innovatively used to simulate a sensory feedback of hardness from the touch sensation, proving WB became tender at 600 W treatment due to the feedback speed to external force. These above results were confirmed by the reduced shear force, increased myofibril fragmentation index (MFI), decreased particle size, and increased myofibrillar protein degradation. Histology analysis and collagen suggested the tenderizing results was caused by muscle fiber rather than connective tissue. Overall, stress relaxation and creep had a potential to predict meat texture characteristics and 600 W ultrasound treatment was an effective strategy to reduce economic losses of WB.

Combined effect of ultrasound and sodium bicarbonate marination on chicken breast tenderness and its molecular mechanism

The objective of this study was to explore the combined effect of ultrasound (20 kHz ultrasound probe (12 mm diameter), an output power of 350 W for 5 min (on-time and off-time pulse durations of 2 s and 3 s, respectively)) with low concentration (0.2 M) sodium bicarbonate solution (USB) on chicken breast tenderness and its preliminary molecular mechanism. Therefore, myofibril fragmentation index (MFI), filtering residues, cooking loss, shear force, histology of meat as well as SDS-PAGE, circular dichroism (CD), synchronous fluorescence spectroscopy, differential scanning calorimetrv (DSC) of actomyosin were investigated and compared with untreated (Control), deionized water (DW), ultrasound in deionized water (UDW), 0.2 M sodium bicarbonate solution (SB), respectively. The results showed that USB can effectively increase MFI, and reduce filtering residues, cooking loss and shear force by compared with UDW or SB. Furthermore, myofibril was presented with the largest interfibrillary spaces and the highest degree of actomyosin dissociation in USB group. The increase in α-helix content and decrease in fluorescence intensity of tyrosine and tryptophan implied that USB caused the conformation change in actomyosin. Additionally, actomyosin in USB group became more sensitive to temperature. Therefore, the treatment of ultrasound combined with low concentration of sodium bicarbonate accelerated actomyosin degeneration was considered as a promising and efficient technique in meat processing, especially for the fitness enthusiasts.

Quality parameters of chicken breast meat affected by carcass scalding conditions

Objective

The influence of broiler carcass scalding conditions on chicken breast meat quality parameters was investigated.

Methods

Two hundred and seventy Cobb broiler chickens from 42 to 48 days old were slaughtered according to the standard industry practice and scalded in five temperature/time combinations—T₁, 54°C/210 s; T₂, 55°C/180 s; T₃, 56°C/150 s; T₄, 57°C/120 s; T₅, 58°C/90 s.

Results

Scalding temperature increase resulted in higher values of external and ventral lightness and in protein functionality reduction—determined by emulsification capacity and protein denaturation—in chicken breast fillets 24 h post-mortem. Protein secondary structures had conformational changes, with a decrease of the α-helix and an increase of the β-sheet and β-turn proportions, mainly in T₁ and T₅ samples, determined by Fourier-transform infrared spectroscopy in an attenuated reflectance mode analysis. The chemical composition, pH, water holding capacity and Warner-Bratzler shear force did not differ among the treatments. In the fatty acid profile, the 18:1n-9 was lower in T₅, which suggested that the high scalding-temperature could have caused the lipid oxidation. The values of the polyunsaturated fatty acids (PUFA), such as 22:2, 20:4n-6, and 22:6n-3, were highest in the T₅, thus being related to the phospholipid cellular membrane collapse in this experimental condition and subsequent release of these PUFA.

Conclusion

Intermediate scalding-parameters avoided the negative changes in the chicken meat quality.