The regulatory mechanisms for beef tenderization by the calcium-independent phospholipase A2 activity of Peroxiredoxin 6

This study investigated the effect of the inhibition of the activity of Ca2+-independent Phospholipase A2 (iPLA2) of Peroxiredoxin 6 (Prdx6) on beef tenderization in the early post-mortem period. Longissimus lumborum (LL) were incubated with or without the inhibitor of iPLA2 activity of Prdx6 (MJ33) for 1, 6, 12, 24, or 36 h, followed by incubation with or without the H2O2. iPLA2 activity, troponin T and desmin, Ca2+ concentration, calpain-1, caspases, apoptosis rate, and cell morphology were examined. It was found that the reduction of the iPLA2 activity of Prdx6 was found to promote degradation of cytoskeletal proteins (troponin T, desmin). The inhibition of the iPLA2 activity of Prdx6 suppressed the caspases activation. This reduced the apoptotic rate, but increased Ca2+ concentrations and calpain-1 activation, outcomes that promoted beef tenderization. This mechanistic characterization confirms the application of Prdx6 as a biomarker for beef of high quality and consumer acceptance.

Exploring the Effects of S-Nitrosylation on Caspase-3 Modification and Myofibril Degradation of Beef In Vitro

This study aimed to explore the effects of S-nitrosylation on caspase-3 modification and its subsequent effects on beef myofibril degradation in vitro. Recombinant caspase-3 was reacted with different concentrations of S-nitrosoglutathione (GSNO, nitric oxide donor) at 37 °C for 30 min and subsequently incubated with purified myofibrillar protein from bovine semimembranosus muscle. Results indicated that the activity of caspase-3 was significantly reduced after GSNO treatments (P < 0.05) and showed a dose-dependent inhibitory effect, which was attributed to the increased S-nitrosylation extent of caspase-3. LC-MS/MS analysis revealed that caspase-3 was S-nitrosylated at cysteine sites 116, 170, 184, 220, and 264. Moreover, the degradation of desmin and troponin-T was notably suppressed by S-nitrosylated caspase-3 (P < 0.05). To conclude, protein S-nitrosylation could modify the cysteine residues of caspase-3, which accounts for the reduced caspase-3 activity and further represses its proteolytic ability on beef myofibrillar protein.

Marine Biopolymers: Applications in Food Packaging

Marine sources are gaining popularity and attention as novel materials for manufacturing biopolymers such as proteins and polysaccharides. Due to their biocompatibility, biodegradability, and non-toxicity features, these biopolymers have been claimed to be beneficial in the development of food packaging materials. Several studies have thoroughly researched the extraction, isolation, and latent use of marine biopolymers in the fabrication of environmentally acceptable packaging. Thus, a review was designed to provide an overview of (a) the chemical composition, unique properties, and extraction methods of marine biopolymers; (b) the application of marine biopolymers in film and coating development for improved shelf-life of packaged foods; (c) production flaws and proposed solutions for better isolation of marine biopolymers; (d) methods of preparation of edible films and coatings from marine biopolymers; and (e) safety aspects. According to our review, these biopolymers would make a significant component of a biodegradable food packaging system, reducing the amount of plastic packaging used and resulting in considerable environmental and economic benefits.

Techniques for postmortem tenderisation in meat processing: effectiveness, application and possible mechanisms

Abstract

Developing efficient and promising tenderising techniques for postmortem meat is a heavily researched topic among meat scientists as consumers are willing to pay more for guaranteed tender meat. However, emerging tenderising techniques are not broadly used in the meat industry and, to some degree, are controversial due to lack of theoretical support. Thus, understanding the mechanisms involved in postmortem tenderisation is essential. This article first provides an overview of the relationship of ageing tenderisation and calpain system, as well as proteomics applied to identify protein biomarkers characterizing tenderness. In general, the ageing tenderisation is mediated by multiple biochemical activities, and it can exhibit better palatability and commercial benefit by combining other interventions. The calpain system plays a key role in ageing tenderisation functions by rupturing myofibrils and regulating proteolysis, glycolysis, apoptosis and metabolic modification. Additionally, tenderising techniques from different aspects including exogenous enzymes, chemistry, physics and the combined methods are discussed in depth. Particularly, innovation of home cooking could be recommended to prepare relatively tender meat due to its convenience and ease of operation by consumers. Furthermore, the combined interventions provide better performance in controlled tenderness. Finally, future trends in developing new tenderising techniques, and applied consideration in the meat processing industry are proposed in order to improve meat quality with higher economical value.

Graphical abstract

Impact of Extraction Method on the Detection of Quality Biomarkers in Normal vs. DFD Meat

The objective of this work was to demonstrate how the extraction method affects the reliability of biomarker detection and how this detection depends on the biomarker location within the cell compartment. Different extraction methods were used to study the sarcoplasmic and myofibrillar fractions of the Longissimus thoracis et lumborum muscle of young bulls of the Asturiana de los Valles breed in two quality grades, standard (Control) or dark, firm, and dry (DFD) meat. Protein extractability and the expression of some of the main meat quality biomarkers—oxidative status (lipoperoxidation (LPO) and catalase activity (CAT)), proteome (SDS-PAGE electrophoretic pattern), and cell stress protein (Hsp70)—were analyzed. In the sarcoplasmic fraction, buffers containing Triton X-100 showed significantly higher protein extractability, LPO, and higher intensity of high-molecular-weight protein bands, whereas the TES buffer was more sensitive to distinguishing differences in the protein pattern between the Control and DFD meat. In the myofibrillar fraction, samples extracted with the lysis buffer showed significantly higher protein extractability, whereas samples extracted with the non-denaturing buffer showed higher results for LPO, CAT, and Hsp70, and higher-intensity bands in the electrophoretic pattern. These findings highlight the need for the careful selection of the extraction method used to analyze the different biomarkers considering their cellular location to adapt the extractive process.

Shockwave processing of beef brisket in conjunction with sous vide cooking: Effects on protein structural characteristics and muscle microstructure

We studied the effect of shockwave processing and subsequent sous vide cooking on meat proteins (molecular size and thermal stability) and muscle structures (molecular, micro- and ultrastructure). Beef briskets were subjected to shockwave (11 kJ/pulse) and were sous vide-cooked at 60 °C for 12 h. Shockwave processing alone decreased the enthalpy and thermal denaturation temperature of the connective tissue proteins (second peak in the DSC thermogram, p < 0.05) compared to the control raw samples, while the protein gel electrophoresis profile remained unaffected. It led to disorganisation of the sarcomere structure and also modified the protein secondary structure. More severe muscle fibre coagulation and denaturation were observed in the shockwave-treated cooked meat compared to the cooked control. The results show that shockwave processing, with and without sous vide cooking, promotes structural changes in meat, and thus may have the potential to improve the organoleptic quality of the tough meat cuts.

Methods for Extraction of Muscle Proteins from Meat and Fish Using Denaturing and Nondenaturing Solutions

The objective of the present study was to test two extraction methods including solutions with different ionic strengths on the extraction and separation of the myofibrillar proteins from meat and fish muscles of different species. Meat samples from longissimus thoracis muscle of beef and lamb, pectoralis major muscle of chicken, and dorsal white muscle of fish from sole (Solea solea), European hake (Merluccius merluccius), and sea bass (Dicentrarchus labrax) were analyzed. The extraction method using nondenaturing solution led to a major extraction of high molecular-weight proteins as myosin heavy chain, α-actinin, and desmin; on the contrary, the denaturing method provided a good protein extractability of proteins and fragments with low molecular-weight as actin, troponin-T, tropomyosin, and myosin light chain 1 and 2 proteins for the most meat and fish samples. The nondenaturing extraction method showed several advantages resulting in time and labour saving and in minimizing the use of toxic and polluting agents.

Effect of electrohydraulic shockwave treatment on tenderness, muscle cathepsin and peptidase activities and microstructure of beef loin steaks from Holstein young bulls

Hydrodynamic pressure processing (HDP) or shockwave treatment improved tenderness (18% reduction in Warner-Bratzler shear force (WBSF) of beef loin steaks. Endogenous muscle proteolyic activities (cathepsins and peptidases) and protein fragmentation of sarcoplasmic and myofibrillar proteins detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were not influenced by HDP. However, microstructure changes were clearly detected using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Specifically a disruption of the structure at the muscle fiber bundles and an increased endomysium space were observed. The present paper supports the evidence of physical disruption of the muscle fibers as a cause behind the tenderness improvement. The paper discusses the possible mechanisms responsible for the meat tenderisation induced by HDP treatment.

Effect of pH and postmortem aging on protein extraction from broiler breast muscle

This study determined the effects of extraction buffer pH and postmortem aging on the extraction of salt-soluble and water-soluble proteins from broiler pectoralis muscle. Deboned broiler breast fillets were collected at 4 h postmortem, packaged, and then stored at 4°C until 1, 5, or 8 d postmortem. After the designated aging period, salt-soluble and water-soluble protein extractions were performed using buffers at 7 different pH levels (pH 5.4, 6.4, 6.9, 7.2, 7.5, 8.0, 9.0). Protein concentrations of the extracts were measured and SDS-PAGE analysis was performed. Salt-soluble protein concentration increased (P < 0.0001) as buffer pH increased from pH 5.4 to 6.9 and then remained unchanged from pH 6.9 to 9.0. Water-soluble protein concentration increased (P < 0.0001) as buffer pH increased from pH 5.4 to 7.2 and then remained unchanged from pH 7.2 to 9.0. There was not a significant extraction buffer pH by aging treatment interaction for the total protein concentration of either the salt-soluble or water-soluble protein extracts. The protein concentrations of salt-soluble extracts were similar at both 1 and 8 d postmortem but lower (P < 0.0001) at 5 d postmortem. The protein concentrations of water-soluble extracts were similar at both 1 and 5 d postmortem, but higher (P < 0.0001) at 8 d. Both extraction buffer pH and postmortem aging influenced the SDS-PAGE protein profiles of salt-soluble and water-soluble protein extracts from breast muscles. Data demonstrate that postmortem aging and extraction buffer pH influence both the total amount and the composition of the myofibrillar and sarcoplasmic proteins that can be extracted from broiler breast fillets.

New developments in shockwave technology intended for meat tenderization: Opportunities and challenges. A review

Meat tenderness is an important quality parameter determining consumer acceptance and price. Meat tenderness is difficult to ensure in the global meat chain because the production systems are not always aiming at this purpose (ex.: cattle derived from milk production) and by the existence within the carcass of "tough" primals. Different methods can be used by the meat industry to improve meat tenderness each with its advantages and drawbacks. The application of hydrodynamic pressure or shockwaves has showed outstanding improvements by reducing the Warner Bratzler Shear Force by 25% or more. However, the technology has not penetrated into the market as first systems were based on the use of explosives and further developments seemed to lack the robustness to fulfill industrial requirements. The present paper describes the main challenges to construct a prototype for the continuous treatment of meat by shockwaves based on electrical discharges under water. Finally, improvements on the tenderness of meat by using the novel prototype are presented.