Oxidative stability and gelation properties of myofibrillar protein from chicken breast after post-mortem frozen storage as influenced by phenolic compound-pterostilbene

Dietary pterostilbene exerts potential protective effects by regulating lipid metabolism and enhancing antioxidant capacity on liver in broilers

Intensive breeding of broilers met the increasing demands of human for broiler products, but it raised their increased susceptibility to various stressors resulting in the disorder of lipid metabolism. Pterostilbene, the methoxylated analogue of resveratrol, exhibits astonishing functions of antioxidant, anti-inflammatory and glycolipid regulatory. The study aimed to elucidate the protective effects of pterostilbene on broiler liver and to explore the potential mechanisms. A total of 480 one-day-old male Arbor Acres (AA) broilers were randomly divided into four groups: the control group (basal diet) and pterostilbene groups (PT200, PT400, and PT600 feeding with basal diet containing 200, 400 and 600 mg/kg pterostilbene, respectively). The results showed that the dietary pterostilbene supplementation significantly improved the ADG of broilers. Dietary pterostilbene supplementation regulated the expression levels of the genes Sirt1 and AMPK and the downstream genes related to lipid metabolism to protect liver function and reduce lipid accumulation in broilers. Dietary pterostilbene supplementation upregulated the expression levels of the Nrf2 gene and its downstream antioxidant genes (SOD, CAT, HO-1, NQO-1, GPX) and phase II detoxification enzyme-related genes (GST, GCLM, GCLC). Collectively, pterostilbene was confirmed the positive effects as a feed additive on lipid metabolism and antioxidant via regulating Sirt1/AMPK and Nrf2 signalling pathways in broilers.

Gelation behavior and mechanism of low methoxyl pectin in the presence of erythritol and sucrose: The role of co-solutes

Co-solutes such as sucrose and sugar alcohol play a significant part in low methoxyl pectin (LMP) gelation. To explore their gelation mechanism, we investigated the gelation behavior of LMP in the presence of erythritol and sucrose with Ca2+. Results revealed that the introduction of erythritol and sucrose improved the hardness of the gels, fixed more free water, accelerated the rate of gel structuring, and enhanced the gel strength. FT-IR confirmed the reinforced hydrogen bonding and hydrophobic forces between the pectin chains after introducing co-solutes. And it could be observed clearly by SEM that the cross-linking density of gel network enhanced with co-solutes. Furthermore, gel disruption experiments suggested the presence of ionic interaction, hydrogen bonding, and hydrophobic forces in LMP gels. Finally, we concluded that the egg-box regions cross-linked only by LMP and Ca2+ were too weak to form a stable gel network structure. Adding co-solutes could increase the amount of cross-linking between pectin chains and enlarge the cross-linking zones, which favored the formation of a dense gel network by more hydrogen bonding and hydrophobic forces. Sucrose gels had superior physicochemical properties and microstructure than erythritol gels due to sucrose's excellent hydration capacity and chemical structure characteristics.

Dietary supplementation with quercetin: an ideal approach for improving meat quality and oxidative stability of broiler chickens

This study aimed to improve the eating quality of yellow-feathered broiler chicks by feeding them corn-soybean meal diets supplemented with 250, 500, and 1,000 mg/kg quercetin. we examined the impact of varying doses of dietary quercetin on the sensory quality of chicken breast meat as well as on the antioxidant enzymes, antioxidant-related signaling molecules, structure and thermal stability of myofibrillar protein (MPs), and microstructure of myogenic fibers in the meat during 24 h of postslaughter aging. Additionally, we investigated the potential correlations among antioxidant capacity, MP structure, and meat quality parameters. The results indicated that dietary supplementations with 500 and 1,000 mg/kg quercetin improved the physicochemical properties and eating quality of yellow-feathered broiler chicken breast meat during 12 to 24 h postslaughter. Additionally, quercetin improved the postslaughter oxidative stress status and reduced protein and lipid oxidation levels. It also increased hydrogen bonding interactions and α-helix content during 6 to 12 h postslaughter and decreased β-sheet content during 12 to 24 h postslaughter in chicken breast MP. This resulted in improved postslaughter MP structure and thermal stability. The correlation results indicated that the enhancement of antioxidant capacity and MP structure enhanced the physicochemical and edible qualities of yellow-feathered broiler chicken breast meat. In conclusion, the current findings suggest that dietary supplementation with quercetin is an ideal approach for improving the eating quality of chicken meat, thereby broadening our understanding of theoretical and technological applications for improving the quality of chicken.

Study of four polyphenol-Coregonus peled (C. peled) myofibrillar protein interactions on protein structure and gel properties

The effects of four polyphenols-chlorogenic acid (CA), gallic acid (GA), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG) on the structure, gel properties, and interaction mechanisms of myofibrillar protein (MP) were studied. The changes in MP structure with polyphenols were analyzed using circular dichroism. The ultraviolet and fluorescence spectra and thermodynamic analysis indicated that the type of binding between the four polyphenols with the MP was static quenching of complex formation. GA had a more pronounced effect on improving MP gel properties. Finally, molecular docking determined that the affinity of the protein with the four polyphenols was in the order EGCG > ECG > CA > GA, with the main interaction force being hydrophobic interactions and hydrogen bonding, but hydrogen bonding dominates the interaction between GA and the protein. The findings illuminate the mechanism of MP binding to different polyphenols and facilitate the study of polyphenol-protein properties.

Egg White Protein-Proanthocyanin Complexes Stabilized Emulsions: Investigation of Physical Stability, Digestion Kinetics, and Free Fatty Acid Release Dynamics

Egg white proteins pose notable limitations in emulsion applications due to their inadequate wettability and interfacial instability. Polyphenol-driven alterations in proteins serve as an effective strategy for optimizing their properties. Herein, covalent and non-covalent complexes of egg white proteins-proanthocyanins were synthesized. The analysis of structural alterations, amino acid side chains and wettability was performed. The superior wettability (80.00° ± 2.23°) and rigid structure (2.95 GPa) of covalent complexes established favorable conditions for their utilization in emulsions. Furthermore, stability evaluation, digestion kinetics, free fatty acid (FFA) release kinetics, and correlation analysis were explored to unravel the impact of covalent and non-covalent modification on emulsion stability, dynamic digestion process, and interlinkages. Emulsion stabilized by covalent complex exhibited exceptional stabilization properties, and FFA release kinetics followed both first-order and Korsmeyer-Peppas models. This study offers valuable insights into the application of complexes of proteins-polyphenols in emulsion systems and introduces an innovative approach for analyzing the dynamics of the emulsion digestion process.

Pterostilbene alleviates abdominal aortic aneurysm via inhibiting macrophage pyroptosis by activating the miR-146a-5p/TRAF6 axis

Pterostilbene (PTE), a natural stilbene found in blueberries and several varieties of grapes, has several pharmacological activities, including anti-inflammatory and antioxidative activities. However, its role in abdominal aortic aneurysm (AAA), which is a severe inflammatory vascular disease, remains incompletely understood. In this study, we investigated the protective effects of natural stilbene PTE on AAA formation and the underlying mechanism. Two AAA mouse models (Ang II-induced model and PPE-induced model) were used to examine the effect of PTE on AAA formation. We showed that PTE administration attenuated AAA formation in mice. Furthermore, we found that PTE significantly inhibited inflammatory responses in mouse aortas, as PTE suppressed macrophage pyroptosis and prevented macrophage infiltration in aortas, resulting in reduced expression of pro-inflammatory cytokines in aortas. We also observed similar results in LPS + ATP-treated Raw 264.7 cells (a macrophage cell line) and primary peritoneal macrophages in vitro. We showed that pretreatment with PTE restrained inflammatory responses in macrophages by inhibiting macrophage pyroptosis. Mechanistically, miR-146a-5p and TRAF6 interventions in vivo and in vitro were used to investigate the role of the miR-146a-5p/TRAF6 axis in the beneficial effect of PTE on macrophage pyroptosis and AAA. We found that PTE inhibited macrophage pyroptosis by miR-146a-5p-mediated suppression of downstream TRAF6 expression. Moreover, miR-146a-5p knockout or TRAF6 overexpression abrogated the protective effect of PTE on macrophage pyroptosis and AAA formation. These findings suggest that miR-146a-5p/TRAF6 axis activation by PTE protects against macrophage pyroptosis and AAA formation. PTE might be a promising agent for preventing inflammatory vascular diseases, including AAA.

Quinoa protein Pickering emulsion improves the freeze-thaw stability of myofibrillar protein gel: Maintaining protein composition, structure, conformation and digestibility and slowing down protein oxidation

In this work, the effects of quinoa protein Pickering emulsion (QPPE) on protein oxidation, structure and gastrointestinal digestion property of myofibrillar protein gels (MPGs) after freeze-thaw (F-T) cycles are revealed. SDS-PAGE results indicated that 5.0 %-10.0 % QPPE addition slowed down the protein degradation. Meanwhile, 5.0 %-7.5 % QPPE maintained the stability of the protein secondary and tertiary structure of MPGs after F-T cycles. The sulfhydryl group, disulfide bond and dityrosine content increased with QPPE supplementation. The conformations of disulfide bond changed from g-g-t and t-g-t to g-g-g after F-T cycles, and 5.0 %-7.5 % QPPE stabilized the changes of t-g-t conformation. Furthermore, the increase of dityrosine content after F-T cycles was significantly reduced with 7.5 % QPPE addition, indicating its effect to slow down protein oxidation of MPGs. In addition, MPGs with 5.0 % and 7.5 % QPPE showed noticeably higher zeta potential values than other groups, indicating the enhanced electrostatic repulsion and weakened aggregation caused by F-T damage. This work showed that 7.5 % QPPE improved the F-T stability of MPGs and reduced the protein denaturation and oxidation caused by F-T treatments, exerting no side effect on the digestion property of MPGs. QPPE can be used as a green and effective antifreeze in meat industry.

Protection of Whey Polypeptide on the Lipid Oxidation, Color, and Textural Stability of Frozen-Thawed Spanish Mackerel Surimi

Repeated freeze-thaw (FT) cycles can have an impact on surimi quality. In this study, we used 0.02% BHA as a positive control group. We examined the effects of different concentrations (0%, 5%, 10%, and 15%) of whey protein hydrolysate (WPH) on surimi, focusing on alterations in color metrics (L* for brightness, a* for red-green, b* for yellow-blue, and overall whiteness), textural characteristics, and antioxidant capacity during various freeze-thaw (FT) cycles. The results showed that the lipid oxidant values of surimi, as well as its a* and b* values, rose as the number of FT cycles increased; whereas the adhesiveness, resilience, gumminess, and shear force dropped, as did L* and the whiteness values, leading to an overall darkening of color and gloss. By contrast, the study found that the addition of WPH could effectively slow down the decrease of surimi textural stability after repeated freeze-thawing, with the textural stability of the group with 15% WPH being significantly superior to those of the other groups (p < 0.05). Under the same number of cycles, adding 15% WPH to the experimental group could successfully lower total volatile basic nitrogen (TVB-N) and effectively increase the antioxidant activity of surimi. This finding suggested that 15% WPH had the greatest effect on increasing surimi FT stability. To conclude, it was proved that WPH can be added to frozen surimi and improve its quality.

Effect of theaflavins on the quality of large yellow croaker (Larimichthys crocea) during refrigerated storage

BACKGROUND

Large yellow croaker (Larimichthys crocea) is an economical marine fish consumed in China. Theaflavins have antibacterial and antioxidant properties. However, there is a lack of research into their application in large yellow croakers during refrigerated storage. This study investigated the effect of theaflavins on the quality of large yellow croaker (Larimichthys crocea) during 12 days of storage at 4 °C.

RESULTS

The results showed that theaflavin treatment was able to inhibit microbial growth and reduce the production of total volatile basic nitrogen (TVB-N). Meanwhile, theaflavins were beneficial in reducing the unfolding of myofibrillar proteins, decreasing the degree of protein aggregation, and improving the stability of protein structure. The degree of protein oxidation was lower in a theaflavin-treated group compared with an untreated group. Theaflavin treatment effectively inhibited increases in acid value (AV), peroxide value (PV), and malonaldehyde (MDA) content. The effect of theaflavin was positively correlated with an increase in concentration under refrigeration conditions. This study therefore suggests that the use of theaflavins is a viable method for extending the period for which refrigerated large yellow croaker can be preserved.

CONCLUSIONS

Adding theaflavins to large yellow croaker can be an effective method for preserving quality during refrigerated storage. © 2023 Society of Chemical Industry.

Effects of carboxymethyl chitosan on the oxidation stability and gel properties of myofibrillar protein from frozen pork patties

The effect of carboxymethyl chitosan (CMCH) on the oxidation stability and gel properties of myofibrillar protein (MP) from frozen pork patties was investigated. The results showed that CMCH could inhibit the denaturation of MP induced by freezing. Compared with the control group, the protein solubility was significantly (P < 0.05) increased, while the carbonyl content, the loss of sulfhydryl groups, and the surface hydrophobicity were decreased, respectively. Meanwhile, the incorporation of CMCH could alleviate the influence of frozen storage on water mobility and reduce the water loss. With the increased concentration of CMCH, the whiteness, strength, and water-holding capacity (WHC) of MP gels were significantly improved, in which the maximum value was at addition level of 1 %. In addition, CMCH inhibited the decrease in the maximum elastic (G') value and loss factor (tan δ) value of samples. By scanning electron microscopy (SEM) observation, CMCH stabilized the microstructure of the gel and maintained the relative integrity of the gel tissue. These findings suggest that CMCH could be used as a cryoprotectant to maintain the structural stability of MP in pork patty during frozen storage.