L-arginine and L-lysine degrade troponin-T, and L-arginine dissociates actomyosin: Their roles in improving the tenderness of chicken breast

Effect of lysine-assisted ultrasonic and vacuum tumbling treatment on the quality of chicken breast meat in canned foods

Curing is a technological process that improves the tenderness, water retention, and overall quality of canned food. This study aimed to evaluate the effects of different exogenous additives, specifically sodium tripolyphosphate and lysine, on the quality of chicken breast meat in canned assorted vegetables and diced chicken using different curing methods: static curing, ultrasonic curing, vacuum tumbling curing, and ultrasonic combined with vacuum tumbling curing. The texture, moisture mobility and distribution, microstructure, and sensory acceptability of the chicken meat were evaluated. The results showed that lysine demonstrates better water retention than sodium tripolyphosphate, combining ultrasonic and vacuum tumbling treatments with 0.2% Lys (SL-UVT) significantly enhanced the texture characteristics and reduced the cooking loss of chicken breast meat. Additionally, SL-UVT treatment improved the texture, appearance, flavor, and overall acceptability scores. Nuclear magnetic resonance (NMR) analysis showed that SL-UVT treatment affected water distribution and flowability, increasing the retention of less mobile water in chicken breasts. In addition, the gap between myogenic fibers increased after SL-UVT treatment, trapping more water. In conclusion, SL-UVT treatment significantly improved the tenderness and water-holding capacity of the chicken breast from both macroscopic and microscopic perspectives. This study provided a theoretical foundation for refining and optimizing canned meat processing techniques.

Ultrasound combined with Adenosine 5'-Monophosphate Treatment: A Strategic Approach for enhancing the tenderness of chicken wooden breast meat

This study aimed to evaluate the effects of ultrasound and adenosine 5'-monophosphate (AMP) treatments on the quality characteristics and tenderness of chicken wooden breast (CWB). Compared to normal breast, CWB exhibits distinct quality characteristics, including increased weight, higher pH, pale color, and a firmer texture. It was found that ultrasound, AMP, and their combined application significantly reduced the shear force of CWB (p < 0.05), effectively improving its tenderness. The combined treatment of ultrasound and AMP significantly decreased the filtering residues of myofibrillar proteins (MPs) and increased myofibrillar fragmentation index (p < 0.05). MPs structure analysis showed that the combined ultrasound and AMP treatment facilitated the degradation of tropomyosin, the transformation of α-helix into β-sheet, and decreased intensity of tryptophan fluorescence, promoting MPs degradation and improving CWB tenderness. Pathological analysis and scanning electron microscopy also observed muscle fiber damage and the loss of myofibrillar membrane integrity following the combined treatment. These findings highlight the potential of AMP and ultrasound treatments in the tenderization process of CWB.

Effect of the Partial Substitution of NaCl with L-Arg on the Gel Properties and Aggregation Behavior of Beef Myosin

With 0.3 M KCl replacing NaCl, the effect of L-Arg on beef myosin's gel, structure, and aggregation was investigated. L-Arg could enhance hydrogen and ionic bonds, increasing myosin solubility and reducing turbidity. The content of regular secondary structures (β-sheet) increased, and the content of random coil structures decreased significantly (p < 0.05). The results of dynamic light scattering (DLS) and atomic force microscope (AFM) further demonstrated that L-Arg could improve the uniformity and dispersion of myosin aggregate size and inhibit the aggregation of myosin between the head and the tail. Moreover, as the hydrophobic interaction and disulfide bonds were the main forces, a thermal gel dominated by myosin oligomers and filaments was formed. In the 0.3 M KCl, 0.1 M NaCl, and 0.2 M L-Arg system, the hardness, elasticity, and water holding capacity (WHC) of beef myosin gel were effectively improved, providing a salt reduction reference for beef products.

Combined Effects of Compound Low-Sodium Alternative Salts and Vacuum Tumbling on the Quality, Water Distribution, and Microstructure of Marinated Beef

This study proposes a compound low-sodium alternative salt (CLSAS) formulation (2.4% sodium chloride, 0.8% K lactate, 0.4% magnesium chloride, 0.4% Ca ascorbate, 0.2% L lysine, and 4% sorbitol) combined with vacuum tumbling for beef marination. The effects of 4% NaCl static marination (F), CLSAS static marination (L), and CLSAS vacuum tumbling (VT-L) on the physicochemical properties, water distribution, and microstructure of marinated beef were evaluated. Compared with F, L maintained similar yield and color, reduced cooking loss, and improved texture while lowering sodium content. VT-L further enhanced product yield, water content, color, texture, and tenderness. Both CLSAS and vacuum tumbling reduced the relaxation time of immobilized water, promoted orderly formation of protein structure, and altered the microstructure of myogenic fibers. VT-L additionally improved the water-holding capacity of myofibrils and further reduced the relaxation times of immobilized and free water. Overall, VT-L could be an effective approach for enhancing the quality of low-sodium meat products, providing a feasible basis for the industrial application of CLSAS for low-sodium marinated meat products.

Microbiota dynamics and metabolic mechanisms in fermented sausages inoculated with Lactiplantibacillus plantarum and Staphylococcus xylosus

Lactiplantibacillus plantarum and Staphylococcus xylosus are common starters for fermented sausages. Several studies have demonstrated the impact of these two strains on the quality of fermented sausages. However, the mechanism underlying the effects of these two microorganisms on co-cultivation in sausages remains unclear. This study aimed to investigate the effects of inoculation with various combinations of starters on the microbial communities and metabolic profiles of fermented sausages. High-throughput sequencing revealed that, during sausage fermentation, Firmicutes was the dominant bacterial phylum, and the primary microorganisms were Lactococcus, Staphylococcus, Lactobacillus, and Pseudomonas. On the last day of fermentation, the highest abundance of Staphylococcus was observed in the co-inoculation group. Furthermore, inoculated fermentation effectively inhibited the growth of pathogenic and spoilage bacteria. Metabolomic analysis of the four groups of samples identified 208 metabolites in positive ion mode and 109 in negative ion mode. A total of 31 differential metabolites were identified (P < 0.05, variable importance in the projection >1.5), primarily benzene and substituted derivatives, carboxylic acids and derivatives, and fatty acyls. Five crucial differential metabolites (subaphylline, naringenin, 1-hexadecanol, beta-alanyl-L-lysine, and 3'-AMP) were identified as potential biomarkers for fermented sausages. Key differential metabolite metabolic pathways indicated that L. plantarum YR07 dominated in metabolite regulation during sausage fermentation, and S. xylosus Y-18 downregulated the fatty acid degradation pathway, which also affected the metabolism of fermented sausages. Co-cultivation of the two bacteria exhibited a synergistic effect on the metabolism of the fermented sausages. This study offers further insights into improving the quality of fermented sausages, thereby establishing a theoretical foundation for the production of excellent fermenters.

Effects of L-arginine on gut microbiota and muscle metabolism in fattening pigs based on omics analysis

Introduction

L-arginine is an α-amino acid and a semi-essential nutrient of significant biological interest. It plays a role in influencing various aspects of animal meat traits, gut microbiota composition, and physiological metabolism.

Methods

This study aimed to investigate the combined effects of L-arginine supplementation on gut microbiota composition and the metabolism of the longissimus dorsi muscle in fattening pigs. Eighteen Yorkshire commercial pigs were divided into two groups: a control group that received no supplements and a treatment group that was given 1% L-arginine for 52  days. The diversity and composition of microorganisms in the feces of the control (NC) and L-arginine (Arg) groups were analyzed by sequencing the 16S rRNA V3 -V4 region of the bacterial genome.

Results

The findings indicated that L-arginine supplementation increased both the abundance and diversity of gut microbiota, particularly affecting the Firmicutes and Bacteroidetes phyla. KEGG enrichment analysis revealed significant changes in several metabolism-related pathways, including amino acid, carbohydrate, and lipid metabolism. Metabolomic analysis identified 85 differential metabolites between the arginine and control groups, with phospholipids ranking among the top 20. Additionally, functional predictions indicated an increased abundance in the glycerophospholipid metabolism pathway. Correlation analysis linked changes in gut microbiota to phospholipid levels, which subsequently influenced post-slaughter meat color and drip loss.

Discussion

These results suggest that L-arginine supplementation positively impacts gut microbiota composition and the metabolic profile of the longissimus dorsi muscle in fattening pigs, with potential implications for meat quality.

Lipidome and metabolome profiling of longissimus lumborum beef with different ultimate pH and postmortem aging

The objective of this exploratory study was to assess the changes on lipidome and metabolome profiling of Longissimus lumborum bull muscle with different ultimate pH (pHu) and aging periods. The bull muscles classified as normal, intermediate, or high pHu were collected from a Brazilian commercial slaughterhouse, cut into steaks, individually vacuum-packaged, and aged for 3 days (3-d) or 21 days (21-d) at 2 °C. Muscle extracts were analyzed for the profiles of both lipids, by mass spectrometry (via direct flow-injection), and metabolites, by nuclear magnetic resonance, with downstream multivariate data analysis. As major results, pairwise comparisons identified C12:0 and C14:0 acylcarnitines as potential biomarkers of the intermediate pHu-muscle, which are related to lipid catabolism for alternative energy metabolism and indicate less protein breakage postmortem. Interestingly, the concentration of arginine at early postmortem aging (3-d) may influence the previously reported improved tenderness in normal and high pHu-muscles. Moreover, upregulation of fumarate, formate, and acetate with increased pHu muscle at 21-d aging indicate more intense tricarboxylic acid cycle, amino acid degradation, and pyruvate oxidation by reactive oxygen species, respectively. These three compounds (fumarate, formate, and acetate) discriminated statistically the muscle with high pHu at 21-d aging. The normal pHu-muscle showed higher concentrations of glycogenolysis and glycolysis metabolites, including glucose, mannose, and pyruvate. Hence, our results enhance knowledge of postmortem biochemical changes of beef within different pHu groups aged up to 21 days, which is essential to understand the mechanisms underpinning bull meat quality changes.

Effects of dietary arginine supplementation on muscle structure, meat characteristics and lipid oxidation products in lambs and its potential mechanisms of action

This study aimed to assess the effect of dietary arginine supplementation on muscle structure and meat characteristics of lambs also considering lipid oxidation products and to contribute to reveal its mechanisms of action using tandem mass tagging (TMT) proteomics. Eighteen lambs were allocated to two dietary treatment groups: control diet or control diet with the addition of 1% L-arginine. The results revealed that dietary arginine supplementation increased muscle fibre diameter and cross-sectional area (P < 0.05), which was attributable to protein deposition, as evidenced by increased RNA content, RNA/DNA ratio, inhibition of apoptotic enzyme activity, and alterations in the IGF-1/Akt signaling pathway (P < 0.05). In addition, dietary arginine elevated pH24h, a* values, and IMF content, decreased shear force value and backfat thickness (P < 0.05), as well as decreased the formation of lipid oxidation products involved in meat flavor including hexanal, heptanal, octanal, nonanal and 1-octen-3-ol by increasing the antioxidant capacity of the muscle (P < 0.05). The proteomics results suggested that seven enrichment pathways may be potential mechanisms by which arginine affected the muscle structure and meat characteristics of lambs. In summary, arginine supplementation in lamb diets provides a safe and effective way to improve meat quality, and antioxidant capacity of muscle of lamb.

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.

l-arginine and l-lysine supplementation to NaCl tenderizes porcine meat by promoting myosin extraction and actomyosin dissociation

This study investigated the individual and combined effects of l-arginine, l-lysine, and NaCl on the ultrastructure of porcine myofibrils to uncover the mechanism underlying meat tenderization. Arg or Lys alone shortened A-bands and damaged M-lines, while NaCl alone destroyed M- and Z-lines. Overall, Arg and Lys cooperated with NaCl to destroy the myofibrillar ultrastructure. Moreover, these two amino acids conjoined with NaCl to increase myosin solubility, actin band intensity, and the protein concentration of the actomyosin supernatant. However, they decreased the turbidity and particle size of both myosin and actomyosin solutions, and the remaining activities of Ca2+- and Mg2+-ATPase. The current results revealed that Arg/Lys combined with NaCl to extract myosin and dissociate actomyosin, thereby aggravating the destruction of the myofibrillar ultrastructure. The present results provide a good explanation for the previous phenomenon that Arg and Lys cooperated with NaCl to improve meat tenderness.

Effect of ultrasound-assisted L-lysine treatment on pork meat quality and myofibrillar protein properties during postmortem aging

This paper aimed to investigate the effects of ultrasound-assisted L-lysine treatment on meat quality and myofibrillar proteins (MPs) properties of pork longissimus dorsi during postmortem aging. The results revealed that the L-lysine (Lys) and/or ultrasound treatment significantly increased (p < 0.05) the water-holding capacity and tenderness of the pork during postmortem aging, while the ultrasound-assisted Lys treatment had the lowest cooking loss, pressurization loss, Warner-Bratzler shear force, and hardness. In addition, L-lysine and/or ultrasound treatment increased (p < 0.05) pH value, T21, and myofibrillar fragmentation index, while the ultrasound-assisted Lys treatment had the highest value. Meanwhile, the protein solubility was increased with Lys and/or ultrasound treatment during postmortem aging, and ultrasound-assisted Lys treatment had the highest solubility, reaching 88.19%, 92.98%, and 91.73% at 0, 1, and 3 days, respectively. The result of protein conformational characteristics showed that Lys and/or ultrasound treatment caused the unfolding of the α-helix structure, resulting in the exposure of more hydrophobic amino acids and buried sulfhydryl groups, ultimately enhancing MPs solubility. In summary, ultrasound-assisted Lys treatment altered the structure of MPs, resulting in the enhancement of the water-holding capacity and tenderness of the pork. PRACTICAL APPLICATION: This study showed that ultrasound-assisted L-lysine (Lys) treatment could enhance the water-holding capacity and tenderness of pork during postmortem aging. The results might provide a reference for the application of ultrasound-assisted Lys treatment on the improvement of pork meat quality. To facilitate practical applications in production, the development of medium and large-sized ultrasound equipment for conducting small-scale and pilot experiments is crucial for future research.

Insight into the evolution of textural properties and juiciness of ready-to-eat chicken breasts upon different thermal sterilization: From the perspective of protein degradation

Texture deterioration of meat products upon high-temperature sterilization is a pressing issue in the meat industry. This study evaluated the effect of different thermal sterilization temperatures on the textural and juiciness of ready-to-eat (RTE) chicken breast. In this study, by dynamically monitoring the texture and juiciness of chicken meat products during the process of thermal sterilization, it has been observed that excessively high sterilization temperatures (above 100°C) significantly diminish the shear force, springiness and water-holding capacity of the products. Furthermore, from the perspective of myofibrillar protein degradation, molecular mechanisms have been elucidated, unveiling that the thermal sterilization treatment at 121°C/10 min triggers the degradation of myosin heavy chains and F-actin, disrupting the lattice arrangement of myofilaments, compromising the integrity of sarcomeres, and resulting in an increase of approximately 40.66% in the myofibrillar fragmentation index, thus diminishing the quality characteristics of the products. This study unravels the underlying mechanisms governing the dynamic changes in quality of chicken meat products during the process of thermal sterilization, thereby providing theoretical guidance for the development of high-quality chicken products.

Effect of ultrasound combined with pineapple protease treatment on the tenderness of dried shrimp

BACKGROUND

In order to improve the tenderness of dried shrimp products as well as to reduce the hardness of the meat during the drying process, shrimp were treated with ultrasound combined with pineapple protease and the tenderization condition was optimized by measuring the texture and shear force of dried shrimp. In addition, the sulfhydryl content, myofibril fragmentation index (MFI) and microstructure were also examined to clarify the mechanisms of shrimp tenderization.

RESULTS

The results showed UB1 group with ultrasonic power of 100 W, heating temperature of 50 °C and pineapple protease concentration of 20 U mL-1 were the optimum tenderization conditions, where shrimp showed the lowest hardness (490.76 g) and shear force (2006.35 gf). Microstructure as well as sodium dodecyl sulfate-polyacrylamide gel electrophoresis results suggested that during the tenderization process the muscle segments of shrimps were broken, degradation of myofibrillar proteins occurred, and MFI values and total sulfhydryl content increased significantly (P < 0.05) (MFI value = 193.6 and total sulfhydryl content = 93.93 mmol mg-1 protein for UB 1 group).

CONCLUSION

Ultrasound combined with bromelain could be used as a simple and effective tenderization method for the production of tender dried shrimp. The best conditions were 100 W ultrasonic power, 50 °C ultrasonic temperature, and 20 U mL-1 bromelain. © 2024 Society of Chemical Industry.

Recent advances and challenges in the interaction between myofibrillar proteins and flavor substances

Myofibrillar proteins are an important component of proteins. Flavor characteristics are the key attributes of food quality. The ability of proteins to bind flavor is one of their most fundamental functional properties. The dynamic balance of release and retention of volatile flavor compounds in protein-containing systems largely affects the sensory quality and consumer acceptability of foods. At present, research on flavor mainly focuses on the formation mechanism of flavor components, while there are few reports on the release and perception of flavor components. This review introduces the composition and structure of myofibrillar proteins, the classification of flavor substances, the physical binding and chemical adsorption of myofibrillar proteins and volatile flavor substances, as well as clarifies the regulation law of flavor substances from the viewpoint of endogenous flavor characteristics and exogenous environment factors, to provide a theoretical reference for the flavor regulation of meat products.

Insights into the mechanism of L-malic acid on drip loss of chicken meat under commercial conditions

BACKGROUND

A deterioration in the meat quality of broilers has attracted much more attention in recent years. L-malic acid (MA) is evidenced to decrease meat drip loss in broilers, but the underlying molecular mechanisms are still unclear. It's also not sure whether the outputs obtained under experimental conditions can be obtained in a commercial condition. Here, we investigated the effects and mechanisms of dietary MA supplementation on chicken meat drip loss at large-scale rearing.

RESULTS

Results showed that the growth performance and drip loss were improved by MA supplementation. Meat metabolome revealed that L-2-aminoadipic acid, β-aminoisobutyric acid, eicosapentaenoic acid, and nicotinamide, as well as amino acid metabolism pathways connected to the improvements of meat quality by MA addition. The transcriptome analysis further indicated that the effect of MA on drip loss was also related to the proper immune response, evidenced by the enhanced B cell receptor signaling pathway, NF-κB signaling pathway, TNF signaling pathway, and IL-17 signaling pathway.

CONCLUSIONS

We provided evidence that MA decreased chicken meat drip loss under commercial conditions. Metabolome and transcriptome revealed a comprehensive understanding of the underlying mechanisms. Together, MA could be used as a promising dietary supplement for enhancing the water-holding capacity of chicken meat.

Effect of dietary arginine supplementation on protein synthesis, meat quality and flavor in growing lambs

This study aimed to assess the effect of dietary arginine supplementation on protein synthesis, meat quality and flavor in lambs. Eighteen Dorper (♂) × Small Tailed Han sheep (♀) crossed ewe lambs of similar weight (27.29 ± 2.02 kg; aged 3 months) were assigned to two groups, the control group was fed the basal diet (Con group), and the arginine group (Arg group) was supplemented with 1% l-arginine based on the Con group for 90 d. The results suggested that dietary arginine significantly increased final body weight, loin eye muscle area, muscle fiber diameter, cross-sectional area (P < 0.050), and decreased shear force value and cooking loss (P < 0.050), as well as altered the composition and contents of volatile flavor compounds in lambs. Importantly, the total protein (TP) content, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AKP) activities in serum, branched-chain aminotransferase (BCAT), AST, ALT activities and neuronal nitric oxide synthase (nNOS) gene expression and content were elevated (P < 0.050), while content of urea nitrogen (BUN) in serum and 3-methylhistidine (3-MH) were decreased in arginine fed lambs (P < 0.050). In addition, arginine triggered muscle protein synthesis through protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway, while minimized protein degradation by regulating gene expression of myogenin (MyoG), myostatin (MSTN), muscle atrophy F-box (MAFbx) and forkhead box O3 family (FoxO3) (P < 0.050). Taken together, this study suggested that arginine can be used to improve protein deposition and meat quality in lamb production.

Dietary threonine improves muscle nutritional value and muscle hardness associated with collagen synthesis in grass carp (Ctenopharyngodon idella)

To further explain the improvement effect of threonine (Thr) on the fillet quality of fish, a 9-week feeding experiment was conducted. After feeding graded levels of Thr (2.38, 5.38, 8.38, 11.38, 14.38 and 17.38 g/kg), the compositions of fillet hydrolyzed amino acid and fatty acid, and the muscle hardness associated with collagen biosynthesis were mainly analyzed in grass carp (Ctenopharyngodon idella). The results showed that Thr increased the pH value, changed the amino acids and fatty acid composition of fillets, especially essential amino acid (EAA), C22:6n3 (DHA) and C20:5n3 (EPA). Furthermore, this study revealed for the first time that the improvement of muscle hardness by Thr was associated with collagen biosynthesis, and the TGF-β1/Smads, LARP6a and Hsp47 regulate transcriptional processes, translation initiation and post-translational modifications in collagen biosynthesis, respectively. This study offered a basis for exploring the contribution of Thr in improving muscle quality in sub-adult grass carp.

Additive Effects of L-Arginine with Potassium Carbonate on the Quality Profile Promotion of Phosphate-Free Frankfurters

The present study investigated the additive effects of L-Arginine (L-Arg) with potassium carbonate (PC) on the quality characteristics of phosphate-free frankfurters. The results showed that L-Arg combined with PC could act as a viable phosphate replacer by decreasing cooking loss and improving the textural properties of phosphate-free frankfurters (p < 0.05), mainly because of its pH-raising ability. Moreover, L-Arg could assist PC in effectively retarding lipid oxidation in phosphate-free frankfurters during storage (p < 0.05). Furthermore, 0.1% L-Arg combined with 0.15% PC was found to exhibit the best optimal phosphate-replacing effect. This combination could also overcome quality defects and promote the sensory attributes of phosphate-free frankfurters to the maximum extent. Therefore, our results suggest that L-Arg combined with PC can be considered a feasible alternative for the processing of phosphate-free frankfurters with an improved quality profile and superior health benefits.

Monitoring the Changes in Heat Transfer and Water Evaporation of French Fries during Frying to Analyze Its Oil Uptake and Quality

The effect of frying temperature on heat transfer, water loss kinetic, oil uptake kinetic, and quality of French fries was evaluated. With increasing frying temperature, the core temperature of fries increased, and the Biot number and heat transfer coefficient (h) first decreased and then increased significantly (p < 0.05). The water loss rate (kw) and water effective diffusion of fries increased with the increasing frying temperature. The kw of fries fried at 150−190 °C were 0.2391, 0.2414, 0.3205, 0.3998, and 0.3931, respectively. The oil uptake rate (ko) first increased and then decreased with increasing frying temperature, and the ko of samples fried at 150−190 °C were 0.2691, 0.2564, 0.4764, 0.3387, and 0.2522, respectively. There were significant differences in the a*, L*, ΔE, and BI between fries with different temperatures (p < 0.05), while there was no significant difference in the b* (p > 0.05). The hardness and crispness of fries increased with increased frying temperature. The highest overall acceptability scores of fries were fried at 170 °C. Therefore, the changes in color, texture overall acceptability, and oil content were due to the Maillard reaction and the formation of porous structure, which was induced by h and water evaporation of fries when they changed.

ε-Polylysine-mediated enhancement of the structural stability and gelling properties of myofibrillar protein under oxidative stress

The effects of ε-polylysine (ε-PL) at different concentrations (0.005 %, 0.010 %, 0.020 %, and 0.030 %) on the structure and gelling behavior of pork myofibrillar protein (MP) under oxidative stress were explored. The incorporation of ε-PL significantly restrained oxidation-induced sulfhydryl and solubility losses (up to 9.72 % and 41.9 %, respectively) as well as protein crosslinking and aggregation. Compared with the oxidized control, ε-PL at low concentrations (0.005 % - 0.020 %) promoted further unfolding and destabilization of MP, while 0.030 % ε-PL led to refolding of MP and enhanced its thermal stability. The ε-PL-induced physicochemical changes favored the formation of a finer and more homogeneous three-dimensional network structure, therefore obviously enhancing the strength and water-holding capacity (WHC) of thermally induced oxidized MP gels, with the ε-PL at 0.020 % showed the greatest enhancement. This work revealed for the first time that ε-PL can significantly ameliorate the oxidation stability and gel-forming ability of meat proteins.

Insight into Ultrasound-Induced Modifications of the Proteome and Flavor-Related Proteins of Unsmoked Bacon by Applying Label-Free Quantitation Technology

The aim of this study was to investigate the modifications of the proteome and flavor-related proteins in unsmoked bacon resulting from ultrasound treatment with the application of label-free quantitation technology together with bioinformatics analysis. Results showed that the expression levels of 137 proteins were markedly affected by ultrasound with most of them being significantly upregulated. The proteins distributed in the cytoplasm and the cytosol, the mitochondrion, and the nucleus were more susceptible to ultrasound treatment. Meanwhile, 20 flavor-related proteins, mostly myofibrillar proteins and metabolic enzymes mainly involved in the metabolic pathways of signaling and cellular processes and environmental information processing, were screened out. In addition, the differential expressions of flavor-related proteins induced by ultrasound were verified by western blotting. This study displayed insightful information from the proteomics perspective for a better understanding of the influential effect of ultrasound treatment on meat flavor.

Evaluation of ultrasound-assisted L-histidine marination on beef M. semitendinosus: Insight into meat quality and actomyosin properties

This paper aimed to evaluate the effects of ultrasound-assisted L-histidine marination (UMH) on meat quality and actomyosin properties of beef M. semitendinosus. Our results found that UMH treatment effectively avoided excessive liquid withdrawal, and disrupted myofibril integrity by modifying the water distribution and weakening connection of actin-myosin with increased muscle pH. The ultrasound-treated sample provided more opportunity for the filtration of L-histidine to intervene the isoelectric point and conformation of muscle protein. The activated caspase-3 and changes of ATPase activity in UMH-treated meat accelerated the postmortem ageing, and L-histidine might competitively inhibit the actin-myosin binding by the imidazole group. UMH decreased the surface hydrophobicity by shielding hydrophobic area and unfolding the actomyosin structure. In addition, the increased actomyosin solubility with smaller particle size enhanced the SH content for better cross-linking of myosin tail, and formation of heat-set gelling protein structure. Therefore, UMH treatment manifested the potential to improve beef quality.

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.

Effect of combined treatment of L-arginine and transglutaminase on the gelation behavior of freeze-damaged myofibrillar protein

This research focused on the effects of L-arginine (Arg, 5 mM), transglutaminase (TG, E : S = 1 : 500), and the combination (Arg + TG) on the physicochemical properties and heat-induced gel performance of freeze-damaged myofibrillar protein (MP). The incorporation of Arg decreased the α-helix percentage (48.4%) and the mean particle size of freeze-damaged MP, as well as cooking loss (46.5%) and the overall textural characteristics of MP gels. The addition of TG reduced the α-helix content by 10.7% but significantly enhanced the crosslinking and heat-induced gel behavior of freeze-damaged MP, resulting in a slight reduction of cooking loss (17.7%) and the most ideal textural properties of MP gels. Although the presence of Arg remarkably suppressed the heat-induced development of storage modulus (G') and reduced the hardness of MP gels (by 13.4%), the combination (Arg + TG) showed the lower cooking loss and the improved textural characteristics, with the set gel displaying the most delicate and compact microstructure. These findings indicated that the combination of Arg and TG could be a potential strategy to enhance the gelling performance of freeze-damaged meat proteins.

The Quality Changes and Proteomic Analysis of Cattle Muscle Postmortem during Rigor Mortis

Rigor mortis occurs in a relatively early postmortem period and is a complex biochemical process in the conversion of muscle to meat. Understanding the quality changes and biomarkers during rigor mortis can provide a theoretical basis for maintaining and improving meat quality. Herein, a tandem mass tag proteomic method is used to investigate the effects of differentially expressed proteins on the meat quality of cattle Longissimus lumborum muscle postmortem (0, 6, and 24 h). The pH, total sulfhydryl content and sarcomere length decrease significantly during storage. In contrast, meat color values (L*, a*, and b*) and the myofibril fragmentation index increase significantly. Altogether, 147 differentially expressed proteins are identified, most being categorized as metabolic enzymes, mitochondrial proteins, necroptosis and ferroptosis proteins and structural proteins. The results also reveal additional proteins that are potentially involved in rigor mortis, such as cardiac phospholamban, acetyl-coenzyme A acyltransferase, and ankyrin repeat domain 2. The current results provide proteomic insights into the changes in meat quality during rigor mortis.

Proteomics analysis to investigate the impact of diversified thermal processing on meat tenderness in Hengshan goat meat

During the thermal processing, proteins of Hengshan goat meat undergo structural modifications such as degradation, oxidation and denaturation, ultimately affect the palatability and acceptability. The results of several objective metrics demonstrated that thermal processing exhibited significant impacts on the tenderness of goat meat. The 551, 84, 72, and 121 proteins were identified in the control and thermal processed groups (boiled, steamed, and roasted), respectively. Compared with the control group, the 101, 98, and 109 differentially-expressed proteins were explored in the treatment groups. Furthermore, the functions of metabolic and skeletal muscle proteome were investigated and discussed. Sensory evaluation and proteomics analysis showed that steaming and boiling treatment had no significant effect on the tenderness of goat meat, while roasting significantly reduced the tenderness, indicating that the available thermal processing methods to ensure the tenderness of goat meat were steaming and boiling treatments. Thus, the established proteomics database of goat meat provided the valuable reference for rational selection of thermal processing methods.

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

l-Arginine and l-Lysine Alleviate Myosin from Oxidation: Their Role in Maintaining Myosin's Emulsifying Properties

This study investigated the alleviative effects of l-arginine and l-lysine on the emulsifying properties and structural changes of myosin under hydroxyl radical (·OH) stress. The results showed that ·OH decreased the emulsifying activity index and emulsifying stability index but increased the creaming index and droplet size of a soybean oil-myosin emulsion (SOME). Confocal laser scanning microscopy demonstrated that ·OH caused larger and more inhomogeneous SOME droplets. l-Arginine and l-lysine effectively alleviated ·OH-induced destructive effects on the emulsifying properties of myosin. In addition, ·OH increased the extent of protein carbonylation and dityrosine formation, surface hydrophobicity, and β-sheet content, but decreased the tryptophan fluorescence intensity, solubility, total sulfhydryl, and α-helix content of myosin. Although l-lysine increased dityrosine fluorescence intensity, l-arginine and l-lysine effectively alleviated the aforementioned structural changes of myosin. Therefore, l-arginine and l-lysine could mitigate ·OH-induced structural changes of myosin, which enabled myosin to maintain its emulsifying capacity under oxidative stress.

A Dietary Sugarcane-Derived Polyphenol Mix Reduces the Negative Effects of Cyclic Heat Exposure on Growth Performance, Blood Gas Status, and Meat Quality in Broiler Chickens

Simple Summary

Heat stress is a main reason of systemic oxidative stress, which compromises broiler meat production and quality. To improve the productivity of poultry meat production, studies have investigated different heat stress amelioration strategies. Among these strategies, low-cost feed supplementations are introduced to potentially reduce the negative effects of heat stress. Previous studies have also investigated the effects of different antioxidants on growth performance and meat quality, while a limited number of studies have been made regarding the impacts of the polyphenols at different doses. Polyphenols with antioxidant properties have positive effects against oxidative stress, and are naturally available in high amounts in plants, which makes them a novel feed supplementation for improving meat production as well as meat quality in heat-stressed broiler chickens. Therefore, this study attempted to investigate the effects of different doses of polyphenols supplementation on growth performance, physiological responses, and meat quality in broiler chickens exposed to cyclic heat stress.

Abstract

Heat stress (HS) compromises growth performance and meat quality of broiler chickens by interrupting lipid and protein metabolism, resulting in increased oxidative damages. The experiment attempted to investigate whether dietary polyphenols (Polygain (POL)) could ameliorate the aforementioned adverse effects of HS on performance and meat quality. One hundred and twenty one day-old-male chicks were allocated to two temperature conditions, thermoneutral (TN) or HS, and fed with either a control diet (CON) or the CON plus four different doses of POL (2, 4, 6 and 10 g/kg). Heat stress caused respiratory alkalosis as evidenced by increased rectal temperature (p < 0.001) and respiration rate (p < 0.001) due to increased blood pH (p < 0.001). Heat stress decreased final body weight (p = 0.061) and breast muscle water content (p = 0.013) while POL improved both (p = 0.002 and p = 0.003, respectively). Heat stress amplified muscle damages, indicated by increased thiobarbituric acid reactive substances (p < 0.001) and reduced myofibril fragmentation index (p = 0.006) whereas POL improved both (p = 0.037 and p = 0.092, respectively). Heat stress impaired meat tenderness (p < 0.001) while POL improved it (p = 0.003). In conclusion, HS impaired growth performance and meat quality whereas POL ameliorated these responses in a dose-dependent manner, and effects of POL were evident under both temperature conditions.