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Hyperuricemia (HUA) is a metabolic disorder caused by abnormal uric acid (UA) metabolism, which is a complex physiological process involving multiple organs (liver, kidney, and intestine). Although UA metabolism in the liver and kidneys has been elucidated, only a few studies have focused on the process in the intestine. With our growing knowledge of the effects of gut microorganisms on health, the gut microbiota has been identified as a new target for HUA treatment. In this review, the relationship between HUA and the gut microbiota is elucidated, and anti-hyperuricemia mechanisms targeting the intestine are discussed, such as the promotion of purine and UA catabolism by the gut microbiota, increases in UA excretion by the gut microbiota and its metabolites, regulation of UA absorption or secretion in the intestinal tract by certain transporters, and the intestinal inflammatory response to the gut microbiota. Additionally, probiotics (Bifidobacteria and Lactobacilli) and prebiotics (polyphenols, peptides, and phytochemicals) with UA-lowering effects targeting the intestinal tract are summarized, providing reference and guidance for further research. [ABSTRACT FROM AUTHOR]

The effect of ultrasonic power (UP) treatment on muscle quality and properties of myofibrillar protein (MP) was investigated. Six ultrasonic powers (0, 160, 200, 240, 280, and 320 W) were used to thawing Bonito fillets. Raman spectra, protein solubility, surface hydrophobicity, and sulfhydryl (SH) groups were used to research the secondary and tertiary structure of protein. Water migration was studied using Low‐field NMR. Microscopic structural was performed to observe the fiber state. The results showed that 280 W can keep protein stability compared with other thawing powers. The cooking loss had no significant difference (p >.05) in all samples. The thawing loss was reduced by ultrasonic treatment. In addition, the myofibril surface was smoother and no fracture at 280W. Meanwhile, the intracellular water was maintained stably. Therefore, appropriate ultrasonic power might be an alternative method to enhance the properties of the MP and the quality of meat during the thawing. Practical applications: In recent years, new thawing methods have been found by more and more researchers, so it is important for frozen food to thawing. In this work, different ultrasonic powers were used to explore protein stability and moisture migration during thawing bonito. The protein structure is more stable. [ABSTRACT FROM AUTHOR]

This study examined the effects on conformation and oxidation of myofibrillar protein in largemouth bass by different thawing methods. The conventional thawing, microwave thawing, microwave (MVT) or ultrasound combined with vacuum thawing, microwave or far‐infrared thawing (FMT) combined with magnetic nanoparticles were used in this experiment. The physicochemical changes were analyzed by differential scanning calorimetry and dynamic rheology. The protein structure changes were measured by Raman, intrinsic fluorescence, and second‐derivative ultraviolet spectrometry. The degree of protein aggregation was evaluated by surface hydrophobicity, particle size, and zeta‐potential measurements. Total sulfhydryl content, protein carbonyl content, Ca2+‐ATPase activity, and SDS‐PAGE were used to analyze the degree of protein oxidation. Results showed that MVT and FMT samples had better thermal stability, more stable protein conformation, and a lower degree of protein oxidation. Thus, these two methods would be beneficial to sustain the quality of thawed fillets. Practical Applications: In the market circulation, largemouth bass (Micropterus salmoides) need to be frozen. The thawing methods can directly affect the quality of frozen fish, thus causing the changes in the conformation of the myofibrillar protein in fish, and also affecting the degree of protein oxidation. The results showed that the microwave combined with vacuum and the magnetic nanoparticles combined with far‐infrared thawing had less effect on myofibrillar protein of fish and were a better thawing method. [ABSTRACT FROM AUTHOR]

Summary: Recrystallisation often occurs in the freeze‐thaw cycles and results in poor food quality. This study was undertaken to analyse the effects of recrystallisation on the changes of protein conformation and moisture migration within red seabream fillets after the freeze‐thaw cycles. The UV second‐derivative spectroscopy, intrinsic fluorescence measurement and Raman spectroscopy were employed to evaluate the protein conformational changes. The Low‐field NMR spectra analysis was used to evaluate moisture migration. The results indicated that the freeze‐thaw cycles altered the secondary and tertiary structure of proteins. It was noticed that interactions between water and protein molecules were decreased gradually and eventually induced the thermal instability of the myosin molecules. The immobilised water content declined and the free water content increased. There were significant destructions in fillet muscle microstructure. These observations unambiguously reflect how the recrystallisations affect the protein conformation and moisture migration patterns of red seabream fillets during freeze‐thaw cycles. [ABSTRACT FROM AUTHOR]

Optimizing the physicochemical properties of microwave-cooked meat needs a better understanding of the mechanisms responsible for protein changes. This paper explored the causes of aggregation of the denatured fish protein in ready-to-eat food by determining the changes in sarcoplasmic and myofibril proteins, which includes the effects of different microwave power levels (300, 600, and 900 W) and heating times (0-60 s) on the aggregation kinetics and physiochemical properties. The determination of aggregation kinetics that accurately describes microwave cooking characteristics is crucial for the optimization of operating parameters, performance improvement of the cooked food system, and product quality. The aggregation rate and turbidity of proteins increased with increasing microwave power and time. A negative correlation was observed between the protein solubility and microwave power and time. Protein aggregation induced by microwave showed a reliable and reproducible characterization of particle size distributions. At longer microwave heating time or higher microwave power, these protein particles formed larger aggregates. [ABSTRACT FROM AUTHOR]

Abstract: The effects of chitosan coating enriched with lemon and thyme essential oils on the physicochemical, microbiological, and quality changes of grass carp fillets during 2 °C storage were determined during 16 days of storage. The pH, total volatile basic nitrogen, thiobarbituric acid reactive substances, color, texture, sensory quality, total viable count, psychrotrophic bacteria, pseudomonads, Shewanella putrefaciens, Enterobacteriaceae, and lactic acid bacteria counts were analyzed. The results indicated that chitosan coating (1.5%) incorporated with lemon or thyme essential oils (0.5%) maintained higher hardness and retarded the oxidation of lipid and protein. The most effective treatment was chitosan coating (1.5%) enriched with lemon and thyme essential oils (0.25 and 0.25%) together, which maintained the color and texture properties, and reduced the microorganisms counts. The results suggested that the synergized use of lemon and thyme essential oils increased the efficiency of chitosan coating, maintained fish fillets quality and extended its shelf life to 16 days. Practical applications: The commercial value of fresh fish fillets is lost in a few days. Many methods have been used to inhibit the spoilage caused by microorganisms, retard the degradation of protein, and extend the shelf life of fish fillets. As an alternative to chemical and synthetic preservatives, many studies are currently focused on using natural products to improve the quality of fish products. This study reports that chitosan coating incorporated with lemon and thyme essential oils together is a promising edible coating for use in commercial applications for prolonging the shelf life of fish fillets. [ABSTRACT FROM AUTHOR]

Polyphenoloxidase (PPO) from prawns (Penaeus vannamei) was purified by ammonium sulphate precipitation, ion-exchange column, and gel filtration chromatography. The specific activity of PPO increased by 9.51 fold to 575.03 U/mg, and the molecular weight of PPO was 66 kDa. The optimal temperature and pH were around 45°C and 6.8, determined by L-β-(3,4-dihydroxylphenyl) alanine (L-DOPA) as substrate. Km and Vmax values were found to be 2.5 mM and 0.062ΔA/min. The effect of thermal treatment on the activity, conformation, and microstructure of the PPO was investigated. Thermal stability of PPO was measured at 40°C, 50°C, 60°C, 70°C, and 80°C, and the half-life values of PPO were 105, 39.6, 13.4, 8.9, and 3.1 min, respectively. PPO activity slightly decreased at 60°C, while the relative enzyme activity remained 9.4% after 80°C for 10 min. The result of differential scanning calorimetry showed that the denatured temperature of PPO was 65°C. Thermal treatment resulted in the changes in the tertiary structure of PPO, and the λmax of fluorescence spectra was red-shifted with decreasing intensity. Curve-fitting analysis showed that α-helix and β-sheet decreased, but β-turns and random coil increased with increased temperature. Atomic force microscopy revealed that PPO molecules aggregated remarkably at 60°C. Moreover, the formation of large globular aggregates occurred as the temperature increased. [ABSTRACT FROM AUTHOR]