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BACKGROUND: Giant salamander protein peptide is a peptide with rich functional properties. Giant salamander protein peptide KGEYNK (KK‐6) is a peptide with both antioxidant and anti‐inflammatory properties. The antioxidant and anti‐inflammatory mechanisms of KK‐6 are still unclear. When we studied the functional mechanism of KK‐6, we found that the antioxidant property of KK‐6 has a synergistic and promoting effect on anti‐inflammatory properties. RESULTS: KK‐6 enhances cellular resistance to LPS via the MAPK/NF‐κB signaling pathway, leading to increased levels of inflammatory factors: interleukin‐1β (764.81 ng mL−1), interleukin‐6 (1.06 ng mL−1) and tumor necrosis factor‐α (4440.45 ng mL−1). KK‐6 demonstrates potent antioxidant properties by activating the Nrf2 signaling pathway, resulting in elevated levels of antioxidant enzymes (glutathione peroxidase: 0.03 μg mL−1; superoxide dismutase: 0.589 μg mL−1) and a reduction in the concentration of the oxidative product malondialdehyde (967.05 μg mL−1). CONCLUSION: Our findings highlight the great potential of KK‐6, a peptide extracted from giant salamander protein, as a remedy for intestinal inflammation. Through its dual role as an antioxidant and anti‐inflammatory agent, KK‐6 offers a promising avenue for alleviating inflammation‐related damage and oxidative stress. This study lays the foundation for further exploration of giant salamander products and highlights their importance in health and novel food development. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Chinese giant salamander protein hydrolysates (CGSPH) are beneficial to human health as a result of their high content of amino acids and peptides. However, the formation of bitter peptides in protein hydrolysates (PHs) would hinder their application in food industry. The ultrasound assisted wet‐heating Maillard reaction (MR) is an effective way to improve the flavor of PHs. Thus, the effect of ultrasonic assisted wet‐heating MR on the structure and flavor of CGSPH was investigated in the present study. RESULTS: The results indicated that the ultrasound assisted wet‐heating MR products (MRPs) exhibited a higher degree of graft and more significant changes in the secondary and tertiary structures of CGSPH compared to traditional wet‐heating MRPs. Moreover, ultrasound assisted wet‐heating MR could significantly increase the content of small molecule peptides and reduce the content of free amino acids of CGSPH, which resulted in more significant changes in flavor characteristics. The changed in flavor properties after MR (especially ultrasound assisted wet‐heating MRPs) were mainly manifested by a significant reduction in bitterness, as well as a significant increase in the content of aromatic aldehyde ester compounds such as furan‐2‐carbaldehyde, butanal, benzaldehyde, furfural, etc. CONCLUSIONS: Ultrasound assisted wet‐heating MR between CGSPH and xylose could be a promising way to improve the sensory characteristics of CGSPH. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Harpadon nehereus is a high‐protein marine fish. A valuable way to add value to H. nehereus is to convert it into protein hydrolysate. The Maillard reaction is an effective way to improve the functional properties of peptides and proteins, which are affected by many factors such as reactant concentration, water activity, pH, temperature, and heating time. However, the traditional Maillard reaction method is inefficient. The purpose of this study was therefore to explore the effect of the ultrasound‐assisted wet heating method on the Maillard reaction of H. nehereus protein hydrolysate (HNPH) in a new‐type green solvent – a natural hypereutectic solvent (NADES). Results: Harpadon nehereus protein hydrolysate‐xylose (Xy) conjugates were prepared via a Maillard reaction in a NADES system using an ultrasound‐assisted wet heating method. The effects of different treatment conditions on the Maillard reaction were studied. The optimized glycation degree (DG) of HNPH‐Xy conjugates was obtained with a water content of 10%, a reaction temperature of 80 °C, a reaction time of 35 min, and an ultrasonic power level of 300 W. Compared with HNPH, the structure of HNPH‐Xy conjugates were significantly changed. Moreover, the functional properties and antioxidant activity of HNPH‐Xy were all superior to the HNPH. Conclusions: An ultrasound‐assisted wet‐heating Maillard reaction between HNPH and Xy in the NADES system could be a promising way to improve the functional properties of HNPH. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: The production of Russian sturgeon is expanding rapidly in China but it is necessary to adopt measures to extend the shelf life of sturgeon meat. Previous studies found that sous vide cooking (SVC) at 60 °C increased the protein and lipid oxidation. The addition of antioxidant substances reduced the acceptance of the product. The effect of combination SVC and ultrasound pretreatment was therefore investigated. RESULTS: Results showed that SVC at 50 °C combined with ultrasound effectively restrained the growth of total viable counts (TVC) in samples. Meanwhile, the main dominant genera changed from Pseudomonas to Carnobacterium and the number of microbial species decreased. The odor profile of Russian sturgeon meat was more stable and the lipoxygenase (LOX) activity decreased more rapidly after treating with SVC and ultrasound. Importantly, more stable protein aggregates were formed in samples treated by SVC 50 °C together with ultrasound pretreatment, so the protein and lipid oxidation were slowed during storage. Higher springiness values were obtained and the color of sturgeon meat was lighter under these conditions. CONCLUSION: The combination of SVC 50 °C and ultrasound pretreatment effectively inhibited the microbial growth of Russian sturgeon meat at lower oxidation levels. These findings theoretically support the preservation and development of sturgeon meat, and the application of SVC technology. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]