In order to develop efficient preserving materials for meat products, sustained-release preservative composite films (CS-GEL-PE) were prepared by casting a mixed solution of chitosan (CS) and gelatin (GEL) added with different volume proportions (2%, 4%, 6% and 8%) of Pickering emulsion (PE) loaded with resveratrol (RES). The microstructure and physical properties of the films were determined by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and an intelligent electronic tensile testing machine, and antioxidant activity, sustained-release performance, and their preservation effect on prepared steak was analyzed. It was found that the addition of PE did not alter the structure of the CS-GEL film, increased its thickness, density, tensile strength, elongation at break, and antioxidant activity while conferring the composite film good sustained-release performance and significantly reducing its water content, solubility, swelling rate and water vapor permeability. The composite film with 6% PE (PE6) had the best overall performance. The preservation effect of the PE6 film combined with vacuum packaging on prepared steak was evaluated using vacuum packaging as a control. After 9 days of storage, the pH of the control group exceeded 6.7, the total volatile basic nitrogen (TVB-N) content was 20.28 mg/100 g, and the total bacterial count (TBC) was 6.37 (lg(CFU/g)), indicating that the steak was spoiled. In contrast, none of the pH, thiobarbituric acid reactive substances (TBARS) value, TVB-N content, and TBC of the PE6 group exceeded the limits, and the preservation effect of the PE6 film was better than the CS-GEL-RES film. In summary, the PE6 film has excellent mechanical properties and can prolong the shelf life of prepared steak.

In this study, chitosan (CS) and collagen (COL) composite nanoparticles were used as stabilizer to prepare Pickering emulsion loaded with resveratrol (PE-R). The particle size, potential, rheological properties, antibacterial effect, antioxidant properties and stability (centrifugal stability, storage stability, salt ion stability, pH stability) of PE-R were determined. According to the experimental results, PE60 (with 60% oil phase) was selected as the optimal one and used to prepare a preservative liner, which was placed in the bottom of the tray for the preservation of chilled beef. The results showed that the swelling rate and solubility of the PE60 liner were both significantly reduced, and this liner significantly slowed down the growth rates of thiobarbituric acid reactive substances (TBARS) value and total volatile basic nitrogen (TVB-N) content, inhibited the reproduction of microorganisms, reduced the centrifugal loss, better maintained the color, and extended the shelf life of beef from 6 to 10 days.

In this study, a novel hypoglycemic peptide Gly-Pro-Ala-Gly-Ala-Pro (GPAGAP) was screened from skin collagen hydrolysates of Andrias davidianus by network pharmacology and bioinformatics, and its hypoglycemic mechanism was predicted. Meanwhile, the improvement of insulin resistance (IR) in HepG2 cells were detected. Through network pharmacology screening, GPAGAP had good drug-like properties, and 105 targets of GPAGAP overlap with diabetes mellitus type 2 (T2DM) targets. These targets were mainly enriched in the PI3K-Akt signaling pathway, TNF signaling pathway, IR and other signaling pathways related to T2DM. The results of IR-HepG2 cell model experiments showed that GPAGAP could reduce IR of HepG2 cells induced by high-glucose and high-insulin, and improve glucose consumption of IR-HepG2 cells. GPAGAP could increase the glycogen content, hexokinase (HK) and pyruvate kinase (PK) activities of IR-HepG2 cells, inhibit the accumulation of triglyceride (TG) and total cholesterol (TC) in IR-HepG2 cells, and enhance the activity of superoxide dismutase (SOD) in IR-HepG2 cells, reduce the content of malondialdehyde (MDA) and reactive oxygen species (ROS) in IR-HepG2 cells. The above results suggested that GPAGAP could through multi-target and multi-pathway to improve the glucose metabolism, lipid metabolism and oxidative stress response of IR-HepG2 cells. It has the potential effect of improving insulin resistance in T2DM.