To isolate a novel peptide with calcium-binding capacity, sheep bone protein was hydrolyzed sequentially using a dual-enzyme system (alcalase treatment following neutrase treatment) and investigated for its characteristics, separation, purification, and structure. The sheep bone protein hydrolysate (SBPH) was enriched in key amino acids such as Gly, Arg, Pro, Leu, Lys, Glu, Val, and Asp. The fluorescence spectra, circular dichroism spectra, and Fourier-transform infrared spectroscopy results showed that adding calcium ions decreased the α-helix and β-sheet content but significantly increased the random and β-turn content (p < 0.05). Carboxyl oxygen and amino nitrogen atoms of SBPH may participate in peptide–calcium binding. Scanning electron microscopy and energy dispersive spectrometry results showed that SBPH had strong calcium-chelating ability and that the peptide–calcium complex (SBPH–Ca) combined with calcium to form a spherical cluster structure. SBPH was separated and purified gradually by ultrafiltration, gel filtration chromatography, and reversed-phase high-performance liquid chromatography. Liquid chromatography-electrospray ionization/mass spectrometry identified the amino acid sequences as GPSGLPGERG (925.46 Da) and GAPGKDGVRG (912.48 Da), with calcium-binding capacities of 89.76 ± 0.19% and 88.26 ± 0.25%, respectively. The results of this study provide a scientific basis for the preparation of a new type of calcium supplement and high-value utilization of sheep bone.

This study aims to establish a preservation method by coupling certain barrier packaging with storage temperatures suitable for extending the shelf of chilled lamb. Chilled lamb was packaged using three different oxygen permeability packaging materials of high-oxygen-barrier packaging (HORP), medium-oxygen-barrier packaging (MORP), and low-oxygen-barrier packaging (LORP) (1.70, 23.95, and 1631.44 cm³/(m²·24·h·0.1·MPa), respectively, then stored at temperatures of 4 °C and −1 °C for 28 days, respectively. The results of total viable count, pH, color, and volatile basic nitrogen indicate that HORP effectively inhibits the growth rate of surface microorganisms and the oxidation rate of proteins in lamb. The sulfhydryl content, carbonyl value, and electronic nose suggest that the oxidative decomposition rate of lamb during storage at −1 °C is lower compared to storage conditions at 4 °C. The microbial diversity suggests that HORP significantly hinders the growth and reproduction of Pseudomonas and Brochothrix aerobic spoilage bacteria, as well as diminishes the abundance of the dominant microbial community. Herein, utilizing high-barrier packaging with an oxygen permeability of lower than 1.70 cm³/(m²·24·h·0.1·MPa) in conjunction with ice temperature storage at −1 °C is a highly effective preservation method for prolonging the shelf life of chilled lamb to 28 days.

To address spoilage and quality deterioration, this study evaluated the synergistic effects of the electrostatic field (EF) combined with packaging (polyethylene, PP; vacuum, VP; modified atmosphere, MAP) on the preservation of Yorkshire pork (hind leg) during controlled freezing-point storage (−2.0 ± 0.5 °C) for 32 days. The results showed that EF treatment significantly enhanced the water-holding capacity of PP-packaged pork, reducing storage loss by approximately 37.89% by day 32 (p < 0.05), and inhibited microbial growth, maintaining total viable counts below 6.00 log₁₀ (CFU/g) (p < 0.05). EF also reduced the relative abundance of spoilage organisms such as Pseudomonas. A synergistic effect between EF and VP/MAP was observed in the optimization of the microbial community structure. Spearman correlation analysis revealed that Pseudomonas abundance was positively correlated with TVB-N and storage loss, linking it mechanistically to quality deterioration. Furthermore, VP and MAP alone were superior in delaying lipid oxidation (TBARS < 0.5 mg MDA/kg) and maintaining color stability. This study provides key process parameters and a theoretical basis for applying EF-coupled packaging in the industrial cold chain.

The water absorption of polyvinyl alcohol (PVA) freeze-dried porous polymer is critically influenced by its molecular structure. The hydrolysis degree and molecular weight of PVA were identified as key factors in the design of freeze-dried porous polymers for enhanced structure and stability. The complex interactions between water absorption and structural characteristics in freeze-dried porous polymers were investigated. This was achieved by varying the degree of hydrolysis and molecular weight of the PVA. The results indicate that as the degree of PVA hydrolysis increases, the water absorption and structural stability of the freeze-dried porous polymer are significantly improved. These performance enhancements are attributed to the synergistic effects of hydrogen bonding interactions and molecular chain entanglement between PVA-sodium polyacrylate (PAAS) chains and PVA-PVA chains, collectively forming a denser and more stable three-dimensional network structure. Additionally, the incorporation of high molecular weight PVA significantly reduced the water absorption capacity of the freeze-dried porous polymer. However, freeze-dried porous polymers prepared using low molecular weight polyvinyl alcohol exhibit poor structural stability. Specifically, when the PVA molecular weight is 7200-8100, and the degree of hydrolysis is 99%, the freeze-dried porous polymer exhibits a maximum porosity of 92%, a density of 82 mg/cm³, and a water absorption capacity of 38 g/g. Overall, this work provides the theoretical basis and technical support for its application in absorbent pads.

Determining the oxygen barrier packaging material is crucial for maintaining the quality and freshness of chilled chicken during low-temperature storage. Chilled chicken was packaged in three materials with different oxygen permeability: medium-oxygen-barrier packaging (MORP, 23.95 cm³/(m²·24 h·0.1 MPa)), low-oxygen-barrier packaging (LORP, 1631.44 cm³/(m²·24 h·0.1 MPa)), and polyethylene packaging (OPP, 10,600.00 cm³/(m²·24 h·0.1 MPa)). The packaged samples were then stored at 4 °C for 9 d. Compared to the OPP group, where Pseudomonas, Acinetobacter, and Lactobacillus dominated, MORP and LORP significantly inhibited Pseudomonas growth, resulting in slower microbial population growth during storage. Owing to the distinct composition of dominant spoilage bacteria, the LORP group demonstrated significantly lower levels of sulfide and nitrogen oxides during storage compared to other groups. Within the first 7 days, the LORP group exhibited markedly lower TVB-N levels in comparison to both the MORP and OPP groups. During the late storage stage, the muscle fiber structure in both the MORP and LORP groups remained relatively intact. In summary, packaging materials with low to medium barrier properties are more effective in maintaining chicken freshness and extending its shelf life to up to 9 days. This method potentially provides an effective foundation for maintaining the quality of poultry meat.