Xiufang Xia

Chilled meat possesses a tender texture, desirable flavor, and enhanced safety. However, prolonging the shelf life of chilled meat is a significant challenge under conventional packaging methods. Chitosan‐based hydrogels present a viable solution to this issue due to their ease of preparation and possession of antibacterial and antioxidant properties. This paper reviews the preparation of chitosan‐based hydrogels from two aspects: methods (solution casting, self‐assembly, freeze–thaw cycles, radiation, electrospinning, and three‐dimensional printing) and influencing factors (pH, temperature, enzymes, ions, radiation conditions, and cross‐linking agents). Second, the applications of chitosan‐based hydrogels in chilled meat preservation are summarized and classified (antibacterial applications, antioxidant applications, freshness indicators, and barrier applications). Third, we elucidate the antibacterial (disrupting cellular structure, chelating intracellular components, and inhibiting genetic processes) and antioxidant (inhibiting chain oxidation, stabilizing structure, and maintaining function) mechanisms of chitosan‐based hydrogels through multiple pathways and provide strategies to enhance preservation performance. We conclude that the composition (chitosan properties and functional components) and structure (microstructure and cross‐linking degree) of chitosan‐based hydrogels exert impacts on preservation performance. To better promote the industrial application of chitosan‐based hydrogels, it is essential to optimize economic costs, establish standardized regulations, accommodate real‐world environments, and integrate advanced technologies. This study offers novel guidance and future perspectives for advancing chitosan‐based hydrogels in sustainable food preservation.

Flavonoids from Pinus koraiensis needle (PN) litterfall were efficiently recovered using an enzyme-assisted ultrasonic extraction (EAU) method optimized via response surface methodology (RSM). The optimal conditions (enzyme dosage 1.7%, ethanol concentration 70%, ultrasonic time 21 min, cellulase–pectinase ratio 1:3, liquid–solid ratio 40:1, enzymatic hydrolysis at 42.5 °C for 1 h, ultrasonic extraction at 50 °C and 150 W) yielded a total flavonoid content (TFC) of 17.08 mg rutin/g, which was significantly higher than that obtained via conventional extraction (CE). Scanning electron microscopy (SEM) confirmed that the treatment disrupted the cell wall, promoting flavonoid release. Ultra-performance liquid chromatography coupled with triple-quadrupole time-of-flight mass spectrometry (UPLC-Triple-TOF/MS) identified 60 flavonoids in the purified extract obtained under the optimal EAU conditions (OT group), including quercitrin, tiliroside, taxifolin, and procyanidin B2. Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) showed higher crystallinity but slightly reduced thermal stability for OT flavonoids. Notably, compared with the purified flavonoids obtained by CE (CK1 group), the OT group achieved a higher TFC and exhibited significantly better in vitro antioxidant activity (DPPH IC₅₀ = 71.82 μg/mL; ABTS IC₅₀ = 28.93 μg/mL) and in vitro carbohydrate-digesting-enzyme-inhibitory activity (α-glucosidase (α-GLU) IC₅₀ = 79.52 μg/mL; α-amylase (α-AMY) IC₅₀ = 793.9 μg/mL), with α-AMY inhibition being approximately 8.2-fold higher. These findings suggest that enzyme-assisted ultrasonic extraction is an efficient and reliable method for recovering flavonoids from PN and may provide a theoretical reference for the development and utilization of these flavonoids.

This study aimed to investigate the effects of different freezing temperatures and storage durations on the digestive and structural properties of chicken meat proteins. The texture, protein digestibility, particle size, and microstructure of the digested samples were used to characterize their digestive properties. Conformational changes in the digested samples were confirmed by infrared spectroscopy, circular dichroism, and endogenous tryptophan fluorescence spectra. The results revealed that the moisture and protein contents decreased with extended storage and increased temperature. Compared to fresh chicken breasts, protein digestibility decreased as the duration of frozen storage increased. Moreover, the samples stored at −40 °C had higher digestibility than those stored at −18 °C, and the protein structure of the samples stored at −18 °C exhibited more damage and was more likely to aggregate compared to the protein of samples stored at −40 °C. Therefore, a higher freezing temperature and an extended frozen storage duration result in greater structural damage to the protein and lower protein digestibility.