Frozen staple food, attributed to its favorable taste and convenience, has a promising development potential in the future. Frequent freezing and thawing, however, will affect its quality. This study simulated several freeze–thaw cycles (FTC) that may occur during the cold chain process of frozen oatmeal cooked noodles (FOCN) production to consumption. The quality changes and their mechanisms were elucidated using methods such as differential scanning calorimetry (DSC), low-field nuclear magnetic resonance (LF-NMR), Fourier-transform infrared spectroscopy (FTIR), confocal laser scanning microscopy (CLSM), texture analysis, and sensory evaluation. The freezable water content of the FOCN decreased because of the FTC treatment, and the relative content of total water in FOCN also decreased accordingly. The increase in β-Turn after FTC induced disorder in the secondary structure of proteins, causing the protein microstructure to become loose and discontinuous, which in turn reduced the water-holding capacity of FOCN. Additionally, FTC reduced the chewiness and sensory score of FOCN. This research will contribute a theoretical foundation for optimizing the cold chain process.

This study explored the effects of ultrasound and airflow pulverization on the structure, physicochemical and digestive characteristics of rice glutelin (RG). Our results demonstrated that ultrasound, airflow pulverization, and the combined treatment enhanced the fluorescence intensity and surface hydrophobicity of RG, leading to a smaller and more uniform microstructure. Furthermore, the combined treatment decreased the β-sheet levels and enhanced the β-turn levels in RG, further enhancing their solubility and antioxidant activity. Moreover, combined treatment promoted the liberation of amino groups throughout the digestion and further enhanced the solubility of RG during the digestion, which correlated with the modification in the spatial structure of proteins. Additionally, combined treatment enhanced the antioxidant activity of RG during gastrointestinal digestion, and the 400 W ultrasound combined with airflow pulverization group showed the highest antioxidant activity. These findings offered new insights for enhancing the performance and applications of RG

Rice glutelin hydrolysates (RGHs) with different degrees of hydrolysis (DH) were prepared using papain, and the structural characterization, physicochemical stability, and antioxidant activity of RGH were analyzed. Results showed that RGH primarily consisted of low molecular weight (MW) peptides (<3 kDa), with hydrophobic/aromatic amino acid content increasing with DH. Higher DH level led to reduced average particle size and zeta potential of RGH. Structurally, as DH increased, a decrease in α-helix content alongside increased β-sheet/random coil ratios was observed in RGH, indicating a transition towards a more disordered structure in RGH. Furthermore, the antioxidant activity of RGH was significantly enhanced with the increase in DH, with RGH-18 showing the highest bioactivity. RGH maintained stability and antioxidant capacity under gastrointestinal digestion as well as various environmental stresses, including varying pH and temperatures, and the presence of metal ions. Cellular experiments demonstrated that RGH-18 alleviated H₂O₂-induced oxidative damage in HepG2 cells, likely by inhibiting Keap1 and activating Nrf2 via the Keap1/Nrf2 pathway. This study supports the potential of RGH as a functional ingredient and provides insights for targeted rice peptide production.

Sweet potato glycoproteins are key bioactive components in sweet potato whole flour, but their composition and structure are poorly understood, and existing detection methods are complex. To address the aforementioned issues, this study utilized infrared spectroscopy, phenol-sulfuric acid, and high-performance liquid chromatography to analyze the glycoprotein content and composition. Additionally, a rapid detection model was developed by combining near-infrared spectroscopy with chemometric methods. The study isolated and purified three glycoproteins from sweet potato whole flour and analyzed their physicochemical properties, including polysaccharide and protein content, as well as monosaccharide and amino acid compositions. A rapid detection model was developed using near-infrared spectroscopy combined with chemometrics. After preprocessing with MSC and feature selection via CARS, a PLSR model was established. The final MSC-CARS-PLSR model achieved high accuracy (calibration R2c=0.98, prediction R2p=0.96, RPD=5.02), demonstrating efficient glycoprotein quantification. This provides a reliable scientific basis for quality control and highlights strong practical application potential.