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In this study, chitosan was used to enhance the photodynamic antibacterial effect of curcumin through ionic interactions, and the antibacterial mechanism of this coating against Staphylococcus aureus at the cellular level was clarified from the aspects of morphological characteristics, cell membrane function, energy metabolism, and DNA structure. The results showed that chitosan significantly improve the antibacterial effect. The number of S. aureus decreased by 6.89 (lg(CFU/mL)) after the coating solution containing 15 mg/L curcumin was exposed to 420 nm blue light for 5 min. Curcumin concentration and illumination time were the major factors affecting the antibacterial effect of this technique. The photodynamic inactivation treatment produced highly oxidizing reactive oxygen species (ROS), damaging the cell membrane and increasing membrane permeability, thus leading to the leakage of cell contents and cell shrinkage. It also led to an increase in intracellular ROS levels, which disrupted the structure of endogenous enzymes to trigger the breakdown of the bacterial defense system and the oxidative decomposition of macromolecules such as DNA and proteins, eventually causing the death of S. aureus. Therefore, chitosan/curcumin photodynamic coating has application potential in controlling foodborne pollution of S. aureus.

Phytoglycogen (PG), a carbohydrate polymer extracted from sugar-containing mutant seeds of plants, is a natural dendrimer-like glucan nanoparticle with high safety. The highly branched structure of phytoglycogen that is externally compact and internally loose provides it with high water retention, low viscosity, good dispersion stability, strong antioxidant and antibacterial activity, film-forming capacity, and excellent load capacity. Thus, in recent years, phytoglycogen has gradually become one of the research hotspots. However, there are few reports on the extraction, structural analysis, and comprehensive utilization of phytoglycogen so far. Therefore, this review focuses on the structure and properties of phytoglycogen, discusses the latest extraction methods for phytoglycogen, summarizes its application in foods, and provides an outlook on future research prospects, aiming to provide a theoretical basis for expanding the application of phytoglycogen.

In order to investigate the intrinsic relationship between protein characteristics and quality changes during the hot air drying of shrimp, Penaeus vannamei was dried by hot air at 55 ℃ after being boiled in 3% salt solution for 2 minutes. We studied changes in the microstructure and quality of shrimp, and systematically investigated changes in the oxidative degradation degree, intramolecular valence bonds, and secondary and tertiary structure of protein. The results showed that the drying treatment gradually decreased the L*, a* and b* values of shrimp, and changed the texture characteristics, and the hardness, adhesiveness and chewiness were increased to 344.78 N, 45.01 mJ and 116.50 mJ at the end of drying, respectively. In addition, oxidative denaturation and degradation of proteins occurred; the total sulfhydryl content decreased to 0.36 μmol/g at the end of drying, while the carbonyl content increased to 2.03 nmol/mg protein, and the trichloroacetic acid (TCA)-soluble peptide content increased to 0.91 μmol/g. The protein structure was significantly changed; the relative contents of ionic and hydrogen bonds decreased, the relative contents of hydrophobic and disulfide bonds increased, the secondary structure was transformed from α-helix to β-fold, β-turn and random coil, the intensity of tryptophan fluorescence decreased, and the tertiary structure was also changed. Pearson correlation analysis showed that the color changes were mainly related to protein oxidation and protein degradation and denaturation significantly affected the textural properties of shrimp. This study can provide theoretical support for further improving the quality of dried shrimp products.

The major bioactive components and flavor characteristics of Toona sinensis buds from different production areas such as Sichuan, Shaanxi, Shandong, Shanxi, Hebei and Yunnan were explored. The overall odor was evaluated by sensory evaluation, and the volatile components were analyzed using electronic nose and gas chromatography-ion mobility spectrometry (GC-IMS) in order to analyze the differences in the flavor characteristics of T. sinensis buds from different production areas. The sensory evaluation results showed that the odor of T. sinensis buds from Yunnan was rich and pleasant, while the odor of T. sinensis buds from Shaanxi was irritating. The results of electronic nose analysis showed that the contents of aromatics and long-chain alkanes in T. sinensis buds from the six production areas were similar, while the contents of nitrogen oxides and sulfides were quite different. A total of 76 volatile substances were identified by GC-IMS, including 12 alcohols, 10 esters, 9 pyrazines, 9 ketones, 8 terpenoids, 7 organic sulfides, 7 aldehydes, 6 acids, 4 phenols and 4 other compounds. The principal component analysis (PCA) of electronic nose and GC-IMS data showed that the flavor of T. sinensis buds from Yunnan was unique, and the flavors of T. sinensis buds from Sichuan, Shaanxi and Shandong were similar. T. sinensis buds from Shanxi was different from those from other geographical origins, and the content of flavor substances in T. sinensis buds from Hebei was low. The results of this study may provide a theoretical basis for the screening of T. sinensis for deep processing.