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.

To explore the bactericidal effect and mechanism of curcumin-mediated photodynamic inactivation (PDI) against Shewanella putrefaciens, this study explored the influence of curcumin concentration, light time and incubation time on the bactericidal effect. Meanwhile, the underlying mechanism and major action sites were elucidated from the aspects of intracellular oxidative stress, bacterial structure, endogenous enzyme activity and macromolecules damage. The results showed that curcumin concentration, light time and incubation time all significantly affected the bactericidal effect of PDI. The total bacterial count decreased by 4.30 (lg(CFU/mL)) with a bactericidal rate of 99.99% after 1 min of incubation with 7.5 μmol/L and 5 min of light exposure. It was found that the bacterium gradually transformed from sublethal to dead cells, the cell membrane permeability increased, and the size of bacterial cells and its internal complexity first increased and then decreased during PDI. PDI caused an increase in the level of reactive oxygen species (ROS) inside the bacteria cells, triggered lipid peroxidation of the cell membrane, which disrupted cell wall/membrane integrity and led to leakage of intracellular contents. The accumulation of ROS during PDI led to the collapse of the oxidative defense system while causing disruption to the energy metabolism system, oxidative DNA breakage and protein degradation, and the accumulation of damage ultimately led to bacterial multi-target death. In summary, curcumin-mediated PDI is potentially applicable to aquatic product preservation and the control of foodborne contamination of S. putrefaciens.

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.