To develop a non-thermal sterilizing agent suitable for fresh fruit juices using Fe3O4 nanoparticles (Fe3O4 NPs) as the core antibacterial material.
Magnetic separation-capable antibacterial hydrogel microspheres were prepared by combining the antibacterial activity of Fe3O4 NPs with sodium alginate. The preparation conditions were optimized to endow the hydrogel microspheres with optimal antibacterial performance, and the resulting microspheres were subsequently applied to the sterilization of not from concentrate (NFC) Citrullus lanatus juice.
The hydrogel microspheres prepared with a mass ratio of Fe3O4 NPs to sodium alginate of 2:1 and solidified in 7.5% CaCl2 solution for 0.5 h exhibited the best antibacterial performance. Fourier transform infrared spectrometer (FTIR) structural characterization, water content, water solubility and component retention tests showed that Fe3O4 NPs were uniformly embedded in the sodium alginate hydrogel network via physical interactions. The water content of 72% ensured that the hydrogel microspheres possessed flexible mechanical properties with low deformability, and the structure and main components of the hydrogel were well retained. Antibacterial experiments demonstrated that the microspheres significantly inhibited both Escherichia coli (Gram-negative) and Staphylococcus aureus(Gram-positive), and maintained good antibacterial activity after 7 cycles of reuse and after 1 month of storage. When applied to the non-thermal sterilization of fresh Citrullus lanatus juice, the hydrogel microspheres achieved commercial sterilization requirements while largely preserving the juice color and heat-sensitive nutrients, and remained reliable in sterilization efficacy even after the 6th reuse cycle.
The prepared Fe3O4 NPs-antibacterial hydrogel microspheres not only possess good stability and physicochemical properties, but also exhibit excellent repeatable sterilization performance and quality retention capability for NFC Citrullus lanatus juice. This study provides an efficient and reusable antibacterial agent for non-thermal sterilization of NFC juice, with promising application prospects.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |