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The various sizes (15, 30, 80, and 100 nm) of nano-SiO2/potato starch films were synthesized and characterized. The gas permeability, antibacterial properties, and mechanical properties of the films were evaluated to their potential for application as food packaging materials. Results indicated that the 100 nm nano-SiO2 was well dispersed in the starch matrix, which induced an active group on the surface of 100 nm nano-SiO2 adequately combined with starch macromolecule. The water resistance and mechanical properties of the films were improved with the addition of nano-SiO2. Notably, resistance to ultraviolet and thermal aging was also enhanced. The nano-SiO2/potato starch films were more efficient against Escherichia coli (E. coli) than Staphylococcus aureus (S. aureus). Remarkable preservation properties of the films packaging the white mushrooms were obtained, with those of the 100 nm films considered superior. This study can significantly guide the rational choice of the nano-SiO2 size to meet the packaging requirements of various agricultural products.

An electrochemical aptasensor was developed for the detection of kanamycin based on the synergistic contributions of chitosan-gold nanoparticles (CS-AuNPs), graphene-gold nanoparticles (GR-AuNPs) and multi-walled carbon nanotubes-cobalt phthalocyanine (MWCNTs-CoPc) nanocomposites. The aptasensor was prepared by sequentially dripping CS-AuNPs, GR-AuNPs and MWCNTs-CoPc nanocomposites onto a gold electrode (GE) surface. During the above process, these nanomaterials showed a remarkable synergistic effect towards the aptasensor. CS-AuNPs, GR-AuNPs and MWCNTs-CoPc as the nanocomposites mediator improved electron relay during the entire electron transfer process and the aptasensor response speed. The electrochemical properties of the modified processes were characterized by cyclic voltammetry (CV). The morphologies of the nanocomposites were characterized by scanning electron microscopy (SEM). The experimental conditions such as the concentration of the aptamer, the time, temperature and the pH were optimized. Based on the synergistic contributions of CS-AuNPs, GR-AuNPs and MWCNTs-CoPc nanocomposites, the proposed aptasensor displayed high sensitivity, high specificity, a low detection limit (5.8 × 10(-9) M) (S/N = 3) and excellent stability. It was successfully applied to the detection of kanamycin in real milk spiked samples.

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The changes in physiology and sensorial qualities of mushroom stored at 2°C for 12 days under high oxygen (100% O 2 , 80% O 2 ) atmosphere and air had been investigated. Respiration rate was suppressed in mushroom in 80% O 2 and 100% O 2 . No significant differences were found between 80% O 2 and 100% O 2 . Weight loss was not more than 1.5% in all treatments. Weight loss and firmness of mushroom held in high oxygen were significantly (P < 0.05) higher than in air. Total soluble solid (TSS) was only slightly affected by high oxygen treatment. High oxygen, especially 100% O 2 treatment was effective at reducing browning degree and electrolyte leakage of mushroom. The surface colour of mushroom changed slightly before tenth day under high oxygen treatment. From day 2 the L-value of mushroom flesh was significantly (P < 0.05) lower under air atmosphere compared with high oxygen treated mushroom. High oxygen, especially 100% O 2 was effective at inhibiting discoloration. The PPO activity of mushroom was significantly (P < 0.05) higher in 100% O 2 compared with air treatment. The POD activity was highest in high oxygen at eighth day, then reduced. High oxygen, especially 100% O 2 was effective at maintaining the quality of mushroom.

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