Study On The Degradation Of Mycotoxin Using Prepared Titanium Matrix Composites And Its Antifungal Activity

Mold is a common contaminant in food,and the food-borne diseases caused by it are an important food safety public health problem.In addition,some strains of molds can produce toxic secondary metabolite mycotoxins,such as Ochratoxin A（OTA）.The development of efficient,green,and cost-effective technologies for the treatment of mycotoxins and molds is the cornerstone of promoting food safety.In order to achieve this goal,people are gradually focusing on photocatalytic technology that exhibits high efficiency and wide application in solving environmental pollution problems.Among them,the representative photocatalyst nano-TiO2 has been widely used in the removal of refractory organic pollutants and antibacterial treatment due to its high photocatalytic activity,non-toxicity,and good chemical stability.In recent years,it has also been used in the field of food.However,nano-TiO2,like other wide band gap semiconductor material,has the defect of low utilization of sunlight.Upconversion materials（UCNP）often act as optical transducer for converting near-infrared light into ultraviolet/visible light.Combining upconversion materials with nano-TiO₂ can improve the above defects and enable the light response range of nano-TiO2 to be extended to the near-infrared light region.In this paper,OTA and Penicillium viridicatum,one of the OTA-producing bacteria,were selected as the target pollutants,and the effects of photocatalytic technology on the treatment of this two target pollutants were studied.First,the hydrolysis of titanate method was used to coat the anatase TiO₂ nanolayer on the surface of upconversion material NaYF4:Yb,Tm to obtain the photocatalytic material NaYF₄:Yb,Tm@TiO₂ with core-shell structure.The structure was characterized by TEM,XRD,UV-Vis DRS and PL.The degradation efficiency of OTA was investigated and the product of OTA in the photocatalytic degradation process was analyzed.Photocatalytic degradation experiment showed that under the irradiation of UV-NIR light（200 nm-2500nm）,NaYF₄:Yb,Tm@TiO₂ can produce photocatalytic effect,release reactive oxygen radicals and degrade OTA.Further optimization of the experimental conditions revealed that when the amount of photocatalytic material was 10 mg/m L and the solution pH was 6.2,the degradation rate of OTA with an initial concentration of 5μg/mL could reach 98.7%after 30 min of illumination with 300 W xenon lamp.This photocatalytic reaction followed the first-order kinetics.Two products C₁₉H₁₆ClNO₅ and C₁₉H₁₇ClNO₄ were formed during the OTA degradation which were assessed by ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry,the mass-to-charge ratios（m/z）were 374.0 and 360.1,respectively.The research provide theoretical reference and practical basis for NaYF4:Yb,Tm@TiO2 photocatalytic degradation of mycotoxins.Secondly,the antifungal properties of NaYF4:Yb,Tm@TiO2 were investigated.In the experiment,the inhibitory effect of NaYF₄:Yb,Tm@TiO₂ on Penicillium viridicatum was investigated by the plate-culture method.The results showed that the photocatalytic treatment of Penicillium viridicatum showed a decrease in the number of colonies,and the inhibitory rate was positively correlated with the time of photocatalysis.Under full-wavelength light,the inhibitory rate reached 98.1%after irradiation for 240 min.SEM revealed that the spores of Penicillium viridicatum in the control group were intact and the surface were full,but after NaYF4:Yb,Tm@TiO2 photocatalytic treatment,the appearance of the spores had changed significantly,and finally shrunk inward.The OD₂₆₀60 and OD₂₈₀80 of Penicillium viridicatum increased with the processing time increased,it indicated that the cell membrane was damaged.Finally,KC/KGM/TiO2 nanocomposite films were prepared withκ-carrageenan（KC）and konjac glucomannan（KGM）as the film-forming substrate and nano-TiO₂ as the filler.The effects of different concentrations of nano-TiO₂ on the morphology,mechanical properties,moisture permeability and other properties of the composite film were studied,and the structure of the composite films were characterized.The results showed that KC/KGM/TiO₂ films possessed higher barrier properties against water vapor and UV light.In addition,TiO₂ addition enhanced the mechanical properties and thermal stability.As the concentration of TiO₂ increased,the tensile strength of the films first increased and then decreased,the elongation at break of the films decreased.When the amount of TiO₂ is 5%,the tensile strength reached the maximum value of 63.7 MPa.The antifungal experiments showed KC/KGM/TiO₂ had significant antifungal activity.When TiO₂ concentration was7%,its antifungal activity against Penicillium viridicatum reached to a maximum value of79%after 6 h illumination（200 nm-2500 nm）.Experiments on freshness preservation of breads and strawberries with different packages showed that KC/KGM/TiO₂ nanocomposite film can delayed the spoilage of food and effectively maintained the quality of food.The present research demonstrated the feasibility of incorporating TiO2 nanoparticles to improve the properties of films,stressing the potential of the novel nanocomposite film for food packaging applications.