Triethylene Tetramine-modified Water-insoluble Corn Flour Caged In Magnetic Chitosan Resin For Adsorption Of Patulin

Patulin is a secondary metabolite mainly produced by certain species of Penicillium,Aspergillus,and Byssochlamys,with a multiplicity of health risks associated with acute exposure,chronic exposure as well as cellular level effect.The incidence of patulin contamination within apple and apple juice is very frequent.This research was to assess adsorption characteristics and mechanism of water-insoluble corn flour?WICF?and triethylene tetramine-modified water-insoluble corn flour caged in magnetic chitosan resin?TETA-WICF/MCR?for the removal of patulin from contaminated juice-pH simulation aqueous and apple juice.The main results are as following:The first objective was to investigate the ability of WICF to adsorb patulin.Batch adsorption experiments were performed to assess the main influence factors on the removal of patulin.Moreover,adsorption isotherm modeling,adsorption kinetic studies,thermodynamic studies,scanning electron microscopy?SEM?study,fourier transform infrared?FTIR?spectroscopic study were evaluated.The results showed that WICF have significant ability in adsorbing patulin from juice-pH simulation aqueous and adsorption was strongly dependent on granularity of WICF,contact time,pH and temperature.Patulin adsorption onto WICF is of a heterogeneous adsorption type.The sorption process is controlled by diffusion step and is endothermic and spontaneous.The maximum patulin adsorption capacity predicted by Langmuir model was 68.02?g/g at 25?.Subsequently,SEM images showed obvious morphological changes in WICF after adsorbing patulin.FTIR spectroscopic evidence demonstrated that the main functional groups involved in the adsorption were O-H,C=O and C-O-C groups.Additionally,WICF was capable of reducing patulin levels in various fruit juices,however,the effectiveness was negatively affected by matrix effects and the acidic nature of fruit juicesThe second objective was to prepare a novel adsorbent TETA-WICF/MCR to further improve adsorption capacity,mechanical strength and separation efficiency.The uptake behaviour of TETA-WICF/MCR obtained towards patulin was assessed.Orthogonal experiments were employed to optimize the synthesis conditions,with the removal rate of patulin as indicators.Moreover,characterization of TETA-WICF/MCR was carried out.The results indicated that modified biosorbent significantly increase efficiency of toxin removal than that of WICF,approximately 62.98%of patulin was absorbed by adding 0.1 g of TETA-WICF/MCR after 10 h.The optimum condition could be concluded as:a WICF dosage of 3.0 g,a TETA dosage of 5 mL,a ethyl acetate dosage of 10 mL and 1.0%?V/V?of glutaraldehyde.The mean diameter of TETA-WICF/MCR was 2.63 mm with good magnetic-responsive ability and high mechanical strength and almost without swelling.Specifically,SEM images showed abundant porous structures of TETA-WICF/MCR are responsible for adsorbing patulin excellently from apple juice.Additionally,FTIR analysis results indicated that-NH₂ groups can be covalently bonded by modification with TETA,thus resulting in the excellent patulin removal capacity of TETA-WICF/MCR.Furthermore,X-ray diffractometer?XRD?pattern of TETA-WICF/MCR indicated Fe₃O₄ with a spinel structure had been successful introduced.The third objective was to evaluate adsorption characteristics and mechanism of TETA-WICF/MCR to adsorb patulin from contaminated apple juice and investigate its impact on juice quality after adsorption.Our results clearly demonstrated that TETA-WICF/MCR has high efficacy in adsorbing patulin from contaminated apple juice.Specifically,contact time,pH value and temperature had a significant impact on the removal of patulin from apple juice.Patulin adsorption onto TETA-WICF/MCR is of a heterogeneous adsorption type,and chemical adsorption is the main rate-limiting step.Moreover,the saturated adsorption capacity of patulin reached 270.27?g/g on the TETA-WICF/MCR at 25?.The adsorption capacity of TETA-WICF/MCR was 4 times of WICF.Furthermore,SEM images showed obvious morphological changes in TETA-WICF/MCR after adsorbing patulin.FTIR analysis provided substantial evidence that the main functional groups involved in the adsorption were-NH₂ and-OH groups of TETA-WICF/MCR.Additionally,for TETA-WICF/MCR applied to apple juice,the results indicated that juice quality parameters such as degree Brix,total sugar,titratable acidity,clarity,color value and turbidity were no significant differences?p>0.05?.