| Zizyphus jujube of Rhamnaceae is rich in nutrient.But jujube can be easily infected by fungus during growth,harvest and storage,and thus be contaminated by mycotoxins including aflatoxin,ochratoxin A,deoxynivalenol,patulin and so on.In addition,patulin is difficult to remove once they are present in jujube juice and other deep processing products.Therefore,the residue analysis and control technology of patulin in jujube and jujube juice were investigated and the main conclusions were summarized as follows:(1)17 jujube samples,4 jujube juice samples and samples from different processes were selected from different provinces to study the residue situation of patulin.Results about jujube samples showed that the patulin detection rate of first grade jujube was 0%,that of second grade jujube and third grade jujube were 60% and 100%,respectively,and the average detection rate was 24%.The content of patulin in all jujube samples were all lower than the standard value in China(50 ?g/L)except one third grade jujube sample.Patulin detection rate of 4 jujube juice samples was 100%,but their contents were lower than the standard value in China,except one sample.Patulin contents were in the range of 0.82– 51.30±2.06 ?g/L.In addition,processes of filtration,pasteurization,centrifugation,ultrafiltration and adsorption all could reduce the content of patulin to some degree.(2)LSA-900 B resin was used to remove patulin in jujube juice.To learn more about the mechanism of adsorption,the adsorption isotherm,thermodynamics and kinetics during adsorption process were investigated,and the physicochemical characteristics of jujube juice were analysis.Results of macroporous resin adsorption showed that the maximum adsorption quantity and removal rate of LSA-900 B resin were 5.31 ?g/g and 73.78%,respectively,when the initial concentration of patulin was 100 ?g/L and the resin content was 14 g/L.In addition,the adsorption quantity of patulin decreased with the increase of temperature from 30 to 50 °C and increased with the increase of patulin content from 30 to 200 ?g/L.The adsorption equilibrium could be described by the Freundlich isotherm.According to the changes of enthalpy,free energy and entropy,it was suggested that the adsorption process was spontaneous,endothermic process and belonging to physical adsorption.Results of kineticanalysis showed that the pseudo second-order model was more suitable than the pseudo first-order model for describing the kinetic data.The adsorption rate was affected significantly by film diffusion and intra-particle diffusion,and the former was the rate-limiting step.Moreover,the contents of total sugar,reducing sugar,total acidity,flavonoids and total polyphenols of jujube juice were significantly decreased after the adsorption treatment,while the color value and transmittance of jujube juice were increased.The order of positive influence index was color value > transmittance,the order of negative influence index was flavonoids > total sugar > total acidity > total polyphenols > reducing sugar.(3)Activated carbon was used to adsorb patulin in jujube juice.The adsorption isotherm and kinetics during adsorption process were investigated,and the physicochemical characteristics of jujube juice were analysis.Results of activated carbon adsorption showed that the maximum adsorption quantity and removal rate were 5.91 ?g/g and 38.19%,respectively,when the initial concentration of patulin was 100 ?g/L and the resin content was4 g/L.In addition,the adsorption quantity of patulin decreased with the increase of temperature from 20 to 50 °C and increased with the increase of patulin content from 30 to150 ?g/L.The adsorption equilibrium could be described by the Freundlich isotherm when the temperature range was controlled at 20-40 °C.Results of kinetic analysis showed that the pseudo second-order model was more suitable than the pseudo first-order model for describing the kinetic data.The adsorption rate was affected significantly by film diffusion and intra-particle diffusion,and the former was the rate-limiting step.Moreover,after the adsorption treatment,the content of total sugar and total polyphenols firstly decreased and then increased,the content of total acidity significantly decreased,while the color and transmittance of jujube juice were significantly increased.The order of positive influence index was color value > transmittance,the order of negative influence index was total sugar >total polyphenols > total acidity.The comparison of LSA-900 B resin and activated carbon adsorption results showed that LSA-900 B resin was more effective and suitable to remove patulin in jujube juice.(4)The effect of UV-ozone combined technology on patulin degradation was investigated and compared with UV,ozone treatments to analysis the synergistic effect between them.Results of patulin degradation by UV-ozone combined technology showed that UV-ozone treatment could decrease the content of patulin significantly,with the degradation rate of 62%,compared to UV or ozone treatments which have only approximate 30%degradation rate.In addition,patulin degradation could be described accurately by first-order kinetic equation,and the degradation rate constant of UV-ozone treatment(0.029 min-1)was significantly higher than that of UV(0.0109 min-1)or ozone treatment(0.0102 min-1).Moreover,the soluble solid content of jujube juice could affect the degradation of patulin by UV-ozone combined technology.UV-ozone treatment increased the titratable acidity and transmittance,while decreased the content of total polyphenols and flavonoids of final jujube juice.The present study demonstrated that UV-ozone combined technology was more effective than UV or ozone in the degradation of patulin of jujube juice,suggesting that there should be a synergistic effect between UV and ozone treatments on the patulin degradation. |
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