等离子体多尺度氧化对展青霉素降解的影响

Effect of multi-scale plasma oxidation on the degradation of patulin

展青霉素(PAT)残留是果汁产业面临的食品安全问题之一,采用新技术开展PAT的降解机制研究对解决PAT残留具有重要意义。采用介质阻挡放电(DBD)低温等离子体处理PAT溶液,使用光学发射光谱仪检测DBD等离子体产生的活性物质,使用高效液相色谱法检测DBD等离子体对PAT的降解率,采用不同自由基屏蔽剂构建多尺度氧化体系探索低温等离子体处理对PAT的降解机制。结果表明:DBD等离子体会产生大量的活性氧和活性氮,且随着处理时间延长,溶液pH值大幅度下降,PAT的降解率高达(90.92±1.98)%(P<0.05);采用屏蔽剂所构建的多尺度氧化活性物质降解PAT的能力为e_((aq))^(-)>O_(2)^(-)>·OH>H_(2)O_(2),短寿命活性物质的作用大于长寿命活性物质;PAT会抑制大肠杆菌(E.coli O157∶H7)的生长,但PAT降解产物对E.coli O157∶H7的影响较小。DBD等离子体可以有效地降解水中的PAT,放电产生的短寿命活性物质在降解过程中发挥了重要作用,PAT降解产物对大肠杆菌没有明显的毒性作用。

Patulin(PAT)residual is one of the main quality problems of fruit juice industry.In the present work,optical emission spectrometry and high-performance liquid chromatography were used to determine the degradation effect of dielectric barrier discharge(DBD)plasma on PAT.Multiscale oxidation system was constructed to explore the degradation mechanism of PAT.The results were as follows:(1)The DBD plasma produced a large amount of reactive oxygen species(ROS)and reactive nitrogen species(RNS).After 3 min treatment,the pH value of the solution decreased from 4.11±0.01 to 1.96±0.06(P<0.05).PAT solution at 500μg/L was treated with DBD plasma(working voltage:50 kV,working current:1.5 A)for 3 min.The degradation rate of PAT solution was up to(90.92±1.98)%(P<0.05).(2)Different scavengers were used to screen the active substance to study the effect of active substance on PAT degradation.The degradation rate of PAT after 2 min of DBD plasma treatment was used as an index to evaluate the effect of multiscale oxidation system on the degradation rate of PAT.The degradation rate of PAT decreased from(71.51±1.91)% to(45.77±0.61)% by manganese dioxide,which is a scavenger of hydrogen peroxide(H 2O 2).The degradation rate of PAT decreased to(41.84±1.32)% by tertiary butanol,which is a scavenger of hydroxyl radical(·OH).The degradation rate of PAT decreased to(37.82±0.94)% by para benzoquinone,which is a scavenger of superoxide radical(O 2-).The degradation rate of PAT decreased to(26.74±1.27)% by sodium dihydrogen phosphate,which is a scavenger of hydrated electron(e-(aq))(P<0.05).The effect of the four free radicals was in this order:e_((aq))^(-)>O_(2)^(-)>·OH>H_(2)O_(2).Short-lived species were more effective than long-lived species.The possible mechanism of DBD plasma degradation of PAT was speculated based on above conclusions.DBD plasma produced a large number of complexes,among which short-lived species attacked the lactone ring and unsaturated double bonds of PAT.Eventually,PAT was degraded to carbon dioxide and water.(3)PAT inhibited the growth of E.coli O157∶H7,while the effect of PAT degradation products on E.coli O157∶H7 was small.In addition,pH value and active species also affected the growth of E.coli.In conclusion,DBD plasma could effectively degrade PAT in water.The short-lived species produced by plasma played an important role in the degradation process.There was no obvious toxic effect on E.coli by PAT.