Effects Of High Voltage Pulse Electric Field On The Quality Of Purple Potato Juice

As a global food,economic crop,with many health care functions.In order to prevent the rotten loss of purple potatoes in storage,it is necessary to deep processing for purple potato.purple potato juice is a deep processing of purple potatoes,which is popular with consumers.Since traditional thermal bactericidal treatment has some adverse effects on the quality of fruit and vegetable juice,non-thermal sterilization technology is increasingly valued.High pressure pulse electric field technology(PEF)is used as a non-thermal sterilization technology,and there is no report on the applicability of purple potato juice.This paper uses high pressure pulse electric field to treat fresh squeezed purple potato juice,which study PEF on the effect of bactericidal effect,physical and chemical indicators of purple potato juice,and in vitro antioxidant capacity.It is designed to explore the applicability of non-thermal sterilization(PET)on purple potato juice,and lay the foundation for improving the quality of purple potato juice.The main findings are as follows:(1)study the effect of sterilization of high pressure pulse electric field(PEF)on the sterilization effect of purple potato juice.pass through the sterilization effect of Escherichia coli and golden staphylococci in purple potato juice,and the content of anthocyanin after sterilization treatment to select proper PEF parameters.The result shows: The sterilization effect of the microbial increases with the increase of electric field strength and the number of pulses,at the same time,the increase in sterilization effect of the microbial will also cause degradation of anthocyanins.The PEF parameter is better sterilization treatment in the electric field strength 20 k V/cm and the pulse number of pulse is 200,which less influence on anthocyanin.Under this condition for the logarithmosis rate of E.coli and golden Staphylococcus aureus was4.92,4.81,respectively,and the anthocyanin content was 80.42 mg/L,and the retention rate was 99.6 %.The result of total number of colonies of purple potato juice in 4 ℃ after PEF treatment: After 30 days,the purple potato juice of the PEF group and the therm bactericidal group were still in accordance with the total number of colonies in the juice beverage GB 7101-2015.(2)study the effect of PEF sterilization on the quality of purple potato juice.which is based on VC,anthocyanin,total phenol,total acid,reducing sugar,soluble solid matter,Δ E as an indicator,compared to change trend of PET bactericidal,therm bactericidal,no bactericidal the juice in the storage period(4 ℃,30 d).The result shows: PEF and thermal bactericidal treatment will affect the quality of purple potato juice,and the quality of purple potato juice in the PEF group is better than the thermal bactericidal group and the no bactericidal group in the storage period.After30 days at 4 ℃,the purple potato juice of PEF treatment(20 k V/cm,pulse number200)was more retention amount of VC and anthocyanins,it was 76.62 mg/L,90.28μg/m L,respectively,and the retention rate is 93.6 %,92.6 %,respectively,which high than retention amount of VC and anthocyanins of therm bactericidal group is 26.3 %,30.9 % respectively.purple potato juice of PEF sterilization and thermal bactericidal less effect on reductant sugar,total phenol,total acid,soluble solids,Δ E during storage(P <0.05).(3)The effect of PEF treatment on the In vitro antioxidant activity of purple potato juice was studied,which is based on scavenging activity of ABTS free radicals,DPPH free radicals,hydroxyl radicals,superoxide anion free radicals,and total reducing force as in vitro antioxidant capacity indicators.The result shows: purple potato juice after PEF treatment has better antioxidant activity than thermal bactericidal treatment,and can maintain vitro antioxidant capacity during the storage of purple potato juice.The purple potato juice after PEF treatment was in scavenging activity of ABTS free radicals,DPPH free radicals,and superior oxygen free radicals were better than that of the VC control group and the thermal bactericidal group,and the scavenging activity reached 90.98%,93.5%,86.63%,respectively.after 4 ℃ storage 30 days,Compared with the thermal bactericidal group and the control group,the PEF group was best in vitro antioxidant capacity.which can better maintains In vitro antioxidant capacity during storage.