Inhibition Of Chlorine Dioxide On Soft Rot Of Chinese Cabbage And Quality Maintain On Cabbage Vegetables

In this study,we take Hangzhou Cabbage soft rot pectic bacillus(Pectobacterium)as the tested microorganism,chlorine dioxide(ClO2)gas and liquid were used respectively to pectic bacillus under the condition of in vitro.Table culturing the pectic bacillus in LB liquid medium,measure the absorbance value(OD)of 600 nm and draw growth curve;Observe and record its survival rate by plate culturing the pectic bacillus on LB;After ClO2 treatment,we measured the cell membrane permeability and cell infiltrates soluble protein content of pectic bacillus separately;Table culturing the pectic bacillus in cell wall degradation enzyme induction medium,to study the bacteriostatic activity of different treatments and different concentration of ClO2 and the correlative mechanism;To study the effect of ClO2 for pectic bacillus in pathogenicity through the living inoculation experiment;Study the infection situation and quality of Hangzhou Cabbage during storage after ClO2 processing.Chlorine dioxide treatment can significantly inhibit the growth of pectic bacillus,reduce survival rate,increase the cell membrane permeability of pectic bacillus and the content of extracellular soluble protein,and the treatment effect and concentration were positively correlated.After table cultured in LB liquid medium 20 h,1.50 mg/L bacteria concentration of chlorine dioxide gas processing was minimal,the inhibition rate was 70.1%,while the inhibition rate of 1.00 mg/L chlorine dioxide liquid processing was 66.6%.Among them,1.50 mg/L chlorine dioxide gas processing with the best inhibition effect of pectic bacillus,the survival rate was 11.96%.The higher the concentration of chlorine dioxide treatment,the cell membrane permeability of pectic bacillus increased.The change of the bacterial cell membrane permeability mainly in 30 min before,the control group,0.25 mg/L,0.5 mg/L and 0.75 mg/L group bacteria cell membrane permeability tend to be stable after 30 min.However,the 1.0 mg/L processing group cell membrane permeability increases continuously,tends to be stable after 120 min.Coomassie brilliant blue staining method was used to test the content of pectic bacillus cell penetrative soluble protein,and found that the soluble protein content was positively correlated with the concentration of chlorine dioxide processing.Among them,the 1.50 mg/L gas group and 1.00 mg/L liquid group had extremely significant difference(P < 0.01)from the control group,which shows that ClO2 treatment can effect on pectic bacillus cell membrane,undermine its permeability,affect the material exchange between cells inside and outside,lead to leakage of nutrients in the cell and Inhibit its growth.Chlorine dioxide treatment can weaken the infection situation of the Hangzhou Cabbage which artificially infected pectic bacillus on stem section,reduce the disease spot diameter and reduce the incidence.20 h after infection,the control group of Hangzhou Cabbage have all come on stem section,while the 0.14 mg/L,0.57 mg/L,1.00 mg/L and 1.50 mg/L treatment group with the disease index of 45%,25%,15% and 5% respectively.Besides,Chlorine dioxide treatment can effectively inhibit pectic bacillus cell wall degradation enzymes,after chlorine dioxide gas processing,the active peak of pectinase,PMG,carboxymethyl cellulose enzyme and beta-glycosidase were delayed one day than chlorine dioxide liquid treatment.In this study,we found that the activity of pectinases are higher than cellulases and the peak appear earlier,which shows that pectinase is the main pathogenic enzyme for pectic bacillus infecting Hangzhou Cabbage.Hangzhou Cabbage is green leafy vegetable,chlorine dioxide liquid handling can lead to water residue,a serious impact to the subsequent storage.So,in this study,we use chlorine dioxide gas to investigate its impact on the storage quality of Hangzhou Cabbage.Take a concentration of 1.01 mg/m L,4.03 mg/mL,and 7.02 mg/m L of 10.00 mL chlorine dioxide solution,then spray in three 70.00 L airtight preservation boxes respectively,quickly add 5.00 kg Hangzhou Cabbage and airtight processing 30 min.Finally,the chlorine dioxide gas concentration is 0.14 mg/m L,0.57 mg/m L,and 1.00 mg/L,results were compared with distilled water.After chlorine dioxide treatment,the Hangzhou Cabbage was stored under condition of 2±1 ?,85.00-95.00 % humidity.At the same time,determination the physiological and biochemical indexes in the storage process.Experiment found that 0.57 mg/L of chlorine dioxide processing 30 min is the best treatment groups for Hangzhou Cabbage,water loss had obvious inhibition under this condition.In addition,chlorine dioxide treatment can effectively slow soluble solids,chlorophyll and vitamin C content,reduce the membrane lipid peroxidation,inhibition of polyphenol oxidase(PPO)and peroxidase(POD)activity increased.the storage time was prolonged under this condition,even after 20 days,Hangzhou Cabbage still kept high quality with significantly reduce the loss of water,soluble solids,chlorophyll and vitamin C.