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Study On Sterilization Mechanism And Application Of Slightly Acidic Electrolyzed Water On Listeria Monocytogenes

Posted on:2020-12-17Degree:MasterType:Thesis
Country:ChinaCandidate:D LiangFull Text:PDF
GTID:2370330575958175Subject:Food Science and Engineering
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Slightly acidic electrolyzed water(SAEW)can be developed as a new food disinfectant because of its strong bactericidal efficacy and non-irritating properties to humans and animals.In this paper,the bactericidal effect and mechanism of SAEW on Listeria monocytogenes(L.monocytogenes),the bactericidal effect of L.monocytogenes on inoculated food materials and the removal effect of L.monocytogenes biofilm on food equipment were studied.The main conclusions are as follows:1.The bactericidal effects of SAEW on L.monocytogenes were investigated and its sterilization mechanisms were discussed.The results obtained from the present study showed that SAEW had strong bactericidal effect on L.monocytogenes which could be completely killed within 150 s by SAEW.Moreover,lower concentration of SAEW(3.54 mg/L)could kill L.monocytogenes for the continuous multi-generation effectively and L.monocytogenes did not produce significant drug resistance within ten generations.Further studies found SAEW destroyed the cell membrane structure of L.monocytogenes,thus resulted in a large amount of leakage of intracellular electrolytes,proteins and nucleic acids,and leaded to the degeneration and degradation of DNA.In addition,SAEW had no effect on the activity of intracellular superoxide dismutase(SOD)of L.monocytogenes but it could reduce the activities of catalase(CAT)and glutathione peroxidase(GSH-PX)significantly,which suggested that the balance of cellular reactive oxygen species(ROS)was broken when L.monocytogenes were treated by SAEW.2.The bactericidal effect of SAEW with 17 mg/L?60 mg/L and 109 mg/L respectively for L.monocytogenes on the surface of ruccola salad and chicken were evaluated in the present study and NaClO solution treatment was used as control.The results showed the natural colonies on the surface of ruccola salad decreased by 0.79,2.12,3.18 and 2.49 log10 CFU/mL and the natural colonies on the surface of chicken decreased by 0.24,0.49,0.7 and 1.0 log10 CFU/mL,which demonstrated that SAEW with different ACC had higher or equal disinfection effect.Moreover,the results showed that L.monocytogenes on the surface of ruccola salad decreased by 1.09,1.17,1.85 and 1.81 log10 CFU/mL,the L.monocytogenes on the surface of chicken decreased by 0.17,0.51,0.68 and 0.16 log10 CFU/mL.the above results found the bactericidal effect of SAEW on the use of ruccola salad was better than that of chicken.SAEW had excellent bactericidal effect on L.monocytogenes after low temperature storage.For chicken,the bactericidal effect after low temperature storage is better than that at room temperature significantly.3.The effect of SAEW on L.monocytogenes biofilm was also investigated in the current study.The results by crystal violet staining and scanning electron microscopy found that SAEW treatment could remove L.monocytogenes biofilm significantly in comparison with NaClO solutions and water.After treatment with different concentrations of SAEW,the reduction of L.monocytogenes biofilm on the surface of the stainless steel reached 4.75 log10 CFU/mL and the glass reached 5.05 log10 CFU/mL in 90 s.The results suggested that SAEW may be a better choice in the removal of biofilm in food industry.
Keywords/Search Tags:Slightly acidic electrolyzed water, Listeria monocytogenes, Sterilization mechanism, Biofilm
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