| This paper addresses the problem of microbial transmission in the cold chain environment,exploring the law of secondary transmission through surface contact on cold surfaces,while going to establish a predictive model of microbial contact transmission on cold surfaces.In this paper,the experimental method of quantitative statistics is used to study the secondary transmission of microorganisms on cold surfaces through surface contact by using the microbial transmission rate of surface contact as the dependent variable,E.coli as an example,steel-cotton gloves,steel-rubber gloves,and two different surface contact pairs:36.5°C versus-18°C(simulated freezing temperature)and 36.5°C versus 5°C(simulated refrigerating temperature)as independent variable factors to study the secondary transmission of microorganisms on cold surfaces through surface contact The regulation.Taking into account the effect of microbial surface contact adhesion,we then analyze the effect of temperature difference between contact surfaces and surface materials on microbial transmission rate,and investigate the relationship between microbial transmission rate and surface contact pair characteristics,so as to establish a mathematical model of the contact process between skin,gloves and other surfaces and cold surfaces in typical cold chain handling conditions,and predict the contact transmission probability of microorganisms between human surfaces and cold surfaces.The main contents of the paper are as follows.Experiments were conducted to study microbial surface contact transmission using E.coli as indicator bacteria,and different contact pressures(0.44 N/cm2,0.86 N/cm2,1.55N/cm2,2.25 N/cm2,2.94 N/cm2),contact times(0s,15 s,30s,45 s,60s),and contact angles(15°,25°),and surface materials(rubber gloves,cotton gloves)at different storage temperatures(5°C,-18°C)to do contact propagation experiments,we found the following conclusions.(1)The cold storage in handling goods as far as possible to choose rubber gloves and other gloves with low surface roughness Rt,compared with cotton gloves can effectively reduce the maximum transfer rate of 28.7%.(2)The lower the temperature,the less likely microorganisms will be exposed to transfer,and the activity of bacteria will decrease while the surface of the goods will freeze,which can reduce the transfer of microorganisms.In the handling of goods,adjust the temperature of the cold storage,can reduce the transfer rate of microorganisms,if the use of rubber gloves handling goods,in-18 ℃ handling goods transfer rate than the transfer rate at 5 ℃ can be reduced by up to 32%;if the use of cotton gloves,the highest can effectively reduce 22.3%.(3)When handling goods in cold storage,the length of handling time does not significantly affect the transfer rate of microorganisms,and the transfer rate of cotton gloves with the increase in time is generally higher than that of rubber gloves.The average transfer rate after contact with rubber gloves was 55.62% and 43.84% for goods weighing 1.12 kg at5℃ and-18℃,respectively,while the average transfer rate of cotton gloves was 62.48% and43.72% at 5℃ and-18℃,respectively.(4)in the cold storage handling goods as far as possible when the flat,reduce the tilt angle,if the use of cotton gloves handling goods tilt angle of 25 °,then the highest transfer rate can reach 76.75%,if the use of rubber gloves handling goods tilt angle of 15 °,then the transfer rate can be as high as 71.12%;if you can not avoid the tilt angle,if the angle is large,the use of rubber gloves handling,as opposed to the use of cotton gloves,the highest transfer rate of 76.75%.Compared with cotton gloves,the highest effective reduction of 30.71%transfer rate,if the angle is small,use cotton gloves,compared with rubber gloves,the highest can be reduced by 33.76%.(5)The factor that determines the transfer rate of cotton gloves is greater than the transfer rate of rubber gloves is the roughness Rt value,not the arithmetic average roughness RaThe probability model of contact propagation of microbial aerosol surfaces at temperatures T>273.5K and T≤273.5K was established by the temperature magnitude of the contact surface,and we found that the most critical factors that really determine the contact propagation of microorganisms on cold surfaces are the parameter Rt in the roughness of each contact surface,as well as the temperature and contact pressure,the greater the contact pressure and the lower the temperature,the higher the roughness Rt,the parameter the higher the contact pressure,the lower the temperature,the roughness Rt,and the parameters,the higher the contact propagation rate. |
