Research On A Pre-manufacture Method Of Rapid Detection For Total Bacteria In Food

Food is the material foundation which human beings rely on for existence in activities of life.It is also vital energy for human beings.The relationship between food hygiene and people's health is extremely close.The Total Bacterial count is the most principal standards in the food detection.At present,it takes a lot of time to use the traditional counting method—Culture Counting Method and it will also consume the high cost,which will not catch up with the rapid pace of life.Especially,the complicated step is needed in the process of the traditional Coliform Bacterial detection,which needs cultivate counting time after time with the expensive culture medium.It wasted a lot of manpower and resource and it will not catch up with the increasingly fast life rhythm.At present, other various methods of detection at home and abroad were born,but they all have respective disadvantages that prevented their expanding and they have not completely replaced the traditional Culture Counting Method.Therefore,our laboratory researched on the food microbial rapid detection system by using the digital micro-image identification technology which is based on Machine Vision and Artificial Neural Network.Before this dissertation,my laboratory has developed a rapid detection system which can identify and count Total Bacteria.However,because of the pre-manufacture handling systemic and the pre-manufacture method ological defects,the detection system has some counting error. Therefore,this dissertation mainly researched on both the pre-manufacture method of the detection system and the accuracy of the rapid detection method which can count the important standard-bacterial number.This dissertation In this paper,the main research results obtained are as follows:1.Research about the cactive coloration of bacterials and found the smear-dry-fixed -dyeing-examination of the coloration method.Comparing three dye TTC,neutral red,methylene blue staining effect on the bacterial cell,and elected the methylene blue dye as the best dye.It will directly distinct sample of the bacterial modality from other impurities or suspected bacterial,thus ensuring the accuracy of experimental results.2.Research about the pre-manufacture methodological of rapid detecting bacterial total number,which from solid foods(cakes,bread,cookies,candied fruit,non-fermented soy products).Finally,provided the detection technology and ruslts are as follows:(1) Detection Technology:In aseptic conditions,pour an accurate metage of 25g solid sample into a tapered bottle with 55ml 0.5%peptone water solution,then placed this sample in shake instrument with 160r/min,oscillation 2min,in order to mix solution. Extract lmL sample solution with adjustable micropipette to the lml centrifuge tube,take a total of 2,at the scale equal to its weight,then place it in centrifuge with 1000r/min,8min. Extract 0.8mL supernatant to the 1ml centrifuge tube,place it in centrifuge with 11000r/min,12min.Then dispose 0.3ml tube supematant,Placing the remaining solution in centrifuge with 12000r/min,8min.Finally,draw 5uL bacilli with adjustable micro-pipette from the bottom of centrifuge tube,dripping on the center of slide.After natural drying,a drop of dye was added dropwise(about 5uL),staining 2min,rinse the slide back and forth with a mirror polish remove excess water paper,placed Sample in the microscope loading platform carefully,and calculate the total number of test results through bacteria rapid detection system.(2) Detection Results:the method can be reached results at 1.5h,and the result for the ratio between rapid detection method and GB method is 1.19,when refer to detect total bacteria of solid food(order of magnitude for the 10~3—10~1).This explains no significant difference between the two methods,but the rapid detection method is more sensitivity and authenticity than GB mehod,and it has a certain warning capacity about food quality early.3,Research about the pre-manufacture methodological of rapid detecting bacterial total number,which from milk.(1) Detection Technology:In aseptic conditions,pour an accurate metage of 25ml liquid milk into a tapered bottle with 55ml 0.5%peptone water solution.Slowly heated to 25℃.Then placed this sample in shake instrument with 160r/min and 2min,in order to mix solution.Adding 2.5ml 100%trichloroacetic acid to it,90s leter,place the beaker in ice water cooling rapidly.filtrate sediment with medium-speed filter,until the filtered liquid to 5ml.Extract 1mL sample solution with adjustable micropipette to the 1ml beaker centrifuge tube,take a total of 2,at the scale equal to its weight,then place it in centrifuge with 12000r/min,12min.Draw 5uL bacilli with adjustable micro-pipette from the bottom of centrifuge tube,dripping it on the center of slide.After natural drying,a drop of dye was added dropwise(about 5uL),staining 2min,rinse the slide back and forth with a mirror polish remove excess water paper.Draw 5uL bacilli with adjustable micro-pipette from the bottom of centrifuge tube,dripping it on the center of slide.After natural drying, a drop of dye was added dropwise(about 5uL),staining 2min,rinse the slide back and forth with a mirror polish remove excess water paper.Placed sample in the microscope loading platform carefully,and calculate the total number of test results through bacteria rapid detection system.(2) Detection Results:The method can be reached results at 1.0h,and the result for the ratio between rapid detection method and GB method is 1.40,when refer to detect total bacteria of milk(order of magnitude for the 10~7—10~1).This explains no significant difference between the two methods,but the rapid detection method is more sensitivity and authenticity than GB mehod,and it has a certain warning capacity about food quality early.This dissertation is based on the coloration modality of bacteria,make a pre-manufacture treatment of sample.Based on image recognition technology,reach the total bacteria directly without cultivating for 48h,quick,online,accurate test results to report.This will promote both the safety of food microbiology and the timeliness of food production,and will play a role in promoting national economy development,but also will produce enormous economic benefits...