Study on Factors Affecting Aerobial Plate Count in Raw Milk

[Objectives]This study was conducted to investigate the main factors affecting the aerobial plate count in raw milk.[Methods]Drinking water,medicated baths and raw milk under different storage and transportation conditions were detected for the values of aerobial plate count to analyze their effects on the aerobial plate count in raw milk.[Results]Disinfection of drinking water tanks could significantly reduce the aerobial plate count in water.The use of medicated baths before and after milking could effectively reduce the aerobial plate count and had a significant bactericidal effect.The growth of microorganisms in raw milk stored below 4℃was relatively slow.Regularly disinfecting drinking water tanks and disinfecting nipples before and after milking could reduce the aerobial plate count in the tanks and nipples.After raw milk was extruded,the temperature should decrease to 0-4℃within 2 h,and the storage time should not exceed 48 h,which could effectively control the aerobial plate count in raw milk.[Conclusions]This study provides a reference for scientific control of the aerobial plate count in raw milk.

Evaluation on Uncertainty of Detection Results of Aerobic Plate Count

[Objectives]To determine the aerobic plate count(APC)in the milk samples,evaluate the uncertainty of the test results,and to provide a scientific basis for the quality control of the testing process.[Methods]In compliance with the national food safety standard Food Microbiological Examination:Aerobic Plate Count(GB 4789.2-2016),the aerobic plate count in the milk samples was detected.The source of the uncertainty of the test result was analyzed and a mathematical model was established in accordance with Evaluation and Expression of Uncertainty in Measurement(JJF 1059.1-2012).Then,the introduced uncertainty components were evaluated to determine the uncertainty of the final combined aerobic plate count.[Results]The expanded uncertainty of the test result of the aerobic plate count in the milk samples was 0.0434,and the logarithmic value interval of the results was(3.924,4.010),and the antilogarithm was taken to get the aerobic plate count in the sample to be 8395-10233 CFU/mL.[Conclusions]This method can effectively evaluate the uncertainty of the aerobic plate count,and ensure the accurate and scientific laboratory test data.

Microbial profile of some ready-to-cook frozen food items sold in Dhaka city,Bangladesh

This study aimed to assess the microbiological quality of 159 animal-and plant-based ready-to-cook(RTC)frozen food items currently popular in Dhaka.Microbiological analyses were carried out to enumerate total aerobic counts of mesophilic bacteria,yeast and mold and to detect some common foodborne pathogens according to standard microbiological criteria.Higher microbial loads in all animal-based food types,other than chicken strips were found.In contrast,plant-based items were relatively safe except paratha,dal-puri,rooti chapati,and aloo-puri.Several common pathogenic bacterial species were screened by analyzing their morphological,cultural,and biochemical characteristics.Escherichia coli was prevalent in most samples,while Salmonella species were least reported.A considerable number of samples exhibited enough microbial loads at infection or intoxication levels.

Characterization of bacterial community dynamics in a full-scale drinking water treatment plant

Understanding the spatial and temporal dynamics of microbial communities in drinking water systems is vital to securing the microbial safety of drinking water.The objective of this study was to comprehensively characterize the dynamics of microbial biomass and bacterial communities at each step of a full-scale drinking water treatment plant in Beijing,China.Both bulk water and biofilm samples on granular activated carbon（GAC） were collected over 9 months.The proportion of cultivable cells decreased during the treatment processes,and this proportion was higher in warm season than cool season,suggesting that treatment processes and water temperature probably had considerable impact on the R2 A cultivability of total bacteria.16 s rRNA gene based 454 pyrosequencing analysis of the bacterial community revealed that Proteobacteria predominated in all samples.The GAC biofilm harbored a distinct population with a much higher relative abundance of Acidobactena than water samples.Principle coordinate analysis and one-way analysis of similarity indicated that the dynamics of the microbial communities in bulk water and biofilm samples were better explained by the treatment processes rather than by sampling time,and distinctive changes of the microbial communities in water occurred after GAC filtration.Furthermore,20 distinct OTUs contributing most to the dissimilarity among samples of different sampling locations and 6 persistent OTUs present in the entire treatment process flow were identified.Overall,our findings demonstrate the significant effects that treatment processes have on the microbial biomass and community fluctuation and provide implications for further targeted investigation on particular bacteria populations.