Achieving Faster Colony Counting for Food Safety Quality Indicator Testing.

The 3M™ Petrifilm™ Plate Reader Advanced can help increase a laboratory’s productivity and may support continuous improvement by freeing technicians to do more value-added tasks.  

Food safety laboratories are challenged each day to quickly meet their testing goals and help reduce delays in shipping food to market for consumers. In addition to supporting consumer safety, these teams of food safety professionals are also responsible for testing the quality of manufactured food to ensure it meets regulatory requirements and product brand standards.  

Limitations of manual counting 

Many of these labs use agar plates and manual counting of colonies by technicians. However, this approach can be time-consuming and tedious. Technicians can sometimes encounter difficult-to-interpret indicator tests, making it a challenge to quickly count colonies; this method uses technicians’ valuable time. Additionally, collecting and analyzing test results can be a considerable challenge as some labs may lack the software infrastructure to turn data into actionable insights. 

However, the advent of artificial intelligence (AI) has enabled the development of automated colony enumeration systems that can provide colony counts that are practically equivalent to a trained microbiologist counts.1 Some systems also create a test results database and provide capabilities for data analysis. 

Proficient food safety testing

To help laboratories achieve faster food safety testing results, 3M has introduced the 3M™ Petrifilm™ Plate Reader Advanced. It utilizes fixed artificial intelligence networks that were trained by a 3M microbiologists to count colonies, using a wide assortment of foods. 

The system enumerates ten different 3M™ Petrifilm™ Plates, including the 3M™ Petrifilm™ Staph Express Disk and entire 3M™Petrifilm™ Rapid Plate portfolio.  

3M Petrifilm Plate Reader Advanced can process up to 900 plates per hour.  Providing results in 6 seconds or less, from time of plate feed to time of results, it can reduce the time it takes to enumerate results by up to 94%.*  

Proactive process improvement

The 3M Petrifilm Plate Reader Advanced recognizes barcodes and allows users to determine the information to be captured such as sample ID, dilution level, food matrix, and more – reducing the time spent manually entering the testing information.  It has a fully customizable dashboard and the easy-to-use software automatically stores results, saving time and preventing transcription errors.  

Reports can be generated, viewed and exported to laboratory information management systems (LIMS). The 3M Petrifilm Plate Reader Advanced also provides results tracking, trending and analysis, enabling users to create reports and graphs to assist in compliance and proactively facilitate actionable insights and continuous process improvement. 

Studies demonstrate accuracy and decreased enumeration time 

In comparison to manual counting, internal and external studies have demonstrated a potential productivity increase based on reduced time to enumerate 3M Petrifilm Plates when using 3M Petrifilm Plate Reader Advanced. Additional internal studies have demonstrated the accuracy of the 3M Petrifilm Plate Reader Advanced.  

Manual Microbial Interpretation versus Automated Interpretation using the 3M™ Petrifilm™ Plate Reader Advanced

A 3M study2 of diluents and 34 foods compared results generated by the 3M Petrifilm Plate Reader Advanced to results obtained by manual counting. Of the ten compatible 3M Petrifilm Plates mentioned, nine were used in this study. 

The diluents portion of the study evaluated 11 diluents and 1,901 plates from the nine 3M Petrifilm Plates plus the 3M Petrifilm Staph Express Disk. Of the 3M Petrifilm Plates that were tested with 7 to 13 different isolates, all achieved an accuracy of at least 94% on two 3M Petrifilm Plate Reader Advanced units with the accuracy criteria that is defined in the study.2   

In the food portion of the study, 34 foods were tested, resulting in 1,636 plates evaluated across the nine 3M Petrifilm Plates plus the 3M Petrifilm Staph Express Disk. The 3M Petrifilm Plates that were tested across 6 to 8 representative food matrices achieved an accuracy of at least 91% on the first reader and 90% on the second reader.2 

Download the studies to read more.   

A Productivity Analysis of the 3M™ Petrifilm™ Plate Reader Advanced

A study, using third-party food testing laboratories3 and funded by 3M, compared the time required for manual counting versus the time required for counting by the 3M Petrifilm Plate Reader Advanced. The study used 3M™ Petrifilm™ Aerobic Count Plates and 3M™ Petrifilm™ Rapid Aerobic Count Plates that contained low, medium and high levels of colonies. 

In one portion of the multi-part study, the majority of technicians required 30 to 45 minutes to count a stack of 25 3M Petrifilm Aerobic Count plates containing an average of 225 colonies per plate. In comparison, the 3M Petrifilm Plate Reader Advanced counted the same plates in only 2 to 4 minutes. 

Overall, when combining the 3M Petrifilm Aerobic Count Plates and 3M Petrifilm Rapid Aerobic Count Plates the study demonstrated time savings with the 3M Petrifilm Plate Reader Advanced of 91% to 94% on average, for plates with high inoculum levels and 83% or greater for plates with medium inoculum levels. Even for plates with low inoculum levels, time savings of 56% or greater were observed when using the 3M Petrifilm Plate Reader Advanced.  

Productive, proficient, proactive 

As labs seek methods for faster food safety processes and testing, the 3M Petrifilm Plate Reader Advanced counts 3M Petrifilm Plates in a fraction of the time. Its fixed artificial intelligence networks, trained by 3M microbiologists, enables it to be accurate. The system’s information management capabilities can be leveraged to support proactive continuous improvement. The 3M Petrifilm Plate Reader Advanced can increase throughput and productivity, providing the opportunity for technicians to perform more tasks. Overall, the 3M Petrifilm Plate Reader Advanced and its built-in counting efficiencies can position food safety testing laboratories for success by enabling more productivity and increased capacity. 

Let us assist you  

Request A Productivity Analysis of the 3M™ Petrifilm™ Plate Reader Advanced for your laboratory. 


3M Petrifilm Plates increase productivity 

3M Petrifilm Plates eliminate the time-consuming agar plate preparation process and enable users to increase their productivity by up to 80%.1 The product provides consistent, reliable results and third-party validations confirm the method is repeatable and has performed equal to or better than the reference method to which it was compared.1  

3M Petrifilm Plates have more than 100 global recognitions and validations including: 

  • AOAC® Official Methods of AnalysisSM 
  • AOAC® Performance Tested MethodsSM 
  • MicroVal Certification 
  • NF VALIDATION by AFNOR Certification 
  • Numerous regional and local approvals 


*Observed on the 3M™ Petrifilm™ Aerobic Count Plates with high counts. 


  1. 3M data on file. 
  2. Manual Microbial Interpretation vs. Automated Interpretation using the 3M™ Petrifilm™ Plate Reader Advanced. 3M Technical Bulletin Number 694432. (2020). 
  3. A Productivity Analysis of the 3M™ Petrifilm™ Plate Reader Advanced.  3M Technical Bulletin Number 729520. (2021).