All standard methods for E. coli search and counting studies in a food product are for coliform group search. These methods can be grouped as follows: most probable number method (EMS), solid media methods, rapid counting method and membrane filtration method.

In general, the most probable number method (EMS) is used in the coliform group or faecal coliform group bacteria / escherichia coli counts. This method is implemented in three steps. In the first step, possible numbers of coliform group bacteria are determined. In the second step, the exact number of coliforms is determined and the number of fecal coliforms on a different medium is determined simultaneously. In the third step, the number of escherichia coli is determined.

The American Public Health Organization (APHA) recommends the most probable number method (EMS) for the search for coliform group / E. coli, especially for the microbiological analysis of water.

In the most probable number method (EMS), or in other words the EMS method with 3, it is essential to cultivate the liquid media from three consecutive dilutions, to evaluate positively those that develop at the end of incubation, and to calculate the number in the analyzed sample using the tables prepared by statistical methods.

The most probable number method is that the number of microorganisms in the analysis sample is calculated by using statistical tables as described above. This method is particularly useful in microbial analysis of foodstuffs containing a small number of microorganisms (e.g., less than 1 per gram of 10). This method is not used in foodstuffs with a high number of microorganisms if there is no obligation.

In advanced laboratories, within the framework of microbiological analysis, E. coli (EMS) ISO method is being studied. The standard taken into account during these studies is:

• TS ISO 7251 Microbiology of food and animal feed - Horizontal method for identification and enumeration of possible escherichia coli - Most probable number technique

This standard specifies the principles for the counting of the most probable number and the detection of the possible escherichia coli bacterium after sowing on liquid medium and incubation at 37, then at 44.