Microorganisms can be divided and analyzed into the following categories and standards:
| Category | Treatment | Min.°C | Optimum.°C | Max. °C | Standard |
| Psychrophilic cell | – | -15 | 10 | 20 | – |
| Psychrotrophic cell | – | -5 | 25 | 35 | ISO 6222, ISO 21527-1, ISO 21527-2 |
| Mesophilic cell Mesophilic spore | – 10 min 80°C | 10 | 35 | 45 | ISO 4833-1, 4833-2 |
| Thermoduric cell Thermoduric cell and spore | – 30 min 63,5°C | 15 | 45 | 50 | NEN 6808 ONLY for Streptococcus thermophilus NEN 6808 ONLY for Streptococcus thermophilus NEN 6807 for all other micro-organisms (incubation 30°C) |
| Thermophilic cell Thermophilic spore | – 30 min 100°C | 40 | 55 | 70 | Not (yet) available |
Table 1: according to Microbiologie van voedingsmiddelen 2015
Psychrophilic
Psychrophilic microorganisms are cold-loving organisms. These bacteria, moulds, and yeast can grow at refrigeration temperatures. Most psychrophilic bacteria can be found in alpine soils, ice formations, and deep oceanic waters. Most of these psychrophilic are Archeas, but also some fungi and yeast.
Psychrotrophic
Psychrotrophic bacteria, yeast, and moulds can grow at room temperature and refrigeration temperatures. These psychotropics can cause spoilage in food and water.
CRM products for the total psychrotrophic count:
- CRM-AQUA (multi-strain of bacteria) – according to ISO 6222
- CRM-PAU (singles-strain mould) – according to ISO 6611, ISO 21527-1, and ISO 21524-2
- CRM-YL (single-strain yeast) – according to ISO 6611, ISO 1527-1, and ISO 21524-2
- CRM-PAUYL (multi-strain mould and yeast) – according to ISO 6611, ISO 1527-1, and ISO 21524-2
Mesophilic count
Mesophilic microorganisms are those that can grow well at body temperatures. This group of microorganisms includes most pathogens.
CRM for the total mesophilic count:
- CRM-SA (single strain bacteria) – according to ISO 4833-1 and ISO 4833-2
- CRM-BCE.MH ((single strain bacteria, with spores) – according to NEN 6813
- CRM-CC (multi-strain of bacteria) – according to ISO 4833-1 and ISO 4833-2
- CRM-BSUBT (single-strain bacteria, with vegetative cells and spores) – according to ISO 4833-1 and ISO 4833-2 and NEN 6813
Thermoduric
Thermoduric bacteria do not love high temperatures but can survive a period exposed to high temperatures. These bacteria can survive pasteurization.
CRM for the total thermoduric count:
- CRM-STHER (single strain bacteria) – according to NEN 6808 ONLY for the thermophilic species Streptococcus thermophilus
- CRM-BSUBT (single strain bacteria, with vegetative cells and spores) – according to NEN 6807 Determination of the content of thermoresistant microorganisms
Thermophilic bacteria
Thermophilic bacteria love to live in high temperatures environments. This can be an indicator of poor hygiene in the dairy industry.
CRM for the total thermophilic count:
- CRM-GSTEA (single strain bacteria, with vegetative cells and spores) – according to NEN 6809
CRM-GSTEA is suitable for both aerobic and anaerobic process control for spore and cell analysis.
