Microorganisms and performance criteria for reference media 'SDA' for Reference of Colony Count used in Food, animal feed microbiology according to ISO 11133.
Quantitative control of Productivity
- Use a quantitative reference material or test suspension with a known number of Saccharomyces cerevisiae and Aspergillus brasiliensis.
- Dilute this material so 50 to 120 cfu is inoculated on the SDA by spreading for example 0.1 mL.
- Do this also for the reference media (Media batch SDA already validated).
- Count the colonies on the medium under test (SDA) and the reference media (Media batch SDA already validated).
- Calculate the productivity ratio PR. The criteria is: PR ≥ 0,7.
- If the PR exceeds 1,4 identify the reason.
- For this the total count of colonies obtained on the culture medium under test (SDA) is divided by the total count of colonies obtained on the defined reference medium (Media batch SDA already validated).
Best Practice SDA
Quantitative control of Productivity solid medium
|Calculate the productivity ratio PR as follows:||PR||NS|
|Ns = total count test medium|
|N0 = total count reference medium|
|Control strain||WDCM number||Ref. media||Incubation||Criteria||Characteristic reaction|
|Saccharomyces cerevisiae||Media batch SDA already validated||PR ≥ 0,7||Characteristic colony/propagules/ germs according to each species|
|+ Aspergillus brasiliensis|
|The best practice for Quantitative control of Productivity for media control of 'SDA' is based on the data displayed in this table according ISO 11133.|