Revealed! The ISO 22467:2021 Method That Ensures Microbial Safety in Herbal Products

 

Summary of the ISO 22467:2021 
Title: Traditional Chinese Medicine — Determination of Microorganisms in Natural Products

 

1. Purpose of the Method

This standard is used to determine the number of microorganisms and to detect specific pathogens in herbal medicinal products or natural materials. The purpose of this testing is to ensure that herbal products are safe for consumption and comply with established microbiological limits.

This method can be applied to various forms of herbal products, including:

• Raw herbs
• Herbal pieces (cut or processed crude herbal materials)
• Finished herbal preparations, such as extracts, capsules, tablets, or herbal powders.

 

2. Types of Tests in ISO 22467:2021

This standard includes two main categories of microbiological testing.

A. Total Aerobic Microbial Count (TAMC)

TAMC is used to determine the total number of aerobic mesophilic bacteria present in a sample.

Principle of the Method

1. The herbal sample is weighed aseptically.
2. The sample is diluted in a sterile diluent solution (e.g., buffered peptone water or saline).
3. Serial dilutions are performed.
4. The suspension is inoculated onto culture media.
5. Incubation is carried out at approximately 30–35°C for 48–72 hours.
6. The colonies that grow are counted and expressed as CFU/g (colony forming units per gram).

Commonly Used Media

• Plate Count Agar (PCA)
• Tryptic Soy Agar (TSA)

This method provides an indication of the hygienic quality of herbal materials during production and storage.

 

B. Total Yeast and Mold Count (TYMC)

TYMC is used to determine the total number of yeasts and molds present in herbal samples.

Principle of the Method

1. The sample is diluted in the same manner as in the TAMC test.
2. The suspension is inoculated onto selective fungal media.
3. Incubation is carried out at 25–28°C for 3–5 days.
4. Fungal colonies are counted and expressed as CFU/g.

Media Used

• Sabouraud Dextrose Agar (SDA)
• Potato Dextrose Agar (PDA)

This test is important because herbal products are frequently contaminated with fungi during drying or storage processes.

 

3. Testing for Specified Pathogens

In addition to determining the total microbial count, the standard also requires the detection of specific pathogenic microorganisms that may pose health risks.

Typical indicator microorganisms tested include:

• Escherichia coli
  Indicator of fecal contamination and poor sanitation.
• Pseudomonas aeruginosa
  An opportunistic bacterium commonly found in moist environments that can cause serious infections.
• Staphylococcus aureus
  A pathogenic bacterium capable of producing toxins and often associated with human contamination.
• Candida albicans
  A pathogenic yeast that can cause opportunistic infections.

Principle of Pathogen Testing

1. Pre-enrichment
• The sample is inoculated into enrichment media to increase the number of target bacteria.
2. Selective enrichment
• The culture is transferred to selective media to inhibit other microorganisms.
3. Isolation
• The culture is grown on selective agar media.
4. Identification
• Typical colonies are examined using biochemical tests or other confirmatory methods.

 

4. Growth Promotion Test

To ensure that the culture media function properly, the standard requires a growth promotion test.

In this test, standard reference strains are used, for example:

• Pseudomonas aeruginosa ATCC 9027

Objectives

• To verify that the culture media can support the growth of the target microorganisms.
• To confirm that the detection method is valid and sensitive.

Brief Procedure

1. Inoculate the reference strain into the culture medium.
2. Incubate under standard conditions.
3. Verify that colonies grow with the expected characteristics.

If the reference microorganism does not grow properly, the culture medium or testing procedure is considered invalid.

 

5. Interpretation of Results

Test results are typically expressed as:

• CFU/g or CFU/mL for TAMC and TYMC.
• Presence or absence for specified pathogens.

Herbal products are considered compliant if:

• The microbial counts are below the permitted maximum limits.
• No specified pathogenic microorganisms are detected.

 

6. Importance of This Method for Herbal Products

Testing according to this standard is important because:

1. Herbal materials originate from natural environments that are susceptible to microbial contamination.
2. Drying and storage processes may increase the risk of bacterial and fungal growth.
3. This testing ensures the safety, quality, and stability of herbal products before consumption.

 

Source:

ISO 22467:2021. Traditional Chinese Medicine — Determination of Microorganisms in Natural Products. International Organization for Standardization.

 

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