Liofilchem® Letheen Broth Base Modified ISO 21149, 500g

Liofilchem® Letheen Broth Base Modified ISO 21149 is a specialized dehydrated culture medium developed for the microbiological testing of cosmetic products, prepared in accordance with ISO 21149 standards.

This broth is designed for the enumeration and detection of aerobic mesophilic bacteria in cosmetics, toiletries, and personal care formulations. It contains neutralizing components such as lecithin and sodium bisulfite, which help inactivate preservatives commonly present in cosmetic products, ensuring accurate microbial recovery and preventing false-negative results.

Letheen Broth Base Modified is widely used in cosmetics quality control laboratories, pharmaceutical microbiology, and regulatory compliance testing.

Intended Use

This medium is intended for:

• Microbiological examination of cosmetics and personal care products
• Enumeration of aerobic mesophilic bacteria (ISO 21149)
• Detection of bacterial contamination in preserved cosmetic formulations
• Neutralization of antimicrobial preservatives during microbial recovery
• Routine quality control testing in cosmetic manufacturing environments

Principle of the Medium

Letheen Broth Base Modified provides a nutrient-rich environment for microbial growth while incorporating preservative neutralizers.

Key Components and Functions

• Peptone, Tryptone & Meat Extract
  Supply nitrogen, amino acids, peptides, and essential nutrients for bacterial growth.
• Yeast Extract
  Rich source of B-group vitamins and growth factors.
• Sodium Chloride
  Maintains osmotic balance within the broth.
• Lecithin
  Neutralizes quaternary ammonium compounds and other preservative agents.
• Sodium Bisulfite
  Neutralizes aldehydes and oxidative preservatives frequently used in cosmetic products.
• Tween 80 Supplement (added during preparation)
  Enhances neutralization of phenolics and other antimicrobial substances.

This formulation ensures that microorganisms present in cosmetic samples can recover and grow without interference from product preservatives.

Typical Formula

Preparation Instructions

1. Suspend 37.8 g of powder in 1 liter of distilled or deionized water.
2. Add 5 mL Tween 80 Supplement (Ref. 80031).
3. Heat until completely dissolved.
4. Dispense into final containers.
5. Sterilize by autoclaving at 121°C for 15 minutes.

Test Procedure (ISO 21149 Workflow)

1. Inoculate 9 mL of prepared Letheen Broth with:
   • 1 g or 1 mL of cosmetic sample
2. Mix thoroughly to homogenize.
3. Incubate at 32.5 ± 2.5°C for at least 20 hours.
4. Transfer 0.1–0.5 mL of suspension onto a nutritive agar plate.
5. Spread evenly using sterile technique.
6. Incubate plates at 32.5 ± 2.5°C for 48–72 hours.

Interpretation of Results

• Count colonies on plates
• Multiply by dilution factor
• Report results as:

CFU (UFC) per gram or mL of sample

Appearance

Quality Control Performance

Sterility controls performed aerobically at 25°C and 36°C.

Storage & Shelf Life

• Store dehydrated powder at 10–30°C, away from light and moisture.
• Prepared broth should be stored at 2–8°C.

Shelf Life:

• Dehydrated medium: 4 years

Packaging Information

Standards & References

• ISO 21149: Cosmetics – Microbiology – Enumeration and detection of aerobic mesophilic bacteria
• FDA Bacteriological Analytical Manual (AOAC International)

Liofilchem® Letheen Broth Base Modified ISO 21149 is an essential microbiological medium for cosmetic product testing. With its combination of nutrient support and preservative neutralizers, it enables accurate detection and enumeration of aerobic bacteria in preserved formulations, ensuring compliance with international cosmetic microbiology standards.