Liofilchem® Beer Universal Agar

Liofilchem® Beer Universal Agar is a nutrient-rich culture medium specifically designed for the isolation and detection of microbial contaminants in beer, brewing yeasts, and other fermented beverages.

The medium supports the growth of beer spoilage bacteria such as Lactobacillus, Pediococcus, and other lactic acid bacteria while allowing optional selective suppression of yeasts when supplemented with cycloheximide (0.001 g/L).

By combining peptonised milk, tomato juice, yeast extract, glucose, and a balanced mineral salt composition, Beer Universal Agar provides optimal nutritional and physiological conditions for detecting microorganisms that cause haze formation, turbidity, and off-flavors in beer.

Key Features

• Selective and differential medium for beer spoilage organisms.
• Supports growth of lactic acid bacteria (e.g., Lactobacillus, Pediococcus).
• Beer-based enrichment enhances recovery of slow-growing spoilage flora.
• Optional addition of cycloheximide suppresses yeast growth for bacterial isolation.
• Reproducible performance for routine quality control in breweries.
• Validated by standard brewing microbiology methods.
• Stable and easy-to-prepare formulation.

Principle of the Medium

• Peptonised milk, yeast extract, and tomato juice provide amino acids, nitrogen sources, vitamins, and growth factors.
• Glucose acts as a fermentable carbohydrate, supporting energy metabolism.
• Phosphate buffers (dipotassium and monopotassium phosphate) maintain optimal pH.
• Mineral salts such as magnesium, manganese, iron, and sodium promote enzymatic activity.
• Beer addition (250 mL/L) provides a natural substrate and simulates fermentation conditions, enhancing selectivity for beer-specific contaminants.
• Cycloheximide (optional) inhibits eukaryotic organisms (yeasts, molds), allowing specific detection of bacterial contaminants.

Typical Formula (per litre)

Preparation

1. Suspend 62.2 g of Beer Universal Agar powder in 750 mL of distilled or deionized water.
2. Heat gently until fully dissolved.
3. Add 250 mL of commercial beer (not degassed) and mix well.
4. Sterilize by autoclaving at 121°C for 10 minutes.
5. Dispense into Petri dishes or suitable containers while molten.
6. (Optional): Add 0.001 g/L cycloheximide to suppress yeast growth and improve bacterial selectivity.

Technique

• Inoculate the sample directly onto the agar surface using sterile technique.
• For liquid samples, use surface plating or pour-plate technique:
  • Add 1 mL of sample (or dilutions) to sterile Petri dishes.
  • Pour 15–20 mL of molten agar (cooled to 45–50°C).
  • Swirl gently and allow to solidify.
• Incubate at 30 ± 2°C for up to 3 days.

Interpretation of Results

Further confirmation of presumptive colonies should be performed using microscopy, Gram staining, and additional biochemical or molecular identification methods.

Quality Control

Appearance (Dehydrated): Free-flowing, homogeneous, beige powder

Prepared Medium: Slightly opalescent, medium-to-dark amber gel

Storage and Stability

• Store dehydrated powder at 10–30°C, in a dry, tightly closed container.
• Protect from moisture and temperature fluctuations.
• Store prepared plates at 2–8°C, protected from light.
• Shelf Life: As indicated on product label (typically 3–4 years).
• Do not use if clumping, color change, or contamination is evident.

Safety and Handling

• Product is not classified as hazardous under current legislation.
• Intended for laboratory use only by trained personnel.
• Refer to Safety Data Sheet (SDS) for handling information.
• Dispose of all media and cultures according to local biosafety regulations.

References

1. Kozulis, J.A. & Page, H.E. (1968). Proceedings of the American Society of Brewing Chemists, 52–58.
2. Murphy, D.T. & Saletan, L.T. (1970). Technical Quarterly of the Master Brewers Association of America, 7:182–187.

Ordering Information

The Liofilchem® Beer Universal Agar is a proven and industry-recognized medium for detecting beer spoilage microorganisms. Its composition, enriched with beer and complex nutrients, promotes the growth of spoilage bacteria while allowing optional suppression of yeast.

Ideal for quality control laboratories in breweries and beverage industries, this medium ensures the reliable detection of contamination sources that compromise product stability and taste.