Raka-Ray 3# Medium – Selective Medium for Lactic Acid Bacteria in Beer and Brewing

Raka-Ray 3# Medium is a specialized agar medium designed for the selective isolation of lactic acid bacteria during beer production and brewing processes. It contains a balanced blend of nutrients, carbohydrates, minerals, and growth factors to support LAB growth while inhibiting unwanted microorganisms.

Product Information:

• Name: Raka-Ray 3# Medium

• Form: Dehydrated powder

• Pack Size: 250g per bottle

• Storage: Room temperature

• Shelf Life: 3 years

Composition (per liter):

• Yeast Extract – 5.0 g

• Tryptone – 20.0 g

• Liver Concentrate – 1.0 g

• Maltose – 10.0 g

• Fructose – 5.0 g

• Glucose – 5.0 g

• Betaine Hydrochloride – 2.0 g

• Diammonium Citrate – 2.0 g

• Potassium Aspartate – 2.5 g

• Magnesium Sulfate – 0.98 g

• Manganese Sulfate – 0.42 g

• K2HPO4 – 2.0 g

• N-Acetyl Glucosamine – 0.5 g

• Potassium Glutamate – 2.5 g

• Agar – 16.0 g

• pH: 5.4 ± 0.2 (25℃)

Preparation Instructions:

1. Dissolve 74.9 g of powder in 1 L of distilled or deionized water.

2. Heat to boiling until fully dissolved.

3. Dispense and add 1 mL Tween 80 per 100 mL.

4. Sterilize by autoclaving at 121℃ for 15 minutes.

5. Cool to ~55℃.

6. Under aseptic conditions, add 0.3 g β-phenylethanol and 0.7 mg actinomycin D per 100 mL, mix well.

7. Pour into Petri dishes and allow to solidify. Medium is ready for selective cultivation of lactic acid bacteria in brewing.