Product number: NCM0192

Raka-Ray No.3 Agar is for the detection of lactic acid bacteria in beer and for monitoring in-process beer quality, and is not intended for use in the diagnosis of disease or other conditions in humans.

Raka-Ray No.3 Agar is for the detection of lactic acid bacteria in beer and for monitoring in-process beer quality. It is recommended for this application by the European Brewing Convention (EBC) and the American Society of Brewing Chemists (ASBC).

Contamination of beer and the beer making process by members of the lactobacilli family results in spoilage, primarily through their production of metabolic products which are detrimental to the flavor of the final product. Detection of these organisms is complicated by their diverse nutritional and environmental requirements.

A number of different formulations have been described for the isolation of lactic acid bacteria in brewing products and processes. Raka-Ray Agar was developed by the addition of various growth promoting compounds to Universal Beer Agar. This work led to the recognition that the addition of sorbitan mono-oleate, liver extract and N-acetylglucosamine produced superior growth when compared to the standard Universal Beer Agar formulation.

Further investigations provided the basis for the final formula of Raka-Ray No. 3 Medium in which fructose is an essential carbohydrate source for Lactobacillus fructivorans. Maltose is present to allow the growth of lactobacilli which cannot utilize glucose. The media can be made selective against yeasts by the addition of 7mg/l cycloheximide (Actidione®) and against Gram-negative bacteria by the addition of 3g/L 2-phenylethanol.

 

Formula Liter
Yeast Extract 5.0 g/L
Tryptone 20.0 g/L
Liver Concentrate 1.0 g/L
Maltose 10.0 g/L
Fructose 5.0 g/L
Dextrose 5.0 g/L
Betaine HCI 2.0 g/L
Diammonium Hydrogen Citrate 2.0 g/L
Potassium Aspartate 2.5 g/L
Potassium Glutamate 2.5 g/L
Magnesium Sulphate 7HO 2.0 g/L
Manganese Sulphate 4HO 0.66 g/L
Potassium Phosphate 2.0 g/L
N-Acetyl Glucosamine 0.5 g/L
Agar 17.0 g/L

Final pH: 5.4 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.

Preparation

  1. Suspend 77.1 grams of the medium in one liter of purified water.
  2. Heat with frequent agitation and boil for one minute to completely dissolve the medium.
  3. Autoclave at 121°C for 15 minutes.
  4. Cool to 45-50°C.
  5. If required, aseptically add 3g of 2-phenylethanol, mix well.

Product was previously known as LabM Product: LAB198 Raka-Ray No.3 Agar

Order Details

Product # Product Description
NCM0192A Raka-Ray No. 3 Agar, 500 g
NCM0192B Raka-Ray No. 3 Agar, 5 kg
NCM0192C Raka-Ray No. 3 Agar, 10 kg
NCM0192D Raka-Ray No. 3 Agar, 25 kg (European only size)
NCM0192E Raka-Ray No. 3 Agar, 50 kg (US only size)

Reference Material

NCM0192 - Raka-Ray No. 3 Agar, Safety Data Sheet [Danish] [Dutch] [English] [EU English] [Finnish] [French] [German] [Italian] [Spanish, Mexico] [Swedish]
NCM0192 - Raka-Ray No. 3 Agar, Technical Specifications Sheet [English]

For additional information or questions about product SDS documents, please contact Neogen at SDS@neogen.com.

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