Raka-Ray No. 3 Agar

Item No.  NCM0192A

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$234.68 each
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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.
Brand Neogen® Culture Media
Analyte Lactic Acid Bacteria
Platform Dehydrated Culture Media
Mass 500 g
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
Grams per Liter 77.10
Liters per 500 g 6.00
Plates per 500 g 350.00
  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.
Previous Item Number Product was previously known as LabM Product: LAB198 Raka-Ray No.3 Agar
Package Weight 1.35 lb



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