Yeasts and moulds · Count agar (aw > 0.95)
Dichloran Rose Bengal Chloramphenicol Agar – reference agar for yeast and mould counts
Dichloran Rose Bengal Chloramphenicol Agar (DRBC) is the reference medium of ISO 21527-1 for counting yeasts and moulds in foods and feeds with a water activity above 0.95. Dichloran and rose bengal restrict the spreading of moulds, so colonies stay separate and countable.
- Reference agar of ISO 21527-1 (aw > 0.95)
- Dichloran and rose bengal limit mould spreading
- Chloramphenicol suppresses bacteria
How Dichloran Rose Bengal Chloramphenicol Agar works
Peptone and glucose support fungal growth, while chloramphenicol inhibits bacteria. Dichloran and rose bengal slow down the radial growth of fast-spreading moulds such as Mucor and Rhizopus. Plates are spread-inoculated and incubated upright at 25 °C, and yeast and mould colonies are counted separately.
Typical colony appearance
| Organism | Colonies |
| Yeasts | Pink colonies |
| Aspergillus brasiliensis | White mycelium with black spores |
| Bacteria | Inhibited |
Technical data
| Preparation | 31.6 g/L; boil to dissolve, autoclave 121 °C 15 min |
| Final pH | 5.6 ± 0.2 |
| Incubation | 25 ± 1 °C, 3–5 days |
| Storage | Dry, dark place; keep the container tightly closed (hygroscopic) |
Applications and practical notes
Yeast and mould counts are part of the routine quality control of food, feed, beverages and raw materials, for example according to ISO 21527-1 and FDA BAM Chapter 18. Typical applications include:
- Yeast and mould counts in food and feed
- Dairy products, bakery products, fruit and vegetables
- Spices, cereals, flour and dried foods
- Raw-material and finished-product quality control
Working with Dichloran Rose Bengal Chloramphenicol Agar: Protect the prepared plates from light, because rose bengal forms inhibitory products in the light, and incubate them upright in the dark.
Good practice with dehydrated media: keep the bottle tightly closed in a cool, dry place, weigh the powder quickly to avoid moisture uptake, and use fresh distilled or deionised water. Check the pH of each new batch after preparation and before use, and label prepared media with the date. Performance of each lot can be verified with reference strains according to ISO 11133, the standard for the preparation, production, storage and performance testing of culture media.
About yeast and mould methods: in the food chain, yeasts and moulds are counted by spread plating on DRBC Agar for products with a water activity above 0.95 according to ISO 21527-1, and on DG18 Agar for drier products according to ISO 21527-2. The FDA BAM Chapter 18 describes similar plate count methods. In pharmaceutical microbiology, the total yeast and mould count (TYMC) and the test for Candida albicans use Sabouraud media according to EP 2.6.12 / 2.6.13 and USP <61> / <62>. COLO.Science offers counting media, identification media, supplements and reference strains for every step.
Complete sets from one supplier: COLO.Science supplies culture media, supplements, rapid tests, identification kits and QC strains as complete sets for the method you follow. Send us your sample types and standards, and we will prepare an offer with the matching products and documentation.
Dichloran Rose Bengal Chloramphenicol Agar is supplied by COLO.Science in the pack sizes listed under Ordering information. For larger quantities, regular deliveries or method-specific sets that include Dichloran Rose Bengal Chloramphenicol Agar, please send us a request. With every delivery of Dichloran Rose Bengal Chloramphenicol Agar you receive the lot number and expiry date, and on request we send the available documentation for Dichloran Rose Bengal Chloramphenicol Agar.
Where Dichloran Rose Bengal Chloramphenicol Agar fits in yeast and mould testing
- Food and feed counts – DRBC Agar for aw > 0.95 (ISO 21527-1) and DG18 Agar for aw ≤ 0.95 (ISO 21527-2); alternatives: Rose Bengal Chloramphenicol, PDA with chloramphenicol, YGC for dairy products
- Pharmaceutical products – Sabouraud Dextrose Agar and Broth for TYMC and the Candida albicans test (EP 2.6.12 / 2.6.13, USP <61> / <62>)
- Cultivation and identification – PDA, Malt Extract and Czapek-Dox Agar for moulds; Corn Meal, chromogenic Candida and BIGGY Agar, Yeast Nitrogen Base for yeasts
- Fermentation and QC – WL Nutrient, Wort Agar and YPD for brewing and culture yeasts; C. albicans and A. brasiliensis reference strains for media testing
See the complete yeast and mould set in the Microbiology Catalogue →
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| Dichloran Rose Bengal Chloramphenicol Agar (DRBC) | PRO7541 | 500 g |
Product notice: preparation, storage conditions and shelf life are given on the label. Technical data on this page are for orientation; the label and the lot documentation apply. B2B prices are quoted net, excluding VAT.
Sales and technical support
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Quotations and technical support for culture media and microbiology products across our international sales territory. B2B prices are net, excluding VAT.
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Need the complete set for your method?
Send the sample type, target organism and the standard you follow. COLO.Science will put together the media, supplements, QC strains and confirmation tests for the whole procedure.
