Ready-to-use media
Gelysate Agar (Plate Count Agar Sugar Free)
Solid culture medium in compliance with the ISO 13559:2002 / IDF 153:2002 standard for the enumeration of contaminating microorganisms in butter, fermented milks and fresh cheeses, by the technique of colony count at 30 °C.
- Cat. No.
- LC-812
- Category
- Ready-to-use media
- Format
- 20 plates, 90 mm
- Storage
- 2 to 14 °C
- Minimum guaranteed shelf life
- 1 month
- Standards
- ISO 13559
- Also available
- Dehydrated medium, 1 format (LC-1187)
This medium is recommended for the detection of contaminants in dairy products, due to its slightly alkaline pH and the absence of sugars in its composition, which strongly inhibit growth of the common microorganisms of dairy products and favor the development of contaminants.
Key features
Applications
Non-selective enumeration (general use).
Industry
Dairy products.
Standards
ISO 13559.
Presentation
20 prepared plates, 90 mm, with 21 ± 2 mL.
Description and technique
ISO 13559:2002 and IDF 153:2002 define contaminating microorganisms such as non-lactic bacteria and molds and yeasts that form enumerable colonies under the conditions specified in those standards. However, it should be noted that certain types of fermented milk products include non-lactic bacteria and/or molds and yeasts involved in their characteristic production.
Each laboratory should establish protocols best suited to their products according to internationally accepted standards (ISO 8266 and IDF 122:2001 Milk and milk products - General guidance for the preparation of samples for testing, initial suspensions and decimal dilutions for microbiological examination).
The assay is performed by seeding, in duplicate, 0.1 mL aliquots of the initial suspension and of each dilution on the surface of the agar plates of Sugar Free Medium. Reading of results is performed after incubation for 72 ± 2 hours at 30 °C.
Pin-point colonies should be neglected.
Presentation
| Presentation | 20 prepared plates, 90 mm |
|---|---|
| Filling | 21 ± 2 mL |
| Packaging | 1 box with 2 packs of 10 plates/pack. Single cellophane. |
Composition
| Ingredient | g/L |
|---|---|
| Gelatin peptone | 7.5 |
| Casein peptone | 7.5 |
| Sodium chloride | 5.0 |
| Agar | 15.0 |
Quality control
Physical/chemical control
| Color | Yellowish |
|---|---|
| pH | 7.5 ± 0.2 at 25 °C |
Microbiological control
Inoculate: practical range 100 ± 20 CFU; min. 50 CFU (productivity).
Microbiological control according to ISO 11133:2014/Amd 1:2018.
Analytical methodology according to ISO 11133:2014/Amd 1:2018; A2:2020.
Aerobiosis. Incubation at 30 ± 1 °C, reading at 72 ± 3 h.
| Microorganism | Growth |
|---|---|
| Stph. aureusATCC 25923, WDCM 00034 | Good (≥ 70%) |
| Enterococcus faecalisATCC 19433 | Good (≥ 70%) |
| Escherichia coliATCC 25922, WDCM 00013 | Good (≥ 70%) |
| Ps. aeruginosaATCC 27853 | Good (≥ 70%) |
| Candida albicansATCC 10231, WDCM 00054 | Good (≥ 70%) |
| Bacillus cereusATCC 11778, WDCM 00001 | Good (≥ 70%) |
Sterility control
Incubation 48 hours at 30-35 °C and 48 hours at 20-25 °C: NO GROWTH.
Check at 7 days after incubation in same conditions.
Bibliography
- FIL-IDF (1991) International Standard 153. Butter, Fermented milk and cheese. Contaminant counting.
- ISO 11133:2014/Amd 1:2018. Microbiology of food, animal feed and water. Preparation, production, storage and performance testing of culture media.
- ISO 13559 IDF 153 Standard (2002) Butter, fermented milks and fresh cheese - Enumeration of contaminating microorganisms - Colony count technique at 30 °C.
- PASCUAL ANDERSON, Mª R. (1982) Técnicas para el análisis microbiológico de alimentos y bebidas. CeNAN. Madrid.
- THOMAS, S.B. (1969) Methods of assessing the psychrotrophic bacterial content at milk. J. Appl. Bact. 32:269-296.
What you receive
The product
Shipped under controlled temperature when the product requires it.
Lot certificate
Every lot comes with its certificate.
Tracked shipment
Follow your shipment live, from our warehouse to your lab.
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Frequently asked questions
Can I ask for formats other than those listed?
Yes: custom formats and OEM packs are available on request. Tell us the quantities you need.
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How long does delivery take?
We give you the availability with the quote, within 24 hours of your request.