PLATE COUNT AGAR
TRYPTONE GLUCOSE YEAST AGAR

Code: CM0325

a medium for the enumeration of viable organisms in milk and dairy products

Typical Formula*	gm/litre
Tryptone	5.0
Yeast extract	2.5
Glucose	1.0
Agar	9.0
pH 7.0 ± 0.2 @ 25°C

* Adjusted as required to meet performance standards 

Directions
Add 17.5g to 1 litre of distilled water. Dissolve by bringing to the boil with frequent stirring, mix and distribute into final containers. Sterilise by autoclaving at 121°C for 15 minutes.

Description
Plate Count Agar is equivalent to the medium recommended by the APHA¹and the PHLS ² for the plate count of micro-organisms in food, milk and other dairy products.
The APHA method consists of the preparation of pour plates using diluted samples, and counting colonies after incubation. Incubation is for 48 hours at 32°C or at 35°C for the Standard Plate Count. For the enumeration of micro-organisms with other temperature requirements, plates may also be incubated for 7-10 days at 5-7°C: for 3-5 days at 20°C; for 2-3 days at 45°C; or for 48 hours at 55°C. See the APHA¹ publication for details.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared plates at 2-8°C.

Appearance
Dehydrated medium: Straw coloured, free-flowing powder
Prepared medium: Straw coloured gel

Quality control

Positive control:	Expected results
Escherichia coli ATCC® 25922 *	Good growth; straw coloured colonies
Negative control:
Uninoculated plate	No change

* This organism is available as a Culti-Loop®

Quality Control
Compare with previous lot/batch using pasteurised and raw milk samples, incubated at 32-35°C for 48 hours.

Precautions
Make sure that the procedures and media used in milk product testing comply with the National Regulations required for each country.