STANDARD PLATE COUNT AGAR (APHA)
Code: CM0463
A standard medium corresponding to the APHA formulation for milk, water, food and dairy products.
Typical Formula* | gm/litre |
Yeast extract | 2.5 |
Pancreatic digest of casein | 5.0 |
Glucose | 1.0 |
Agar | 15.0 |
pH 7.0 ± 0.2 @ 25°C | |
* Adjusted as required to meet performance standards
Directions
Suspend 23.5g in 1 litre of distilled water. Bring to the boil to dissolve completely. Dispense into bottles and sterilise by autoclaving at 121°C for 15 minutes.
Description
Standard Plate Count Agar was developed by Buchbinder et al.1 who wished to use an agar without milk solids in the formulation and investigated the control tests necessary to give standard results in dairy products with statistically valid counts.
Standard Plate Count Agar meets the formulation of the APHA2, AOAC3 and PHLS4 .
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 medium | No change |
* This organism is available as a Culti-Loop®
Precautions
When carrying out prescribed Standard Methods it is essential to follow the protocols given in precise detail.