3M Petrifilm 6478 Instrucciones Del Producto página 4

Interpretation
1. 3M Petrifilm RAC Plates can be counted using a standard colony counter or other illuminated magnifier. Count all colonies regardless of color, size
or intensity.
2. The circular growth area is approximately 30 cm
can be made on 3M Petrifilm RAC Plates containing greater than 300 colonies by counting the number of colonies in two or more representative
squares and determining the average number per square. Multiply the average number by 30 to determine the estimated count per plate.
3. High concentrations of colonies on the 3M Petrifilm RAC Plates will cause the entire growth area to become blue or red. Occasionally, on
overcrowded 3M Petrifilm RAC Plates, the center may lack visible colonies, but many small colonies can be seen on the edges. When any of these
occurs, record results as too numerous to count (TNTC). When an actual count is required, plate at a higher dilution.
4. Food samples may occasionally show interference on the 3M Petrifilm RAC Plates, for example:
a. A uniform light blue background color (often seen from the organisms used in cultured products) should not be counted as TNTC.
b. Intense, pinpoint blue specs (often seen with spices or granulated products) should not be counted as colonies.
5. Where necessary, colonies may be isolated for further identification. Lift the top film and pick the colony from the gel. Test using standard
procedures.
6. If the 3M Petrifilm RAC Plates cannot be counted within 1 hour of removal from the incubator, they may be stored for later enumeration by freezing
in a sealable container at temperatures less than or equal to minus 15°C (5°F) for no longer than one week.
For further information refer to the "3M™ Petrifilm™ Rapid Aerobic Count Plate Interpretation Guide." If you have questions about specific
applications or procedures, please visit our website at www.3M.com/foodsafety or contact your local 3M representative or distributor.
Specific Instructions for Validated Methods
AOAC-RI Performance Tested Methods (PTM)
In an AOAC RI PTM study, the 3M Petrifilm Rapid Aerobic Count Plate method was found to be equivalent to or better than the average log counts of
the FDA/BAM Chapter 3 reference method and the Standard Methods for the Examination of Dairy Products Chapter 6.
Scope of Validation:
Raw ground beef, raw ground pork, ground turkey, chicken carcass rinsate, fresh swai, fresh tuna, fresh tiger shrimp, easy-peel shrimp, cherry tomato
wash, frozen blueberries, Mediterranean apricots, creamy salad dressing, fresh pasta, vanilla ice cream, dry milk powder, and pasteurized skim milk.
Incubation:
Dairy (not including powders) & Seafood:
Incubate 3M Petrifilm Rapid Aerobic Count Plates 24 hours ± 2 hours at 32°C ± 1°C.
All other foods:
Incubate 3M Petrifilm Rapid Aerobic Count Plates 24 hours ± 2 hours at 35°C ± 1°C.
Dairy Powders including whey powders:
Incubate 3M Petrifilm Rapid Aerobic Count Plates 48 hours ± 3 hours at 32°C ± 1°C
. Gridlines are visible with the use of a backlight to assist with estimated enumeration. Estimates
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