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1) Write the test date, sample number and dilution ratio on the top of the MC-Media Pad cover film.
2) Make a 10-fold diluted solution.
3) Add the 10-fold diluted solution to MC-Media Pad.
4) Make a 100-fold diluted solution and add it to MC-Media Pad.
5) Make a 1000-fold diluted solution and add it to MC-Media Pad.
6) Put this MC-Media Pad into incubator, incubate at the temperature and time specified for each product.
7) Take out the MC-Media Pad from incubator, count the number of colonies with interpretation for each product.
8) Culculate tne number of microorganisms in the food sample with counted colonies and dilution ratio. The unit is "cfu / g" or "pieces / g".
・10-fold dilution : Number of microorganisms = Counted colonies x 10
・100-fold dilution : Number of microorganisms = Counted colonies x 100
・1000-fold dilution : Number of microorganisms = Counted colonies x 1000
Notice)
MC-Media Pad CC, EC, SA, Salmonella may be colored on entire the pad for non-heated food inspection.
This is because enzyme in the food reacts chromogenic substrate for colony counting. In this case, pad will be colored in a short time (2-3 hours) from start of incubation.
If counting the colony is difficult, further dilution is recommeded to decrease the influence of food enzyme.
Appropriate dilution ratio is different by food, confirm appropriate dilution ratio for inspected food.
If the sample pH is signifiacantly low or high, accurate counting of microorganisms can be difficult for poor growth or coloring of microorganisms.
Add solution of sodium hydroxide or hrdrochloric acid, adjust sample pH to nuetral.
If the salt concentration of sample is high, accurate counting of microorganisms can be difficult for poor growth of microorganisms.
Further dilution is recommeded to decrease the salt concentration.
Dilution by culture medium does not occur in MC-Media Pad, unlike agar medium.
Be careful that MC-Media Pad is more sensitive to pH and salt concentration than agar medium.
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