. A sample of \"Sams\' Hot-N-Spicy Salsa\" was received for microbiological anal
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Question
. A sample of "Sams' Hot-N-Spicy Salsa" was received for microbiological analysis. The salsa is fresh packed (no heat treatment) and sold under refrigerated conditions in local supermarkets. Sam would like you to determine the aerobic plate count of the salsa for him. You diluted 25 grams of the salsa in 225 ml sterile 0.1% peptone, blended the sample in a stomacher blender, and serially diluted the sample using 9 m dilution blanks. After spread plating the salsa using plate count agar the following counts were recorded: Dilution 10-1 10-2 10-3 10-4 10-5 10-6 Count TNTC TNTC 168 60 a. What is the aerobic plate count for the salsa sample in scientific notation? b. What is the aerobic plate count for the salsa sample in logarithmic form? c. What is the limit of detection (sensitivity) that this method could detect?Explanation / Answer
After counting the CFU we must express in CFU/ml. Also, we must consider the 10^-3 plate. The colonies obtained in the next dilution may not be statistically accurate.
So, for the question a. The aerobic plate count for the salsa sample in scientific notation is 168x10^3 CFU/mL.
For question b, we must use the formula log(cfu/mL).
The value of cfu/mL is 168x10^3.
Now we shall apply the formula
log(168x10^3)=0.1913
Answer to the question c: this method could detect as low as one colony in a given sample. Hence, it is highly sensitive.
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