GIFSQ Tools · Module 3 — Food Microbiology & Enumeration · Tool 059 of 500
Judge a microbial result against a three-class specification: pass, marginal or fail against limits m and M.
Try sample values — fills the form with the worked example below.
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log₁₀ result
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Result ÷ m
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Verdict
Equation: log₁₀ result = log₁₀(result); ratio = result ÷ m; verdict: pass if result ≤ m, marginal if m < result ≤ M, fail if result > M.
Method: Three-class attribute sampling plan (n, c, m, M) per ICMSF Sampling for Microbiological Analysis and ISO 4833-1:2013 enumeration; m and M are the limits in the product specification.
Assumptions: The result is a single representative count and m and M are the specification limits for that organism and product.
Limitations: A single result cannot judge a lot — the full n, c plan decides acceptance. A marginal result still needs the remaining samples before any release decision.
Rounding: log₁₀ to 3 decimal places; ratio to 2 decimal places; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: Three-class attribute sampling plan (n, c, m, M) per ICMSF Sampling for Microbiological Analysis and ISO 4833-1:2013 enumeration; m and M are the limits in the product specification.
Assumptions: The result is a single representative count and m and M are the specification limits for that organism and product.
Limitations: A single result cannot judge a lot — the full n, c plan decides acceptance. A marginal result still needs the remaining samples before any release decision.
Rounding: log₁₀ to 3 decimal places; ratio to 2 decimal places; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: Aerobic plate count 500 CFU/g against m = 1,000 and M = 10,000: log₁₀ = 2.699, ratio 0.50 — pass. At 5,000 CFU/g the same limits give a marginal result.
Enter values above to see results.
One result is not a lot decision — apply the full n, c sampling plan before releasing or rejecting. Tool 059 of 500 — GIFSQ
