GIFSQ Tools · Module 3 — Food Microbiology & Enumeration · Tool 051 of 500
Plot a four-phase microbial growth curve from a starting count, growth rate and lag time, and read the count, phase and doublings at any time.
Try sample values — fills the form with the worked example below.
—
log₁₀ count at plotted time
—
Count at plotted time
—
Doublings completed
| Time (h) | Phase | log₁₀ count | Count |
|---|
Equation: log₁₀ N(t) = log₁₀ N₀ for t ≤ lag; log₁₀ N₀ + (μ / ln 10) × (t − lag) in the log phase, capped at the stationary maximum; doublings = (log₁₀ N − log₁₀ N₀) / log₁₀ 2.
Method: Exponential growth model in the log phase, as used with FDA BAM Chapter 3 aerobic plate count data and ISO 4833-1:2013 enumeration; lag and stationary phases follow the standard four-phase growth curve.
Assumptions: Growth is exponential at a constant μ through the log phase, with a sharp lag-to-log change and a flat stationary cap.
Limitations: Real curves bend at the transitions and μ changes with temperature, pH and food matrix; this plotter does not model death phase or nutrient depletion.
Rounding: log₁₀ count to 3 decimal places; counts shown in scientific notation; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: Exponential growth model in the log phase, as used with FDA BAM Chapter 3 aerobic plate count data and ISO 4833-1:2013 enumeration; lag and stationary phases follow the standard four-phase growth curve.
Assumptions: Growth is exponential at a constant μ through the log phase, with a sharp lag-to-log change and a flat stationary cap.
Limitations: Real curves bend at the transitions and μ changes with temperature, pH and food matrix; this plotter does not model death phase or nutrient depletion.
Rounding: log₁₀ count to 3 decimal places; counts shown in scientific notation; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: A culture starts at 1,000 CFU/mL, μ = 1.386 /h, lag 1 h, cap log₁₀ 9. At 3 h: log₁₀ N = 3 + (1.386 / 2.303) × 2 = 4.204, N ≈ 1.60 × 10⁴ CFU/mL, 4.00 doublings, log phase.
Enter values above to see results.
Use log-phase points only when estimating μ from real counts — lag and stationary points bend the curve. Tool 051 of 500 — GIFSQ
