GIFSQ Tools · Module 17 — Food Processing, Thermal Engineering & Utilities · Tool 324 of 500
Analyse a heat-penetration run with the Ball formula method: work out the cold-point temperature at any time from fh and jh, and the time needed to reach a target cold-point temperature.
Try sample values — fills the form with the worked example below.
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Cold-point temp (°C)
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g value (°C)
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Time to target (min)
Equation: Cold-point temperature T = Tr − jh × (Tr − Ti) × 10^( −t / fh); g = Tr − T; time to target = fh × log10(jh × (Tr − Ti) / (Tr − Ttarget)).
Method: Ball formula method for heat penetration (Ball and Olson), as used for scheduled-process work under FDA 21 CFR 113; fh is minutes per log cycle, jh the heating lag factor.
Assumptions: log-linear heating after the lag period; constant retort temperature; fh and jh come from a fitted heat-penetration curve for this product and container.
Limitations: the Ball formula does not describe the early lag period well and must not be extrapolated far beyond the measured data; broken-heating curves need the full Ball treatment.
Rounding: temperatures and times to 2 decimal places; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value. A calculated lethality is an estimate only — a scheduled process must be established by a qualified process authority; never present this calculation as a validated process.
Method: Ball formula method for heat penetration (Ball and Olson), as used for scheduled-process work under FDA 21 CFR 113; fh is minutes per log cycle, jh the heating lag factor.
Assumptions: log-linear heating after the lag period; constant retort temperature; fh and jh come from a fitted heat-penetration curve for this product and container.
Limitations: the Ball formula does not describe the early lag period well and must not be extrapolated far beyond the measured data; broken-heating curves need the full Ball treatment.
Rounding: temperatures and times to 2 decimal places; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value. A calculated lethality is an estimate only — a scheduled process must be established by a qualified process authority; never present this calculation as a validated process.
Worked example: fh = 40 min, jh = 1.5, retort 121.1 °C, initial 25 °C, 60 min: cold point = 116.54 °C, g = 4.56 °C, time to 115 °C = 54.94 min.
Enter values above to see results.
fh and jh come from plotting log(Tr − T) against time from a real heat-penetration run — never guess them. Tool 324 of 500 — GIFSQ
