Come Up Time For Retort Calculator

Work out come up time for retort instantly with clear inputs, formula shown and shareable results.

About Come Up Time For Retort Calculator

In the straight-line portion of a heat penetration curve, time is fh x log10(g0/g), where g is the difference between retort and product temperature. The heating rate index fh is the time for that difference to fall by a factor of ten and is determined experimentally for each container size and product.

Formula

Heat penetration

Time = fh x log10((T_retort - T_initial) / (T_retort - T_product))

Worked example

With the default values below, Come Up Time For Retort Calculator returns Come-Up Time of 20.346. Change any input above and every figure here is recalculated in your browser.

Inputs used

Retort Operating Temperatureminimum 20 degrees C: 121 degrees C
Initial Product Temperatureminimum -20 degrees C: 40 degrees C
Heating Rate Index fhminimum 0 minutes: 18 minutes
Product Temperature To Reachminimum 0 degrees C: 115 degrees C

Results

Come-Up Time: 20.346
Initial Temperature Deficit: 81.00
Final Temperature Deficit: 6.000
Assumed Lag Factor: 1.050

Step by step

1Values used
2Heat penetration
3Come-Up Time= 20.346
4Initial Temperature Deficit= 81.00
5Final Temperature Deficit= 6.000
6Assumed Lag Factor= 1.050

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Retort process schedules must be established from measured heat penetration data at the slowest heating point by a recognised process authority.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Retort process schedules must be established from measured heat penetration data at the slowest heating point by a recognised process authority.

Frequently Asked Questions

Why does the last few degrees take so long?

The driving temperature difference shrinks as the product approaches retort temperature, so the approach is asymptotic. Reaching within 1 degree takes as long again as reaching within 10.

Is come-up lethality credited?

Yes, and it can be significant at retort temperatures. Full process design integrates lethality from the start of heating, which is why measured heat penetration data is required.