Science, technology and consultancy services

Download thermal processing spread sheets

Technologists must be able to calculate the cumulate lethality of a heat process normally referred to as F. This is done by defining a reference temperature, e.g. 121.1 °C for a F0 calculation using a low acid food or e.g. 93.3 °C for an acid product, at which the equivalent lethal effects experienced during heating and cooling at lower temperatures are calculated.

The area under the lethality curve is normally calculated using numerical integration. The most commonly used method is the trapezium or trapezoid method. An alternative, more accurate, but slightly more complicated method, is to use Simpson's rule or to be more correct Simpson's rules.


Producing commercially sterile acid foods

Technologists producing acidic foods such as pickles and sauces often find it difficult to get information on the processing conditions required to obtain commercial sterility. Following experience of working with processors experiencing technical issues including spoilage problems and difficulties in exporting products I have produced a focussed and concise report (Thermal processing of acid fruit and vegetable products. Significant microorganisms, recommended processing time / temperatures, and public health significance of spoilage) that:


Calculator for determining the F value of a thermal process

The calculator converts temperature readings to lethal rates, plots the lethal rates against time, and determines F values for a heat process. The area under the curve is determined using the trapezoid rule. Accurate F determinations for most thermal processes can be obtained. In general the more values, the more accurate the value for F will be.


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