Having established a method of describing microbial death rates it is
necessary to find a way of characterizing a sterilization process so that its
effectiveness for any given application can be judged. Because a range of
temperature/time combinations can be used to achieve the same reduction in
population of a given micro-organism, different sterilization processes can be
compared using a quantity known as total process lethality, F, which represents
the total temperature/time combination to which a food is subjected. Less
commonly this is called thermal death time.