Sigmoid Microbial Survival Curves

model

type I

type II

model parameters

a

1

1.

c

1

0.5

a

2

0.5

c

2

60.

axes limits

t

max

80.

lsr

min

-10.

This Demonstration simulates and plots static sigmoid survival curves for microbial cells or spores subjected to heat treatment or exposed to a lethal agent such as a chemical preservative or disinfectant, ultra-high hydrostatic pressure, radiation, etc. The generated survival curve is plotted in semilogarithmic (top) and linear (bottom) coordinates. The curve can be of type I, where the initial upper concavity, when plotted on semilogarithmic coordinates, progressively changes to downward concavity, or type II, where the initial downward concavity progressively changes to upper concavity (tailing).