About salt tolerance

Q: On the web, we can find that salt tolerance limit of Clostridium perfringens is 6%, different from the 10% we used in the notes. How to judge?

A: You can always find different limits for  the parameters of a microbe. There are many factors affecting the reporting of the limits. The better way to deal with this is to use the least stringent one to assume the growth or survival of the microbe. For example, if you find 6-10% as the salt content limit for C. perfringens, take it that it can grow at 10% salt. You will have a good margin to be safe.

In the real world, you will need to do the experiment to determine the limits for your own target food and microbe.

The main effect of adding salt is to lower water activities. Low water activities will never kill all the microbes.