The high temperatures of canning, cooking, and pasteurizing microbes, and the low temperatures of freezing and refrigeration microbes.

Hey! I’m probably way too excited to answer this question, but who cares. I think bacteria is so cool.

This is a very important piece of food safety! High temperatures KILL microbes. The whole process creates an environment that makes it very difficult for bacteria/microorganisms to grow. Milk straight out of the cow contains a lot of bacteria that can be harmful, and this is why the process of pasteurization is really important. Raw milk can cause food-borne illness with listeria monocytogenes, which can pose a serious health risk, causing serious infections that can lead to deadly illnesses like meningitis. Pasteurization increases the shelf life and creates a clean product that won’t cause sickness in consumers.

Low temperatures will not only keep the food from spoiling and allow us to save leftover food, but also slow microbial growth. There are lots of things to take into consideration for safely cooling and storing food. Food should not be left out for an extended period of time at room temperature before it is refrigerated or freezes. This can greatly increase the risk for harmful microorganisms to grow, thus increasing the risk for food-borne illness.

Hopefully this does a little more than answer your question. It’s so important to understand why we use these two methods.