The intricate microflora in a food product is generally influenced by its extrinsic environmental conditions (i.e., temperature, relative humidity, etc.) and intrinsic composition of food (i.e., water activity, pH, etc.).
Extrinsic factors refer to factors that do not make up the food itself. These factors refer to temperature, relative humidity, and the gaseous environment. They are also related to the food processing procedures and storage conditions. More often than not, these are the conditions that we have a direct control over.
The first extrinsic factor that we will be looking into would be temperature. When environmental temperature increases, the enzyme efficiency of the microbe increases, and this allows microbes to grow faster.
Now what are enzymes? Enzymes are a class of proteins that are responsible for speeding up biochemical reactions in our cells. The faster the biochemical reactions within the microbe, the higher the microbial growth rate.
However after reaching a certain temperature, enzymes will begin to denature (not function), causing a decline in microbial growth.