why does peanut butter not need to be refrigerated after opening?
In: Chemistry
Microorganism needs water to grow and peanut butter contains only 2% water and that is not enough for them to survive. You can compare to if you let bred out to dry there will be no growth on it in a dry climate. Look at other dry products like rice, pasta, beef jerky, etc they do not need refrigeration.
Peanut butter is soft because it contains a lot of fat but other fart stuff like cooking oil is sored at room temperature with no problem. So you can have soft produce at room temperature if they have enough fat in the and almost no water.
What limits the shelf life is rancidification. That is when the fat gets oxidized by the oxygen in the air and the taste change. So an unopened jar might have a gas-tight layer on top and be filled with just nitrogen so it is last longer unopened. You can also add preservatives that reduce the rate it goes radical.
So the way peanut butter ger should do not involve any for if living organisms like bacteria or fungus. It is just a chemical reaction between the fat and oxygen in the air.
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