why does peanut butter not need to be refrigerated after opening?


why does peanut butter not need to be refrigerated after opening?

In: Chemistry

depends on the peanutbutter, the one I tend to buy says it’s recommended to keep it refrigerated after opening

Low moisture levels and salty water.

Not enough water for most bacteria to live, and that little water available is too salty for those bacteria to live.

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.

It is due to the fact that Peanut Butter comes in a one serving container. Because of this there is no need to refrigerate it. I hope this answers your question.

What everyone else has said, plus sugar and salt.

Sugar and salt lower the pH of food and make it less hospitable to bacteria and pathogens. This is why a lot of northern cultures have salted beef or fish as traditional foods. Same goes for pickles — pickled and fermented foods as staples become scarce the farther south you go, because there’s no reason pickle a vegetable when it can grow fresh all year.

In the case of processed peanut butter: high sugar content, salt, and low hydration (water).