How Long Does Butter Last and Why Does Cheese and Butter Spoil Less Quickly Than Milk?

Butter spoils less quickly than milk because of the amount of free water or available water in the food.

The microbes involved in spoilage require water to live and multiply.

Milk has a huge amount of available water, 93 or 94 percent, and butter has much less, so bacteria, yeast and molds are less able to grow in butter.

Milk lasts a matter of days, butter a matter of weeks.

Dry cheeses like Romano last even longer than butter because the cheese-making process is in large part the removal of water from milk.

Some milk is ultra-pasteurized for a longer shelf life, meaning that it is treated at an ultra-high temperature to kill off the bacteria that lead to spoilage.

About Karen Hill

Karen Hill is a freelance writer, editor, and columnist. Born in New York, her work has appeared in the Examiner, Yahoo News, Buzzfeed, among others.

1 thought on “How Long Does Butter Last and Why Does Cheese and Butter Spoil Less Quickly Than Milk?”

  1. I have heard all my life that you are not supposed to leave mayonnaise out because it spoils so quickly. I read an article not long ago that’s just the opposite is true. So which is it?

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