Why is butter hard, and what is the solution?

Butter is a mixture of fat and water emulsions, with a fat content of about 80% and a water content of about 15-20%. When butter is at room temperature, the fat molecules are fluid and mobile, which makes the butter soft and easy to spread.

However, when it is placed in the fridge, the cold temperature solidifies the fat molecules, which hardens the butter. This solidification occurs because the fat molecules move closer together, which increases their order and crystalline structure. This leads to a firmer texture and a decrease in the butter's fluidity.

In general, solidification of butter in the fridge is desirable because it keeps it longer and maintains its freshness. However, if you want to soften butter quickly, you can leave it at room temperature for a short time or use a technique such as flattening it with a rolling pin to soften it, but the simplest for personal use is the Butter Cow, which turns this butter into little strands that are easy to spread.