Butter frozen for one year is inedible and has expired. Expired butter will breed harmful bacteria, which is not good for human body, and expired butter will lose nutrition, produce odor and be inedible.

Butter is made of milk, which is the product of filtering out some water from the thick substance on the upper layer after the fresh milk is stirred. Mainly used as seasoning, rich in nutrition but high in fat, don't overdo it.

In the 5th century BC, the Mongolians in China had already matured and spread various dairy production technologies at home and abroad because they were mainly engaged in animal husbandry. What foreigners call butter is edible oil extracted from milk called cream in China. Mongolians are the first people in the world to process edible butter.