Interpretation and analysis: ham coated with paraffin or grease can be preserved for a long time, which is the concrete application of the principle of isolating air. The method of sealing raw materials in a certain container to isolate sunlight and air to prevent raw materials from being polluted and oxidized.

This method can keep raw materials such as canned food from deteriorating for a long time. Some raw materials, such as aged wine, pickles, etc. Can be sealed for a certain period of time, which can also make the taste better. Also, put bean paste and soy sauce into a bottle and inject a little sesame oil, so that mold will not grow easily; Ham coated with paraffin or grease can be preserved for a long time, which is the concrete application of the principle of isolating air.

Related methods: food preservation.

The traditional concept of food preservation is that salt is called curing (such as pickles and bacon), and the amount of salt is small. The basic principle of food preservation by salting, dry salting or wet salting is to use a series of biochemical functions such as high salt permeability, microbial fermentation and protein decomposition to inhibit the activities of harmful microorganisms and increase the color and flavor of products. Its changing process is complex and slow.