In the cold winter, Under 0 ℃. The clothes are washed and dry in the outdoor, it will soon be frozen, but after a period of time, the clothes will dry. This is because the moisture in the clothes has been frozen to the air. Freeze drying equipment is developed by using this principle.

    In the development of freeze drying equipment technology, the three major events completely changed the freeze drying technology, which has promoted the development of it.

    1. There are two college students named E.W. Flosdorf and S.Mudd Pennsylvania in the United States, they has successfully realized serum freeze drying by using glassware system in 1933.

    2. Penicillin was first discovered by A.Fleming in 1928. E.B.Chain, students at university of Oxford. He first realized that penicillin was stored by freezing and drying. Then he applied the technique of freezing dry penicillin to the clinical medicine of the Second World War with L．H．W．Florey.

    3. In order to store coffee, solve the problem of excess Brazil coffee. Nestle has invented the coffee freeze dry storage in 1938.

    These events greatly promoted the development of microbial research and food freezing drying technology.