A method of pre-freezing hydrated materials and then drying them under vacuum through sublimation. Vacuum Freeze Drying technology, commonly known as lyophilization, or sublimation drying. Items dried by freeze drying retain their original biological and chemical properties largely unchanged, are easy to store long-term, and can revert to their pre-freeze dried form when water is added, while maintaining their original biochemical characteristics. Large-scale food lyophilizers are aesthetically pleasing, designed ergonomically, and easy to operate. Equipped with an original imported fully enclosed compressor, it features low noise. The cold trap has a large opening and includes a sample pre-freezing function. The cold trap is made of full stainless steel with no coils inside, ensuring smoothness and corrosion resistance. The stainless steel sample rack allows adjustable spacing between sample dishes.