Freeze drying is carried out in a state of low temperature and high oxygen deficiency, so microorganisms and enzymes do not work, and food is not oxidized. The color, aroma, taste, and nutritional components of food are minimally damaged, making it particularly suitable for drying extremely heat sensitive and easily oxidizable food. The flavor of banana products obtained by vacuum freeze-drying is better than that of hot air drying and microwave drying. According to reports [11], freeze-drying has no damage to protein in foods such as meat, eggs, beans, vegetables, and sweet corn. Vitamin C, beta carotene, and other water-soluble vitamins are only lost by 5%, while fat soluble vitamins such as VA and VD are not lost. Taking spinach [12] as an example, vitamin C can be retained by 93% after freeze-drying, while hot air drying can only retain 59%, shade drying can only retain 7%, and sun drying can retain even less, only 4%. Foreign research data shows that freeze-dried food stored for 1-2 years can replace fresh food in terms of nutrition.