Fruit and vegetable crisps are primarily processed using two techniques: Freeze Drying (FD) and Vacuum Frying (VF).

1. Introduction to the Two Technologies

Vacuum Frying (VF)
Currently, most domestic manufacturers use this method. By maintaining a vacuum environment and controlling oil temperatures between 90–120°C, the process is quick, preserving the original flavor and most nutrients of the fruits and vegetables.

Compared to traditional deep-frying, VF prevents charring, retains color better, and avoids producing toxic fat polymers. The crisps are delightfully crunchy, making them a popular choice.

While VF crisps still contain over 10% oil, this is significantly lower than conventional fried foods (e.g., French fries, which contain around 30% oil and are high in salt and fat).

Freeze Drying (FD)
This method dehydrates food through low-temperature freezing, a technology that originated in the early 20th century and is hailed as the food processing technology of the 21st century.

During WWII, FD was used to dehydrate blood plasma, making it lightweight and portable—just add saline to reactivate the cells. Post-war, FD expanded into medicine, biology, aerospace, and aviation.

• 1960s: The U.S. adopted FD for astronaut food.
• 1970s: Japan refined American FD technology, advancing its industrial applications in food processing.
• China: Began using FD for vaccines before 1949, with rapid post-liberation development. By 1952, it was applied in veterinary medicine, and large-scale FD machines were manufactured nationwide.

FD Principle
Water exists in three states: solid, liquid, and gas. At <0°C and 646.6 Pa pressure, ice sublimates directly into vapor. FD food uses this principle—pre-frozen materials are placed in a vacuum chamber, where radiant heating removes moisture.

FD Advantages

• Preserves 96%+ of nutrients and heat-sensitive compounds.
• Retains natural aromas on the food surface.
• Considered the gold standard in food processing.

2. Cost Comparison

• VF is cheaper to produce than FD.
• Most VF manufacturers lack FD equipment.

How to Tell Them Apart?

• VF crisps: Crush into small pieces when pinched.
• FD crisps: Turn into powder when crushed.

四、那么，这两种技术的产品该如何选择？

1. 两种产品的优劣势非常明显，真空低温油浴干燥VF价格低，但是还有含油量；真空冷冻干燥FD更加健康甚至超越原味，但是价格稍贵。
2. 对健康追求甚高的健身、高品质追求等人士，婴幼儿等，可以选择口感好且营养成分保留较高的真空冷冻干燥FD产品。
3. 对于追求更健康的零食人群，真空低温油浴干燥VF是一个不错的选择，果蔬脆可一定程度上补足人体所需的膳食纤维，而且相较薯条等更加健康。无多余添加剂的果蔬脆，较市面上很多的零食都是更健康美味的。