Comparison between dehydrated and freeze-dried foods

Many people take dehydration and freeze-drying as one thing. Actually, there is a big difference between them. Below is an explanation of the specific differences between these two food preservation technologies.
Dehydration process
Regardless of the food preservation method used, it is necessary to remove moisture. Dehydration is one of the commonly used methods. Dehydration is a food preservation method with a history of thousands of years, dating back to at least 12000 BC. The Romans and Middle Easterners once put fruits and vegetables in a house, and then baked and smoked them to make dry food.
Modern dehydration technology has become very simple, using machines to circulate hot and cold air through food. This can remove most of the moisture. The temperature is controlled at a level sufficient to remove moisture without cooking food. Dehydrated food withers and hardens.
Freeze drying process
Freeze drying is a relatively new modern preservation process. But it should be noted that without high-tech equipment, it is not possible to freeze dry at home. Some reports suggest that freeze-drying originated in the Inca Empire. But more reliable sources indicate that freeze-drying was invented during World War II and was used to preserve plasma, drugs, and later military food.
The freeze-drying process is relatively simple. The food is placed on a large shelf inside the vacuum chamber. The temperature drops below freezing point and gradually increases. The water in food changes from solid form to gas, thus maintaining the structure and nutritional value of the food.
Main differences
Moisture - The main goal of food preservation is to remove moisture, so food will not spoil or grow mold. Dehydration can remove 90-95% of water, while freeze-drying can remove 98099% of water. Dehydrating food at home usually leaves 10% humidity, but professional technology dehydrates thoroughly, so it can have a longer shelf life.
Shelf life - The moisture removal rate directly affects the shelf life. The shelf life of dehydrated foods such as dried fruits, vegetables, and powders is approximately 15-20 years; The shelf life of dehydrated foods such as honey, sugar, salt, hard wheat, and oats can be extended to over 30 years. On the other hand, frozen dehydrated foods have a longer shelf life, such as dried fruits and vegetables, which can be stored for 25-30 years.
Nutrients - According to research reports from US health institutions, freeze-drying preserves most vitamins and minerals. But compared to fresh fruits and vegetables, freeze-dried foods lack some vitamins, such as vitamin C, which decomposes quickly. Dehydration does not alter the fiber or iron content of food. However, dehydration can decompose vitamins and minerals during the preservation process, making it less nutritious than freeze-dried foods. Dehydration can easily cause the loss of vitamins A and C, niacin, riboflavin, and thiamine.
Appearance and Structure - One of the main differences between dehydrated and freeze-dried foods is appearance. Dehydrated food will become brittle and hard, while frozen dehydrated food will immediately become soft when placed in the mouth. Weight is another difference. The weight of freeze-dried food is much lighter than that of dehydrated food.
Cooking - Dehydrated foods need to be cooked before consumption. Many times, they also require seasoning. This means spending time boiling the product in hot water, cooling it down before consumption. Preparing dehydrated food takes between 15 minutes and 4 hours. However, freeze-dried food only requires boiling water. Add hot or cold water and wait for 5 minutes before eating.
Price - Overall, dehydrated foods are cheaper than cold dried foods. Freeze dried and dehydrated foods each have their own advantages and disadvantages, and if the budget is tight, dehydrated foods are clearly a better choice.