Many people think of dehydration and freeze-drying as the same thing. They are not. They are very different from each other.
The following explains exactly what the differences are between these two food preservation techniques.
Regardless of the type of food preservation used, water needs to be removed. And dehydration is the most common of these methods.
Dehydration is a food preservation method that has been used for thousands of years, dating back to at least 12,000 BCE. The Romans and Middle Easterners used to put fruits and vegetables in a house and then roast and smoke them to make dry food.
Modern dehydration techniques have become simple, using machines to circulate hot and cold air through food. This removes most of the moisture. The temperature is controlled to a level sufficient to remove the moisture, but not to cook the food. The dehydrated food wilts and hardens.
Dehydrated food is food that has had most of its water content removed through a drying process, typically through the use of low-heat or air-drying techniques. This process makes the food lighter, more compact, and less perishable, which makes it an ideal option for long-term storage, camping, hiking, and emergency preparedness kits.
Dehydrated food can be made from a wide variety of fruits, vegetables, meats, and grains. Some common examples include dried fruits such as raisins and apricots, beef jerky, and powdered milk. Dehydrated foods can also be purchased in bulk or pre-packaged form for convenience.
Dehydrated food is best used in situations where fresh food is not readily available or where long-term storage is required.
For example, hikers and backpackers often rely on dehydrated food for sustenance during extended trips because it is lightweight and easy to carry. Similarly, individuals who live in areas prone to natural disasters may stockpile dehydrated food as part of their emergency preparedness plan.
Additionally, dehydrated food can be a convenient option for people who want to have a healthy snack on hand without having to worry about spoilage or refrigeration.
Freeze-drying is a relatively new modern preservation process. It was invented during World War II when it was used to preserve blood plasma, drugs, and later troop food.
The freeze-drying process is relatively simple. Food is placed on a large shelf in a vacuum chamber. The temperature is lowered to below freezing and then gradually increased. The water in the food is converted from a solid form to a gas, thus preserving the structure and nutritional value of the food.
Freeze-dried food is a type of food that has been dehydrated using a process called lyophilization. This process involves freezing the food and then placing it in a vacuum chamber where the ice crystals are sublimated, meaning they go directly from a solid to a gas state, without passing through the liquid phase. This results in a dry and lightweight product with a longer shelf life than traditional dehydrated food.
Freeze-dried food is a popular choice for camping, backpacking, and emergency preparedness, as it is lightweight, easy to transport, and has a long shelf life.
It is also commonly used by astronauts and space agencies as it is an efficient way to provide food for space missions.
Freeze-dried food can be made from a wide variety of ingredients, including fruits, vegetables, meats, and even full meals. Some common examples include freeze-dried fruit snacks, instant coffee, and freeze-dried entrees such as pasta dishes or soups.
Freeze-dried food is best used in situations where long-term storage and portability are important factors. It can be particularly useful for people who enjoy outdoor activities such as hiking, camping, or backpacking, as it is easy to carry and prepare.
It is also a popular choice for emergency preparedness, as it can be stored for long periods without spoiling and can provide a quick and easy source of nutrition in the event of a natural disaster or other emergencies.
Difference Between Freeze-Dried and Dehydrated
The main goal of food preservation is to remove water so that food does not spoil and grow mold. Dehydration removes 90-95% of the water, while freeze-drying removes 98099% of the water.
Dehydrating food yourself at home usually leaves 10% moisture, but professional techniques dehydrate more thoroughly and therefore provide a longer shelf life.
Moisture removal rate directly affects shelf life. Dehydrated foods such as dried fruits, vegetables, and powders have a shelf life of approximately 15-20 years; dehydrated foods such as honey, sugar, salt, durum wheat, and oats have a shelf life that can extend to 30+ years. On the other hand, frozen dehydrated foods have a much longer shelf life, such as dried fruits and vegetables can last 25-30 years.
Freeze drying retains most vitamins and minerals, according to a study by the American Institutes of Health. However, compared to fresh fruits and vegetables, freeze-dried foods lack some vitamins, such as vitamin C, which breaks down more quickly.
Dehydration does not alter food fiber or iron content. However, dehydration breaks down vitamins and minerals during the preservation process, so the nutritional value is not as good as freeze-dried foods. Dehydration tends to cause loss of vitamins A and C, niacin, riboflavin, and thiamin.
Appearance and Structure
One of the main differences between dehydrated and freeze-dried foods is their appearance. Dehydrated foods become crisp and hard, while freeze-dehydrated foods soften immediately in the mouth.
Weight is another difference. Freeze-dried foods weigh much less than dehydrated foods.
Dehydrated foods need to be cooked and eaten. Many times, they also need to be seasoned. This means taking the time to cook the product in hot water, cooling it, and then serving it. It takes between 15 minutes and 4 hours to prepare dehydrated foods. Freeze-dried foods, however, only require boiling water. Add hot or cold water and wait a minimum of 5 minutes before eating.
Overall, dehydrated foods are cheaper than cold-dried foods. There are pros and cons to both freeze-dried and dehydrated foods, and if you are on a tight budget, dehydrated foods are the better choice.