The Allure of Freeze Dryers and Dehydrators
Preserving food at home is a cost-effective way to extend food shelf life, reduce food waste and make versatile snacks for the whole family. A freeze dryer and a food dehydrator use different approaches to preserve a variety of foods. We’ll give you the rundown on both to help you decide which appliance is best for you.
What Is a Freeze Dryer?
A freeze dryer is an appliance that preserves food by first freezing it and then removing water using warm circulating air. Without moisture, bacteria and mold cannot build up and the food can safely be stored with proper packaging.
Freeze-dried foods absorb moisture faster which allows them to rehydrate quickly.
How Does a Freeze Dryer Work?
Freeze dryers freeze food at a temperature of about -40 degrees Fahrenheit to lock in the food’s structure, flavor and nutrients before moisture is removed. Once frozen, the food is sealed inside the chamber, the air is pumped out and a low-pressure environment is created. As the trays gradually warm with the food still frozen, a process called sublimation takes place which extracts water from the food. This process preserves the food's original flavor and nutritional value.
Freeze drying food takes from 24 to 48 hours or more; however, this depends on the food, moisture content, whether the food is pre-frozen, as well as the food’s size and thickness. Sensors in the freeze dryer determine when the food is completely dry and the freeze dryer alerts you with a beep once the process is complete.
Once the food is freeze dried, you can immediately place it in mylar bags or mason jars for storage, along with an oxygen absorber package to protect against moisture and oxygen. When properly sealed and stored, freeze dried food has a shelf life of up to 25 years.
What Is a Food Dehydrator?
A food dehydrator is an appliance that removes moisture from food by applying low heat (85 to 160 degrees Fahrenheit) over an extended period, causing the moisture to evaporate.
Dehydrated food has a shortened lifespan in humid temperatures.
How Does a Dehydrator Work?
A food dehydrator contains a heating element and fan that evenly circulates air at very low temperatures around the food on trays. As it does so, it removes moisture and slows the growth of bacteria and mold while drawing water out in the form of vapor. The dehydrator then vents the humid air outside of the unit.
The temperature and timing required for dehydration both vary depending on the type of food being dehydrated. The dehydrating process can take 8 - 20 hours, or depending on the thickness and moisture content of the food, several days. Dehydrating produces a chewy or crunchy texture depending on how much moisture is removed. The food loses its original taste and the nutritional elements are reduced.
Dehydrated food can last for a few months up to a year.
Features of a Freeze Dryer vs a Dehydrator
When considering a freeze dryer or dehydrator, these are a few key features you may want to consider.
Size
Freeze dryers are mostly large, heavy units. They require a refrigeration system, a powerful vacuum pump and a sealed drying chamber. Even some of the smaller home units are about the size of a mini-fridge and can weigh up to 150 pounds. They would be best placed in a garage or basement.
Dehydrators are lightweight appliances that don’t take up much space. They’re compact enough to fit on the kitchen countertop. Sizes range from small (about the size of a toaster) to large (about the size of a small microwave).
Food Shelf Life
Freeze drying food removes up to 95 to 99 percent of water from food, resulting in preserved food which can last for 25 years or more. Dehydrators remove 80 to 95 percent moisture from food, with a shelf life of several months to a year.
Affordability
A residential freeze dryer cost ranges from $2,000 to $5,000 or more. The operating costs are higher than that for a dehydrator because a cycle takes 20 to 40 hours to complete, using more electricity. Some models use an oil pump; the vacuum pump, seals and filters all require maintenance.
A dehydrator is a better choice for those who are more cost conscious. A basic dehydrator costs $40 to $100, with a high-end professional model costing $400 - $700 or more. Dehydrators have much lower energy usage and maintenance is minimal.
Food Texture
While freeze-dried food retains its original shape, its texture becomes porous or sponge-like. It’s crispy and easy to crumble when squeezed. Once rehydrated, the food becomes close to its original texture prior to dehydrating. Not all dehydrated food needs to be rehydrated. Some foods can be eaten as snacks, like vegetable chips. Dehydrated foods can also be added directly to stews, soups and other simmering liquids and the food will naturally rehydrate during the cooking process.
Dehydrated food tends to be chewy or leathery, like a fruit rollup or jerky (right), when much of the water content is removed. The food also becomes denser, wrinkled and more concentrated. The heat-based drying process usually leaves about 10 to 15 percent of the original moisture content, which results in a tougher texture.
Types of Food Preserved in a Freeze Dryer
A freeze dryer can freeze a variety of foods like:
- Strawberries
- Bananas
- Blueberries
- Apples
- Green beans
- Corn
- Broccoli
- Cabbage
- Leafy greens (spinach, kale, etc.)
- Root vegetables (carrots, potatoes, etc.)
- Meats (boneless)
- Eggs (scrambled or raw)
Foods Not Suitable for a Freeze Dryer
While many foods will benefit from going in the freeze dryer, there are some that, for one reason or another, don’t:
- Foods with a high-water content (lettuce, cucumber, watermelon, etc.)
- Foods with high fat content (butter, oil, nut butters, pure chocolate, etc.)
- Foods with high sugar content (jams, jellies, etc.)
- Foods with very soft consistencies (mayo, pudding, etc.)
- Fatty meats (sausage, bacon, etc.) - can become rancid)
- Foods with bones (pork chops, steak, etc.)
- Some baked goods (bread, muffins, etc.)
- Alcoholic beverages
Types of Food Preserved in a Dehydrator
Dehydrators preserve a variety of foods, including:
- Bananas
- Apples
- Strawberries
- Mushrooms
- Herbs
- Meats (boneless, for jerky)
- Leafy greens (spinach, kale, etc.)
- Root vegetables (turnips, beets, etc.)
- Tomatoes
- Peppers
Foods Not Suitable for a Dehydrator
Dehydrators are great for preserving a variety of foods, but there are certain foods that don’t do well in them. Here are some examples:
- Most dairy products (milk, cream, butter, soft cheeses, etc.)
- Very watery fruits and vegetables (watermelon, cucumber, lettuce, etc.)
- Foods with high fat content (nut butters, bacon, avocados, etc.)
- Foods with high sugar content (jellies, jams, honey, etc.)
- Eggs (raw or improperly cooked)
- Foods with strong odors (onions, garlic, etc.)
A Freeze Dryer or a Dehydrator: The Choice is Yours
A freeze dryer and a dehydrator both preserve foods but in different ways. A freeze dryer removes moisture though sublimation, preserving both flavor and moisture. It’s ideal if you want long-term food storage with food lasting up to 25 years with proper storage. Freeze dryers are costly, ranging from $2,000 to $5,000 or more.
A dehydrator removes moisture from food using low heat, giving the food a chewy texture. Unlike a freeze dryer, dehydrated food will typically last up to a year. Dehydrators are more affordable at $40 to $700 or more.
Your choice between a freeze dryer and a food dehydrator depends on your preservation needs, budget, available space and the types of foods you plan to store. Still undecided? Head to your local Lowe’s and a friendly Lowe's Red Vest associate will be happy to talk with you about each appliance.