What is the best method for dehydrating garden-fresh food? Should you dry in the sun or in the oven? Use a dehydrator or try one of the new home freeze dryers?
Gardening and preserving the harvest go hand-in-hand. Once seedlings are lovingly coaxed into producing plants, our thoughts turn to preserving the bounty. While freezing extra food to use at a later time is probably the most familiar preserving method, and many of us can jars of fruit and veggies, drying food is the oldest, easiest, and least expensive preservation technique.
Bacteria, mold, and other pathogens that cause food spoilage are not very selective. They happily multiply anywhere the conditions are agreeable, which for them is someplace light, moist, and warm. Preserving outsmarts these busy creatures by making their lives very uncomfortable. Canning makes the environment inhospitable by adding acid or exerting too much pressure. Freezing puts pathogens in a state of suspended animation. Drying removes water that pathogens need to multiply, making food less likely to spoil. Pre-treating specific foods by either blanching or soaking in an acid bath before drying works to kill even more pathogens. Follow the dehydrating directions for the food you are drying and rest assured that your product will stay free from spoilage for a long time!
But there is more than one way to dry or dehydrate your food bounty. Which method should you use?
Drying food in the open-air, under sunny skies, is no doubt the oldest food preservation method. Spread sliced produce on screens and cover with cheesecloth. This protects the food from birds and insects. Place screens in full sun until food is dry. Also, some fruits and vegetables dry naturally while still on the vine, like dry beans or raisins.
Sun Drying Advantages
This oldest and easiest method requires no special equipment, and almost no work! Therefore, sun-drying is the least expensive way to preserve food.
Sun Drying Disadvantages
To safely sun dry food, the air temperature must be at least 90 degrees Fahrenheit with low humidity, throughout the entire drying period. Sun dry outside of these requirements and the food may spoil before it is dehydrated. Sun drying also sometimes takes a long time, leading to a lower quality product. Conversely, sun drying sometimes takes almost no time, leading to an over-dried product. This especially is an issue when drying herbs.
- Foods that dry on the vine, like dry beans
- Small, high acid fruits like blueberries
- Teaching children about food science and food preservation!
Drying in the oven can be an efficient way to preserve the harvest. Pre-treat food and spread it on a parchment lined cookie sheet. Set the oven to its lowest temperature, 130-150 degrees Fahrenheit, and prop the oven door open. Watch closely until dry. Microwave drying is appropriate for drying herbs.
Oven Drying Advantages
No extra equipment is necessary if you already have a cooking range! You don’t need to spent more money on equipment, and you don’t need to find room to store a food dehydrator. I find oven drying to be more convenient when drying small batches of food.
Oven Drying Disadvantages
If you are drying food during the summer, having the oven heating for hours, even at low temperatures, can quickly make the room too hot. Some ovens don’t have a very low temperature setting. Using any temperature above 150 degrees will cook your food instead of dehydrating it, adversely affecting food quality. If the food pieces are too thick, the outside may dry before the inside had dried, leading to spoilage.
- Small batches of vegetables
Food dehydrators are electric appliances. They have screens to hold whatever you are drying, a fan to continuously blow air, and a thermometer to regulate temperature. Food dehydrators come in both horizontal and vertical configurations.
Food Dehydrator Advantages
Most dehydrators maintain a consistent temperature throughout the drying period, which means the end product will be a higher quality. Dehydrators come in all shapes and sizes, so by shopping around you will find one that fits with your kitchen or storage space. They are fairly inexpensive, anywhere from $40-$200, and will last for decades.
Food Dehydrator Disadvantages
You have to purchase the dehydrator, and find a place to store it when not in use. I find food dehydrators to be a bit noisy, especially when running all day. Some people dry food overnight so they won’t notice the noise. I tend to move the dehydrator outside on the deck during the busy summer season. Dehydrators that have a vertical air flow will mix the flavors if you are drying more than one type of food at a time. Usually this isn’t a problem, for example I often will dry a tray of garden peas below a tray of green beans. But I only dry onions with other onions as I don’t want my peas to taste like onions!
- Most fruits and vegetables
- Most prepared meats and fish
Freeze drying works by freezing a product to the point that sublimation occurs; which is when the solid (ice crystals) bypass the liquid stage and go directly to the gas stage, leaving the solids behind. Freeze drying has long been the purview of commercial manufacturers, but smaller freeze dryers are now available for home preservers.
Freeze Drying Advantages
Freeze drying definitely leads to a high-quality product, with a fresh, vibrant flavor, and a crispy texture. Freeze dried foods also retain more nutrients than conventionally dehydrated foods. Freeze dried foods have a longer storage period, with some manufacturers claiming that the food remains fresh up to 25 years.
Freeze Drying Disadvantages
Although home freeze drying units are significantly less expensive than commercial units, they still cost between $2000-$5000 each. The cost is probably prohibitive unless you dry very large quantities of food each year, or are interested in starting a small manufacturing business. There are additional costs for needed accessories. The machines are heavy, weighing between 100-300 pounds, and need to be on an elevated platform to allow for drainage.
- Dehydrating large amounts of fruits or vegetables or meat
- Vegetables that don’t dry well in a dehydrator like cauliflower
- Starting your own small freeze-drying business
While most of the garden harvest can be safely dried with a home food dehydrator, there is a place for each dehydration method. If you live in an arid area, sun drying herbs and berries is a safe and expedient preservation method. Drying small amounts of vegetables in the oven can save time. Freeze drying will give you a tastier product, but the costs are certainly higher. Personally, I sun dry leaves from my basil plants, oven dry vegetable odds and ends when making soup mixes, and use my dehydrator almost non-stop during the harvest. I dream of one day owning a home freeze dryer!
More About Food Dehydrating
Also see these previous posts
How to Dry Vegetables in the Oven
Profitable Preserves – see how to start a small food business, apply the same principles to a freeze-dry business
Dehydrate Grapes and Make Succulent Raisins
Make Your Own Vegetable Powders