Food dehydrators offer fast drying which results in the immediate removal of moisture, this in turn inhibits bacterial growth. Bacteria do not get enough time to multiply as with each passing minute they find worse conditions to grow (less moisture). Dehydrators are good for drying thinly sliced fruits and vegetables, small fruits like grapes or pitted plums and thinly sliced meat. Dehydration obviously is a more expensive method (electricity cost), however, it can be controlled and is independent of weather changes.
Dehydrators give us control over the drying process:
- Temperature – fully adjustable.
- Ventilation and removal of moisture – provided by a fan.
There is no humidity control in small dehydrators, most of drying is done inside of the house where high humidity is not present.
Home-food dehydrators fall into two categories:
- Those with stackable trays.
- Those constructed of a rigid box with removable shelves.
There are models with base-mounted fans that move hot air vertically; others have a rear-mounted fan for moving air horizontally. Some models rely on convection drying, with no fan at all.
What Dehydrator to Buy?
Look for the following features:
1. Temperature control. Get the unit that allows you to set temperature by degree, and not just low, medium or high setting. All dehydrators will dry vegetables and fruits, but if you want to dry jerky the unit must be capable of maintaining 160° F (72° C).
Do not relay on the dehydrator’s temperature setting. Get a dehydrator with temperature control. You can determine the true drying temperature of your dehydrator using a dial-stem thermometer, then compensate the dehydrator’s temperature control for any difference. Switch the dehydrator on to its maximum setting and record the temperature. For safely drying jerky at home, the dehydrator must be able to maintain the temperature of 155° F (68° C). Some dehydrators come with factory preset temperature that can’t be controlled and they cannot be adjusted.
2. The timer. Look for dehydrator with the timer, but keep in mind that the timer does not decide when the food is dried, this is your job. You may have moist apples and drier ones and the drying times will be different. You may have different foods on different trays and the drying times will be different. Different brand dehydrators dry foods in different time. A dehydrator is just a tool, you are the cook.
It does not matter whether dehydrator comes with a mechanical or digital controls, but you need a timer. Most dehydrators are not equipped with an On/Off switch.
3. The size. Nine tray dehydrator may look impressive, but do you have enough counter space for it? A smaller 4-tray Nesco dehydrator will fit everywhere and you can add more trays to it later.
4. Accessories. Make sure you can get non-sticks trays and mats for fruit roll-ups and finer mesh screens for small diameter items.
Stackable Trays Dehydrator
Nesco makes round and rectangular stackable tray dehydrators. FD-1040 Gardenmaster Digital Pro Food Dehydrator comes with the adjustable 90-160° F degree digital control. This four-tray unit can be expanded with accessory Add-A-Trays®, up to 20 trays (20 sq. ft.) Drying pressure adjusts automatically to the number of trays.
Power head unit sits on top of trays and contains controls, the heater and the fan. The fan blows hot air downwards and there is no possibility of liquids dripping into the heater chamber. Patented Converga-Flow® forces heated air down the exterior pressurized chamber, then horizontally across each individual tray, converging in the center, for fast, even and nutritious drying. No flavor mixing! No need for tray rotation.
Nesco FD-80 Square Dehydrator incorporates the standard design of Nesco dehydrators: the top mounted power head contains the heater and the fan. The hot air is forced horizontally across each individual tray, converging on the core for fast, even and nutritious drying. No flavor mixing and no need to rotate trays. FD-80 comes with 4 trays, but is expandable to 8 trays.
Some dehydrators, for example L'Equip 528, have the fan and the heater mounted in the base, and blow heated air up through the trays.
Stackable trays dehydrators may stack up to 30 inches tall, but they consume little counter space. They offer inexpensive way to get started with food dehydrating. Older models suffered from one limitation: the trays closest to the heater and fan dried much faster than those further away and the tray rotation was needed. Recent models provide equal air distribution in all areas and the trays do not need to be rotated.
Box and shelf dehydrators are made by different companies, Excalibur has been produced since 1973, so it the best known brand. It is, however, very expensive. In Excalibur, the heat source and fan at the back of the shelves instead of beneath them. Hot air blowing across the shelves eliminates the need for tray rotation, although the company advocates the tray reversal as the rear of the tray gets most of the heat.
Living Foods dehydrators do not have fans, but rely instead on convection drying. Heat, generated by a heating element mounted at the base of the box, rises through the trays. They provide silent operation and less use of electricity but the drying process is longer. If they are designed like a traditional smokehouse, they can operate on gas burner or even wood, however, it is advisable to have a separate heating chamber. This chamber can be connected to a drying box with a pipe, exactly like a smoke generator is connected to a smokehouse.
Need a Really Big Dehydrator?
If you need a very large-capacity dehydrator, you have to build one yourself. Check related books on Amazon and see our section on Building Smokehouses.
The smokehouse design principles can be directly applied to drying foods as meats are smoked below 140° F (60° C). You can smoke/dry meat jerky in a smokehouse, something that cannot be accomplish even in the most expensive dehydrators.