Food Dehydration Methods

Perhaps the Oldest Food Preservation Technique and One That We Should Understand as Another Step Towards Self-Reliance.

It’s impossible to establish how food dehydration emerged as a food preservation process but it’s a good bet we have the sun to thank for it.  To this day, primitive cultures continue to sun-dry meats and fish on racks in the sun to preserve them for future use. 

Fruits and vegetables were also dried and raisins, prunes and many of the herbs we use to this day are the result.  The various approaches are easy to do and range from free to inexpensive.  That’s a pretty good range in anybody’s book.

Why Dry?

The enemy of food stored for any length of time is bacterial and fungal growth.  Both can make you sick and in the case of food borne illnesses like E. coli, Salmonella, Listeria and Botulism -kill you.  But to understand the benefits of drying foods it’s important to consider the needs of any microbe to survive, thrive and multiply.  Here’s a short list of what any bacterium or fungus needs to make your life miserable:

  1. An organic medium like the muscle of meat and fish, blood, organs, tissue, or fruit and vegetable pulp -germs and fungus aren’t fussy.
  2. Temperatures above freezing and below the boiling point of water.  In fact, some germs like Botulism microbes can even survive the boiling point of water at 212° F.  It takes a temperature of at least 250° F. to knock out the botulism bug.  Assuming they have a moist environment.
  3. Moisture is the condition that really puts microbes and fungus into their comfort zone.  If they have access to a food source like an organic medium, the proper temperature range, and moisture they’re going to be tough to beat.   And that’s where drying comes into play.

Drying foods removes the moisture bacteria and fungi need to survive and reproduce.  Without moisture the other factors like temperature and an organic medium aren’t enough to create the best environment for microbial and fungal growth.  That’s why food drying works as a preservative process.

Food Dehydration Techniques in a Nutshell

Sun Drying

Native Peoples are often seen in photographs and documentaries carefully drying racks of salmon and strips of meat on racks in the sun.  It’s not the best approach from a food safety standpoint given the easy access to the food for insects and airborne pathogens, but to many cultures the risk is outweighed by the need. 

Sun drying can be done safely if the food is enclosed behind glass to protect it from outside invaders like germs and bugs, but there’s still a question of bacterial growth internally in the muscle of any meat or seafood.  Foods can also be dried indoors next to a window with steady exposure to the sun.

Indoor Sun-Dried by Window

The addition of salt as a dry-cure applied externally, as a brine or marinade, or an injected wet-cure can lessen the growth of harmful bacteria.  Klippfisk is a Norwegian example of dried Cod that is highly salted and was traditionally sun dried on cliffs.  Klippfisk actually translates as “Cliff-fish.” The resulting Cliff-fish is then soaked in water to remove the salt, and the Cod is then cooked by conventional means.  To some people it tastes horrible but if it’s all you have to eat, you get used to it.

While it’s quaint and a bit curious to think about sun-drying for food preservation there are better and safer techniques.  The one exception may be fruits like grapes and plums that seem to do quite well with sun drying before they turn into raisins and prunes.  In fact, very moist fruits like whole grapes, plums and cranberries don’t dehydrate well in a traditional dehydrator.  Crushing them halfway through the process helps, but it takes a convection dehydrator with a constant and hot air-flow to dry most large, moist whole fruits. 

Air Drying

This is another ancient technique.  The only difference between air drying and sun drying is that air drying is intentionally done in a place without sunshine.  Caves were often used for this purpose and the cool air helped to keep any food relatively stable while it slowly dried. 

Perhaps the most well- known, air-dried product still consumed today is the Italian Parma Ham.  The whole hams are injection cured and dry cured and hung high in open-air towers out of direct sunlight where the Mediterranean breezes slowly dry-age the hams.  Everything about the process is strictly monitored to ensure food safety and the high concentrations of salt in the cures is a critical step to inhibit the growth of bacteria. 

Open Coal Drying

A precursor to smoke cooking but this approach did not enclose the meat or fish in an area filled with smoke.  Instead, the meat or fish were suspended over an open bed of hot coals.  The heat was more of a suggestion and the scant amount of smoke and heat probably did a good job of keeping the flies away.  

Open coals on outdoor grill

It was a long, slow process and open flames were discouraged to keep the heat low.  For those of you who like to cook low and slow you can thank the people who pioneered this method for the first time.  This approach to drying also had the advantage of partially cooking the meat or fish which worked well to further inhibit the growth of bacteria. 

Oven Drying

The first choice of large, corporate food manufacturers.  Oven drying offers the highest degree of food safety because all of the factors affecting effective drying can be carefully managed and monitored and controlled from moisture content to time and temperature. 

Toaster oven

An oven at home can offer the same degree of control and is a low-impact, low-cost and low-mess way to dry fish and game, and to some degree -fruits and vegetables.  The primary drawback is that even the lowest oven temperature can be too high for some fruits and vegetables.  You want your vegetables dried, not cooked and oven drying can make more delicate foods hard to effectively dry to a desired result.  Regardless, an oven can make quick work of drying meat or fish successfully.  The result is often referred to as “jerky.”

Food Dehydrators

Food Dehydrator

Food dehydrators are the most expensive option, but some food dehydrators fall into a price range that make some of the more basic dehydrators affordable.  How much you choose to invest depends on the amount and quantity of foods you want to dry, and your frequency of use. 

Benefits of Do-It-Yourself Food Dehydration

Avoids Food Waste

We don’t do it on purpose, but in spite of our best efforts we often waste food.  Harvest time often presents a cornucopia of choices, and how many times have we had to clean out the crisper in the fridge to get rid of some soft or rotting fruits or vegetables that we never got around to eating.

Fish, game and store-bought meats often find their way into the freezer and never leave until we notice freezer burn, discoloration or the sneaking suspicion it’s been in there too long.

It’s easy to overstock fresh foods on some fronts especially when we have a food-storing and stocking mentality.  Food Dehydration can avoid most waste and give any food a second chance before it hits the trash.  That’s a money saver and that’s a second benefit of food dehydration.

Money-Saver

Small bottles of herbs can show up on grocery store shelves with jaw-drop prices.  This is especially true for obscure herbs that we don’t use that often.  Food dehydration can solve that problem when you grow the herbs you think you’ll want to use in recipes and dehydrate them yourself. Many herbs are highly decorative plants and can easily be substituted in landscaping or grown in a dedicated herb garden.

Even if your primary objective is not cost-savings, anyone with an herb garden dreads the day that the first frosts and hard freeze wipe out the herbs for the winter.  Food dehydration lets you harvest and keep those herbs all year long.

dehydrator tray with fresh oregano

Dehydration also lets you make many of the other products you buy.  A package of beef jerky always seems a bit expensive.  This is mostly due to the fact that the total weight of the meat reduces significantly during the drying process. 

Beef Ready for Dehydration

But you’re still paying for all of the costs associated with manufacturing, packaging, distributing and marketing those products.  Making it yourself in a food dehydrator keeps some money in the bank.

Emergency Food Storage

Emergency food storage

It’s unlikely that you’ll be able to beat the 10, 20 and 30-year shelf-lives of many commercially manufactured foods for long-term food storage, but you may come close with some simple fruits and vegetables.  A food dehydrator is your best bet.  We’ll get into specific detail on how to dehydrate a variety of foods yourself using a food dehydrator, and how to package and store them. 

dehydrator stacked up and ready to go

You may also want to consider food dehydration as a regular activity.  In that case, very long shelf-lives measured in decades aren’t as much a factor as long as you eat what you store and store what you eat. 

Anatomy of a Food Dehydrator

We’re going to use a basic, low-cost food dehydrator as an example.  Some of these models start as low as $30.  It consists of 4 components.

1. The Base

The base of a food dehydrator has a heating element that runs at a very low and constant temperature.  More advanced dehydrators give you various temperature options and some have a small fan to create convection currents to make the drying more uniform and efficient.

Dehydrator base

Our basic model has only a heating element and runs at one temperature.

2. Foundation Tray

Dehydrator foundation tray

The foundation tray can be used as a dehydrating tray if needed but its primary purpose is to raise sliced foods to an appropriate height above the heating element and support the food trays.

3. Food Trays

Food trays

Dehydrators can accommodate numerous layers of trays.  Some of the more complex dehydrators can feature up to a dozen trays. 

Fresh cranberries

As a general rule, the foods that are thicker, denser or have higher moisture are placed on the first levels of dehydrator trays with more delicate foods like herbs or leafy vegetables on the higher levels.

4. Vented Lid

Food Dehydrator completed

The lid encases the heat and has vents that can be opened or closed to varying degrees to manage both temperature and air flow.  Because heat rises, even a basic dehydrator without a dedicated fan will create some air circulation as the heat rises up through the vents.

Dehydrator Recipes:

Most of these recipes assume the use of a standard food dehydrator although we will explore a couple that use a conventional oven or a kettle grill for meat or fish.  All of the dehydrator recipes feature either fruit, vegetables or herbs.

Leafy Herbs

Leafy Herb

INGREDIENTS AND DIRECTIONS:

  • Leafy herbs include oregano, thyme, dill, sage, parsley, lovage, basil, chives, mint, lemon balm or any other herb that is defined by its leaf.  This could also include tea sources like blackberry leaf. 
Dehydrator tray with fresh oregano
  • Choose enough bunches of leaves from an herb to fill a dehydrator tray.  The leaves should still be attached to the stem.  The stems are removed after drying and the dried leaves have been stripped. 
Dried oregano
  • The leaves are then crushed in hand over a clean countertop and scooped up with a couple of sheets of paper or thin cardboard and poured into the jars.
Crushed oregano
  • The same type of herb should each have its own dedicated tray in the dehydrator.  That way, you can remove and process a tray of herbs that are done while the other herbs on their own trays continue.
  • Timing varies depending on the number of trays you are using and the type of leaf.  Basil dehydrates faster than chives. 
  • To assess doneness, lift a sprig from the tray and crush over a counter top in your hand.  If the leaf crumbles easily, you’re done.

Sliced Fruits

INGREDIENTS AND DIRECTIONS:

  • Various fruits are suitable for dehydration after slicing. 
Sliced fresh apple
  • These include bananas, apples, apricots, plums, pears, mangoes, peaches, ginger, strawberries and Kiwi fruit.
Sliced fresh banana
  • The fruit is washed, peeled and then sliced.  The size of the slices can vary.  You can use either a mandolin to get consistently thin slices, or a knife to get thicker slices.  The thicker the slice, the longer the drying time.  There are no hard and fast rules for slice thickness.  You need to experiment to determine the slice that works best for you
Sliced fresh ginger
  • Some fruits dehydrate with a better color when they have been tossed in lemon juice before dehydrating.  These include apples, bananas and pears.
Dried Banana chips
  • To assess doneness, feel a slice and see if the texture is what you are looking for.  If you want a longer shelf-life, dehydrate until the slices are crisp and break like a potato chip.  If you are okay with a shorter shelf-life you can pull the slices when they are dried but still pliable.  Don’t forget to taste as you go.

Whole fruits

  • Some smaller fruits can be dried without slicing.  These include cranberries, blueberries, red and black raspberries, mulberries, and wild berries like gooseberries.
Dried cranberries
  • Even small, whole fruits will take longer than sliced fruits.  Sometimes days.  Here again, look, touch and taste as you go.
  • Some fruits like cranberries and gooseberries will need to be poked with a fork after a day and lightly crushed.  They are so filled with water that in their whole state it would take a week or more to dehydrate them.
Crushing Partially Dried Cranberries
  • Tart fruits like cranberries can be sweetened with sugar.  Sprinkle the sugar over the cranberries after they have been crushed with a fork.  Make sure you remove the tray from the machine before you sprinkle the sugar or the sugar granules that fall through the cracks will burn on the heating coils.

Sliced vegetables

  • Vegetables that are often dried in a food dehydrator include carrots, potatoes, sweet potatoes, onions, garlic, celery, beets, and other root vegetables. 
  • As a general rule, sliced root vegetables lend themselves to dehydrating best.
Carrots from a Mandolin Slicer
  • A mandolin is the best slicer to use because it delivers consistent thickness on each slice.
Fresh sliced carrots
  • Typically, sliced vegetables need no pretreatment with lemon juice although potatoes can discolor so tossing them in lemon juice before dehydrating is an option.
Dried carrots ginger and apples
  • Most sliced vegetables are dehydrated until crisp and break like a potato chip.

Meats

  • Beef is the primary source for dried meat today although venison and other game are often preserved this way.  
Beef Jerky
  • The most common result is something we often refer to as “jerky.” 
Fresh Beef on Dehydrator Tray
  • Jerky is a thin strip of meat that is sometimes marinated in a brine or dry-cured with various spices and salt before dehydration.
Beef Strips Marinating
  • A food dehydrator can be used to make jerky, but an oven or outdoor grill can also be used if the temperature is kept low.
Open coals on outdoor grill
  • The best temperature for drying meat is between 200° F. and 275° F.
Toaster oven drying
  • The duration varies depending on the method and the thickness of the meat, but figure on hours in an oven or outdoor grill, and possibly days in a food dehydrator. 
Venison jerky

The best way to assess doneness is based on appearance, touch and texture, and taste.  Sample as you go and when you feel it has the texture and taste you like, you’re done.

Fish

  • All fish can be dried but fatty fish like Salmon, Trout, Mackerel and Whitefish are the most commonly dried.
  • The fish are cut into thick strips and sometimes brined in a solution of water and salt before drying.
  • A food dehydrator, oven or outdoor grill can be used.
  • The time is usually less than most meats, but doneness should once again be assessed based on appearance, texture and taste. 

Packaging and Storing Dehydrated Foods

You have a few options when it come to packaging dehydrated foods.  A lot of it depends on the quantity you make and your intended storage time.  Resealable plastic bags can be used for many dehydrated foods if you are consuming them in a matter of weeks or months.

Jerky, fruits and vegetables

If you intend to keep your dehydrated foods for a long duration you should either seal them in canning jars or vacuum-seal them in plastic bags.  Typically, the drier the food the longer the storage time but you should still abide by the mantra of “Eat what your store, and store what you eat.”  Any food that has been dried after curing or brining with salt will resist bacterial and fungal growth better than foods that are simply dried without any previous processing.

Storage considerations range from a freezer to a refrigerator, root-cellar or pantry.  It should always be a dry, cool, dark place.  Before eating any dried food that has been stored for any length of time, observe its appearance, smell it for off-odors, and give it a little taste.  If anything doesn’t appear, smell or taste right -discard it.  That’s where another food-storage mantra comes into play, “If in doubt, throw it out.”

Putting it All Together

Regardless of how you choose to dry, package or store your food you will find that you can sharpen your skills with this food preservation method as you continue to experiment.  You should also take the time to do some additional research to understand better the food dehydration process.

Most dried foods require some rehydration either by soaking in cold water or adding to a recipe that has a stock, broth or gravy as a foundation.  Then again, a piece of jerky or a chewy dried apple always makes a special treat right off the pantry shelf.  

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