FREEZE DRYING IS COOL

 

 

When folks think of food preservation, usually canning and freezing comes to mind. These are the most popular methods. However, with recent food shortages along with shortages of canning and freezing supplies including freezers themselves, people are looking for options and also methods that give food longer shelf lives.

When produce comes on this summer, I plan on preserving it by freeze drying it, at least some of it. Instead of running out of space in my freezer, like I usually do, this process lets me use the freezer as a method of drying food that can then be stored on the shelf. So, pardon the pun, but this is what makes freeze drying “cool.”

Make no mistake, freeze drying is definitely not the same as merely freezing food since simply freezing doesn’t remove the moisture whereas freeze drying does. Lyophilization is the technical term for freeze drying and is explained as “the process where water is removed from a product after it is frozen and placed in a vacuum, allowing ice to change directly from a solid state to a vapor without passing through a liquid phase.”

This process consists of three separate and unique, interdependent stages; freezing then primary drying (sublimination) and then secondary drying (desorption).

Freeze drying works great for fruits, vegetables, meats, dairy products, meals and desserts. About the only things that can’t be preserved this way are any foods that consist of mostly fat or sugar since fat won’t dry but instead heats up and melts, making a big mess. Sugar, on the other hand, binds to water, trapping it in the food making the food a prime candidate for bacteria growth. For this reason, jams and jellies can’t be freeze dried, yet cooked pasta and grains are safe to be freeze dried but not canned.

Once foods are freeze dried, they must be packaged in moisture-proof containers like Mason jars, cans or Mylar bags. Oxygen absorbers can be added for extra protection.

 

 

FREEZE DRYING VS. DEHYDRATING

Although closely related, freeze drying and dehydrating are completely different processes. Dehydrated uses dry air and sometimes heat to remove moisture whereas freeze drying uses cold. Dehydrated food shrinks up and tends to have a leathery texture. It can be eaten as is (think jerky) or it can be re-hydrated with plenty of water. On the contrary, freeze dried food is light and more airy, with very little shrinkage. The food is more like sponges, once exposed to air, they can go from crisp to soggy in a couple hours.

Freeze dried foods have longer shelf lives than dehydrated but the process is a bit more complicated. Low fat foods like fruits, vegetables, lean meat, rice and noodles have shelf lives of 20 years and higher fat foods are good for 10 to 15 years.

 

WHY FREEZE DRY?

Freeze drying definitely has its advantages. If you have abundant produce and not a lot of freezer space, you can freeze dry it for years when the foods are not so plentiful. Also, you could put out a large crop of one item like green beans and freeze dry enough to last several years and then the next year concentrate on a different food.

Also, freeze dried foods are great for traveling since they don’t require refrigeration. You can only fit so much in a cooler!

Freeze drying lets you have healthy snacks on hand to grab and go. Combining berries and yogurt creates a creamy, berry-flavored snack. Freeze dried beet slices, sweet potato fries and other vegetables make unique snacks.

You know how couples freeze the top layer of their wedding cake for their first-year anniversary but don’t usually eat it because the flavor just isn’t there? Freeze drying preserves that flavor and also is great for the bride’s bouquet! One guy even had his grandmother cook some of his favorite meals and he freeze dried them so he could have them after she was gone…just saying!

 

 

HOW TO FREEZE DRY AT HOME

Freeze dryers for home use can be purchased but they are bulky, take up a lot of space and can be pricey, anywhere from $1995 to $3495, depending on size.

You can use your freezer or dry ice to get the same results as buying a counter top freeze dryer although the process may take a little longer. Both use basically the same method.

To use your freezer, follow these steps:

*Set the freezer to its lowest temperature setting, usually around -10 F. Most freezers are pre-set to 0* F. If yours doesn’t go this low, it will still freeze dry, it just may take a little longer.

*Choose foods to freeze dry. Fruits and vegetables with a higher water content like apples, berries, potatoes and carrots along with noodles and meats are easiest to freeze dry. Also, whole meals, desserts, soups, herbs and instant coffee are other prime candidates.

*Cook the meat before freezing it. You can do chicken, deli meats, steaks, ground beef, fish and shrimp.

*Wash and dry the fruits and vegetables.

*Chop produce into pieces one to two inches in size. Uniform pieces dry the same. Line a cookie sheet with a piece of parchment paper and place the pieces so that each one has at least a half inch of space around it.

*Place the tray in the freezer for seven to ten days. To test for doneness, take a piece out, if it turns black it needs more time. There should be no change in color. For meat, let it set 10 minutes then bend it in half. If you see any moisture, it needs more time.

*When done, transfer to freezer bags, pushing as much air out as possible. Store in a cool, dry place at or below 75* F.

 

*USING DRY ICE

*Prepare food same as above. Place in freezer bags.

*Put a layer of dry ice in the bottom of a box. Lay one layer of bags on it then add more dry ice. Multiple layers of food can be in a box as long as dry ice is all around it.

*Close the box and poke a few holes, not many, in the lid for the dry ice to dissipate and food to dry. Put the box in the freezer for at least 24 hours. Food is done when all the dry ice is gone.

*Store in pantry.

 

TO USE FREEZE DRIED FOOD

*Freeze dried food can be eaten dry.

*To rehydrate, do not add too much water or it will make the food mushy and drain nutrients. Only add enough that it “pools” at the bottom and stir often.

*If food is to be covered in liquid like in spaghetti sauce or soup, add only two to four tablespoons extra water for every cup of freeze dried food.

Freeze drying is an option for preserving food for the long haul. It is an inexpensive way since it only requires space in the freezer for a short time.