freeze-drying


Also known as lyophilization, freeze-drying is a method of dehydrating a food (or any perishable item, such as blood plasma) by freezing it and subjecting it to a vacuum. This allows the ice to break free and form a vapor that's easily extracted. This instant ice crystal-to-vapor process is called sublimation. The dehydrated food is immediately packaged and sealed before moisture can be reabsorbed. Moisture contributes to decay and freeze-dried foods have almost none, which means they may be stored at room temperature for many years. They're also much lighter due to lack of water weight, particularly foods like fruit, which are 80 to 90 percent water. Foods that have been freeze-dried have microscopic pores where the ice crystals once were. When the substance is reconstituted with water, these areas are ready for quick absorption. Of all the techniques for drying food, freeze-drying has the least impact on flavor and texture. Such foods have proven invaluable for military and astronaut use, as well as for hikers.

From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.

Next Up

Freeze Some Bacon

Bacon is much easier to chop when it's cold. Keep a stash in the freezer for weeknight meals.

Freeze Pie Crust

Curious if you can make pie crust ahead of the Thanksgiving holiday and store it in the freezer? Food Network has the answer.

Foods to Freeze

Utilizing your freezer can mean big savings of time and money. But what should you freeze and how?

Can You Freeze Eggs?

In a word: yes. But it’s important to follow a few rules.

Can You Freeze Tomatoes?

Stretch tomato season indefinitely with these easy tips.

Can You Freeze Milk?

Is freezing dairy liquids like milk and heavy cream a do or a don't? Here are our thoughts.

How to Freeze Zucchini

Make squash season last forever with these easy tips.

How to Freeze Bananas

Keep that fruit appealing for smoothies, baking and more.

How to Freeze Mushrooms

Find out how to make the most of that earthy flavor.

Can You Freeze Avocado?

Extend the life of perfectly ripe avocados easily and effectively.

Related Pages