Do you want to reduce your food waste? Would you like to have shelf stable foods in case of emergency? Do you like to prepare healthy snacks? Do you enjoy camping, hiking, or hunting? If you answered yes to one or all these questions, freeze drying may be for you!
According to the FDA: “Lyophilization or freeze-drying is a process in which water is removed from a product after it is frozen and placed under a vacuum, allowing the ice to change directly from solid to vapor without passing through a liquid phase. The process consists of three separate, unique, and interdependent processes: freezing, primary drying (sublimation), and secondary drying (desorption)”. Through the process of sublimation, many of the food products retain their original texture, flavor, and nutrients once reconstituted.
Almost any food can be freeze-dried. The foods that work best with freeze-drying are:
- Fruits
- Vegetables
- Dairy foods including cheese, milk, yogurt, ice cream
- Proteins including poultry, seafood, red meat, eggs
- Mixed foods including casserole, soup, lasagna, quiche
Foods that do not freeze-dry well:
- Foods high in fat content
- Foods high in sugar content
- Baked goods including breads, muffins, cake
Once you have a freeze-dried product, storage becomes a consideration. Iowa State University suggests, “The storage container must eliminate oxygen, light, and moisture. In order of long-term to short-term storage, the following containers may be used: Mylar® bags, vacuum-sealed canning jars, #10 cans, vacuum sealed bags, and PETE re-sealable containers”. PETE bags and glass Mason-type jars are the most readily available storage options. If you wonder what PETE
bags are, they are made of polyethylene terephthalate, a food grade, non-toxic, and typically opaque silver pouch. For long term storage, oxygen absorbers are required. Oxygen absorbers are materials in a pouch that removes oxygen from space around food particles. Oxygen absorbers extend the shelf life of products by preventing color change and reducing the growth of microorganisms. While this term may be new to you, you have seen them in purchased items like baked goods, cheeses, pet foods, and seasonings. Freeze-dried foods that will be stored for no more than a few months (for example, fruits that you plan to snack on soon), can be stored in food storage containers or Mason-type jars without oxygen absorbers.
Oxygen absorbers can be found in many sizes varying from 20cc to 2000cc. (The “cc” stands for cubic centimeters as it related to amount of oxygen absorbing capacity). According to Utah State University, “A quart container will need one 50cc, a gallon container and #10 can will need 300cc of oxygen absorption and a 5-gallon container will need three of the 500cc packet”. Once purchased, oxygen absorbers should be used within 6 months to 1 year. Store unused oxygen absorbers in an airtight glass jar for up to 6 months.
Overall Safety of Freeze-Dried Food
For the highest quality, all home preserved foods should be stored in a cool, dry location. This includes foods that are home canned, dehydrated, and freeze dried. Labeling is even more important for freeze-dried foods because you cannot see what is in your PETE pouch. Always include date, preparation method (raw or cooked), product name, amount (for some foods like soup), and directions or notes, for example, how a tomato is sliced, or how a food is seasoned.
While freeze drying can sound exciting, there is a financial investment to get started. The cost range to purchase a home freeze dryer is between $2,000 and $6,000. Other considerations are machine location, supplies for storage, electric use, noise, temperature, accessories, and time needed to complete the process. Stay tuned for more information on the Freeze-Drying: Consider This blog series.
Resources:
Utah State University: https://extension.usu.edu/preserve-the-harvest/research/buying-a-home-freeze-dryer-what-to-know-before-you-go
Iowa State University Extension and Outreach: https://blogs.extension.iastate.edu/answerline/2023/06/13/preserving-by-home-freeze-drying/
Written by: Lisa Barlage, Extension Educator, Ohio State University Extension, Ross County and Megan Taylor, Extension Educator, Ohio State University Extension, Union County.
Reviewed by: Ohio State University Extension, Food Preservation Team.
Photo credit: Laura Halladay, Extension Educator, Ohio State University Extension, Greene County.
Leave a comment