With time, food in your freezer will lose moisture through sublimation. The best example of this it to look at an ice cube tray that has been in the freezer for a long time. Notice the ice cubes shrink? Also, see the History section – Peruvian Incas, Eskimos, Buddhist Monks, and the Vikings used their local climate.
However, the freeze drying process can be sped up
- Freeze the food to a temperature below water’s triple point
- Taste, structure, and appearance are more likely to preserve by freezing food
- Freeze drying does not cook the food
- The food can be frozen with:
- Mechanical refrigeration (the most common today)
- Other methods:
- Dry ice in liquid Methanol
- Liquid nitrogen
- Ammonia
- Use a vacuum to bring the surrounding pressure below water’s triple point.
- Mechanical vacuum pump (the most common today)
- Chemical – Displacement of the air with ethyl ether
Freeze drying was first used at a large scale in the 40s during WW2 for blood plasma and penicillin transportation. It became more popular for drying food during the 60s. [source]
Normal commercial applications
- Pharmaceuticals — this is where freeze drying got its start at scale
- Space — obvious weight advantages (in spite of its name, “astronaut ice cream” never made it to space source)
- Transportation
- Milk & other dairy products — Other benefits: retain color, flavor, nutrients, and consistency source
- Hiking meals — who wants to pack extra water weight?
- Food storage — 20+ year shelf life
Freeze drying has historically been too expensive for home use. Entry-level freeze drying units started at $30,000 and were for commercial use.
The only “reasonable” option to have your own freeze dried food was to buy it.
Today, that is changing.
Some have tested a jar vacuum with silica beads to partially freeze dry food. This is a fun video. Realize that jar vacuum sealers do not accomplish enough of a vacuum to completely freeze dry. The cellular collapse is a good indication of the incomplete freeze drying.
Others have built their own freeze dryers. This guy has given every step to build your own. As you can see from the video, it required a lot of mechanical expertise to build one.
While freeze drying itself is an old technology, at-home freeze drying is opening the technology to everybody. Harvest Right has built the first freeze dryer designed for the home consumer. Instead of the prohibitive $30,000 price tag for a freeze dryer, every-day consumers can now get their own home freeze dryers starting at about $2400.
Home freeze drying is still in its early stages. But the ability to create your own recipes has many advantages. You also have have the cost-saving advantage of saving your leftovers. Harvest Right has opened freeze drying to an exciting new audience. Many will enjoy doing their own home food preservation.