Freeze drying is one of the processes of preservation where the food is kept at low temperature till it solidifies and then subjected to high vacuum that removes ice by sublimation. This is done to prevent the food from spoiling and damage, giving it a longer lifespan, around 25 to 30 years!

If a freeze-dried substance is packed to thwart the re-absorption of water, the substance can be kept at normal temperature without having to refrigerate it, and be protected from going bad for years. This is done as a result of reduced water level from the foods that hinder the growth and survival of microorganisms and enzymes that would normally tarnish or spoil the substance.

This method of freeze drying is less damaging to the substance as compared to other methods of dehydration at high temperature. This preservation process is popular since it does not usually cause compression and toughening and hardening of the material, but also maintains the flavors, smells and nutritional content. However, along with water, many other elusive contents, such as acetic acid (vinegar) and alcohols are lost in the sublimation process that can harvest repellent results.

The process leaves microscopic pores that are created by the sublimated ice crystals, leaving gaps in their place and contributing to a quicker and easier rehydration of freeze dried products. This is of special importance for pharmaceutical uses that help the products give a much longer shelf-life.

Freeze drying comes in handy in many industries, and for multiple uses, the most common one being food and agricultural industry. Because heat, commonly used in crop and food processing, unfailingly affects the structure and chemistry of the product, the main purpose of freeze drying is to avoid heat and thus preserve its structure and chemistry.

Instant coffee, culinary herbs, vegetables and sensitive baker’s yeast are some of the example of foods that are freeze dried. It is also used in chemical synthesis for better dissolving and stability in the technological industry. In bioseparations, freeze drying can be used for late-stage purification and concentrating substances with low molecular weights that are too small for removal through membrane filtration.

Other uses include recovery of water damaged books and documents, conserve special stains in bacteriology, producing natural mummies in high-altitude environments through low temperatures and pressures, forming powder from a sprayed slurry mist in ceramics industry, preserving flowers, and for burial purposes by freezing the body with liquid nitrogen.

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