Difference between Freeze Drying and Dehydration
When it comes to freeze-drying and dehydration food we often interchange the term. While both the techniques result in a very similar end product but the process is very different and the shelf life of the product vary as well!
Dried food implies that the water or moisture content of the food product has been reduced or nullified either by old fashioned methods such as air or sun drying techniques or by the use of modern appliances.
It is important to note that while all dehydrated or freeze-dried food is “Dry Food” not all dry food is dried using freeze-dried or dehydration method.
In order to be dehydrated, food has had between 90% to 95% of the moisture removed were on the other hand while using a freeze-drying technique the moisture is removed from around 98% to 99%
What makes the 2 processes different is the types of machinery, technique and texture retained from the product.
- What is dehydration?
The process happens to be one of the eldest and authentic methods for drying food. The process includes food items or ingredients dried with the help of sun-drying or by using electrical fan drying techniques.
Due to constant climate change, people have now started shifting to using electrical devices for dehydration methods, in which the temperature is controlled between 95 F to 165 F depending on the food group. To dehydrate food you need both airflow and heat.
Sun-dried food is the oldest form of food preservation and can be found throughout many ancient cultures.
- What is Freeze Drying?
Freeze drying happens to be one of the most advanced processes, the technology requires special and well-equipped types of equipment.
Food products or items are layered on the trays and moisture is removed at an extremely low temperature around -40 degrees or cooler until the food item is completely frozen.
Once the food items are frozen, a vacuum is formed around the food and then the temperature is slowly and gradually raised.
The technique is mostly seen being used in commercial kitchens and pantries.
- The texture of the final food products:
It is nearly impossible to confuse the final result of the Freeze-Dried and Dehydrated food items.
the touch, feel and taste of both the end result in products is highly different due to differences in the texture and feel.
Dehydrated food items are generally hand and brittle, some food items such as fruits, fruit leathers and maybe pliable, but the end result of the food products is still tough and hard.
Wherein on the other hand freeze-dried food products are porous and offer an airy texture and feel. The food is soo light that it will crumble up if pressed with pressure.
The food items will melt in your mouth and offer you a refreshing taste and texture. The food items also tend to weigh less but take up space in the volume.
- Nutritional Values:
Yes! Both dehydrated food and freeze-dried food retain a high nutrition profile and also retain the actual nutritional values and components of the food items.
Because freeze-dried removes more moisture than dehydrated, freeze-dried food products do have a longer shelf life.
However, with proper use of high barrier pouches and oxygen absorbers, both dried foods can have a shelf life of over a year.
Freeze-dried technology rehydrates slightly better and faster than dehydrated food due to the more porous nature of freeze-dried food items.