Do you know that ‘freeze-dried food’ is not the same as ‘dehydrated food’? Everyone thinks they are the same, but they are not.
History of Food Drying
Moisture has to be taken out of foods for them to last longer on the shelf. This method of food preservation was discovered in the olden days, and has been in use ever since then.
The dehydration method of moisture removal has been in use since 12,000B.C. Roman and Middle Eastern natives preserved fruits and vegetables in ‘still houses’ by using fire to smoke and dry them out.
On the other hand, freeze-drying is a new method of food preservation. It was first used to preserve drugs, and blood plasma during the World War II. Eventually, freeze-drying found use in food preservation.
Eliminates 99% of food moisture
Original appearance is not lost
Conserves 97% of nutrients
Retains the taste of foods
Less weightier than dehydrated counterparts
Can last up to 25 years under the right conditions
How is Dehydrating Different from Freeze Drying?
The fundamental principle behind food preservation is the removal of moisture from the food without destroying its composition and nutritional content.
Basically, dehydration involves the application of heat and air current to preserve foods. Usually, the foods to be dried are placed on trays over which heated air is allowed to flow for a given period. At the end of a dehydration cycle, up to 70% of the foods water content is removed.
Freeze-Drying involves an advanced moisture-removal process. The food to be dried is first frozen to temperatures of about -40ºC before a vacuum is introduced to the system. Afterward, steady heat is introduced to the system to sublime the ice i.e. vaporize the ice without turning it to liquid.
While Dehydration removes about 70% of food moisture, freeze-drying removes up to 99% moisture from food. The 30% water content left in food after dehydration makes the food prone to spoilage after a few months. On the other hand, freeze-drying ensures that almost all microbiological activities in food are destroyed to extend its shelf life.
As an example, food items preserved by dehydration can only boast of shelf lives of about 12 months. But the same foods are freeze-dried they can last for over 300 months.
Based on data from the American Institute of Cancer Research, freeze-dried foods contain almost all of the nutrients found in its fresh counterpart. Freeze-dried foods are also known to retain their original tastes after the preservation process, and will also not have any observable change in appearance.
Finally, freeze-dried foods weigh a lot less than their dehydrated counterparts. Hence, they are easier to store and carry about within and outside the home. In addition, you’ll not need any kind of cold storage to keep freeze-dried foods from going bad. Freeze-drying simply means that you get to have fresh food, but with longer shelf lives and lesser weight.