Monday, July 23, 2012

Nutrition- Dehydrated vs. Freeze Dried

Dehydrated Vs. Freeze Dried
 What is the Difference? 
Bell peppers before drying
bell  peppers

People have been dehydrating foods for centuries.  Our foods are dehydrated at low temperatures to preserve the nutrients.  Dehydrating removes most of the water from the food, making it more shelf stable, while preserving the nutrients and taste.  They are less expensive than freeze dried foods and the texture tends to be more chewy, although some foods are quite crispy.

Freeze drying is a newer process in which the food is flash frozen, placed in a vacuum chamber, and then the water is removed by evaporating the ice at temperatures as low as -50 Farenheit.  Freeze dried foods are also very shelf stable but will rehydrate quickly when opened and exposed to air. Freeze dried foods have a crunchy texture. Nutrients are lost when foods are frozen because freezing causes the cells to rupture. 
Here is an interesting comparison of frozen vs. canned vs. dehydrated foods.  Overall, 
Bell peppers after drying
Bell peppers after drying
dehydrating only causes about 3-5% nutritional loss, whereas freezing causes 40-60% from the cells rupturing and canning causes 60-80% from the high heat used. So since freeze drying uses freezing in the process, we don't believe it is a good choice compared to dehydrated foods.  It is also much more costly.   

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