Freeze Drying VS. Dehydration

FREEZE DRYING VS DEHYDRATION

Whether you’re new to the world of food dehydrating or freeze drying, or you’re a seasoned pro, there’s no doubt that both methods are a great way to preserve food. They’re great money-savers—being that you can literally make your own herbs or cocktail garnishes instead of purchasing store-bought products—and they’re both a great way to cut down on food wastage by repurposing fruits and veggies that may be almost ready for the organics bin. 

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But what is the difference between freeze-dried and dehydrated? Which is healthier? And, what are the benefits of dehydrating vs freeze-drying? Read on to find out.

WHAT’S THE DIFFERENCE BETWEEN FREEZE DRIED AND DEHYDRATED?

• Both freeze drying and dehydrating are effective ways of preserving food by removing moisture and therefore preventing decomposition or the growth of bacteria. However, there are a few key differences between the two methods. The main difference between freeze drying and dehydrating is the shelf life of the finished product and the consistency of the finished product. Freeze dried products can have a shelf life of up to 20-25 years, whereas the shelf life of dehydrated foods is more around the 5-15 year mark. This is because the moisture level with freeze drying is brought down to about 5%, with dehydrating generally being closer to 10-15%.  It’s important to remember that when stored correctly, freeze drying and dehydration are both great options for long term storage and preserving foods.

• The next major difference is texture. Freeze drying is generally quite crunchy whereas dehydrating can give you a chewy or crispy texture depending on how much moisture is removed which can be controlled by how long you leave your product in the dehydrator. Another thing to remember is that when you freeze dry meat, what you are basically doing is putting a stop to the aging process. Whereas with dehydration you are creating a new product. So if you freeze dry meat you will be left with a product that once rehydrated will still be raw meat. But with a dehydrator when you dehydrate meat you will be left with jerky that is ready to eat. Both methods will extend shelf life but comparatively you are left with two very different products.

• Size of finished product is another place where these two machines differ as dehydrated foods have a much larger size reduction of finished product compared to a freeze dried product. Dehydration can reduce the size of a product up to 50% which for food storage this is ideal. You would be able to store more food while taking up less space compared to freeze dried products. With freeze dried foods the size of the completed product is the same as the original product.

• You may have read that freeze drying retains a lot more nutrients in food products over dehydrating, however, this is actually a large misconception. The main reason for this school of thought is that the size and color of the product does not change much during the freeze drying process compared to that of dehydrating. There are many recent studies that show that the ice crystals formed during freeze drying actually causes heavy cell damage and disruption. During the freeze drying process, food is brought down to -40 to -50°C (-40 to -58 °F). From the literature of these studies, we’ve found that drying food at either really high temperatures or really low temperatures has a similar negative effect on the bioavailability of macro and micronutrients found inside of food products.

• Most foods can be effectively dehydrated at temperatures of 45-55°C although our dehydrators at Commercial Dehydrators can heat anywhere up to 90°C. When dehydrating at these mid-range temperatures, foods will preserve most of their nutrients—it’s when going above 70°C that you may notice a drop in nutritional value. Food must be stored correctly, free of oxygen and in a cool dark place otherwise, the nutrients will be lost quickly during storage. Dehydrated foods should also be stored in airtight containers and in a cool, dark place. 

• Another difference between freeze drying and dehydrating is the actual drying times. Food dehydration on average takes approximately 8-12 hours, whereas freeze drying is a much longer process and can generally take between 20-40 hours for an average load. 

• When we look at cost of running these machines we have a very clear difference as a food dehydrator is considered more cost effective, efficient to run and has a greater capacity inside the machine. Using our smallest unit as an example which has a drying area of 27.5sq/ft., the average cost of 1 dry cycle of 10 hours would cost you a grand total of $2.11. When you have a look at the largest residential freeze dryer which only have a 6.4sq/ft. drying area. For an average dry cycle of 30 hours it would cost you a total of $12.65. But to dry the same surface area of produce as the dehydrator does the cost would increase up to $54.79. This is over a 2400% increase of running costs compared to our dehydrators. *Price for electricity was based on the AU average 2021*