Freeze Drying Vs. Dehydration

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. 

‍

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 $0.86. 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 $6.51. But to dry the same surface area of produce as the dehydrator does the cost would increase up to $27.97. This is over a 3200% increase of running costs compared to our dehydrators. *Price for electricity was based on the US average*

At Commercial Dehydrators, we’re proud to offer dehydrators that are made with premium materials, are lightweight and produce high quality results. Our 16 tray dehydrator—which is the smallest unit in our range—is made completely from commercial grade stainless steel, has almost 28 square feet of dehydrating space and can dehydrate approximately 25 pounds of product at a ¼ inch thickness.

In comparison, a larger freeze dryer on the market is only 5 trays, can dry approximately 12-16 lbs of product, and weighs around 274 lbs for a stainless steel version (253 lbs for non-stainless steel). Besides the actual unit itself, a vacuum pump is also included (another 32 lbs) which sits outside the freeze dryer and needs to be maintained regularly by replacing the oil about every 3 cycles. The alternative here is to choose an oil-free pump, but this will set you back additional costs of close to US$1500.

This larger size freeze dryer retails for US$3595, which is approximately 4 times the price of our 16 tray food dehydrator. Our unit also has triple the capacity but is over 4 times lighter in weight than a freeze dryer. Apart from this, our dehydrators require little to no maintenance besides cleaning the trays and a wipe down of the unit itself. The operation of a freeze dryer can also be considerably louder than a dehydrator with the running of the machine and pump being quite noisy.

‍

HISTORY OF DEHYDRATED FOODS

Dehydrating foods is a process that has been around since ancient times when the main method of drying would be laying food out in the wind and sun—this was seen in a lot of Middle Eastern and Oriental cultures. Following this, Europeans built houses that were specifically made to dehydrate food, where fresh produce was dried by the heat of a fire. From here, we move on to the first food dehydrator which was invented in France in the 1800s, where the method of hot air in a machine was used to dry out fruits and vegetables. Since then, the process of dehydrating foods became common during the World War 2 period, and in the 1960s its popularity grew with the campers and hikers of the world who were looking for meals and snacks that were lightweight and nutritious for their adventures. 

‍

HISTORY OF FREEZE DRIED FOODS

The process of freeze drying foods originates back to the 15th century when the Incas stored food in the high mountain altitudes, with cold temperatures freezing their produce and the water content slowly vaporizing. In the early 1900s, the first freeze dryer was invented and later modified by using an electrical pump to create the necessary vacuum. In World War 2, freeze drying was a method used more for medicinal purposes, preserving and transporting blood, medical supplies and even food to the soldiers in the war. It has since been used a lot throughout the medical industry and in the 1960s NASA incorporated the freeze drying process to provide food for astronauts. One of the most common freeze dried products, and by far the most popular, is freeze dried coffee.

‍

WHAT ARE THE BENEFITS OF FREEZE DRYING?

• Freeze drying works well on vegetables and dairy products, including cheese, ice cream and eggs.
• Freeze dried products have a shelf life – up to 25 years.
• Freeze dried products are generally lighter in weight.
• Freeze drying retains the original color and size.

WHAT ARE THE BENEFITS OF DEHYDRATING?

• Quicker dehydrating times.
• Works well for fruit and meat products / jerkys
• Food dehydration produces a shelf life of approximately 5-15 years.
• Food dehydrators are more cost effective offering larger drying capacity for a cheaper price.
• Food dehydrators do not require ongoing maintenance.

So, there’s our breakdown of freeze dryers vs dehydrators. Whilst there are benefits of both, it all comes down to individual preference and the purpose of the finished product. For more information on our food dehydrators, check out our resources section on the website, or contact us directly—we’re always here to help.

‍