Something to keep in mind is that oil and fat will NOT dehydrate or freeze-dry.
What is "Dehydrating" and how does it work?
Before I explain, I want to mention that some dehydrators do not have a temperature chart. In fact, some dehydrators only run on one temperature. Basically, turn on and turn off. The one that I recommend is the Excalibur.
As you can see, it gives you specific temperature settings for each type of food.
Now, how does it work? For starters, you can put, fresh, frozen, cooked, or raw food in a dehydrator. I've done all of these, and everything turns out great. The process is pretty simple.
Dehydration is a method of food preservation, in which moisture is removed from the food. Drying food extends the shelf life of a food by decreasing growth of bacteria and minimizing spoilage.
Dehydrated foods can be eaten in their dried state or rehydrated for future use. Removing the desired amount of moisture can take several hours. Dehydrated foods may change color, weigh less, and appear irregularly shaped compared to their fresh state.
Components
Dehydrators operate by using a heating element, fan, air vents, and food trays.
The heating element, fan and vents work together to circulate air and remove moisture. Heating the food allows for moisture to be released from the food and into the dehydrator.
The fan then pushes excess moisture to the vents, where it is released outside of the dehydrator. Air may circulate vertically or horizontally.
Temperture
Most foods are dehydrated at temperatures between 95 and 145 degrees Fahrenheit.
Meats should be dehydrated at higher temperatures than fruits or vegetables to discourage bacteria growth. Temperature and air circulation should be consistent to allow for even dehydrating. Dehydrating foods at too high a temperature will result in uneven drying, leaving foods with dry exteriors and moisture in the interior.
Food Texture
Dehydration is complete when fruits appear leathery and are dry throughout.
Dried vegetables may be tough or crunchy and are done when there is no internal moisture. Jerky should also appear leathery and have a tough, chewy texture.
What does the food look like? Here are some examples:
Fruits
Vegetables
Meat
The longevity of the food can last for up to 10 years.
What is "Freeze-Drying" and how does it work?
Again, you can put, fresh, frozen, cooked, or raw food in a freeze-dryer.
Freeze-Drying is basically the most expensive way to preserve your food. The only freeze-dryer on the market for home is the Harvest Right. It ranges from $2395 - $3595 for home freeze-dryers. These prices are at time of posting this article.
How does it work? Well, here's a short video that explains it way better than I can. LOL!
Sublimation is the transition of a substance directly from the solid to the gas state, without passing through the liquid state. Here's a Wikipedia article explaining the process.
Freeze-drying or lyophilization is a dehydration technique based on the sublimation of water in a product.
This means that the product’s water content transitions from a solid to a gas state — or from ice to vapor — without going through the liquid state.
Freeze-drying is considered a high quality dehydration method for a couple of reasons, including:
it operates at low temperatures, which contributes to preserving a product’s nutritional value, taste, appearance, and heat-sensitive compounds.
freezing inhibits chemical and microbiological processes, which significantly delays the product’s deterioration (thereby extending its shelf life).
The freeze-drying process can be divided into three steps;
Freezing: The product is often frozen under atmospheric pressure.
Primary drying: Also known as proper freeze-drying, this is the sublimation step in which frozen free water is removed.
Secondary drying: Also known as desorption drying, it’s the drying of products to their desired humidity by removing the remaining bound water.
The Components of a Freeze-Drying System
The main components of freeze-drying equipment are:
Refrigeration System
Vacuum System
Control System
Product Chamber or Manifold
Condenser
The refrigeration system cools the (ice) condenser located inside the freeze dryer. The refrigeration system can also be employed to cool shelves in the product chamber for the freezing of the product.
The vacuum system consists of a separate vacuum pump connected to an airtight condenser and attached product chamber.
Control systems vary in complexity and usually include temperature and pressure sensing ability. Advanced controllers will allow the programming of a complete “recipe” for freeze drying and will include options to monitor how the freeze-drying process is progressing. Choosing a control system for the freeze dryer depends on the application and use (i.e. lab vs. production).
Product chambers are typically either a manifold with attached flasks, or, a larger chamber with a system of shelves on which to place the product.
The purpose of the condenser is to attract the vapors being sublimed off of the product. Because the condenser is maintained at a lower energy level relative to the product ice, the vapors condense and turn back into solid form (ice) in the condenser. The sublimated ice accumulates in the condenser and is manually removed at the end of the freeze drying cycle (defrost step). The condenser temperature required is dictated by the freezing point and collapse temperature of the product. The refrigeration system must be able to maintain the temperature of the condenser substantially below the temperature of the product.
In shelf freeze dryers, the condenser can be located inside the product chamber (internal condenser) or in a separate chamber (external condenser) connected to the product chamber by a vapor port.
Manifold freeze dryers rely on ambient conditions to provide the heat of sublimation to the product. This heat input does not melt the product because an equivalent amount of heat is removed by vaporization of the solvent. Advanced shelf freeze dryers can provide a heat source to control/expedite the drying process and they can also employ the refrigeration system to allow freezing of product inside the unit.
What does the food look like? Here are some examples:
Steaks
Chicken
Pork Chops
Shrimp
Fruits
Vegetables
The longevity of the food, when properly stored, can last for up to 25 - 30 years.
Thank you for stopping by!
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