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Let’s talk about why the temperature of food matters when freeze drying.
Understanding the importance of temperature in the freeze-drying process is key to preserving the quality and longevity of your freeze-dried foods. Freeze drying, also known as lyophilization, involves removing moisture from food by first freezing it, then creating a vacuum to turn the ice directly into vapor. The final phase, where temperature is crucial, ensures your food’s quality and longevity. Here’s why the temperature of food matters when taking it out of the freeze dryer.
1. Preventing Moisture Absorption
When you take freeze-dried food out of the dryer, it’s very porous and can easily absorb moisture from the air. If the food is cold, it can cause condensation of moisture on its surface, leading to spoilage, mold, and reduced shelf life. Warm food is less likely to cause immediate condensation, reducing the risk of moisture reabsorption.
2. Sublimation Efficiency
The efficiency of the freeze-drying process depends heavily on temperature. Sublimation, the transition of ice directly into vapor, happens most efficiently at specific temperatures, usually reached towards the end of the cycle. Removing food at the correct temperature ensures that the sublimation process is complete and the food is thoroughly dried.
3. Packaging and Storage
The temperature of food at removal affects its readiness for packaging and storage. Warm, properly dried food can be immediately packed in moisture-proof containers for long-term preservation. Cold and potentially moist food may need extra steps to ensure it’s completely dry before packaging, which can be time-consuming and less efficient.
Is Freeze Drying For You?
Many people think it’s next to impossible to do the freeze drying for themselves. This is far from factual. Freeze drying at home is made easy by Harvest Right. They sell three different sizes of freeze-drying machines that do everything in the machine – except prep and package.
That’s up to you.
For all intents and purposes, here at Freeze Drying Mama we use the medium sized freeze dryer. You can check out the sizes offered at Harvest Right here.
What this machine does is first freeze the items on stainless steel trays to -41 degrees or lower. This takes about 10 hours or so.
Then a vacuum pump turns on and creates a vacuum inside the drum. This is the drying stage and will vacillate the heat of the tray up and down to a pretty warm temperature. This makes the frozen items release any water in them in vapor form. The vacuum sucks the moisture to the drum. This collects in ice form on the inner circle of the drum.
Then there’s the final dry which is essentially the same thing, but with a time associated with it and an end in sight!
