Automated Cycle 3: Freeze-Drying Soups and Pastes using the temperature probe

Freeze-drying is an excellent method for preserving liquids and pastes, making it ideal for extending the shelf life of cooked foods. But there is a common issue for freeze drying liquids and pastes in a home freeze dryer:  the machine does not know if the liquid food is completely frozen, and therefore sometimes lead to mini 'explosion' of liquid food inside the freeze dryer when the pump kicks on. This happens because the inner part of the soup or paste may still be unfrozen even the outer part and shelf temperature are low. One solution is to set the shelf temperature to -10F or even lower as a condition to start the drying process. But this solution is inefficient as it may much longer time than needed to start the drying process. A better solution is to use temperature probe, which is unique feature on Stay Fresh machines among all home freeze dryer brands. 

Here are several important notes to keep in mind before starting such a batch.

Some notes:

  1. Select 'Probe In Use' : Hit the ‘Probe in use’ button after you hit 'freeze drying' button to let the freeze dryer to utilize the probe temperature information for the freeze drying process. By default, the drying process starts when the probe temperature reaches below 5F and shelf temperature reaches below -5F. 
  2. Weigh Each Tray: While it’s generally a good practice to weigh each tray before drying, it’s particularly crucial for soups and pastes. Ensuring each tray is loaded evenly and without significant weight differences will help them dry uniformly, preventing scenarios where one tray is completely dry while another is still moist.

Steps for Freeze-Drying with a temperature probe:

  1. Preparation:

    • Evenly distribute the soup or paste across the trays. It’s important not to overload the trays to allow for efficient drying.
  2. Setting Up the Probe:

    • Remove the shelf from the chamber and connect the probe using the 3-pin plug. Then put the shelf back in the chamber. 
    • Carefully place the trays onto the shelf.
    • Insert the temperature probe into the thickest part of the paste or soup on the trays.
    • Close the acrylic door and ensure both vacuum valve and drain valve are closed.
  3. Starting the Cycle:

    • On the main screen, select the 'FreezeDrying' option.
    • Hit the 'Probe In Use' button, it will turn green—this enable the freeze dryer to adjust the cycle according to temperature detected by the probe.
    • Press 'Start' to begin the freeze-drying process. The cycle will now adjust based on the probe readings, ensuring the food is dried  thoroughly.
    • When freeze drying is complete, check if the food is dry and remove it  from chamber while it’s still warm. Quickly pack your dried food to avoid moisture.

By following these detailed steps, you can efficiently use your freeze dryer for soups and pastes, preserving your cooked foods for long-term storage. This method not only saves time but also maximizes the energy efficiency of your freeze dryer.

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