Master the Freeze Drying Process: Check If Food Is Done By Weight Change

Ensuring that food is adequately dry after a freeze-drying cycle is crucial for its preservation and quality. When 98-99 percent of the moisture is removed during the process, the food can typically last 25 years or more, emphasizing the importance of thorough drying. While methods like visual inspection, texture, and sound checks help, more accurate methods are recommended. Today, we'll focus on measuring weight change.

  1. Initial Weighing:

    • After the auto freeze-drying cycle completes, if the food has cooled down, warm the trays first by selecting the 'Warm Tray' button. After the tray is warm, open the vacuum valve to let air in, then open the acrylic door.

    • Quickly weigh each tray of food separately, record the weight, and immediately return the tray to the chamber. Close the acrylic door and the vacuum valve promptly to avoid moisture reabsorption.

  2. Go Back to Final Dry for Extra Hours: Click the ‘Return to FinalDry’ button, adjust the time by pressing the 'INC' button, and add 2-3 hours. Hit the 'Final Drying' to continue drying.

  3. Second Weighing: After the final drying cycle, remove the food and weigh it again immediately. This final weight should be compared to the initial weight to assess if the drying process is complete. 

  4. Interpreting Weight Change:

    • Know your scale's precision. Most scale's measuring error should be within 1 gram. If your scale's measuring error is 1g and you see weight change in the (-2g, 2g) range, it could be attributed to measuring error.
    • Significant Weight Change: If there's a noticeable difference in weight between the initial and second weighings, it indicates that the food was not completely dry. For example in this experiment, the first measure of the orange tray is 249g, the second measure 242g, so a total of 7g drop in weight, a lot more than measuring error. The drying process should be repeated until no significant weight change is observed.
    • No Weight Change: If the weight remains consistent, this indicates that the food is adequately dry. Proceed to exit the current cycle by pressing the ‘Exit’ button on the Freeze Drying Complete screen. Store the food in sealed myler bags or other airtight containers to maintain freshness.

By measuring the weight changes, you can ensure that your food is properly dried and preserved, ready to be enjoyed or stored for later use.

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