Can I Freeze-Dry That? A Practical Guide to Safe and Effective Freeze-Drying Victoria Carlile, Morgan Wayment, and Jose Brandao, USU Extension Food Safety Specialist
Introduction Freeze-drying can preserve most everyday foods, but not all foods work well. Whether you are preparing for a long trip or are interested in long-term storage, it is important to know which food can be freeze-dried safely and which ones should not be attempted. This knowledge helps ensure food safety, quality, and success. This fact sheet provides information on how freezedrying works, the risks involved, and which foods can be more challenging to freeze-dry.
What Is Freeze-Drying, and Why Is It So Popular? Freeze-drying (also known as lyophilization) is a method that removes water from foods by using a vacuum. This happens in three steps (Nowak & Jakubczyk, 2020): Step 1. Initial freezing (turning all the water in the food into ice at very low temperatures, usually below 0 °F), Step 2. Primary drying or sublimation (turning ice directly into vapor by raising the temperature under a vacuum), and Step 3. Secondary drying or desorption (removing the last bits of moisture with higher heat). Freeze-drying is popular because it preserves a food’s original texture, flavor, and nutrients more effectively than other drying methods, such as dehydration and conventional drying. Although freeze-drying takes longer, requires a higher initial 1
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Freeze-drying is a food preservation method that removes water from foods by using a vacuum to turn ice into vapor. Freeze-drying can preserve most foodborne bacteria, and even when they cannot grow, they are still a hazard. Freeze-drying is popular because it preserves a food’s texture, flavor, and nutrients. Freeze drying requires strict sanitation at every step. Foods like meats and eggs should be cooked before freeze-drying or after rehydration to make them safe to eat.