Fst 151 food freezing food science and technology 151 Special topics: Freeze Drying

Effects of freeze drying on foods

• Advantages:
• Very high retention of sensory characteristics and nutritional qualities and a shelf-life longer than 12 months when correctly packaged.
• Aroma retention up to 80 – 100 %
• The texture of freeze-dried foods is well maintained; little shrinkage and no case hardening.
• The open porous structure allow a rapid and full re-hydration, but it is fragile and requires protection from mechanical damage.
• Only minor changes to proteins, starches or other carbohydrates.
• Disadvantage:
• The open porous structure of the food may allow oxygen to enter and cause oxidative degradation of lipids (packaging in inert gas necessary).