How freeze-drying works

What is freeze-drying?

Freeze-drying is a way of preserving food by removing most of its water. The food is frozen, then the ice is turned into vapour under a vacuum instead of being melted or cooked off. What's left is light, dry food that keeps much of its original shape, colour and flavour.

Common foods that freeze-dry well

• Fruit, such as strawberries, apples, bananas and berries
• Vegetables, such as peas, sweetcorn, peppers and carrots
• Cooked meals, such as soups, stews, curries and pasta dishes
• Meat and fish, cooked or raw (raw food stays raw and must be cooked before eating)
• Dairy, such as yogurt and cheese
• Eggs
• Herbs
• Coffee
• Sweets and candy, and desserts

Benefits of freeze-drying

• Long shelf life without refrigeration: properly sealed, freeze-dried food can last years.
• It keeps its flavour and much of its nutrients, better than heat drying.
• It's very lightweight, because most of the water is removed.
• Most foods rehydrate well with water.
• Less waste: surplus food can be preserved instead of thrown away.

Good to know

Not everything freeze-dries well. Very fatty or oily foods, pure butter, honey and jam don't dry properly, and high-fat or very sugary foods generally behave differently. Food safety still matters: freeze-drying doesn't cook food, so raw meat, fish and eggs stay raw, and good hygiene and storage are still important.