Every few weeks an entrepreneur comes to us with an idea for a freeze-dried product: fruit, a snack, ice cream, a whole meal, a vegetable powder. The idea is almost always good. The question is whether it is also a product, that is, whether someone will pay the price that freeze drying demands.

What freeze drying does

The product is frozen (with us in a blast freezer down to −35 °C), and then, under vacuum, the ice turns directly into vapour without passing through water (sublimation). Because there is no liquid water and no high heat, the structure stays: shape, volume, colour, aroma and heat-sensitive components are preserved better than with any other drying method. The product comes out porous, light and crisp, and dissolves or rehydrates quickly.

What it costs

A freeze-drying cycle takes many hours, sometimes more than a day, and uses a lot of energy. Industrial equipment is expensive, and its capacity is small compared with a spray dryer or an air dryer. The result is a cost per kilogram of dry product several times that of the alternatives. Plus packaging with a moisture and oxygen barrier, which is almost always required.

When it pays for itself

When shape and appearance are the product: whole fruit slices, pieces in ice cream, a meal that looks like a meal.
When the aroma is delicate and heat sensitive: strawberries, berries, herbs, coffee.
When there are sensitive actives: probiotics, enzymes, vitamins.
When the shelf price is high anyway: premium snacks, baby food, trekking and space food, supplements.

When it does not

Simple powders that dissolve (fruit powder for a shake, vegetable powder for soup): spray drying is far cheaper and usually good enough.
Stable ingredients whose shape does not matter: air or vacuum drying.
Price-sensitive products sold in volume.

What one trial tells you

At Foodlab we run the same raw material through two drying methods side by side, and measure water activity, moisture, texture on the analyser, colour and rehydration. Then we taste. The difference between the numbers and between the tastings is exactly the data you need before deciding on equipment or a manufacturer.

What happens after drying

A freeze-dried product is highly hygroscopic: it picks up moisture from the air within minutes and softens. The fat in it is exposed to oxidation, because the surface area is huge and the water activity is low. So the packaging (low WVTR and OTR, a foil-laminate pouch, nitrogen or an oxygen scavenger) is part of the development, not a check at the end. That is the part that surprises the most entrepreneurs, and the part that The Whole Package handles.

Have a product you want to test? More on freeze drying with us, or write to us and we will schedule a trial.

Freeze drying for food: when it is worth the cost, and when ordinary drying is enough