A study into free drying has found that freeze dried strawberries largely preserved vitamin C and total phenolic content (TPC), compared to equivalent chilled strawberries stored over seven days.

The research, carried out by Sheffield Hallam University, in collaboration with Chaucer Foods, also found that the freeze drying process had little or no detrimental effect on vitamin C, TPC or total antioxidant capacity of other fruits and vegetables tested, which were lime, orange, blackcurrant, broccoli and red bell pepper.

Freeze drying works by freezing the material and then reducing the surrounding pressure to allow the frozen water in the material to sublimate directly from the solid to the gas phase. Previous studies undertaken by Chaucer Foods on strawberry drying using alternative drying methods has highlighted a significant loss in their nutrient content in terms of vitamin C levels.

Chaucer Foods technical director John McAughtrie said: "This research clearly highlights the nutritional benefits of freeze drying fruit and vegetables. We are now planning to undertake further studies to compare the nutrient retention of freeze dried fruit and vegetables against those that have been dried using alternative technologies, and also to consider the effects of packaging and storage on nutrient retention."