Instructions

1. Sort the berries and throw out anything soft, split or showing grey. One going-over berry will spoil a jar and you cannot pick it out once they are all shrivelled.
2. Break the skin before drying on anything waxy — blueberries, goji, raspberries, blackberries. An intact berry skin is close to waterproof and a whole one will still be wet inside when everything around it is done.
3. Dip them in boiling water for half a minute and then into ice water, or freeze them for a couple of hours and let them thaw. Freezing is the gentler of the two and keeps more of the colour; blanching is faster and takes a little more with it.
4. Drain them well and spread them one layer deep with none touching. Berries stick to each other as their sugars concentrate, and a clump dries as one wet mass.
5. Dehydrate at 52 °C for 30 hours. This is one of the longest runs in the catalogue, so check a few times through rather than at the end — big berries can need half as long again as small ones.
6. Roll the berries around the tray whenever you check. The face sitting against the mesh flattens and holds moisture if it is never turned.
7. They are done when a berry is shrivelled and firm, no juice appears when you squeeze one, and a handful poured into a bowl falls apart rather than clumping. Test them cooled, since warm berries are always firmer than they will be.
8. Condition the cooled berries in a loosely closed jar for a week with a daily shake, then seal them and keep them dark for a year. If you want powder, grind the berries from frozen and use it within three months.