In general, any food with a skin will have a harder time freeze drying. Blueberries are especially difficult
to freeze dry. If possible, purée such foods and freeze dry the purée. If that is not possible cut the berries
into halves or quarters. Additionally, using a tooth pick or other small sharp object to puncture holes in
each of the berries can help. This technique can be used for blueberries, cherries, grapes, huckleberries,
etc.
0
Grapes,
Wash and de-stem.
Bring a large pot of water to a boil.
Put a portion (depending on pan size) of the grapes into the boiling water, letting the water come back to a boil (sometimes water will not come back to a rolling boil before they start floating). Grapes will float after a couple of minutes and are ready. As they start to float, use a slotted spoon to remove them to a drain pan. When drained, place them on your trays to pre-freeze or into your machine after they are cooled.
They will not float all at once, I remove them as they float. Leaving them floating in the boiling water to long, they lose flavor.
This process splits the skin for drying. Depending on the size and type of grape, it can take 30-40 hours to properly dry. Its worth the wait. They will not shrink and look like split grapes and taste great. As they are sugary, I only do a single layer on the trays or you will be cleaning more than necessary.
The sweet taste will slightly vary, the better in the better out.
My settings, 115 degree trays, 900 mtorr. Yours may vary, just the way I do it.
Makes a great crunchy snack, have not tried reconstituting.