Use clean, food-grade dehydration equipment or oven with drying trays or racks that allow for good air circulation.
Many types of food dehydrators can be used and are explained in detail in Food Dehydrators.
Conditioning containers
Large, clean plastic or glass container with lid
Storage containers
Clean, dry home canning jars, plastic freezer containers with tight-fitting lids or plastic freezer bags
Vacuum packaging is also a good storage option
Cooking pot with lid (for boiling water to crack skins)
Large bowl (for soaking fruit in pre-treatment solution)
Colander, strainer or slotted spoon (for draining fruit)
Large pot for boiling water (if drying whole grapes)
Ice water (if drying whole grapes)
Cutting board
Knife
Timer or clock
3. Prepare Ingredients
Thoroughly wash grapes.
Cut in half or leave whole.
If drying whole, crack skins by dipping in briskly boiling water for 30 seconds.
Dip in ice water to stop further cooking.
Drain on absorbent towels before placing on drying trays.
If drying halved, soak grapes in ascorbic acid or other anti-darkening or antimicrobial solution for 3-5 minutes. Remove from solution and drain well before placing on drying trays.
4. Dry
Arrange pretreated grapes in single layers on drying trays.
Dry at 140 degrees F (60°C) in an oven or dehydrator.
If necessary, turn large pieces over every 3 to 4 hours during the drying period.
Fruits can scorch easily toward the end of drying, so monitor more closely as drying nears completion.
Dried fruits should be leathery and pliable.
Total Drying Time: 12-20 hours in a dehydrator (may take up to twice as long in a conventional oven)
5. Condition
Condition grapes by placing cooled, dried fruit loosely in large plastic or glass containers, about two-thirds full.
Lightly cover and store in a dry, well-ventilated place for 4 to 10 days.
Stir or shake containers daily to separate pieces.
If beads of moisture form inside the container return grapes to drying trays for further drying, then repeat the conditioning step.
6. Store
Store small amounts of conditioned dried grapes/currants in moisture-vapor-proof containers or bags.
Label packages with name of product, date and method of pretreatment and drying.
Store in a cool, dry, dark place or in the refrigerator or freezer.
Properly stored, dried fruits keep well for six to 12 months.
Discard foods that have off odors or show signs of mold.