Get the Recipe
I've never been much of a dried fruit fan, and I think I can trace the root of this back to those little red boxes of raisins so frequently tossed onto my elementary school lunch bag. In my memory, the raisins always ended up packed tightly into the bottom of the box, requiring precision coaxing to remove them from their cardboard shell. They may very well have been nature's candy, but I would just as well have skipped dessert altogether.
Considering the marketing tag line that raisins are just "grapes and sunshine," DIYing your own might not seem all that necessary or cost effective, and I would give you that. Still, I had read some things about how lovely homemade grapes could be and wanted to try them out before those really amazing grapes I can never stop myself from purchasing in large quantities hit the farmers' market this year.
I ended up being very glad I did, because even though the process is rather obvious, the taste was something of a surprise. I've always found commercial raisins to be small and papery bits of sugar that practically dissolve on the tongue after one or two bites. However, the Red Magic seedless I dehydrated last week, for example, offered a subtler though richer sweetness and more complex flavor overall. I don't mean to get all wine snob on you—though, admittedly, I just used writing that description as an excuse to eat a few more handfuls—but as you might expect, different varieties will net different flavor profiles.
Most commercial raisins are made from sultana, aka Thompson Seedless, grapes. Dehydrating your own opens up your options and is perhaps the biggest reason to do so. For those who have their own vines, another big motivator may be managing a sudden yet bountiful harvest. Either way, you will likely want to select a seedless variety, unless you're game to de-seed them yourself (I've done this for other projects and will never, ever do it again) or chew through seeds in your dried fruit.
One thing I noticed when purchasing fresh grapes to dehydrate is that some are treated with sulphur dioxide as a food preservative, while the raisins in my pantry specifically say "sulfite free" (not the same thing, but related). Point being, if additives are of concern, be sure to read your labels/chat with your farmers.
Before You Dehydrate
The dehydration of fruits and berries with a waxy skin is more efficient if they're blanched or "checked" for about a minute in hot water so that the skin develops cracks through which moisture can better escape. I've also read that following that up by freezing the fruit for a few hours before dehydrating aids the process, but I've never taken it that far.
Dehydrator vs. Oven (vs. Sunshine)
I find that using a dehydrator is the most efficient way to make raisins at home with less chance of over drying. However, realizing that not all readers have that option, I also tried a batch in the oven at 165°F with the fan on (if you have a convection option) and the door cracked a couple of inches (I use a old wine cork wedged in over top of the oven light switch on the door). The higher temperature resulted in faster drying, but required diligent tossing and more careful babysitting.
Sun drying is also an option once the weather is offering high heat and low humidity. Even if the steamy summers here in Maryland would cooperate, I doubt the pests in my urban lot would let me get very far with this method unless I also developed a screened-in drying cage that could fight off attacks by land and air. But by all means, make use of the free sunshine if you can. Drying this way will likely require at least a few days in strong sun.
This is a DIY project I would say is all about unique taste and quality rather than cost—at least until the season hits locally. What began as two pounds of grapes (@ $4.98) reduced to approximately six ounces after drying. To put that in perspective, I can buy 20 ounces of standard commercial raisins for $3.19. Still, as a former raisin-despiser, I have now found a dried grape product so attractive to me that it seems quite worth the occasional time and expense.