The concept of raisin juice might seem a bit odd, since raisins are, after all, dried grapes, and grape juice is an already well known substance. However, raisin juice is not the same thing as grape juice. Because raisins are dehydrated, their juice is in turn a highly concentrated substance, with less water than grape juice. It is also intensely sweet, as typically sweet varieties of grapes are used to make raisins, and their sugar content increases with dehydration