Quality control plays an important part once the raisins are at the plant. Before the raisins are taken from their bins, government inspectors use long prods to take samples from the middle of each box. Strict standards must be met to ensure each box of raisins are free of mold, pests and other imperfections.
Next, the raisins are "processed". They are poured into a hopper which feeds onto a series of conveyor belts and drums that remove any remaining stems, chaff or lightweight fruit.
From this point, the raisins are sent through a brisk vacuum air stream to catch any undesirable material that may have been missed. Then they're size-graded and thoroughly washed in pure water.

Due to the high sugar content in raisins, they don't need preservatives to keep them fresh. Also, raisins will keep their flavor, color and nutritional value for up to 15 months when stored between 40-50 degrees Fahrenheit. Raisins can also be frozen and thawed easily for later use.

Store your raisins in an airtight container to keep them fresh, soft and free from humidity that can cause the fruit sugar to crystallize on the raisins' skin. Also, store your raisins away from brick and concrete walls where they can absorb moisture.