Raisins can be used right out of the case, but experienced bakers commonly condition raisins in advance. This involves re-hydrating raisins to the desired moisture level.
 
Conditioning is an important step in the production of raisin breads. If raisins are not conditioned but added directly to the dough, they will draw moisture from the bread during fermentation and baking. This also causes the bread to stale during shipping and distribution, which reduces the shelf life.
 
For small quantities, the American Society of Bakery Engineers recommends that quantities of not more than 30 pounds be conditioned by adding 12 to 15 percent of warm water by weight to the raisins right in the case. Temperature of the water should not exceed 75° to 80°F and 3.6 to 4.5 pounds of water to 30 pounds of raisins.
 
Re-close the poly-liner, cover the container, and turn it a number of times to distribute the water uniformly. Turn again after about 2 hours and let stand for an additional 2 hours for a total conditioning time of at least 4 hours or overnight.
 
Longer periods may over condition and release more solids from the raisins. Any remaining liquid should be added to the dough as part of the liquid component in the formula. Do not condition raisins in excessively hot water. For best results, raisins should be about 75°F at the end of the process.
 
For larger quantities, the American Institute of Baking recommends that raisins be placed in a trough or tank with a screened bottom opening for draining the water. Completely cover the raisins with water at 75° to 80°F and then, drain. 
 
Close the drain to retain leached solids and cover the trough or tank and allow the raisins to absorb the surface water for at least 4 hours or overnight. Longer periods may over condition and release more solids from the raisins. Any remaining liquid should be added to the dough as part of the liquid component in the formula. Do not condition raisins in excessively hot water. For best results, raisins should be about 75°F at the end of the process.
 
California raisins are shipped in poly-lined boxes. They are available in bulk packages of 30 pounds and other size cartons. This is ideal for purchase by a full container load of approximately 17 metric tons per 20-foot container, where 1,250 to 1,800 cases may be loaded depending on the carton size. California raisins are available in a variety of snack and consumer packs, too. Most bakers purchase California raisins in 25- or 30-lbs cases.
 
California seedless raisins are available in a variety of sizes appropriate for bakers. These include mini small raisins, small raisins, select raisins, and jumbo raisins. Different packers have different terms to describe size but, for the most part, California raisins are sized either by count per pound or kilogram or by screen size. Bakers should specify screen size if a special size is important and integration throughout the product is required. Golden raisins, Zante currants and other dried grape varieties are also available for specialized applications.