Raisins are primarily preserved through drying, which removes moisture and inhibits the growth of spoilage-causing microorganisms.
The main method for preserving raisins is dehydration, significantly reducing their water content. This low moisture environment makes it difficult for bacteria, yeasts, and molds to grow and multiply, thus extending their shelf life naturally.
While the core principle is drying, the specific process can vary, particularly between standard dark raisins and golden raisins.
Standard Raisins
Typically, standard dark raisins are made by sun-drying grapes directly in vineyards. The natural heat and air circulation reduce the moisture content to below 16%, a level sufficient for preservation.
Golden Raisins
As mentioned in the reference, golden raisins often utilize a slightly different process and may include additional preservatives. They are frequently dried in a dehydrator rather than solely relying on sun-drying. Furthermore, to prevent their skins from darkening during the drying process and to maintain their characteristic gold color, sulfur dioxide is often used. The reference explicitly states: "Golden raisins are often dried in a dehydrator and contain sulfur dioxide, which is used as a preservative and to prevent their skins from darkening, making them gold in color." Sulfur dioxide acts as a preservative, inhibiting enzymatic and microbial browning and spoilage.
In summary, drying is the fundamental preservation method for all raisins. Golden raisins often involve accelerated drying via dehydrators and the addition of sulfur dioxide for color retention and enhanced preservation.
