Freeze-drying is the process of removing liquid from a product, such as food, to extend shelf life, reduce weight, and maintain quality. Due to the cost of freeze-drying, it is best used for premium, high-quality products. Freeze-drying begins with freezing the item and subjecting it to vacuum pressure to remove the solvent content (usually water). The product is then heated, allowing the solvent to evaporate through a process known as sublimation.