Food desiccants refer to substances that can remove moisture from damp materials, such as calcium sulfate and calcium chloride, which dry by forming hydrates when combined with water; physical desiccants, such as silica gel and activated alumina, dry by physically adsorbing water. Moisture control is closely related to product yield. For food, under appropriate temperature and humidity, bacteria and mold in food can multiply at an astonishing rate, causing food spoilage, dampness, and discoloration. Electronic products can also suffer from metal oxidation due to excessive humidity, leading to defects. The use of food desiccants is precisely to prevent the occurrence of defective products caused by excess moisture.
Food desiccants are generally non-toxic, odorless, non-corrosive upon contact, and environmentally friendly. Food desiccants are used to reduce humidity in food packaging, preventing food spoilage; while laboratory desiccants such as concentrated sulfuric acid, soda lime, etc., are too dangerous, they do have advantages such as extremely fast water absorption, high efficiency, and low cost. Commonly used desiccants in food include Calcium Oxide and Silica Gel, montmorillonite desiccant, calcium chloride desiccant, and fiber desiccant.
Types of Food Desiccants
1. Quicklime Desiccant
Quicklime desiccant's main component is calcium oxide, and its water absorption capacity is achieved through chemical reactions, making the absorption irreversible. Regardless of external humidity levels, it can maintain a moisture absorption capacity greater than 35% of its own weight, making it more suitable for low-temperature storage. It has excellent drying and moisture absorption effects and a lower price. It can be widely used in industries such as food, clothing, tea, leather, shoemaking, and electrical appliances. This type of desiccant is most commonly found in 'snow cakes'. However, due to its strong alkaline corrosiveness, quicklime desiccant has often caused harm to children's or elderly people's eyes and is gradually being phased out.
2. Silica Gel Desiccant
This desiccant consists of various types of silica gel packaged in moisture-permeable sachets. The main raw material, silica gel, is a hydrated silicon dioxide with a high microporous structure, non-toxic, odorless, tasteless, chemically stable, and possesses strong moisture absorption properties. Therefore, it is widely used in the storage and transportation of instruments, meters, equipment, leather, bags, footwear, textiles, food, pharmaceuticals, etc., to control environmental relative humidity and prevent items from moisture, mold, and rust. For example, it is used in xylitol and is also the only desiccant approved by the European Union.
3. Calcium Chloride Desiccant
The main raw material for calcium chloride desiccant is calcium chloride, refined from high-quality calcium carbonate and hydrochloric acid through reaction synthesis, filtration, evaporative concentration, and drying processes. It is a white porous block, granular, or honeycomb solid. It has a slightly bitter taste and is odorless. Its aqueous solution is colorless. It is primarily used as a raw material for producing various other calcium salts in inorganic chemical production; it is also used as a desiccant for gases, and as a dehydrating agent in the production of alcohols, esters, ethers, and acrylic resins. In the food industry, it is used as a calcium fortifier, firming agent, chelating agent, desiccant, etc.
4. Fiber Desiccant
Fiber desiccant is refined from pure natural plant fibers through a special process. Among them, film-coated fiber desiccant sheets are particularly convenient, practical, and space-saving. Its moisture absorption capacity reaches 100% of its own weight, which is unparalleled by ordinary desiccants. In addition, this product is safe, hygienic, and moderately priced, making it an ideal choice for many biological products, health foods, and medicines.
