Dehydration is one of the oldest methods of preservation used by prehistoric people. Products of various types require drying to improve their shelf life, palatability, or to create a chemical change within the product. Many types of food can be preserved for indefinite periods by extracting the moisture, thereby inhibiting the growth of microorganisms in them. Drying reduces moisture content within the product and thus, lowers water activity in perishable products to safe levels, prolonging the shelf life and adding value. Food products, when dehydrated, can have an almost unlimited shelf life. Dehydration of products, also, substantially lowers the transportation cost, handling and storage costs as well. Modern dehydration techniques have been largely stimulated by the advantages dehydration gives.
Typically product dehydration has two critical factors
Moisture is present in the food products as:
Food products dehydration operations involve the removal of free moisture, hygroscopic moisture or combination of both. Conventionally, products are dehydrated with hot air! However, most food products which require drying are temperature sensitive. Additionally, dehydrated food if exposed to a humid environment even for a short time, absorb water from surrounding air and become soggy and unappetizing. Vegetables and fruits like Onion, Garlic, Peas, Grapes, Walnut Kernels, Ginger, Dryfruits (Almond, Pista etc.), Coconut, Katha, dates and many more have to be dried to the desired moisture content at low temperature. These dehydrated foods also tend to pick up moisture from surrounding air during processing, packaging and storage.
Desiccant Dehumidification is the simplest and the most cost-effective method to ensure drying without spoilage. The drying is based on the difference in vapour pressures of water in the product and the surrounding air. Moisture is released from the product to the surrounding air by maintaining the surrounding air at a lower moisture level which forces the product to release its moisture. When the released moisture goes into the air, it is physically removed from the air using desiccant driers. Hence it increases drying potential and the drying rate. More importantly, it removes the variable weather factor in the drying operation.
Bry-Air specialises in product drying at a temperature below 75°F. The application areas extend to the drying of myriad products. In conjunction with air-conditioning plants, dry air at low temperatures can be supplied for the product dehydration. Typical products which need low-temperature drying are Seeds, Gelatine, Katha, Cocoa, Instant Coffee Powder and Gelatine.