Drying And Dehydration Techniques

Drying And Dehydration Techniques

Drying and Dehydration Techniques Principles of Drying and Dehydration Drying and dehydration are methods used to remove moisture from materials, primarily food and agricultural products, to extend shelf life, reduce weight, and prevent microbial growth. Basic Principles of Drying and Dehydration Moisture Removal The primary goal is to reduce the water activity (aw) of a product to a level where microbial growth is inhibited. Water exists as free water and bound water ; drying typically removes free water. Heat and Mass Transfer Drying involves two simultaneous processes: Heat Transfer : Heat is supplied to the material to evaporate moisture. Mass Transfer : The vaporized water moves from the interior to the surface and is removed into the air or vacuum. Drying Rate Affected by: Temperature Humidity of the drying air Air velocity Surface area Product characteristics (e.g., porosity, moisture content) Key Terms Critical Moisture Content : The point at which drying shifts from a constant rate (surface moisture removal) to a falling rate (moisture diffusion from inside). Equilibrium Moisture Content (EMC) : The moisture level where the product no longer loses water to the environment. Types of Drying Techniques 1. Air Drying / Convective Drying Hot air blows over the

Updated July 15, 2026