Food industrial drying

Author: Christopher G.J. Baker
Publisher:
Publish Date: 2003-04-01
Features: This book dedicates a significant portion of its content to elucidating the principles of moisture transfer within solid materials, with the aim of helping readers better understand the subject. Theoretical analysis and calculations are minimized because the drying rate curves must be determined through experiments rather than solely through theoretical calculations. The theoretical models used for interpolation analysis of data obtained under different drying conditions have practical applications, which are discussed in the relevant chapters of this book. Traditionally, drying has been defined as a unit operation that transforms high-moisture liquid, solid (or semi-solid) feedstocks into low-moisture solid products. In most cases, drying involves the application of thermal energy. This thermal energy causes water to evaporate into a gaseous state. In practice, this definition encompasses a wide range of technologies, such as the methods of energy supply to food and the ways in which products are transported within dryers. Depending on the type of dryer, the residence time inside the machine can vary from seconds to hours. Dryers used to process liquid feedstocks differ significantly from those designed to handle water-containing solids. However, many dryers with vastly different characteristics have been improved to meet specific processing needs. In the manufacturing of dehydrated foods, drying is typically the final processing step. Therefore, it not only reduces moisture content to the desired level but also has a significant impact on many other quality characteristics (such as flavor, color, texture, activity of special components, and preservation of nutritional value). These quality characteristics affect the sensory qualities of the final product, and the feedstock is often subjected to a comprehensive influence of temperature—moisture content—time as it passes through the dryer. The chemical and physical changes that occur are extremely complex, and it can be said that our understanding of them is still limited. Therefore, dryers are not simply devices for removing moisture. The main purpose of this book is to provide practical assistance to processing engineers and technicians working in the food manufacturing industry regarding food drying. As a result, a significant portion of the book focuses on providing details relevant to practice, supported by appropriate theory. The main content includes fundamental discussions on drying, descriptions of various types of dryers commonly found in the food industry, recommendations for selecting dryers, and finally, discussions on topics related to dryer operation and control.