Book excerpt: Thickening and gelling agents are invaluable for providing high quality foods with consistent properties, shelf stability and good consumer appeal and acceptance. Modern lifestyles and consumer demands are expected to increase the requirements for these products. Traditionally, starch and gelatin have been used to provide the desired textural properties in foods. Large-scale processing technology places greater demands on the thickeners and gelling agents employed. Modified starches and specific qualities of gelatin are required, together with exudate and seed gums, seaweed extracts and, most recently, microbial polysaccharides, to improve product mouthfeel properties, handling, and stability characteristics. These hydrocolloids have been established as valuable food additives as a result of extensive practical experience with different products. Nevertheless, the last few years have produced much additional research data from sophisticated new analytical methods. Information on the fine structure of these complex molecules has given a tremendous insight into the three-dimensional conformation of hydro colloids and their behaviour in solution. Critical components within the biopolymer have been identified which provide particular thickening, suspending, stabilising, emulsifying and gelling properties. Contributions for this book have been provided by senior development managers and scientists from the major hydrocolloid suppliers in the US and Europe. The wealth of practical experience within this industry, together with chemical, structural and functional data, has been collated to provide an authoritative and balanced view of the commercially significant thickening and gelling agents in major existing and potential food applications.