Chapter 13 - Food gels: Gelling process and new applications

Abstract

Food gels have been classified into different types based on different classifying parameters. A large number of protein and carbohydrate-based gels have a wide range of applications in the food industry as ingredients. Frequently used polysaccharides are natural gums, agar, carrageenan, alginate, glucomannan, starches, and pectin. At critical polymer concentration and at a certain degree of crosslinking, the polymer solution (dispersion) ultimately turns into a gel comprising of a firm network structure. While the food gels most commonly made from the proteins are gelatin, casein, whey protein, soy protein, egg protein, and zein. The gelation requires a certain degree of unfolding (denaturation or destabilization) of protein structure to increase the intermolecular interactions. This partial denaturation of proteins may be carried out through different means such as heat, pressure, enzymes, and some chemical denaturants. Binary or mixed gels may be composed of a combination of polysaccharide–polysaccharide or polysaccharide-protein due to the synergistic effect of polysaccharides. Rheological characterization of a gel may help to establish a relation between its constituents and structure, and the effect of processing on its structure. The modern rheometers are capable of accurately measuring the complex material’s response to applied stress or strain. The concept of microrheology has been established to describe how materials store and dissipate mechanical energy as a function of length scale.