Mixed Polymer Gels

Abstract

Food products very often include in their formulation more than one hydrocolloid to achieve the desired physical structure, perceived `eating quality' and behaviour during processing. Many such mixed systems behave as would be expected from the known properties of the individual polymers, as detailed in other chapters. In others, however, the properties of the blend are superior to those of either component alone or are qualitatively different. For example, some binary mixtures of gelling hydrocolloids give stronger gels than either of the individual polymers or, equivalently, give the same gel strength at a lower total concentration, with obvious cost advantages. More spectacularly, some polymers that are individually non-gelling will form gels on mixing. Such advantageous, non-additive behaviour is often described as `synergism', and forms the main topic of this chapter.