Gellan gum fluid gels

Abstract

Gellan gum is a multifunctional hydrocolloid for use in a wide variety of food products as a gelling, texturizing, stabilizing, film forming, suspending and structuring agent. It can also be used, like other gelling agents, to prepare structured liquids, sometimes referred to as ‘fluid gels’. Fluid gel formation is commonly employed in the production of custards and gravies, the fluid mass being formed during homogenization or HTST/UHT processing. Fluid gels are particularly useful for suspending dispersed materials, for example herbs and spices in pourable dressings. In contrast to other gelling agents, gellan gum is functional at very low use levels and is capable of forming gels with all ions presented to it. For foods, sodium, calcium and hydrogen ions are frequently used, texture, setting point and melting point being dependent on the types of ions present and their concentrations. Because of its versatility and efficacy, gellan gum is an extremely interesting gelling agent to study in the context of fluid gels. A method has been developed using a Bohlin VOR rheometer in which gellan gum fluid gel systems are prepared by cooling during application of a constant shear rate. Then, without disturbing the sample, structure development is determined using oscillatory shear measurements. Using this method, the influence of ionic environment and gellan gum concentration on the transition temperature, viscosity and structure development in the fluid gel systems has been studied. A comparison between effects in fluid gels and quiescent gels has also been made.