Designing biopolymer fluid gels: A microstructural approach

Fluid gels are suspensions of gelled particles whose elasticity and physical dimensions can be manipulated to impart a range of material properties. The formation and physical properties of fluid gels are discussed with the focus being on the process-structure relationship. Recent work in this area has led to the development of new techniques for the production of thermostable fluid gels. An overview is provided on these techniques which have been successfully employed to produce thermo-stable fluid gels from both alginate and proteins. An enhanced understanding of the molecular events occurring during fluid gel formation is outlined which has enabled greater control over the microstructure. This has allowed the production of small (< 10 mu m), spherical and reasonably soft particles which resemble oil droplets. These particles when used in emulsion based products to replace a significant proportion of the oil, show rheology matching that of the full fat original product. Increasing the volume fraction and elasticity of fluid gel particles has been shown to decrease the friction measured at the contact between the soft surfaces of a tribometer. This ability of fluid gel particles to provide lubrication through entrainment to the contact zone suggests that fluid gels have the potential to impart sensory attributes typically associated with fat. Directions for future research are also discussed which may provide further insights into food structuring and breakdown thereby assisting the design of more complex structures with novel functional attributes. (C) 2014 The Authors. Published by Elsevier Ltd.