Emulsification properties of pectin

Abstract

In this chapter, the efficacy of pectin as emulsifier and the structural components that influence its emulsification properties are discussed. The complex molecular structure of pectin makes the assignment of structure vs. function relationships particularly challenging. Nevertheless, around 3% protein with a minimum of 10% degree of acetylation is sufficient for effective arrangement of pectin at the oil-water interface and efficient long-term stabilisation. In addition, side chains present in the rhamnogalacturonan-I regions, provide effective barriers to emulsion coarsening through steric mechanisms whereas the degree of methylesterification appears to have ancillary role. Pectins with intermediate molecular weight (~150,000 g mol-1) are preferred, as smaller chains do not provide successful steric stabilisation whereas the high molecular weight counterparts with high viscosity restrict interfacial accessibility thus impeding fast adsorption of functional groups at the interface. Pectin may be described as a block co-polymer and depending on the botanical source and method of extraction it may be di-block, triblock, or grafted. Accordingly, theories that have been developed for co-polymer adsorption at interfaces may be used to theoretically analyse and treat experimental data.