Hydrocolloids as filmogenic material for edible coating use

Low methoxyl pectin in various conditions of ionic strength and pH, or in the presence of co-solvents has been used in coatings formulations. Soy isolate proteins has been eventually used in addition to hydrocolloids. Film-forming attitudes of the filmogenic pectin /soy protein solutions, the mechanical stability of coatings and physico-chemical stability and properties in terms of molecular mobility useful to predict barrier properties have been assessed. Solutions or weak gels obtained have been characterized for their rheological properties: flow behavior, tixhotropy, and eventually viscoelastic properties evaluated in dynamic testing mode. In order to get information on film/surface adhesion interfacial rheological properties, i.e. interfacial viscosity and elasticity, have been collected by means of an interfacial rheometer. Mechanical characteristics of dried films have been assessed in tension tests using a dynamometer. Films exposure to various Aw ambient conditions have been evaluated and modelled by means of the isothermal GAB fitting equation. Pectin results to be an interesting versatile biopolymer for food coating purposes, extremely adaptable by its controlling the structurization mode.