Water vapor sorption and permeability of sustainable alginate/collagen/ SiO2 composite films

Abstract

Films based on polysaccharides and proteins have been widely studied as possible substitutes for food packaging from fossil sources. However, its notorious sensitivity to water is still one of the primary drawbacks. In this study, sodium alginate (SA) and hydrolyzed collagen (HC) blend films containing SiO2 nanoparticles were prepared to reduce the water sensitivity. The behavior of these films regarding water vapor sorption and permeability (WVP) was reported for nano-SiO2 concentrations ranging from 2 to 10%. At each concentration evaluated, several classical mathematical models of moisture sorption isotherms were adjusted to identify the mechanisms of interactions between films and water. A reduction of approximately 8% in the film water content, and 30% reduction of WVP were observed for concentrations of nano-SiO2 higher than 6%. In addition, it was exposed that the moisture sorption exhibited a type III isotherm behavior, suggesting reduced interactions between the polymeric matrix and water vapor at low water activity. Therefore, SA/HC/SiO2 composite films could represent a simple, economical and sustainable alternative for packaging material with reduced sensitivity to water vapor.