Effect of Surface Density on the Engineering Properties of High Methoxyl Pectin-Based Edible Films
The effect of pectin surface density ( ρ s ) on the engineering properties of high methoxyl (HM) pectin-based edible films was determined in order to explore the role of ρ s on structure and functional properties. Films at different ρ s values (2.5, 3.2, 3.8, 4.5, 5.1, 5.8 mg cm −2 ) were analyzed by means of microscopy, thermal, mechanical, and barrier (water vapor permeability WVP, oxygen permeability $$ \textkP_\textO_2 $$, carbon dioxide permeability $$ \textkP_\textCO_2 $$) properties. Microscopy, thermal, and mechanical results showed that by increasing ρ s from 2.5 to 5.8 mg cm −2 , the film structure does not change. HM pectin-based film has a tensile strength of 20 ± 7 MPa and an elastic modulus ( E ) equal to 2,400 ± 200 MPa. However, it is quite brittle as the elongation to break ( e ) is close to 1%. Although the film structure was unaffected by ρ s , WVP increased with the rise in ρ s while $$ \textkP_\textO_2 $$ and $$ \textkP_\textCO_2 $$ decreased. On the whole, HM pectin-based film showed barrier properties comparable to biodegradable commercial film and low selectivity.