Effect of Surface Density on the Engineering Properties of High Methoxyl Pectin-Based Edible Films

The effect of pectin surface density (rho (s)) on the engineering properties of high methoxyl (HM) pectin-based edible films was determined in order to explore the role of rho (s) on structure and functional properties. Films at different rho (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 kPo(2,) carbon dioxide permeability kP(CO2)) properties. Microscopy, thermal, and mechanical results showed that by increasing rho (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 rho (s), WVP increased with the rise in rho (s) while kP(O2) and kP(CO2) decreased. On the whole, HM pectin-based film showed barrier properties comparable to biodegradable commercial film and low selectivity.