Physical-chemical properties of alginate/chitosan composite films containing natamycin as antimicrobial agent

摘要

The physical-chemical properties of alginate/chitosan composite films containing natamycin as antimicrobial agent were evaluated. Composite films with two different mass proportions of alginate and chitosan, 82.5:17.5 and 65:35, were obtained by casting. The film formulations received natamycin (0, 4 and 8 g/100g biopolymer) as antimicrobial agent. Films without and with natamycin were characterized according to their thickness, equilibrium moisture content, soluble matter in water, water vapor permeability, swelling degree, mechanical properties, morphology and glass transition temperature. Composite films with 17.5% chitosan, containing 8 g natamycin/100g biopolymer were 63 μm thick and showed the following characteristics: moisture content of 0.20 g H_2O/g film, soluble matter in water of 0.23 g/g dry matter, a swelling degree of 1.27 g H_2O/g film, water vapor permeability coefficient 6.39 g.mm/m~2.day.kPa, tensile strength of 64.5 MPa and elongation at break of 11.99 %. The tan δ curve showed two glass transition temperatures corresponding to the alginate and chitosan fractions. Composite films added with natamycin obtained in the present study exhibit suitable functional attributes and show good perspectives for acting as antimicrobial films intended for food applications.