Biodegradable films based on commercial κ-carrageenan and cassava starch to achieve low production costs.

Biodegradable films have been a great alternative compared to non-renewable sources because of their cytocompatibility, biodegradability, and antimicrobial features. These properties may raise the foodstuff shelf life, reducing costs and economic losses. Indeed, biodegradable films can also reduce the environmental pollution promoted by non-biodegradable conventional packs. For the first time, biodegradable films were produced by casting commercials kappa-carrageenan (κ-car) and cassava starch at different κ-carrageenan/cassava starch weight ratios. Physical, thermal, and mechanical properties were evaluated. Apparent opacity and color analyses suggest that the films present high transparency. The sample 0κ-c supported a film with high water solubility (39.22%) and a low swelling degree (391.6%). The lowest water vapor permeability (WVP) was observed for 50κ-c (3.01×10-8g (Pams)-1). The oil permeability varied from 0.0033 to 0.0043mmm2 d-1. The 100κ-c and 75κ-c films (with high κ-carrageenan contents) had higher stiffness (19.23 and 25.88MPa, respectively) than the 25κ-c and 0κ-c films with elongation at break (ε) of 21.60 and 67.65%, respectively. The thermal stability increased as the starch concentration raised in the blend. We produced low-cost biodegradable films from commercial polysaccharides. These films can be used as food packs.

Durable pectin/chitosan membranes with self-assembling, water resistance and enhanced mechanical properties.

Processing water-soluble polysaccharides, like pectin (PT), into materials with desirable stability and mechanical properties has been challenging. Here we report a new method to create water stable and mechanical resistant polyelectrolyte complex (PEC) membranes from PT and chitosan (CS) assemblies, without covalent crosslinking. This new method overcomes challenges of obtaining stable and durable complexes, by performing the complexation at low pH, enabling complex formation even when using an excess of PT, and when using PT with high degree of O-methoxylation. By performing the complexation at low pH, the complexes form with a high degree of intermolecular association, instead of forming by electrostatic complexation. This method avoids precipitation, and overcomes the aqueous instability typical of PT/CS complexes. After neutralization, the PEC membranes display features characteristic of a high degree of intermolecular association because of the self-assembling of polymer chains. The PT/CS ratio can be tuned to enhance the mechanical strength (σ = 39 MPa) of the membranes. These polysaccharide-based materials can demonstrate advantages over synthetic materials for technological applications.