Development and Characterization of Edible Films Based on Cassava Starch Modified by Corona Treatment

Abstract

Corona treatment (CT), a surface treatment widely used in the plastic industry, can be used to alter the properties of cassava starch. In the present work, CT was performed on dry granular starch (DS), water-suspended humid granular starch (HS), and gelatinized starch (GS). Different properties and structural characteristics of treated starches were studied. A lowering in pH was generally observed after CT and the rheological properties depended on the starch presentation. A reinforcement of DS and HS samples after CT was deduced from higher viscosity values in flow assays and viscoelastic moduli, but weak gels were obtained when CT was applied to GS. Changes in the A-type polymorphic structure, as well as a drop in relative crystallinity, were produced by CT for DS and HS. Additionally, changes in O-H and C-O-C FTIR bands were observed. Therefore, CT can be applied for starch modification, producing predominantly cross-linking in the DS and de-polymerization in the HS. Casting films made from the modified DS showed higher tensile strength and lower hydrophilicity, solubility, water absorption capacity, and water vapor permeability. Thus, the DS cross-linking induced by CT improved mechanical characteristics and hydrophobicity in edible films, which can be better used as packaging materials.

Effect of Ultrasound and Freeze‐Drying to Enhance the Extraction of Phenolic Compounds in Dragon Fruit Peels and Apply Them in Edible Starch‐Based Films

“…Single-layer films were produced by casting, following the protocol described by Otálora González et al [28]. An aqueous gelatinized solution of high-pressure-modified black rice starch (600 MPa/30 min), provided by Almeida et al [29], at a concentration of 5% (w/w), was employed as the base system.…”

“…One of the main constraints of starch-based films application is their predominantly hydrophilic nature, leading to high water transfer rates due to water molecule clustering and diffusion through microcavities [28]. Therefore, we also assessed the WVP of the produced films (Figure 4D).…”

“…This interaction results in the formation of a denser and less permeable structure, hindering the passage of water molecules through the film [55]. The relationship between WVP and solubility is related to the particles' ability to reduce the availability of water sorption sites in the film matrix, consequently decreasing its solubility and making it less prone to water absorption [28]. Values ranging from 4.32 × 10 −8 to 7.13 × 10 −8 g mm s −1 m 2 Pa were obtained by Saores and Santana [56] for chitosan films incorporating jatobá fruit peel extract (Hymenaea courbaril L.).…”