Modified Starch-Chitosan Edible Films: Physicochemical and Mechanical Characterization

Abstract

Starch and chitosan are widely used for preparation of edible films that are of great interest in food preservation. This work was aimed to analyze the relationship between structural and physical properties of edible films based on a mixture of chitosan and modified starches. In addition, films were tested for antimicrobial activity against Listeria innocua. Films were prepared by the casting method using chitosan (CT), waxy (WS), oxidized (OS) and acetylated (AS) corn starches and their mixtures. The CT-starches films showed improved barrier and mechanical properties as compared with those made from individual components, CT-OS film presented the lowest thickness (74 ± 7 µm), water content (11.53% ± 0.85%, w/w), solubility (26.77% ± 1.40%, w/v) and water vapor permeability ((1.18 ± 0.48) × 10−9 g·s−1·m−1·Pa−1). This film showed low hardness (2.30 ± 0.19 MPa), low surface roughness (Rq = 3.20 ± 0.41 nm) and was the most elastic (Young’s modulus = 0.11 ± 0.06 GPa). In addition, films made from CT-starches mixtures reduced CT antimicrobial activity against L. innocua, depending on the type of modified starch. This was attributed to interactions between acetyl groups of AS with the carbonyl and amino groups of CT, leaving CT with less positive charge. Interaction of the pyranose ring of OS with CT led to increased OH groups that upon interaction with amino groups, decreased the positive charge of CT, and this effect is responsible for the reduced antimicrobial activity. It was found that the type of starch modification influenced interactions with chitosan, leading to different films properties.

Current Research and Applications of Starch-Based Biodegradable Films for Food Packaging

“…A comparison study focusing on the main and physical features of chitosan and altered starches of edible films was examined by Garcia et al [ 67 ]. The films’ arrangement was made using a casting strategy that utilises chitosan, waxy, oxidized, and acetylated corn, and their respective blends.…”

Vegetable Additives in Food Packaging Polymeric Materials

“…Starch is the most abundant and commonly used renewable, biodegradable natural resource, with recognized flexibility, transparency, and film-forming ability, but with low mechanical and barrier properties that are usually improved by mixing the starch with other polymers (e.g., chitosan) [168]. For example, previous studies have reported that the chitosan-starch blends exhibited an improved barrier and mechanical properties as well as good antimicrobial effect [169,170]. Alginate is a naturally occurring polysaccharide can be used in coating for extending the shelf-life of fruit, vegetable, meat, poultry, and film preparation [171].…”

Application of Industrially Produced Chitosan in the Surface Treatment of Fibre-Based Material: Effect of Drying Method and Number of Coating Layers on Mechanical and Barrier Properties

“…However, previous investigations such as influence of drying on barrier and strength properties were mostly performed using casted freestanding films. Furthermore, the cellulosic fibre based substrates that have been used for coating are laboratory-produced paper sheets, which serve as a model for possible industrial applications [29,30,31]. The results of already published work represent valuable basis for further development and practical applications of chitosan in surface treatment of fibre based packaging material presented in our work.…”