Development of Pectin and Sodium Alginate Composite Films with Improved Barrier and Mechanical Properties for Food-Packaging Applications †

Abstract

The rate of plastic deterioration is currently significantly outpacing the rate at which plastic waste is being produced, leading to a biome-wide imbalance. Biopolymers derived from sustainable raw materials are widely explored as potential alternative packaging materials to increase the shelf-life of fresh produce and processed food. The present work aims to develop polysaccharide-based composite films. Sodium alginate- and castor oil-blended pectin films were developed as per the 23 (two-level three-factor) factorial design of experiments. Sodium alginate was used as a stabilizer and film-forming agent to enhance the mechanical properties of the films. Castor oil was used as an additive to improve the moisture barrier and antimicrobial properties. D-sorbitol was used as a plasticizer to improve the flexibility of the films. The amounts of sodium alginate (25% and 50% w/w), castor oil (10% and 15% w/w), and D-sorbitol (15% and 30% w/w), with respect to pectin, and the sonication time were chosen as the four factors. Based on our prior optimization studies, all other process variables, such as pH (<4), drying temperature (60 °C), and humidity (40%), were maintained constant. The moisture barrier, mechanical, surface hydrophobicity, morphological, thermal stability properties, and biodegradability characteristics of each film were studied. All films were thin (~0.110 ± 0.004 mm) and transparent (ΔΕ = 3 to 11). The moisture barrier properties improved three-fold compared to pure pectin films. The elongation at break increased at least three times. The films were thermally stable at 400 °C. The melting point of the films increased to 150 °C, compared to 95 °C of the pure pectin film.