# Synergistic effects of Malva sylvestris gum and chitosan in bilayer films: Optimizing physical and functional properties with Salvia abrotanoides essential oil

## TL;DR

Researchers created edible films using Malva sylvestris gum and chitosan, and found that adding Salvia abrotanoides essential oil improved their physical and functional properties for packaging.

## Contribution

The novel contribution is the synergistic use of Malva sylvestris gum, chitosan, and Salvia abrotanoides essential oil to optimize bilayer films for packaging applications.

## Key findings

- Adding Salvia abrotanoides essential oil significantly reduced moisture content and solubility while increasing thickness.
- Essential oil improved thermal stability, antioxidant activity, and elongation at break in the bilayer films.
- SEM and FTIR confirmed strong interactions in the films, and DSC showed reduced Tg and increased Tm with essential oil.

## Abstract

This study developed edible bilayer films from Malva sylvestris gum (MSG) and chitosan (CH), with a focus on incorporating Salvia abrotanoides essential oil (EO) as a bioactive additive. EO addition remarkably decreased moisture content from 0.096 ± 0.028 to 26.08 ± 0.15, solubility from 65.84 ± 0.54 to 31.45 ± 0.19, while thickness increased significantly from 0.096 ± 0.028 to 0.118 ± 0.09 for MSG/CH and MSG/CH-2 %EO, respectively. Color and optical characteristics were determined. SEM images revealed film's microstructure and FTIR analysis evaluated chemical interactions within polymer matrix. Differential scanning calorimetry revealed a reduction in Tg, from 27 °C (MSG/CH) to 10.8 °C (MSG/CH-2 %EO), indicating enhanced chain mobility. Mechanical evaluation showed a decrease in tensile strength (12.5 to 5.1 MPa) but an improvement in elongation at break (12.2 % to 18.6 %) (p < 0.05). Antioxidant evaluation demonstrated a significant rise in DPPH scavenging activity at 2 % EO in bilayer films. These findings highlight EO-incorporated MSG/CH films as a promising biodegradable packaging material with enhanced functional properties.

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•Malva sylvestris gum-chitosan (50:50) films showed balanced mechanical strength and barrier properties for packaging.•The incorporation of Salvia abrotanoides EO improved thermal stability, antioxidant activity, and elongation at break while reducing moisture content and transparency.•SEM and ATR-FTIR analyses confirmed strong hydrogen bonding and electrostatic interactions, representing compact and cohesive bilayer films.•Differential scanning calorimetry revealed EO incorporation reduced Tg via plasticization and increased Tm through crystalline reinforcement.

Malva sylvestris gum-chitosan (50:50) films showed balanced mechanical strength and barrier properties for packaging.

The incorporation of Salvia abrotanoides EO improved thermal stability, antioxidant activity, and elongation at break while reducing moisture content and transparency.

SEM and ATR-FTIR analyses confirmed strong hydrogen bonding and electrostatic interactions, representing compact and cohesive bilayer films.

Differential scanning calorimetry revealed EO incorporation reduced Tg via plasticization and increased Tm through crystalline reinforcement.