Biodegradable bioactive films based on sorghum starch and glycerol incorporated with jabuticaba (Plinia cauliflora) and jambolan (Syzygium cumini) peels extracts.

Abstract

Growing interest in renewable and biodegradable resources has encouraged industries to reduce reliance on petrochemical-based packaging. As an alternative, films developed from unconventional starch sources and fruit by-products have been explored. This study aimed to produce films from sorghum starch combined with jabuticaba and jambolan extracts from freeze-dried peels and to evaluate their physical, barrier, optical, thermal, mechanical, and biodegradation properties. Films prepared with sorghum starch were supplemented with glycerol and incorporated with jabuticaba (JT) or jambolan (JB) freeze-dried peels extracts. The formulations included control film (without extract) and films with added extract at concentrations of 5% (JT5% or JB5%) and 10% (JT10% or JB10%). Anthocyanin levels above 4.40 and 7.29 mg C3Geq 100 g-1 were detected in JT5% and JT10%, respectively. The highest luminosity (L* = 88.82) was observed in the control film. Extract-enriched films showed opacity values above 1.7. JT10% exhibited the greatest thickness (0.17 mm), while JB10% had the highest water solubility (22.36%). JT5% displayed the highest water vapor permeability (2.09 g·mm/h·m2·kPa). Extract addition did not influence puncture resistance, however, tensile strength decreased, with JB10% showing the lowest value (1.65 MPa). JT10% demonstrated the greatest flexibility, with 26.86% elongation at break. Scanning electron microscopy revealed no cracks but a more homogeneous surface in the control film. All films exhibited characteristic bands of starch-glycerol thermoplastics and fully degraded within 7 days. Overall, the films developed exhibited a combination of adequate mechanical performance, modified optical, and rapid biodegradation, supporting their potential use as materials for packaging food applications.