Active Starch Films Incorporated with Citrus Essential Oils: Properties, Bioactivity, and Biodegradability

The demand for sustainable food preservation has driven the development of biodegradable alternatives to conventional, petroleum-based plastics. This study developed and evaluated bioactive starch-based films incorporated with citrus peel essential oils (lemon, orange, and tangerine) at concentrations ranging from 0.5% to 2% (w/w). The physical, chemical, mechanical, and antimicrobial properties of all film formulations containing 0.5–2% (w/w) essential oils were evaluated. Based on the experimental design, only the selected formulations containing 1 and 2% essential oils were subjected to structural and thermal characterization (XRD, SEM, FTIR, and TGA/DTG), transparency measurements, soil biodegradation, and phytotoxicity assays. FTIR spectroscopy revealed that oil incorporation did not alter the characteristic chemical bands of starch, indicating predominantly physical interactions. The essential oils modulated the physical and mechanical performance of the films. The films containing lemon and tangerine essential oils exhibited superior antimicrobial activity against foodborne pathogens. Furthermore, soil biodegradation was concentration-dependent, with mass loss exceeding 50% within 15 days, while phytotoxicity tests confirmed the environmental safety of the degraded residues. These findings demonstrate that the developed citrus-infused starch films hold great promise as active biodegradable packaging to extend the shelf life of bakery products and mitigate plastic waste.