ACTIVE PACKAGING SYSTEM USING A PAPERBOARD TRAY COATED WITH ESSENTIAL OIL TO EXTEND THE SHELF LIFE OF SLICED BREAD

Bread spoilage caused by filamentous fungi is a major factor limiting product stability and increasing food waste. Active packaging containing natural bioactive compounds represents a promising strategy to delay fungal growth while reducing the use of conventional preservatives. Lemongrass essential oil (LEO) exhibits antifungal activity; however, its incorporation into packaging requires an appropriate matrix to improve system stability and control the release of volatile compounds. This study aimed to develop and evaluate a chitosan–carnauba wax active packaging system containing LEO to delay fungal spoilage of sliced bread. Different LEO incorporation strategies were initially investigated in a 1% (w/w) chitosan film-forming system, including direct incorporation, encapsulation, and incorporation into a lipid matrix. Based on formulation performance, a system containing 1% chitosan, 1% carnauba wax, and 20% LEO (w/w), applied as a three-layer coating onto paperboard, was selected for evaluation in sliced bread. Three treatments were evaluated: uncoated paperboard (Control), paperboard coated with chitosan–carnauba wax without LEO (T1), and paperboard coated with chitosan–carnauba wax containing 20% LEO (T2). In all treatments, paperboard was placed in direct contact with the bread as the inner packaging component inside a polyethylene (PE) bag. Fungal deterioration (visual analysis), water activity (aw; n = 9), color (CIELAB, D65, 10°; n = 9), and instrumental texture (TPA; n = 15) were monitored during storage at 23 ± 2 °C and 50 ± 2% relative humidity. Data were subjected to ANOVA followed by Tukey’s test at a 5% significance level (p < 0.05). Visible fungal deterioration was observed by day 7 in the Control and T1, whereas T2 remained free of visible fungal deterioration. From day 8 onward, only T2 was further monitored and remained free of visible fungal growth through day 12, corresponding to a 5-day extension of the visible fungal-free period compared with the Control. Water activity remained within a narrow range (0.91–0.94), although significant differences (p < 0.05) occurred at some storage points. Significant differences (p < 0.05) were also observed for color parameters and instrumental firmness among treatments and/or storage times. The LEO-containing treatment showed more negative a* values and higher b* values at selected storage times, indicating changes in green–yellow color components. Firmness generally increased during storage, indicating progressive bread hardening, with T2 showing high firmness at the end of storage. Overall, LEO incorporation into the chitosan–carnauba wax matrix enhanced active packaging performance and maintained bread free of visible fungal deterioration through day 12. These findings demonstrate the potential of LEO as a natural bioactive compound in active packaging based on bio-based materials. The authors gratefully acknowledge the São Paulo Research Foundation (FAPESP, Grant No. 2025/07349-6) for financial support.