3D-Printed Bilayer Active Film with Anise Oil Nano-Emulsion and Carbon Quantum Dots for Shelf-Life Extension of Sugar Tangerines

This study developed a novel 3D-printed bilayer film (BF) embedded with star anise essential oil nanoemulsion (AEO-NE) and tamarind shell-derived carbon quantum dots (CQDs) for preserving sugar tangerines (Citrus reticulata Blanco). The BF comprised an outer chitosan-alginate-CQD barrier layer and an inner AEO-NE active layer, fabricated using dual-extrusion 3D printing. Results showed that BF-treated fruits had significantly lower weight loss (23.6% reduction) and decay rates (0% spoilage until day 10) compared to controls (p < 0.05). The film’s controlled release (31% AEO release over 15 days) and UV-blocking properties (CQDs) maintained fruit firmness, color stability (ΔE < 2.0), and sugar content (TSS increase of only 3.7%). Sensory evaluation confirmed BF’s superiority, with treated fruits retaining freshness for 15 days, while controls deteriorated rapidly. The study demonstrates that 3D-printed active films synergizing AEO and CQDs offer a sustainable, high-performance solution for citrus preservation, extending shelf life by 10–15 days.