Preparation of a Pickering emulsion film loaded with essential oils extracted from chili pepper leaves and its application in the post-harvest preservation of fresh broccoli

This study developed a novel and green active film by incorporating chili pepper leaf essential oil (CPLEO)-loaded Pickering emulsion (stabilized by tremella polysaccharide) into chitosan/polyvinyl alcohol matrices via single factor trails and response surface methodology. Results demonstrate that composite film containing 1.5% CPLEO Pickering emulsion (1.5%TC-CP) had an 18.5 MP tensile strength, 280% elongation at break, 80° water contact angle, 2.0 g/m 2 /h water vapor permeability, and a smooth/dense structure with a thickness of 0.11 mm. The antioxidant activity was statistically significantly higher than that of the chitosan/PVA film ( p < 0.05), with DPPH and ABTS radical scavenging rates reaching 21.95% and 20%, respectively, and a FRAP value of 7.65 μmol/g. The developed film increased inhibition zone diameter by 50% against Listeria monocytogenes and 158% against Erwinia carotovora . During 10 days of storage at 4 ± 2 °C, broccoli packaged with 1.5%TC-CP film maintained a higher hardness value (72.32 vs. 47.20 N), but lower malondialdehyde content (10.98 vs. 15.60 nmol/g), and total viable count (6.18 vs. 6.41 lg CFU/g) compared to the blank control group. Additionally, the new film suppressed the transcriptional abundances of chlorophyll degradation genes (e.g., BoCLH2 by 12.53 fold) and thus delayed yellowing of broccoli. This work provides a novel strategy for valorizing agricultural by-products and developing biodegradable packaging for vegetable preservation.