Cinnamaldehyde nanoemulsion-loaded pectin films for delaying quality deterioration of fresh-cut chili pepper during refrigerated storage: Influence of pectin esterification and nanoemulsion concentration

Abstract

The objective of this study was to fabricate antibacterial pectin-based active films activated with trans-cinnamaldehyde delivered through a nanoemulsion system. A whey protein isolate-inulin complex-stabilized nanoemulsion was incorporated into high-methoxyl pectin (HMP) and low-methoxyl pectin (LMP) matrices at four levels (0, 5, 17.5, and 30% w/w). The film morphology, physicochemical properties, trans-cinnamaldehyde retention, and antibacterial activity against Enterobacter cloacae were systematically investigated. Average droplet diameter and ζ-potential of the nanoemulsion were 162.77 ± 1.07 nm and − 30.08 ± 0.48 mV, respectively. Hydrogen bonding, electrostatic forces, and hydrophobic associations synergistically facilitated the assembly of a compact film network. Increasing emulsion content significantly enhanced surface hydrophobicity, water vapor and ultraviolet shielding capacity, and antibacterial efficacy. Films based on HMP exhibited superior UV-blocking performance, enhanced hydrophobicity, more controlled release of trans-cinnamaldehyde, and stronger antimicrobial activity. Furthermore, HMP-based active films effectively maintained visual quality and delayed firmness loss in fresh-cut chili peppers throughout refrigerated storage. Collectively, the fabricated trans-cinnamaldehyde-loaded pectin films demonstrated great potential as antibacterial active packaging for perishable vegetables.