Konjac glucomannan/apple pectin-based nanocomposite coating with dual-precursor-derived carbon dots for antibacterial activity and fresh-cut kiwifruit preservation

The short shelf life and high susceptibility to spoilage of fresh-cut fruits present a major challenge for the food industry. To address this, D-glutamic acid-functionalized Forsythia suspensa carbon dots (D/F-CDs) were synthesized via a hydrothermal method. The obtained D/F-CDs exhibited abundant surface functional groups and optical properties. Antibacterial assays revealed potent activity, with inhibition rates exceeding 90% against Escherichia coli (E. coli) and 96% against Staphylococcus aureus (S. aureus) at 10 mg/mL. Mechanistic studies indicated that the bactericidal action originated from membrane disruption and cytoplasmic leakage. By incorporating D/F-CDs into a konjac glucomannan (KGM) and apple pectin (AP) matrix, an antimicrobial coating (D/F-CDs@KGM/AP) was prepared. Furthermore, rheological measurements demonstrated that D/F-CDs treatment altered the viscosity and viscoelastic moduli. The D/F-CDs 3 @KGM/AP coating not only effectively maintained the moisture and overall quality of fresh-cut kiwifruit during storage but also kept the total viable count (TVC) at only 4.73 log CFU/g on day 9. Consequently, the D/F-CDs 3 @KGM/AP coating represents a promising antibacterial strategy for maintaining the quality of fresh-cut kiwifruit.