ε-Poly-L-lysine/rhamnolipid bifunctional coating based on green electrostatic assembly technology for fruit packaging and preservation

Fresh fruits and vegetables are highly susceptible to spoilage, resulting in significant unavoidable waste during harvesting, transportation, and storage. The development of coatings with antimicrobial and antifogging properties has paramount importance for extending the shelf-life of these perishable products. In this study, a multifunctional food packaging composite coating (PRL) was developed by incorporating ε-poly-L-lysine (ε-PL) and rhamnolipid (RL) through a convenient and environmentally friendly electrostatic self-assembly process. The resulting PRL coating exhibited antimicrobial, antifogging transparency and biodegradability properties. The exceptional antimicrobial and fogging effects of PRL could be attributed to the synergistic effects of ε-PL and RLs. In antifogging tests, PRL demonstrated outstanding antifogging performance due to its unique structure. Furthermore, in antimicrobial tests, PRL at a concentration of 0.8% had an inhibition rate of 99% against Escherichia coli, 95% against Staphylococcus aureus and 98% against Botrytis cinerea and could effectively extend the storage time of various fresh fruits. Using strawberries as a model fruit, a preservation film containing 0.8% PRL effectively maintained the firmness and colour of the strawberries and reduced their weight losses. Compared with that of the control group (CK), the storage time of the strawberries was extended by three days. Therefore, the PRL multifunctional coating has significant potential for application in fresh fruit and vegetable packaging and provides a promising solution to effectively reduce waste and increase shelf life.