Layer-by-Layer Application of Edible Coatings in Postharvest Handling of Horticultural Crops

Layer-by-layer (LbL) electrostatic deposition is a process that consists of the dipping of food into solutions that contain oppositely charged compounds. This technique is employed to enhance the performance of edible coatings. These coatings may comprise bilayers, multilayers, repeated LbL units and a wide variety of components. Several studies have shown the successful application of edible coatings using LbL deposition of chitosan, sodium alginate, pectin, carboxymethylcellulose, calcium chloride, calcium lactate, pullulan and mucilage on horticultural crops. However, this technique can be limited by the lack of chemical affinity between selected molecules; therefore, molecule selection choice is important in the LbL method. This chapter highlights the main function of LbL edible coatings as an encapsulation matrix that prevents food products from being damaged by reactive oxygen species (ROS). Furthermore, the dominant use of chitosan is recognized due to its antimicrobial, antioxidant, nontoxic, biodegradable and film-forming potential. Overall, this chapter reveals the capability of LbL edible coating to prolong shelf life, enhance physicochemical and phytochemical qualities, improve appearance and inhibit microbial attack. It also highlights the major drawbacks of this technique, including mechanization and lack of knowledge on the barrier properties of coatings.