BIOPOLYMERS-BASED COMPOSITES TO PREPARE ACTIVE EDIBLE FILMS FOR FOOD PACKAGES AND COATINGS. THE NANOTECHNOLOGICAL APPROACHES

Biopolymers-based edible films and coatings are a promising approach for controlling the quality and extending the postharvest shelf-life of agricultural produce. To be applicable, edible coatings have to answer a long list of various requirements that single coating material is often unable to satisfy.

Natural polysaccharides were implemented for coating of various fresh fruit utilizing Layer-by-Layer (LbL) method. LbL approach is based on the alternate deposition of polymers and enables to control properties and functionality of edible coatings. The performance of the LbL coatings was compared with single-layer coatings and with a non-coated control. The LbL coating was found to possess the beneficial properties of all ingredients, combining good adhesion to food matrix of the inner polyanion layer with beneficial activity of the outer polycation layer. The LbL coating slowed down tissue texture degradation, prevented an increase in headspace CO₂ and ethanol the signs of hypoxic stress and off-flavor and effectively inhibited microbial spoilage allowing significant elongation of fruit shelf life.

Nanoemulsions were also utilized to incorporate active agent, food sourced citral, into a coating matrix. The properties and functionality of the nano-emulsified active edible films were compared to those of the coarse-emulsified films. Average droplet diameter of the citral emulsions was found to be 4000-5000 nm for coarse emulsions and 100-200 nm for nanoemulsions. The nano-emulsified films demonstrated improved mechanical properties (tensile strength, elongation at break and Young modulus) as compared to the corresponding coarse-emulsified films. The effect of active edible coatings on quality, storability and microbial safety of the food products was examined on fresh-cut melon model. Active coatings demonstrated improvement of physiological parameters of the fruit and reduction of the bacterial growth.