Advances in biopolymer nanocomposite edible coatings for postharvest preservation

Global postharvest losses of fresh horticultural produce currently range from 30% to 50% of total harvested volume. This significant wastage primarily results from intense postharvest metabolic activity, rapid physiological senescence, and high vulnerability to fungal and bacterial decay throughout cold chain storage and commercial distribution. In response to the environmental impact of synthetic non-biodegradable packaging and conventional chemical postharvest dips, the development of biopolymer-based nanocomposite edible coatings offers a sustainable and high-precision technological alternative.

Internal atmosphere modification and water barrier enhancement

The review details how incorporating nanomaterials into biopolymer matrices—derived from polysaccharides (chitosan, starch, alginate), proteins (zein, whey protein isolate), and lipid fractions—substantially alters the physical performance of coatings. When applied to fruit cuticles, the film forms a semi-permeable barrier that restricts gas exchange, decreasing internal oxygen (O2) concentrations while elevating carbon dioxide (CO2) levels. This altered gas composition directly depresses cellular respiration rates and suppresses ethylene biosynthesis, effectively slowing enzymatic pathways involved in flesh softening and chlorophyll degradation.

Simultaneously, the integration of nanoscale reinforcements—such as inorganic zinc oxide (ZnO) and silver (Ag) nanoparticles, or organic nanofillers like cellulose nanocrystals—increases the structural tortuosity of the biopolymer network. This "tortuous path" impedes the diffusion of water vapor molecules, resulting in a dramatic reduction of the water vapor transmission rate (WVTR) and minimizing weight loss caused by transpirational desiccation.

Active antimicrobial mechanisms and food safety regulations

Beyond physical barrier capabilities, the study highlights the integration of active functional additives into nano-coatings. Incorporating essential oils encapsulated within nanoemulsions and botanical extracts facilitates a controlled release of active compounds. These bioactive agents disrupt pathogen cell membranes via targeted generation of reactive oxygen species (ROS) and enzyme inhibition, effectively preventing postharvest decay.

Finally, the review thoroughly addresses the food safety dimensions of nano-coatings. It evaluates nanoparticle migration dynamics from the coating matrix into edible tissues and analyzes current regulatory frameworks set by the FDA and EFSA. Establishing clear toxicological thresholds remains vital to guarantee safe commercial adoption across international postharvest supply chains.

Source

Abdulraheem, M. I., Mukaila, Y. O., Pérez-Alvarez, M., Cadenas-Pliego, G., & Fawole, O. A. (2026). Biopolymer-Based Nanocomposite Edible Coatings for Postharvest Preservation of Horticultural Crops: Mechanisms, Functional Additives, and Safety Perspectives. Polymers, 18(21), 2680.