Innovations, Trends, and Future Directions in Edible Films and Coatings

1. Foundational Role of Edible Films and Coatings in Food Preservation

Edible films and coatings are thin, ingestible layers produced from biopolymers such as polysaccharides, proteins, and lipids, often combined with plasticizers and bioactive compounds. When applied to the surface of foods, they act as semipermeable barriers that modulate the transfer of gases, water vapor, and solutes between the product and its environment, thereby slowing down respiration, moisture loss, oxidation, and microbial growth [2,3,4,6].

For climacteric fruits and other highly perishable commodities, EFCs are now recognized as one of the most promising tools to extend shelf life while preserving firmness, color, aroma, and nutritional attributes [3,4,5,6]. Recent reviews have shown that appropriately designed coatings can delay senescence and quality degradation in stone fruits and subtropical fresh or fresh-cut fruits, offering an alternative or complement to controlled atmosphere and refrigeration [3,4]. At the same time, broad analyses of postharvest chains emphasize that fruit and vegetable losses can still reach substantial proportions of prouction, underscoring the need for cost-effective and scalable coating strategies [13].

The application of EFCs has also expanded beyond whole and fresh-cut fruits and vegetables (F&Vs) to include minimally processed products, ready-to-eat meals, and meat and muscle foods, where safety, texture, and sensory acceptance are critical [14,15]. In these matrices, coatings must not only control mass transfer but also interact with complex surfaces, processing steps, and storage conditions.

2. Materials, Structure, and Functionality

The performance of EFCs is determined by the intrinsic properties of their primary film-forming components and the way these components are combined and structured [1,2,3,14,15]. Polysaccharide-based systems such as chitosan, alginate, starch, pectin, or cellulose derivatives generally provide good oxygen and aroma barrier properties but limited resistance to water vapor. Chitosan, in particular, is valued for its intrinsic antimicrobial activity and good film-forming behavior [2,15]. Recent work has also emphasized its potential as a platform for loading plant extracts and essential oils in the context of the Sustainable Development Goals [16]. Lipid-based components (waxes, fatty acids, and oils) contribute excellent moisture barriers and can significantly reduce weight and frying oil uptake, but typically require a combination with hydrophilic polymers to avoid brittleness and poor mechanical performance. Protein-based films (e.g., gelatin, casein, and whey proteins) often exhibit good gas barrier properties and flexibility, but their hydrophilic nature also limits water vapor resistance [1,2,3].

Recent reviews emphasize that the most effective EFCs increasingly rely on composite and multilayer structures that combine polysaccharides, proteins, and lipids, sometimes reinforced with nanostructured fillers [2,14,17,18]. These architectures have the capacity to decouple gas and moisture transport from mechanical stability and offer a platform for the integration of active functions, such as antioxidant or antimicrobial protection [1,2,3,17,18]. Consequently, incorporating plant extracts, essential oils, organic acids, and other bioactive molecules has become central to the development of “active” EFCs that actively improve safety and quality rather than merely serving as passive barriers [1,2,3,6]. However, the release kinetics, stability, and sensory impact of such bioactive compounds must be carefully controlled to avoid off-flavors, discoloration, or negative consumer perception [1,2,3].

3. Smart and Nanostructured Systems

A second major trend is the convergence between EFCs and nanotechnology [2,17,18]. Nanoparticles and nanofibers, including metal and metal-oxide nanoparticles, nanoclays, and cellulose nanostructures, can substantially enhance mechanical strength, barrier performance, and, in some cases, antimicrobial activity [2,14,17,18]. At the same time, nanostructured carriers (such as nanoemulsions) enable the protection and controlled release of hydrophobic bioactive compounds, including essential oils and lipophilic antioxidants [1,2,3]. Recent dedicated reviews on nano-edible coatings for fruits and vegetables further illustrate how nanostructured carriers and fillers can be tailored to specific commodities and spoilage pathways [7].

Beyond reinforcement, nanomaterials and nanosensors also support the development of smart EFCs and intelligent packaging, capable of responding to changes in pH, gases, or volatile compounds and providing real-time information on product status [17]. These systems open new opportunities to link quality monitoring to preservation strategies, but they also raise important questions regarding regulatory evaluation, migration, long-term safety, and public perception. In most cases, these regulatory and perception challenges are directly linked to the incorporation of nanostructured ingredients, which, despite their clear functional benefits, still suffer from uncertainty in toxicological assessment and labeling requirements [17,18]. Recent work on smart EFCs underlines that such questions must be addressed in parallel with materials development if these solutions are to reach large-scale commercial adoption [17].

4. Insights from the Special Issue Contributions

The six contributions in this Special Issue exemplify how these general trends translate into concrete material designs, target applications, and methodological innovations [8,9,10,11,12].

Macieja et al. investigated the effect of melanin on the stability of casein films exposed to artificially accelerated ultraviolet (UV) aging [8]. By introducing melanin into casein-based films, the authors demonstrated improved resistance to UV-induced degradation, including changes in color, mechanical properties, and chemical structure. This work illustrates how bioinspired pigments can endow protein-based films with added photoprotective functions, thereby enhancing their potential as sustainable packaging materials.

Boninsegna et al. evaluated ready-to-eat clementine (Citrus × clementina) segments coated with different edible formulations [9]. Their study showed that appropriate coatings can slow the metabolic activity of citrus segments, maintaining acidity, color, and sensory quality during refrigerated storage. The work offers a clear example of how EFCs can support the growing demand for convenient, minimally processed fruit products, while mitigating quality losses and extending distribution windows [9,14,15].

Lengowski et al. developed unbleached nanofibrillated cellulose (NFC) as an additive and coating for kraft paper [10]. Using NFC obtained from unbleached fibers, they improved the mechanical strength and barrier properties of paper substrates without resorting to conventional synthetic coatings. This approach contributes to the broader transition from fossil-based packaging to bio-based systems and highlights the relevance of cellulosic nanomaterials as functional components in coating formulations [10,17,18].

Nascimento et al. proposed nanocellulose–tocopherol edible coatings to protect Brazil nuts against lipid oxidation [11]. By combining nanocellulose as a structuring matrix with tocopherol as a lipophilic antioxidant, the authors demonstrated significant improvements in oxidative stability during storage. The study underscores the potential of EFCs not only to manage moisture and gas transfer but also to directly stabilize sensitive lipids, thus reducing rancidity and preserving nutritional quality.

Acuña-Pacheco et al. designed and characterized an alginate–chitosan-active bilayer film incorporating asparagus (Asparagus officinalis L.) residue extract [12]. Their bilayer system exploits sodium alginate and chitosan as complementary polysaccharides and valorizes asparagus processing residues as a source of phenolic compounds with antioxidant and antibacterial activity. The results show that films containing 1% residue extract offer a favorable balance between mechanical, optical, and bioactive properties, while higher loadings may compromise film integrity. This work exemplifies how EFC research can align with agri-food waste valorization and circular-economy goals.

Finally, Dávalos-Saucedo et al. introduced a microfluidic strategy for producing edible coatings, integrating multiphase Volume-of-Fluid (VOF) modeling, physicochemical characterization, and image analysis, with applications in fried foods [19]. Using a flow-blurring microfluidic atomization approach, the authors demonstrated precise control over droplet size distributions and coating deposition on complex fried matrices. Their study connects computational fluid dynamics with experimental coating performance, offering a powerful framework to optimize oil uptake reduction, texture, and appearance in fried products [16]. This contribution also shows how microfluidic tools can accelerate the rational design and scale-up of EFCs for industrial processes.

Collectively, these six articles cover a continuum from fundamental materials science (casein–melanin films, NFC-based papers) to application-driven systems for ready-to-eat fruits, lipid-rich nuts, and fried foods, as well as bioactive bilayers that valorize vegetable residues [8,9,10,11,12,19]. They collectively highlight that future progress will depend on coordinated advances in formulation, processing, modeling, and application-specific validation.

5. Challenges and Remaining Knowledge Gaps

Despite rapid progress, several challenges remain. A primary concern is that many studies still focus on laboratory-scale formulations and short-term storage trials under controlled conditions that may not fully represent heterogeneous industrial supply chains [2,5,14]. In our view, there is a clear need for more longitudinal, multifactorial studies that integrate variable temperature, humidity, mechanical handling, and realistic logistics scenarios, especially for emerging markets where cold-chain infrastructure is limited [2,5].

Moreover, standardization and comparability remain limited. Differences in film thickness, application method (dipping, spraying, casting, or microfluidic atomization), and evaluation protocols complicate direct comparison across studies [3,6,14,19]. Harmonized methodologies for measuring key properties—such as water vapor permeability, oxygen transmission, mechanical strength, release kinetics of active compounds, and sensory acceptance—would significantly improve the robustness and transferability of research outcomes [2,3,6,18].

Beyond technical hurdles, the rapid incorporation of nanomaterials and smart sensing elements requires clear regulatory frameworks and risk assessment protocols [17,18]. While several studies report promising barrier and antimicrobial enhancements, questions remain regarding migration, accumulation, and long-term impact on human health and the environment. Addressing these concerns transparently is essential for consumer trust and for the adoption of next-generation EFCs in sensitive markets such as baby food, organic products, and minimally processed produce [5,17,18].

Ultimately, consumer acceptance and communication must be integrated early in the development pipeline. Even when EFCs demonstrably improve shelf life and reduce waste, skepticism can arise if consumers perceive coatings, nanomaterials, or bioactive additives as “artificial” or unnecessary [1,3,17]. Clear labeling, education about benefits, and sensory-driven product design are, therefore, key elements for successful commercialization.

6. Future Directions

Looking forward, several converging lines of research appear particularly promising. One is the development of multifunctional bio-nanocomposites, where biopolymer matrices are combined with natural fibers, nanocellulose, functionalized nanoparticles, and encapsulated bioactives to achieve tailored barrier, mechanical, and active properties [2,10,12,15,18,20]. Another priority is advanced fabrication and application technologies, including microfluidic spraying, flow-focusing or flow-blurring atomizers, and in-line coating processes compatible with existing industrial equipment [19]. These tools can provide fine control over coating thickness, droplet size, and surface coverage, enabling more efficient use of materials and more consistent product performance.

There is also growing interest in data-driven and model-based design, where computational fluid dynamics, transport modeling, and statistical learning are used to link process parameters, coating microstructure, and functional outcomes such as oil uptake, firmness, and oxidative stability [6,18,19]. Such approaches can reduce trial-and-error experimentation and accelerate optimization.

Finally, EFCs are likely to play an increasingly important role in circular and climate-resilient food systems, by reducing waste, enabling the use of underutilized crops and by-products, and decreasing reliance on non-biodegradable packaging [1,2,3,4,5,12,21]. The contributions assembled in this Special Issue illustrate how fundamental materials research, process innovation, and application-oriented studies can be combined to move from conceptual promises to tangible, scalable technologies [8,9,10,11,12,19]. Continued collaboration among food scientists, materials engineers, microfluidics and process engineers, industry stakeholders, and regulators will be crucial to fully realize the potential of edible films and coatings in the coming decade.