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1. Introduction

The increasing global production of plastic waste, caused by rising consumer demand and increasing industrial activity, has become a major environmental challenge ^[1]. Therefore, there is an urgent and growing need for sustainable, biodegradable, and environmentally friendly packaging solutions that can effectively replace conventional plastics in food packaging and other applications ^[2][3]. In response to this global concern, extensive research has been conducted to develop biopolymers and natural materials from renewable resources that offer potential pathways to environmentally friendly packaging options that are in line with the principles of sustainability and the circular economy ^[4][5] Promising candidates for sustainable packaging materials include polysaccharides, a diverse class of natural biopolymers derived from plants, algae, and bacteria. These polymers are inherently biodegradable, biocompatible, and non-toxic, and many of them possess intrinsic film-forming capabilities that make them particularly suitable for food-contact applications ^[6]. Among polysaccharides, sodium alginate (Na-alginate) has attracted considerable attention due to its unique physicochemical and functional properties ^[6][7]. Alginate films are transparent, flexible, odorless, and safe for consumption (generally recognized as safe) while also offering biodegradability and compostability, making them environmentally friendly alternatives to petroleum-based plastics. Furthermore, their hydrophilic nature facilitates compatibility with a variety of natural additives, including plasticizers, nanofillers, and bioactive compounds, enabling the design of multifunctional packaging systems. Despite these advantages, sodium alginate films face significant limitations that restrict their direct commercial application ^[7]. Moreover, alginate films have limited resistance to flavor and aroma transfer, which reduces their effectiveness in maintaining food sensory quality. To overcome these drawbacks, numerous modification and reinforcement strategies have been investigated. The incorporation of nanostructured biopolymers such as BNC has proven effective in enhancing tensile strength and barrier properties through polymer–nanofiber interactions. The unique nanofibrillar architecture gives BNC a set of remarkable physicochemical properties. It exhibits very high crystallinity (typically above 80–90%), exceptional tensile strength, and a high degree of polymerization compared to plant cellulose. The abundant hydroxyl groups on its surface enable strong hydrogen bonding, which facilitates excellent interfacial interactions when combined with other biopolymers.

This improvement in barrier properties is especially important for food packaging, where moisture retention and oxidative stability are crucial in determining product shelf life. Excess moisture can encourage microbial growth, enzymatic activity, and texture deterioration, while oxidative reactions may cause discolouration, nutrient loss, and off-flavours. By reducing water vapour permeability and providing a more compact film structure, BNC-reinforced alginate films directly address these challenges, offering a protective barrier that slows degradation and maintains product quality over extended storage periods. Additionally, the intrinsic ability of BNC to form strong hydrogen bonds with other natural additives – such as phenolic compounds, proteins, or essential oils – facilitates the development of active packaging systems with highly tailored properties. These interactions not only improve the physical integrity of the films but also enhance the uniform distribution and stability of incorporated bioactive compounds, enabling multifunctional performance.

For example, when combined with antioxidant-rich grape seed extract (GSE), BNC provides both structural reinforcement and a stabilising matrix for bioactive compounds. The nanofibrillar network of BNC effectively traps and immobilises phenolic molecules from GSE, reducing their susceptibility to leaching or degradation during storage. This synergistic interaction leads to marked improvements in mechanical properties – such as tensile strength, elasticity, and dimensional stability – and in functional performance, including antioxidant and antimicrobial activities. The strong hydrogen bonding and physical entanglement between the nanocellulose fibres and phenolic compounds also help regulate the release kinetics of these bioactives, enabling a sustained protective effect against oxidative damage and microbial contamination. As a result, BNC-GSE-alginate films do not merely act as passive barriers but function as active packaging materials that contribute to the preservation of perishable foods.

2. Enhanced Food Packaging Using Alginate, Nanocellulose, Grape Extract

According to research presented in Bio-Based Alginate Films Incorporating Bacterial Nanocellulose and Grape Seed Extract for Enhanced Food Packaging, the primary aim was to develop and thoroughly characterise biodegradable, active packaging films composed of sodium alginate, BNC, and GSE, with a focus on preserving highly perishable fruits such as blueberries. Blueberries were selected as a model system due to their sensitivity to moisture loss, oxidative degradation, and microbial spoilage, making them ideal for evaluating the effectiveness of active packaging strategies. The study was designed to exploit the synergistic properties of the film components: sodium alginate provides excellent film-forming capability and biocompatibility; BNC acts as a nanostructured reinforcement that enhances mechanical strength, barrier performance, and film compactness; and GSE contributes potent antioxidant and antimicrobial functionalities. The integration of these components offers multiple layers of protection. Sodium alginate serves as the primary polymer matrix, creating a continuous and cohesive film, while BNC introduces a nanoscale fibrous network that strengthens the film, reduces permeability, and improves thermal and mechanical stability. At the same time, GSE delivers bioactive protection, mitigating oxidative processes through its rich polyphenolic content and inhibiting microbial growth through direct antimicrobial activity. By combining these elements, the resulting films achieve a balance of structural integrity, barrier effectiveness, and active functionality that is rarely attainable with single-component systems. This synergistic approach highlights the potential of combining renewable biopolymers, nanostructured reinforcements, and natural bioactives to create multifunctional, sustainable packaging solutions. Moreover, this research provides significant insights into sustainable food packaging by demonstrating how bio-based materials can be engineered for high-performance applications. Alginate-based films, reinforced with bacterial nanocellulose and enriched with natural antioxidants such as GSE, offer a promising route towards packaging that not only reduces reliance on conventional plastics but also actively enhances food preservation. Such films exemplify the convergence of green chemistry, nanotechnology, and food science, showing the potential to create packaging systems that are biodegradable, environmentally friendly, and capable of extending shelf life without the need for synthetic additives. The findings indicate that these multifunctional films can be tailored for a wide range of perishable products, providing customisable solutions for the food industry while simultaneously addressing critical sustainability challenges such as reducing food waste and mitigating environmental impact. In summary, the use of BNC- and GSE-enriched alginate films represents a holistic strategy for active food packaging. By combining mechanical reinforcement, barrier enhancement, and bioactive protection, these materials not only preserve the quality and safety of perishable foods but also align with global efforts to develop sustainable and biodegradable packaging technologies. The study demonstrates that leveraging the synergistic interactions between natural polymers, nanostructured fillers, and bioactive compounds can lead to packaging solutions that are both high-performing and environmentally responsible, opening avenues for future research and industrial implementation in the field of bio-based active packaging.

This study demonstrated that incorporating bacterial nanocellulose (BNC) and grape seed extract (GSE) into sodium alginate-based films significantly enhanced their mechanical, barrier, and functional properties, highlighting their potential as multifunctional bio-based packaging materials. The addition of BNC effectively reinforced the alginate matrix, as shown by increased tensile strength, improved elongation at break, and reduced water vapour permeability, confirming its role as a robust structural and barrier component. These improvements can be attributed to strong hydrogen bonding between BNC fibres and alginate polymer chains, which enhances the compactness and integrity of the film network. Beyond structural reinforcement, the incorporation of GSE imparted substantial bioactive functionality. Antioxidant activity, assessed through free radical scavenging assays and total phenolic content analysis, increased proportionally with GSE concentration, indicating efficient incorporation and retention of bioactive compounds within the film matrix. Antimicrobial evaluations against Escherichia coli and Staphylococcus aureus revealed clear concentration-dependent inhibitory effects, with S. aureus exhibiting greater sensitivity. This differential response aligns with the known structural differences between Gram-positive and Gram-negative bacterial cell walls, which influence susceptibility to phenolic compounds. The synergistic combination of BNC and GSE resulted in films that not only maintain mechanical integrity but also actively contribute to food preservation. Among the tested formulations, the film containing 1% GSE displayed the most favourable balance of properties. It achieved enhanced mechanical strength, reduced water vapour permeability, and robust antioxidant and antimicrobial activity, making it an ideal candidate for active food packaging applications where both moisture control and microbial inhibition are critical for extending product shelf life.

Despite these promising results, several challenges must be addressed before industrial implementation. The long-term stability of GSE within the film matrix under varying storage conditions remains uncertain, as phenolic compounds may degrade over time, potentially reducing bioactivity. Additionally, potential sensory effects on packaged foods, such as changes in taste, aroma, or colour, require thorough evaluation to ensure consumer acceptance. Scalability of production processes is another important consideration, as translating laboratory-scale fabrication to industrial-scale manufacturing may encounter technical and economic constraints. Future studies should therefore focus on extended storage trials, migration and sensory assessments, and pilot-scale validation to confirm the practical applicability of these films. Nevertheless, GSE-enriched sodium alginate/BNC films represent a promising class of multifunctional, sustainable packaging materials. By combining mechanical reinforcement, barrier enhancement, antioxidant activity, and antimicrobial performance, these films offer a holistic strategy to reduce food spoilage, prolong the shelf life of perishable products, and contribute to food waste reduction. Their development aligns with the growing demand for eco-friendly and active packaging solutions, providing a pathway towards more sustainable and effective food preservation technologies.