Polysaccharides

Valorisation of agro-industrial biomass into functional coatings offers a sustainable approach to developing bio-based materials for postharvest applications. Although polysaccharide–lipid coatings are widely studied for their barrier properties, their effects on fruit–packaging friction remain poorly understood. This study recovered pectin-rich polysaccharides (OP) from okra-processing biomass and developed OP–beeswax (BW) composite coatings to modify mango–packaging friction and evaluate selected postharvest quality attributes. Conventional thermal extraction (CTE) and microwave-assisted extraction (MAE) yielded OP with comparable degrees of esterification but distinct hydration properties, with extraction yields of 4.28% and 5.47%, respectively (p > 0.05). The recovered OP exhibited low-methoxyl characteristics, with a degree of esterification of approximately 47%. Film optical and microstructural properties varied with OP and BW levels. Coating performance was evaluated on three independent mango fruits per treatment (n = 3; 21 fruits in total), with the same fruits used for friction and all quality measurements. Static and kinetic coefficients of friction (COFs) at the mango–corrugated plastic board interface were in the ranges of 0.45–0.59 and 0.42–0.58, respectively, demonstrating formulation-dependent frictional behaviour. T3 (1.0% OP + 1.0% BW) exhibited static and kinetic COFs of 0.46 and 0.42, respectively, comparable to the uncoated control (0.46 and 0.45), whereas T4 (2.0% OP + 1.0% BW) showed the highest values (0.59 and 0.58). After three days of storage, coating treatments significantly affected weight loss, firmness, and titratable acidity (TA), with the lowest weight loss observed in T6 (3.25%) and the highest TA in T2 (0.47%), whereas total soluble solids and pH did not differ among treatments. These findings demonstrate the potential of okra-processing biomass for developing bio-based coatings with tunable fruit–packaging friction, although their effectiveness in reducing transportation-induced damage requires further investigation.

Bacterial nanocellulose (BNC) is a promising polysaccharide whose properties depend on the supramolecular structure of its crystalline component. The search for cost-effective alternative nutrient media for BNC production requires a deep understanding of how their composition affects the structure. This study aimed to investigate the structural features of BNC synthesized by the symbiotic culture SCOBY on enzymatic hydrolyzates prepared from chemically treated Miscanthus × giganteus (cv. KAMIS) in comparison with BNC synthesized on a control medium. The study methodology relies on X-ray diffraction analysis performed in reflection and transmission geometries using a full-profile analysis (the Rietveld method) to determine the unit cell parameters and angles, coherent scattering domain (CSD) sizes, and degree of crystallinity (DC). The main results showed that all five BNC samples were identified as Iα cellulose with a content of 95–100% and identical unit cell parameters. The CSD sizes in the reflection and transmission geometries varied in the range of 4.0–7.7 nm, and the longitudinal size was between 12.1 and 18.1 nm. The BNC samples obtained on hydrolyzates exhibited a higher DC (85, 83, 82 and 84%) compared with BNC synthesized on the control medium (78%). It was established that the crystallites of the five BNC samples exhibit anisotropy: the T/R ratio varied from 0.76 to 1.46, depending on the crystallographic direction. The scientific novelty of this work lies in the results of a comprehensive systematic study of the structural features of BNC samples synthesized on miscanthus enzymatic hydrolyzates. It was shown for the first time that replacing the control medium with hydrolyzates improves the BNC quality, which in turn enhances the practical significance of alternative nutrient media. The topic of the cost reduction in the nutrient medium for BNC biosynthesis remains debatable, but this direction aligns with the global trend.

The growing demand for sustainable and effective food preservation has increased interest in edible coatings as environmentally friendly alternatives to conventional packaging. This narrative review synthesizes and critically evaluates studies published between 2021 and 2026 on nanoparticle-loaded polysaccharide-based edible coatings and films for food preservation, highlighting recent advances, emerging research trends, current challenges, and future research directions. Edible coatings/films based on natural polymers, including polysaccharides, proteins, and lipids, provide biodegradable barriers against moisture, oxygen, and microbial contamination. However, their practical use is often limited by inadequate mechanical strength, high water vapor permeability, and limited antimicrobial activity. Recent studies have shown that incorporating nanoparticles into edible coating matrices can improve these properties. This review summarizes recent developments in nanoparticle-loaded edible coatings for food preservation, with emphasis on inorganic nanoparticles (zinc oxide, titanium dioxide, and silver nanoparticles) and biopolymeric nanomaterials (e.g., nanocellulose and nanochitosan). Reported studies indicate that nanoparticle incorporation (typically 1–5% w/w) can increase tensile strength by 30–70%, reduce water vapor permeability by up to 60%, and provide antimicrobial inhibition exceeding 90% against common foodborne pathogens. The review also discusses nanoencapsulation systems for the controlled delivery of bioactive compounds, including essential oils, with reported encapsulation efficiencies of 70–95% and sustained release during storage. In addition, recent fabrication approaches, such as ultrasonication, electrospinning, and cold plasma modification, are outlined for their potential to improve coating performance. Finally, current challenges related to nanoparticle safety, migration, regulatory considerations, and toxicity assessment, including the application of new approach methodologies (NAMs), are highlighted. The review identifies recent advances and remaining challenges in nanocomposite edible coatings to support future research and the development of sustainable food preservation technologies.