Okra Biomass-Derived Pectin-Rich Polysaccharide Composite Coating for Formulation-Dependent Surface Friction on Mango Fruit

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.