From lemongrass to cellulose nanocrystals: Synthesis, characterization, and application in postharvest quality control of cherry tomato (Solanum lycopersicum).

Developing natural and multifunctional edible coatings that preserve fruit quality and delay ripening while minimizing synthetic preservative use remains a critical challenge in postharvest technology. In this study, lemongrass straw, an abundant agricultural residue, was upcycled into cellulose nanocrystals (CNCs) through alkaline-bleaching pretreatment and sulfuric acid hydrolysis, and employed as a natural stabilizer for clove essential oil (CEO)-based Pickering emulsions (CEO-PE). The CNCs exhibited rod-like morphology and high crystallinity, while the optimized CEO-PE showed a droplet size of 928.5 ± 65.6 nm and a polydispersity index (PDI) of 0.349 ± 0.016, indicating a well-dispersed and kinetically stable emulsion. The system displayed excellent stability under near-neutral pH (6-7) and low ionic strength, and strong antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Colletotrichum spp. When applied as an edible coating on green grape cherry tomatoes stored for 12 days under ambient conditions, CEO-PE significantly delayed ripening, reduced O2 consumption and ethylene production, minimized weight loss, preserved firmness, and maintained higher total phenolic, carotenoid, and ascorbic acid contents (p < 0.05). The performance was attributed to the synergistic functions of CNCs and CEO, where CNCs formed a semi-permeable oxygen barrier and CEO imparted antioxidant and antimicrobial protection. This work demonstrates a sustainable valorization approach that transforms agro-waste into bioactive Pickering emulsions for edible coating, offering a green and effective strategy for extending the postharvest shelf life of fresh produce.