Smart Nanosensor Technology for Fruit Preservation: In vivo Papaya Model with Ethylene Scavenging and Colorimetric Indication.

A nanosilica-permanganate colorimetric nanosensor (NS) was developed for ethylene scavenging in postharvest papaya, offering sustainable shelf life extension. Incorporated in a polyethylene nonwoven pouch (tag), NS was compared to control (CO) and vermiculite (VR) treatments. NS particles measured 15-25 nm, negatively charged, and characterized by FTIR, SEM-FEG, SEM-EDS, and zeta potential. GC-FID analysis showed ethylene release at climacteric peak: CO = 0.50 μL/kgh, VR = 0.49 μL/kgh, NS = 0.35 μL/kgh, confirming NS's superior scavenging. Ripening was monitored over 17 days at 16 °C. Deconvolution revealed ethylene peak at day 15 for NS vs day 13 for CO/VR. Firmness declined (peel: ∼30-6 N; pulp: ∼11-0.5 N), pH rose (5.4-5.9), titratable acidity (∼0.085-0.052%), and soluble solids rose (∼10.0-12.7). Statistical analysis did not demonstrate a significant difference among treatments. Hue angle in NS changed from 240° to 320° (violet to brown), indicating continued ethylene adsorption, unlike VR. NS color shift aligned with fruit ripening, supporting its use in smart packaging.