Eco-Friendly Calcium Nanoparticle Coatings: A Sustainable Strategy for Postharvest Preservation of Food Crops

Abstract

Tomato spoilage remains a major postharvest challenge in Nigeria, where poor preservation methods cause 40–50% annual yield losses. This study explored the use of eco-friendly calcium nanoparticles (CaNPs) synthesized from orange peel extract (OPE) as a sustainable coating to extend tomato shelf life. OPE was prepared by aqueous extraction at 60 °C for 1 hour and reacted with 1 mM calcium nitrate (Ca(NO?)2) to produce CaNPs via green synthesis. Colour transition from light to deep golden brown was observed, with UV–Visible spectroscopy showing maximum absorbance at 326 nm and TEM revealing spherical nanoparticles and particle size (72.35–93.34 nm). Fresh tomatoes coated with 0.5 mM and 0.8 mM CaNPs were stored for 28 days at ambient temperature and compared with uncoated controls. Coated fruits retained higher moisture (84.01–84.22%) and showed enhanced crude protein, fat, fibre, and carbohydrate contents. Colour analysis (L*, a*, b*) indicated better retention of brightness, redness, and yellowness. CaNPs coatings effectively preserved nutritional and sensory qualities, reducing water loss and pigment degradation. Using orange peel as a reducing agent valorises agricultural waste and promotes green nanotechnology as a low-cost, biodegradable strategy for reducing postharvest losses and improving food security in developing nations’ economies.