Nano selenium–alginate edible coating extends hydroponic strawberry shelf life and provides selenium fortification as a micro-nutrient

Although selenium nanoparticles (Nano Se) have gained attention for their anti-cancer and antioxidant activity, this nanomaterial's antimicrobial activity also has great potential. The aim of this study was to synthesize Nano Se edible coating solution through gamma irradiation technique with a bio-stabilizer of sodium alginate (Na-alg.), which is an ingredient commonly used in food preservation. Dynamic light scattering and transmission electron microscopy identified 94-nm-diameter Nano Se, and energy dispersive X-ray spectroscopy and Raman spectroscopy confirmed the formation of Nano Se. Antifungal studies revealed that Na-alg./Nano Se coating solution well inhibited both Neopestalotiopsis rosae and Fusarium oxysporum in single species culture conditions. The effectiveness of edible coatings containing Nano Se and Na-alg. on the physicochemical properties of strawberries at 24 ± 2 °C during 5-day storage period was evaluated. The results showed coated strawberries enhanced firmness by as much as 26% and a significantly less weight loss by as much as three fold compared to the control. The coating application was effective in maintaining a natural appearance and preserving half the amounts of vitamin C and B9 in the strawberries. In addition, the Na-alg./Nano Se coating was utilized as an additive to increase Se nutrient in strawberries. The Se content was supplemented from 0.28 to 0.56 μg per 100 g FW after coating. This study may potentially be used in the bio-preservation and Se-enrichment of various fresh fruits and other foods.