Nutritional Changes in stored Tomatoes (Solanum lycopersicum L.) as influenced by Silver Nanoparticles Coating

Abstract

This study evaluated the influence of silver nanoparticle (AgNP) coating on the nutritional content of stored tomato fruits. Silver nanoparticles was fabricated via the green method of synthesis using ethanolic extract of Moringa oleifera leaves as reducing, capping and stabilizing agent. The antimicrobial efficacy was evaluated at various concentrations (10 – 100 ppm) against Aspergillus niger, Aspergillus paraciticus, Aspergillus flavus and Fusarium oxysporum. Silver nanoparticle coating was prepared from a mixture of silver nanoparticles, carboxyl methyl cellulose (CMC) and sodium caseinate with glycerol as plasticizer. Fresh tomato fruits were treated with AgNP coating and observed for 20 days with chemical analyses carried out every 5 days. Results showed that AgNP was able to inhibit A. nigar from 40 ppm with 0.72 cm inhibition zone, A. parasiticus and A. flavus at 80 ppm with 0.72 and 0.95 cm inhibition zones respectively. No inhibition was observed for Fusarium oxysporum. There was an observed increase in the ascorbic acid, lycopene and β-carotene contents over the storage period, showing AgNP coating was able to effectively retain the nutrients better than the other treatments. Potassium was well preserved by the application of AgNP coating while the control samples retained calcium and sodium better than the coated fruits. Silver was not detected in any of the fruits. The findings suggest that silver nanoparticle coatings can effectively inhibit microbial growth, thereby preserving the nutritional integrity of stored tomato fruits. However, further research is recommended to evaluate the long-term effects and stability of silver nanoparticle coating.