Development of Antimicrobial Paper with Ag Nanoparticles Synthesized Using Rubus coreanus Leaf Extract to Extend the Storage Period for Strawberry

Abstract

This study developed an antimicrobial paper against major putrefactive pathogens in strawberry through integrating Rubus coreanus leaf extract and silver nitrate (AgNO3). The R. coreanus extract and silver nitrate were synthesized and then assayed by spectrophotometry. A peak was found around 400 nm, the wavelength of silver particle absorption. Synthesis of R. coreanus extract-silver nitrate was confirmed by transmission electron microscopy (TEM). It was found that R. coreanus extract was combined with round nanosilver particles 100 nm or smaller, along with some triangular, polygon, and stick forms. Nanosilver synthesis was developed using the R. coreanus extract as a reducing agent and then the developed antimicrobial paper was investigated by scanning electron microscope (SEM). Nanosilver particles of nanometer level were also found in the antimicrobial paper. Ag was found to be evenly distributed through energy dispersive x-ray spectroscopy (EDS) analysis, and R. coreanus extract was also contained in the antimicrobial paper. The developed antimicrobial paper showed antimicrobial effects against all three putrefactive pathogens: Botrytis cinerea, Alternaria tenuissima, and Rhizopus stolonifer. Compared with general paper, the antimicrobial paper also minimally changed postharvest strawberry weight and hardness, helping to maintain fruit quality and lengthen the storage period. Additional key words: fruit quality, natural extracts, postharvest, putrefactive microorganisms, silver nitrate