Fabrication of Grape Pomace Extract-Loaded Electrospun Nanofiber Films as Active Packaging Material for Walnut

Abstract

Grape pomace is a valuable residue of wine, vinegar, juice, and molasses industries with its high phenolic compound content. In this study, fabrication of gelatin/zein nanofiber films with antioxidant properties due to addition of grape pomace extract (0-20%, GPE) was assessed. This nanofiber film is designed to be evaluated as an active packaging material for coating walnuts. SEM analysis revealed that the nanofibers were uniform and bead-free, with the diameter ranging from 239 to 343 nm, and the FT-IR spectra showed that the GPE was enclosed in nanofibers successfully. The thermal stability of the extract appeared to be improved by encapsulation. The nanofibers demonstrated DPPH scavenging activity with the one containing 20% GPE exhibiting 75% inhibition. Walnuts were placed into polyethylene bags including nanofibers, and after 21-day storage, a significant (p<0.05) decrease in the peroxide values (from 1.92 meq 0(2)/kg walnut oil to 1.39 meq 0(2)/kg walnut oil) and Totox values (from 4.05 to 3.01) was shown by using GPE-loaded nanofiber. This study's results indicate that nanofibers with GPE content could be a promising package material for preserving food quality.