Evaluate the Efficacy of Guava-Derived CuO, and ZnO Nanocomposite Coating on Shelf life of Grapes

Abstract

Abstract Pectin’s anionic heteropolysaccharide structure makes it suitable for coating metal nanoparticles (MPNs) by preventing their accumulation and thus, improves MPNs acceptability for formulation of edible coatings. The presence of functional moiety preferably, hydroxyl group and carboxylic acid in pectin promote their covalent bonding with metal nanoparticles, proteins, and other biomolecules. Accordingly, the present investigation explored the efficacy of guava-derived pectin-based zinc oxide (ZnO) and copper oxide (CuO) nanocomposite biopolymer coatings on the quality attributes and shelf-life extension of berries. The solvent casting and chemical reduction methods were used to synthesized guava-derived ZnO and CuO nanoparticles coatings, respectively. Simultaneously, berries submerged in three different biopolymer coatings viz., guava-derived pectin (GDP), GDP/ZnO and GDP/CuO for three minutes and stored at refrigerated temperature (i.e., 7oC) along with uncoated samples. The samples were evaluated for physicochemical changes and sensorial parameters at an interval of 2 days for 19 days of storage period and FTIR spectroscopy. The nanocomposite coatings were effective in reducing the berries' weight loss, water activity and minimized the reduction in pH, and titratable acidity. Comparably, an increase in total soluble solids (TSS) were observed in all coated samples but it was lower than uncoated ones. Furthermore, compared to controlled and other coated samples, only ZnO-coated berries had retained their texture, odor and were of acceptable quality to a lesser extent until 19 days of storage. The results of FTIR spectroscopy reveals the presence of alcohol and carboxylic acid group in the GDP structure. Supposedly, nanocomposite coatings could be harnessed as an active biopolymer packaging material that can prolong the lifespan and maintain the quality of grapes for an adequate period (at least two weeks) under refrigerated conditions.