Soluble solids content monitoring for shelf-life assessment of table grapes coated with chitosan using hyperspectral imaging

Abstract

Table grapes have a relatively short shelf-life and degradation rate due to pathogen infestation during postharvest storage. Chitosan (CTS) edible coatings offer a potential alternative for extending the shelf-life of fruit. The objective of this study was to explore the efficacy of CTS edible coatings on the shelf-life of table grapes by the application of hyperspectral imaging for non-invasive and rapid soluble solids content (SSC) monitoring. Table grapes were coated with CTS solutions (0.5%, and 1%, w/v), while the uncoated fruit served as controls. Spectral changes over storage days were investigated using principal component analysis (PCA), and principal component images were extracted to visualize the degradation evolution. Table grapes coated with edible coatings presented significant delays in SSC change and degradation process compared with uncoated fruit. Moreover, partial least squares regression (PLSR) combined with feature bands selected by competitive adaptive reweight sampling (CARS) provided the better performance for SSC prediction with R2 higher than 0.801 for the uncoated and coated grapes. Conclusively, hyperspectral imaging was capable of monitoring the evolution of SSC, and 1% CTS coating was more effective in extending the shelf-life and maintaining postharvest quality of table grapes.