Effect of storage conditions on ‘Deglet Nour’ date palm fruit organoleptic and nutritional quality

Abstract

The aim of this study was to identify optimal storage conditions able to preserving date palm quality and minimising their loss in the supply chain. Hence, the effect of storage at −18, 0, 2 and 4 °C for 3, 6 and 9 months during two harvest seasons (2017 and 2018) on sugars, organic acids, polyphenols and cell wall yields and composition of ‘Deglet Nour’ Tunisian dates, were studied. Mid Infrared Spectroscopy (MIR) as a non-targeted method allowed to highlight a year effect on chemical composition and to discriminate samples stored at 4 and 2 °C regarding to major components (moisture, sugars, organic acids.). Cell wall yields were stable during the time. However, galactose from pectin side chains decreased with time, causing an increase of lignin, cellulosic glucose, fucose and rhamnose. Procyanidins, accounting for 98% of total polyphenols, were not affected by storage. Regarding quality parameters stability, stored fruits at −18 °C could be the solution for a long term storage but due to its high energetic costs, 2 °C must be the optimal temperature with a lower time.