Effet des conditions d'entreposage sur la degradation de la couleur des dattes tunisiennes de type Deglet Nour.Effect of storage conditions on the color degradation of Tunisian Deglet Nour dates.

摘要

Introduction. In Tunisia, Deglet Nour dates are famous for their gilded yellow color and they present a high commercial value; they constitute the majority of dates exported towards Europe. The aim of our work was to study effects of oxygen and temperature on the color degradation of this date type during the storage period. Materials and methods. The color evolution of Deglet Nour dates stored under a constant relative humidity (75%), at three different temperatures [(10, 25 and 37) degrees C] and in the presence of three oxygen concentrations [(0, 20 and 40)%] was followed each week for 35 days using the measurements of L* and b* parameters of the Hunter Lab scale. Results. The temperature played a determining part in the date color degradation during storage and the effect of oxygen was important, though secondary. Conclusion. Date color during storage proves to be able to be predicted starting from the only parameter b* of the Hunter Lab scale. in the case of dates conditioned under various oxygen concentrations and at various temperatures, the loss of the fruit's initial color was explained more by an ambient temperature increase than by the variation of the oxygen concentration of the storage environment. The degradation of the color would be caused by nonenzymatic and oxidative enzymatic tannings.