Physical pre-treatment of plums (Prunus domestica). Part 2. Effect on the quality characteristics of different prune cultivars

The effects of an alternative physical pre-treatment for enhancing the drying rate of different plums (Stanley, Angeleno®, and Empress), are evaluated by means of the principal chemical parameters and by skin colour. The pre-treatment consists of the superficial abrasion of the plumsʹ peels using an inert abrasive material to remove the cuticular waxy layer, the limiting factor for moisture loss. The drying process was carried out at 60 °C to reduce the plumsʹ quality loss, the latter being assessed by analysing the changes in skin colour, sugars by HPLC, total phenols, total anthocyanins, and reactive substances to the vanillin–HCl reagent. The proposed physical pre-treatment, without significantly altering the other qualitative characteristics of the plums, markedly reduced the dehydration time and, as a result, caused a smaller loss of sugars in Empress and Angeleno than Stanley plums.