AIR-DRYING OF PLUMS - A COMPARISON AMONG 12 CULTIVARS

The air drying kinetics of twelve cultivars of plums have been evaluat ed and compared. Trials have been conducted in a pilot plant under sta ndardized process conditions for all samples. Morphological parameters of fresh fruits such as weight, volume, surface area, pulp/stone rati o and skin colour were evaluated ; moreover, on fresh pulp, pH value a nd Brix degree were measured. Skin colour, drying kinetics and drying rates were evaluated for dried products and a panel test on dried plum s was carried out. Results showed the different drying behaviours of p lums as a function of the size and morphological characteristics of fr uits ; in particular, if has been verifed how the smallest fruits were dried in periods of time that were about 1/2 and 2/3 shorter than tho se needed for medium and large sized fruits. The browning reactions in duced by the heat treatment on plums of different colours, led to drie d products with same colour characteristics. The judgements expressed during the panel test put in evidence that the dried products, even if some of them were judged as ''good'', were not peculiar for one or mo re quality characteristics.