Response to hot air drying of some olive cultivars of the south of Italy

Olive fruit dehydration is always done locally in non-industrial ovens. This technology poses concern about the quality and safety of the end product. Most of the problems involved in this empirical technology may be solved by a proper control of process parameters. Olive fruits of fourteen Italian cultivars underwent hot air dehydration in mild conditions in a tangential airflow cabinet dryer. At the start, at regular intervals and at the end of the process, sampling was performed to calculate dehydration curves and quality loss. Pre-treatments such as blanching in hot brine, piercing of the skin and salting after blanching were applied. The drying kinetic is strongly affected by pre-treatments and olive characteristics: fruit size, flesh to pit ratio, dry matter. Results showed that mild drying temperature led to slow drying kinetics, even if pre-treatments reduced drying time to a certain extent. Blanched olives showed, in general, the highest polyphenols content. The fastest drying was measured in the pierced olives, but the best taste was achieved for the salted product.