Aroma active compounds during the drying of grapes cv. Pedro Ximenez destined to the production of sweet Sherry wine

Changes in odorant compounds of musts from cv. Pedro Ximenez grapes sun-dried for 0, 2, 4, 6, 8 days, as well as dried in chamber after 5 days at controlled conditions were studied. The compounds were analyzed by GC-MS and classified into two groups according to a named production factor (PF), it calculated as ratio between the average concentration of each compound at the end of the sun-drying and its starting concentration. Acetoin was the odorant showing the highest content at the end of the sun-drying process. Musts from chamber-dried grapes exhibited the same aroma terms as those from sun-dried grapes, although in general with higher odor activity values (OAVs), in addition to chemical odorant term that was only observed in the former. The results suggest an increased extent of raisining in the controlled conditions of the chamber-drying, which is, reasonably, contributing to improve the raisining process of the grapes for the production of Pedro Ximenez sweet Sherry wine.