Effect of skin contact on bound aroma and free volatiles of Listán blanco wine.

Listán blanco is the major grape variety of the Canary Islands. Aroma precursors in musts and free volatiles in wines and their variations due to the skin contact process (10°C and 0-12h of maceration) were determined in samples of the Listán blanco grape variety. Aroma precursors of must were isolated by absorption on XAD-2 resin and the aglycone liberated by means of acid hydrolysis. Free volatiles from wines and from aroma precursors were extracted with dichloromethane and then analysed by GC-MS. The results of two consecutive vintages show that only aroma precursors of some terpenes and phenols may affect the final wine aroma. However, the majority of the free compounds of the wines did not present differences in content that could be related to the skin contact process.