Volatile composition of ‘grappa low-wines’ using different storage methods and conditions on an industrial scale

This is a study on the volatile composition of grappa low-wines. Grappa low wines are the first distillation products, with about 15-20% v/v ethanol, when grappa is produced using continuous distillation. Different methods and conditions of marc and wine lees storage on an industrial scale have been considered. New technology for the storage of large amounts of grape marc, called the 'Grappa system', was evaluated. By comparison with a traditional ensilage method, the low-wines obtained from the Grappa system resulted in higher concentrations of ethanol, lower levels of methanol, slightly different concentrations of fusel alcohols and higher concentrations of ethyl esters and terpenes. The use of phosphoric acid and sodium methabisulphate to achieve a partial control of marc fermentation had no effects using the Grappa system method. This could be the result of the mixing technique used which was spraying alone and was only slightly effective for the homogenous treatment of the mass. On the contrary, the lower content of methanol, 2-butanol and n-propanol confirmed the effectiveness of phosphoric acid addition to the wine lees.