Secondary Aroma Compounds in Fresh Grape Marc Distillates as a Result of Variety and Corresponding Production Technology

In order to investigate the composition of secondary aroma compounds of fresh grape marc distillates as a result of variety and production technology, 30 samples (6 varieties×5 samples) were analysed. White grape marc samples from Malvazija istarska, Chardonnay and Muscat Blanc were obtained as by-products in standard white wine production, while red grape marc samples from Teran and Cabernet Sauvignon were obtained after standard red wine production procedures. Marc from red grape variety Muškat ruža porečki was obtained during the production of rosé wines. All fermented marc samples were distilled using a traditional copper alembic. The obtained distillates were subjected to GC/MS and GC/FID analyses. Malvazija istarska distillates exhibited exceptionally high methanol content. Distillates from white grape varieties were found to be characterized by higher C6 alcohol and 1-propanol concentrations, while red grape distillates contained higher amounts of the majority of alcohols, acids, and esters. In Muškat ruža distillates intermediate concentrations of many important aroma compounds were found. It was concluded that differences in the production technology parameters, depending on the variety, resulted in differences in secondary aroma profiles, most evident between distillates from white and red varieties. These findings were confirmed applying stepwise linear discriminant analysis (SLDA), which resulted in 100 % correct classification of distillates according to the variety and corresponding production technology.