Achieving Tropical Fruit Aromas in White Wine through Innovative Winemaking Processes
Angelica Iobbi, Elizabeth Tomasino,* and Yanming
Di
*Oregon State University, 3051 SW Campus Way, Corvallis, OR
97330, Wiegand hall, Corvallis, OR, 97330
(elizabeth.tomasino@oregonstate.edu)
While tropical fruit aroma is often attributed exclusively to volatile thiols, contributions of other compounds and their interactions that cause this desired aroma are yet unexplored. In a previous study, the highly fruity sensory profile of esters transmitted tropical fruit aromas in a model wine spiked with acetate and ethyl esters. Moreover, samples that contained only thiols resulted in grassy and earthy aromas, not tropical fruit aromas as expected. Thus, this study hypothesized that, while the presence of thiols is critical to green aroma perception, tropical fruit aromas are caused by esters. This work investigated specific winemaking procedures that could increase both aroma families, esters and thiols, in white wines. Chardonnay grapes were harvested at the Oregon State University (OSU) experimental vineyard and processed at the OSU research winery during the 2020 vintage. The control (standard winemaking) and four treatments were evaluated: skin contact (10°C for 18 hrs), enzyme addition (β-lyase, 40 μl/L), and two fermentation gradient temperature procedures (FGT 1: start at 20°C and after 100 hrs change to 13°C; FGT 2: start at 20°C and at ~12 Brix, change to 13°C). A full factorial design with all possible treatment combinations was proposed. An ester method (HS-SPME GC-MS) was developed to measure ethyl and acetate esters. The volatile thiols 3-MH, 3-MHA, and 4-MMP were quantified using a method by Capone et al. (2015). Results showed that skin contact, fermentation gradient temperature, and their interaction played a significant role in the concentrations of thiols. Significant differences were observed in skin contact and both FGT treatments for esters, but their interaction was not significant. Finally, the interaction of skin contact and FGT 1 resulted in the highest concentrations of both esters and thiols.
Funding Support: American Vineyard Foundation
