Achieving Tropical Fruit Aroma in White Wines: From Winemaking to Consumer Acceptance

The overall goal of this project is to produce Chardonnay wines with increased tropical fruit aroma perception. In a previous study developed by Dr. Elizabeth Tomasino’s research group, we found that wines with higher concentrations of fermentation esters and volatile thiols imparted more intense tropical fruit aroma nuances. Therefore, in this project specific winemaking processes (skin contact, β-lyase addition, and two fermentation gradient temperature regimes) were performed with the intent to either increase or decrease these aromas in the wine. The first two processes (skin contact and β-lyase addition) are known for increasing volatile thiol concentrations in wine. The latter (fermentation temperature) is expected to increase thiol concentrations and preserve fermentation esters. The accomplishments for the project for the 2 nd semester of 2020 have been to design and perform the winemaking experiment for objective 1, measure the basic wine quality parameters (pH, titratable acidity, malic acid, acetic acid, and ethanol content), and collect wine samples for the analytical chemistry analysis. Much of 2021 has been spent on developing the analytical methods to measure thiols and esters on wine samples from objective 1. Treatments that presented higher concentrations of both aroma families were scaled up in objective 2. Winemaking experiment for objective 2 was performed and juice and wine samples were collected for basic wine quality parameters and analytical chemistry analysis. Treatment wines were bottled and stored for sensory descriptive analysis (objective 2) and consumer testing (objective 3). We are currently designing and recruiting panelists for sensory analysis and extracting free thiols for HPLC analysis for wines in objective 2, and purchasing chemicals for thiol precursor analysis for wines from objective 1 and 2. We are on schedule for this project except for the thiol precursor analysis which has been delayed due to the standards being backordered. They are anticipated to ship in March 2022.