Ioan Pavel Gitsov and Tom Collins*
*Washington State University, 359 University Dr., Richland, WA 99354 (tom.collins@wsu.edu)

Smoke exposure to grapes prior to vinification can lead to the presence of smoke-related volatile phenols and associated glycosides. These compounds provide negative sensory attributes to the wines, including ashy, medicinal, and smoky aromas and aftertastes. A method for alleviating this taint prior to bottling is needed to mitigate the negative impacts of smoke exposure in finished wines. Smoke-affected wines from the ongoing smoke taint project in the Collins lab, as well as affected wines from commercial wineries, were treated using a small-scale reverse osmosis (RO) filtration system, in which the smoke taint compounds migrated into a permeate stream. The permeate stream was then passed through carbon filters to remove the smoke-taint compounds. The compositions of the permeate and retentate streams were analyzed using gas chromatography-mass spectrometry (GC-MS) and ultra-high-pressure liquid chromatography-quadrupole time of flight-mass spectrometry (UHPLC-QTOF-MS). Principal component analysis of compositional data collected during an RO time study found separation between samples from the permeate and retentate streams. The permeate stream contained smaller compounds associated with smoke taint such as pyrocatechol, syringic acid, and caffeic acid, while the retentate stream contained larger compounds, including several flavonoids. Samples taken before and after the carbon filters became more similar as processing time increased, with peak areas decreasing for prefiltration samples and remaining steady for postfiltration samples for several smoke-related compounds. The treated wines are being monitored using GC-MS and UHPLC-QTOF-MS for posttreatment release of free smoke taint compounds through hydrolysis of smoke taint-related glycosides. This study serves as an initial evaluation of the kinetics of hydrolysis post-RO to determine whether RO treatment can be an effective tool for mitigation of smoke taint in affected wines.

Funding Support: Washington State Grape and Wine Research Program