The Crush July - 2

role in smoke exposure susceptibility; looking at the
chemical and biological interactions between key grape
components and VPs; and analyzing the differences
among skin vs. pulp cell wall material, cultivars, and skin
Baseline Smoke Marker Data
Because both free and bound (or glycosated) levels of
VPs naturally occur in grapes, researchers are collecting
baseline data for VP levels in grapes without smoke
exposure. Benchmarking baseline data will help the
industry make better harvest and winemaking decisions
during smoke events. With funding from the American
Vineyard Foundation (AVF), UCD Professor Susan Ebeler,
Oberholster, and others have collected baseline data
from vineyard locations in California since the 2021
harvest with a focus on Cabernet Sauvignon vineyards
in Napa and Sonoma Counties. Beginning in 2022, 21
locations had air quality monitoring sensor stations
installed to record daily air quality parameters (for days
with and without smoke) to compare air data with grape
VP data. Data is also being collected for Chardonnay,
Merlot, and Sauvignon Blanc. Free and total levels of ten
grape VPs measured are: guaiacol, 4-methylguaiacol,
phenol, 4-ethylguaiacol, o-cresol, m-cresol, p-cresol,
4-ethylphenol, 4-methylsyringol, and syringol. Data to
date show a high degree of variability across varieties,
regions, and years indicating that it will be important to
have a large multi-year database to assess the impacts
of smoke exposure on free and total VP composition.
Funding for this project will continue for 2023-24.
The Australian Wine Research Institute (AWRI) has
collected and analyzed baseline data on VP smoke
marker compounds for a longer period and has data
from grape and wine samples representing 21 varieties
from 23+ regions across Australia. More information can
be found here.
ETS Labs, based in St. Helena, analyzed smoke-exposed
wine samples from West Coast vineyards from the
widespread 2020 wildfire season for six volatile markers
and six glycosated markers used by AWRI. At the ASEV
Conference, ETS R&D scientist Dr. Eric Herve presented
results from the data collected and said, " As a general
rule, when volatile markers are high, glycosated markers
are also high. " But he noted exceptions exist, such as
with Pinot Noir from Oregon and California. In many
cases, levels of both volatile and glycosated markers
in wines appeared closely related to the intensity of
vineyard smoke exposure. This study confirms the
relevance of these markers and that measuring both
volatile and glycosated markers is advisable to identify
wines from smoke-exposed grapes.
Vineyard Smoke Barrier Materials
An activated carbon fabric (ACF) barrier is a promising
strategy to mitigate smoke taint in vineyards being
researched in Australia by the University of Adelaide
Professor Kerry Wilkinson, who has conducted smoke
exposure research for 16 years. At the ASEV Conference,
Wilkinson said initial trials with ACFs made into bags
and placed around grape bunches showed a reduction
in VP marker levels by up to 95 percent, compared
with control (non-covered) bunches in smoking trials.
Wilkinson admits that the placement of bags on clusters
is impractical in commercial vineyards. However,
researchers are looking at incorporating ACF into larger
fabric structures that can be placed over vine rows earlier
in the season and used similarly as bird netting or shade
Trials with barrier spray materials continue by researchers
at West Coast universities with products such as kaolin,
bentonite, V4 charcoal, and film coatings such as
chitosan and cyclodextrin. Some materials show good
potential to block smoke marker chemicals and mitigate
grape smoke exposure when sprayed directly onto
grape clusters. However, developing effective spray
application equipment and procedures for practical use
in commercial vineyards is still needed.
Mitigating Wine Smoke Impacts with MIPs
ASEV research posters presented trials with smokeimpacted
wines using molecularly imprinted polymers
(MIPs)--synthetic polymers made with target molecules
designed to specifically remove smoke marker
compounds and smoke aromas--conducted by the
Oberholster Lab at UCD and conducted in separate
trials by Jackson Family Wines. In contrast to current
remediation technologies, such as reverse osmosis and
activated charcoal treatments that can impact desired
wine qualities, MIPs offer promise to better remediate
smoke-affected wines without compromising other wine
quality factors.
Susceptible Varieties
During the Smoke Summit, Tomasino and Collins said
based on their experiences, Pinot Noir and Petit Verdot
are more susceptible red varieties to smoke taint, and
among white varieties, Pinot Gris and Sauvignon Blanc.
Cabernet Sauvignon and Merlot are in the middle of
susceptibility. Tomasino said, " High levels of fresh
smoke for one hour are enough to cause smoke taint
in susceptible varieties such as Pinot Noir. " She also
observed, " High levels of smoke exposure cannot
be mitigated, but with more lightly impacted wines,
mitigation can be more successful. "
Page 2 | July 2023

The Crush July

Table of Contents for the Digital Edition of The Crush July

The Crush July - 1
The Crush July - 2
The Crush July - 3
The Crush July - 4
The Crush July - 5
The Crush July - 6
The Crush July - 7
The Crush July - 8
The Crush July - 9
The Crush July - 10