The Crush July 2022 - 2

Oregon State University SCRI grant researchers led
by Enology Professor Elizabeth Tomasino recently
announced the discovery of a class of sulfur-containing
compounds--thiophenols--that were found to cause
smoke taint when in combination with VPs. Up to now,
VPs used as markers for smoke taint in wine and grapes
have not been a reliable predictor in all cases. High
VP levels in wine did not always taste smoke tainted,
and in some cases, lower VP levels did taste smoke
tainted. Analytical work by Collins at WSU confirmed
these sulfur containing compounds were found in wines
that had been exposed to smoke and not in samples
with no smoke exposure. Researchers are hopeful
that further work in this area will provide more reliable
chemical markers to predict smoke taint and lead to
better mitigation strategies.
To evaluate smoke exposed grapes pre-harvest for
making harvest decisions, it is recommended to collect
berry samples within two weeks before harvest and
perform small-scale micro- or bucket fermentations for
both lab and sensory analyses. More detailed protocols
and a video to conduct bucket fermentations to predict
smoke impact can be found at the UCD webpage at:
researchers began conducting smaller scale
" nanofermentations " in 2020 with glass canning jars
(Mason jars) and received comparable results to bucket
fermentations in less time--3 to 5 days as compared
to 8 days. A link to nanoscale fermentation protocols
can be found at
UCD researchers presented a seminar with guidance
to evaluate smoke sensory impacts on grapes and
wines and for training tasting panels to recognize
and rate smoke impacts. Grapes can have smoke
exposure without having smoke taint. Smoke taint
can be described as smoky, burnt, tar, campfire,
ashy, medicinal or earthy. To assess smoke taint, UCD
focused on tasting for " ashy aftertaste " or a " lingering
retro-nasal ashy character " on the palate. UCD created
a smoke impact sensory assessment rating scale
ranging from 0 (not affected) to 8 (very high impact).
Smoke-related attributes on the nose are not rated
due to a range of potential origins that may not be
related to smoke exposure. A covered container with
a solution spiked with an " ashy standard " (retro-nasal
ash taint character) is sampled first as a baseline
to evaluate other wine samples. Judges should be
screened for their ability to detect smoke taint. An
Page 2 | July 2022
estimated 25 percent of the population does not have
saliva chemistry that reacts with smoke compounds
and cannot detect smoke taint. In other cases, people
can be overly sensitive. When tasting, because of the
carryover effect of the ashy taste, after spitting out each
sample, a mouth rinse solution of dextrose, pectin and
water is used, followed by waiting 2 minutes before the
next sample.
Both free and bound VPs naturally occur in grapes, and
there is insufficient baseline data for the normal levels
of VPs found in grapes without smoke exposure. In
addition, VP numbers can vary based on grape variety,
site and seasonal conditions. To better understand
the sensory impacts of total VP levels in grapes, UCD
researchers are conducting analyses on the main grape
varieties--Cabernet Sauvignon, Merlot, Pinot Noir,
Syrah, Zinfandel, Chardonnay and Sauvignon blanc-from
different California sites to collect baseline data
on VP levels from non-smoke exposed grapes. Growers
and winemakers are encouraged to collect their own
baseline data. It could take 3 to 5 years to obtain
adequate data for these varieties.
Kristine Fox of Pan American Insurance provided advice
to growers on filing a crop insurance claim for smoke
exposure impacts:
* Contact your agent to open a claim as soon as
you believe an issue exists. There are no penalties
for filing a claim. Work closely with the assigned
* Collect grape samples before harvest by variety
and block. Identify sample locations with
photographs and labels. Do not comingle grapes.
Identity of grapes must always be maintained.
Freeze samples to test later if necessary.
* Prior to harvest, grape samples must be
tested by an approved lab for guaiacol and
4-methylguaiacol. There is no minimum threshold,
they must just show " elevated levels. " Testing
after harvest is too late.
* A winery rejection or price reduction letter stating
the reason for such action is required.
* Continue to market grapes noting all attempts to
sell them.
New 2022 contract price rules allow California growers
to increase the price/ton on their policy up to 2.5 times
the established insurance price (up from 2 times in past

The Crush July 2022

Table of Contents for the Digital Edition of The Crush July 2022

The Crush July 2022 - 1
The Crush July 2022 - 2
The Crush July 2022 - 3
The Crush July 2022 - 4
The Crush July 2022 - 5
The Crush July 2022 - 6
The Crush July 2022 - 7
The Crush July 2022 - 8
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The Crush July 2022 - 11