Enology Notes # 98 February
17, 2005

To: Regional Wine Producers

From: Bruce Zoecklein, Head, Wine/Enology-Grape Chemistry Group, Virginia
Tech

Subjects: Wine Closures, continued; American Society for Enology and
Viticulture-Eastern Section; Annual meeting of the American Society for
Enology and Viticulture; Juice and Wine Fining Workshop

I. Wine Closures. As discussed in Enology Notes # 97, as wines age in the
bottle, the oxidation-reduction potential decreases until it reaches a
minimum value, which is largely dependent on the wine and how well it is
sealed.

The nature and intensity of bottle bouquet is, in part, dependent on the
redox potential. Thus, variations in closures and/or closure performance
can impact the redox potential and the sensory characteristics of a wine.
This issue continues the discussion of wine closures and the role of
oxygen.

As discussed in Enology Notes # 97, the ullage space in bottles can be
substantial. I reported that 30-mm headspace for screwcap closures was an
international standard. Such a headspace could provide 9 mL of volume.
However, Bruce Scott of Scott Labs reports that North American standard
cork-finished bottles have fill heights ranging between 61 and 67 mm, with
an average of about 64.

Bruce Scott notes that using a 45- or 49-mm cork in a bottle with a 64-mm
fill height at 20°C provides an ullage space of 19 or 15 mm, respectively.
The throats of bottles average approximately 0.3 mL per mm. This would
result in a 5.7 or 4.5 mL volume at 20°C, using a 45-mm or 49-mm cork,
respectively. If this volume is composed mainly of oxygen (air) it could
impact wine development. Naturally, variation in the oxygen concentration
in the ullage space can result in bottle variation.

Sulfur Dioxide. The free sulfur dioxide and optical density (OD) at 420 nm
are perhaps the best predictive measures of how wines will hold up
post-bottling, regardless of closure type. For example, there is a
non-linear relationship between oxidized character development and the
concentration of free sulfur dioxide. The cut-off appears to be about 13
mg/L free sulfur dioxide for white wines.

As wines develop in the bottle and retain a level of free sulfur dioxide
exceeding 13 mg/L, the likelihood of developing oxidized aroma/flavors is
minimized and the wine will usually remain sound. When the free sulfur
dioxide level drops to less than about 13 mg/L, we can expect perceptible
"developed" and/or oxidative aromas.

A level of 13 mg/L or more free sulfur dioxide should be considered an
average concentration. Naturally, different wines have differing oxidative
buffering capacities due to their redox potential, which is impacted by the
total antioxidant concentration.

Antioxidants include phenols, ascorbic acid, glutathione, sulfur dioxide,
etc. Regardless, small differences in post-bottling sulfur dioxide has been
found to be strongly correlated to later sensory scores (Godden et al.,
2001). Such differences can result from different oxygen levels as
suggested by Brajkovich (2004):

a.. Wine absorbs oxygen at bottling, dependent on the bottling equipment.
b.. Wines continue to absorb oxygen from the ullage gas in the bottle.
c.. With corks and synthetics, this absorption can be from within the
closure.
d.. Oxygen absorption ends within several months if the closure makes a
complete seal.
The ratio of free to total sulfur dioxide may also be important. When there
is a large difference in this ratio, the free is being bound. Several
compounds in wine are active in binding free sulfur dioxide, including
sugars, anthocyanins and acetaldehyde.

Acetaldehyde formation is a direct result of oxygen exposure. Differences
in ratios of free to total sulfur dioxide have been observed in studies
comparing screwcaps with natural and synthetic closures. Presumably, these
differences are due to oxygen.

Monitoring the free sulfur dioxide concentration could be an effective means
of reviewing both the impact of different closures, and how a wine bottled
with a particular closure is holding up. This may allow for a periodic
review of longevity so as to aid in wholesale and retail distribution as
suggested by Godden et al. (2001).

A periodic evaluation of the free sulfur dioxide level from an adequate
number of randomly selected bottles is an effective gauge for monitoring
wine development. Again, if the free sulfur dioxide level in a white wine
is maintained at 13 mg/L or above, oxidative aromas will be minimal.

Naturally, measuring sulfur dioxide concentration and the change in
concentration over time to predict wine longevity implies a certain level
of analytical accuracy and precision. Note that the Ripper titration
method, and associated kits that may employ the same chemistries, may not
be sufficiently accurate for such a review. I suggest using the Aeration
Oxidation method (see Zoecklein et al., 1999), with reference standards.

The Wine/Enology-Grape Chemistry Group is currently evaluating the impact of
accelerated aging, as a means of determining shelf life and differences
among closures. This follows a study conducted by one of our students
several years ago (Mansfield and Zoecklein, 2003). This will be discussed
at the Wine Closure Roundtable to be held this spring (Check future Enology
Notes and my website for the date, time, and location).

It is likely that critical loss of antioxidant levels relate, at least in
part, to oxygen and oxygen permeability via closures. This will relate to
the development of oxidized aroma and flavors, and the variation among
wines bottled with different closure types. More to follow.


II. The American Society for Enology and Viticulture-Eastern Section. All
wineries, regardless of size, operate within the global marketplace. This
marketplace has been subject to a steadily increasing disparity between
wine production and wine consumption.


This disparity (currently estimated at 50 million hectoliters) has resulted
from a dramatic decline in consumption in traditional European
wine-producing countries, and increased production in ever-increasing "new
world" regions and subregions.


What does this imbalance in supply and demand mean to the eastern US wine
industry? It is safe to say that market forces will promote additional
competition, and some producers that do not adjust will not survive. Our
challenge is not unique: like all regions, we need to retain current
customers and persuade potential new ones. How do we do this?


To increase consumption of our region's wines, we need wines with desirable
sensory characteristics, products that present no risk, perceived or real,
to the health of individuals and the environment, and distinctive wines
that are of a competitive price per quality, while remaining profitable.


There is no question that the development and application of new
technologies can assist the industry in meeting these challenges.
Winemakers in our part of the world must become more sophisticated in
applying new technologies, when appropriate, while maintaining the cultural
and traditional nature of our industry.


Through the exchange of scientific research findings, student scholarships,
and practically oriented industry symposia, the American Society for
Enology and Viticulture-Eastern Section has been working to aid the
industry in meeting today's challenges.


A significant portion of the Society's revenues go toward providing
scholarships to viticulture and enology students working throughout the
region. In virtually every state in the Midwest and East, ASEV-ES students
are engaged in practical research studies that could impact our industry.
Most of these students are training to become our industry's future grape
growers and winemakers.


In recent years, the Society has sponsored symposia on a broad range of
practical vineyard and winery issues, including a cork symposium, and
programs on varietal wine production, sparkling wines, wine taints, and
grapes, wines and the environment. The purpose of these programs has been
to provide the best technically oriented information available, to allow
our industry to reach its full potential.


The American Society for Enology and Viticulture-Eastern Section is the
professional society for your industry. Your support of the Society helps
to assure that all of us meet the challenges of today and the future. If
you are not a member, I urge you to become one today. Membership is very
inexpensive.

III. Annual Meeting of the American Society for Enology and Viticulture,
2005. I am pleased to announce that the 2005 annual meeting of the American
Society for Enology and Viticulture-Eastern Section will be held July 13-15
in St. Louis, Missouri, at the Millennium Hotel. This spectacular facility,
on the banks of the Mississippi, is within walking distance of the Arch and
downtown cultural attractions.

The meeting will involve technical presentations, the Viticulture Consortium
East research summit, wine industry trade show, annual banquet, local wine
industry tour, and a symposium.

This year's symposium will involve viticulture and enology discussions, and
sensory evaluations, on the Cutting Edge Varieties: Norton, Pinot Gris,
Traminette, and the cold-hardy Frontenac and La Crescent. Speakers from the
academic community, commercial growers, and winemakers will present
practical information and extensive sensory evaluations. For information,
see the website at www.nysaes.cornell.edu/fst/asev/.

IV. Juice and Wine Fining Workshop. The Wine/Enology-Grape Chemistry Group,
in conjunction with Scott Laboratory, will offer an afternoon advanced
workshop on juice and wine fining, February 28, 2005, at White Hall
Vineyards, from 12:30 to 4:30 pm. Fee is $30. See Enology Notes # 95for
details.

Enrollment for the program is limited. For registration and questions,
contact Terry Rakestraw at 540-231-6805 or .

All past Enology Notes newsjournals are posted on the Wine/Enology - Grape
Chemistry Group's website at: http://www.vtwines.info

To be added to (or removed from) the Enology Notes listserv, send an email
message to with the word ADD or REMOVE in the subject line.

Dr. Bruce Zoecklein

Professor and Enology Specialist

Head, Wine/Enology - Grape Chemistry Group

Department of Food Science and Technology

Virginia Tech, Blacksburg, VA 24061

Wine/Enology - Grape Chemistry Group website:

www.vtwines.info



References

Brajkovich , M. 2004. Bottle maturation. In: New Zealand Screwcap Wine Seal
Initiative. First New Zealand Screwcap Symposium, Marlborough, New Zealand,
November 10-13.

Godden, P., Franccis, L., Field, J., Gishen, M., Coulter, A., Valente, P.,
Hoj, and E. Robinson. Wine bottle closure. 2001. Aust. J. Grape and Wine
Research.

Mansfield, A.K. and B. W. Zoecklein. 2003. Effect of fermentation,
post-fermentation and post-bottling heat treatment on Cabernet Sauvignon
glycoconjugates. Am. J. Enol. Vitic. 54: 99-104.

Zoecklein, B., Fugelsang, K.C. and B. H. Gump. 1999. Wine Analysis and
Production. Kluwer Academics, New York, New York. pp 621.

"...The Wine/Enology-Grape Chemistry Group is currently evaluating the
impact of accelerated aging, as a means of determining shelf life and
differences among closures...".

Accelerated aging ???


"Paul E. Lehmann" > wrote in message
...
> Enology Notes # 98
> February
> 17, 2005

On Fri, 18 Feb 2005 06:11:16 -0500, "frederick ploegman"
> wrote:

> "...The Wine/Enology-Grape Chemistry Group is currently evaluating the
> impact of accelerated aging, as a means of determining shelf life and
> differences among closures...".
>
> Accelerated aging ???

Perhaps the article means the scam currently targeting wine
drinkers. Maybe not.

There are some goddamn fools who have been told to believe that a
magnetic field "accelerates" wine aging. Bogus devices are being
sold to these damn fools, generally under the term "the wine
clip." It is merely a magnet than clips onto a wine bottle. 30% of
people will find the fraudulent device improves their wine: in
other words, the placebo effect.

---
http://lastliberal.org
Free random & sequential signature changer http://holysmoke.org/sig

"Well Jack, I guess I don't have to floss anymore." --- upon hearing he
had pancreatic cancer (false diagnosis). -- Edward Abbey

Yes, magnets are a scam, though I didn't read the above article close
enough to identify it as a scam. Nonetheless, accelerated aging is
really neat science,and actually we kinda use it in reverse when we age
wines.

Accelerated aging is a standard way of testing materials to identify
how they will age. You heat and store the materials for testing to a
value below where they are known to fall apart (so, plastics, below
where they soften or melt, metals below recrystallization temperatures,
etc.). It's not exact, but a rule of thumb was that storing materials
10 degrees celsius warmer than the expected storage temperature will
speed up the aging of the material by a factor of 2.

I used to be a medical device designer, and one of the things we would
have to do was put an expiration date on our product, usually some set
time following manufacture (1 year, 3 years, etc.). To do that, you
had to test the product to show it still functioned following this
time. Well, the only way to do that would be wait the time, do the
test, then put your product out, but that meant that once you were done
designing a product, you'd have to wait the expiration period until you
could sell it, which means you'd probably have lost your market by the
time you actually started selling. But with accelerated aging, you
might be able to complete testing in 3-6 weeks for each year you wanted
to have as an expiration date.

Having said all that, I'm not sure what they'd be testing for that
wouldn't degrade with heat in wine. Perhaps they're looking at some
chemical drop that would be at different rates in different closures,
and accelerated aging would make the difference more obvious.

In wine-making and aging, we're using decelerated aging by keeping our
wines below room temperature. We're giving the various chemicals in
the wine more time to perform their magic without losing the flavor
components.

Hope that explains it. I don't endorse the above, just explaining it.

Rob

"frederick ploegman" > wrote in message
...
> "...The Wine/Enology-Grape Chemistry Group is currently evaluating the
> impact of accelerated aging, as a means of determining shelf life and
> differences among closures...".
>
> Accelerated aging ???

Partying til dawn with strippers.....

>
> "Paul E. Lehmann" > wrote in message
> ...
> > Enology Notes # 98
> > February
> > 17, 2005
>
>

<desertphile@hot mail. com (Desertphile, American Patriot)> wrote in message
...
> On Fri, 18 Feb 2005 06:11:16 -0500, "frederick ploegman"
> > wrote:
>
> > "...The Wine/Enology-Grape Chemistry Group is currently evaluating the
> > impact of accelerated aging, as a means of determining shelf life and
> > differences among closures...".
> >
> > Accelerated aging ???
>
> Perhaps the article means the scam currently targeting wine
> drinkers. Maybe not.
>
> There are some goddamn fools who have been told to believe that a
> magnetic field "accelerates" wine aging. Bogus devices are being
> sold to these damn fools, generally under the term "the wine
> clip." It is merely a magnet than clips onto a wine bottle. 30% of
> people will find the fraudulent device improves their wine: in
> other words, the placebo effect.

If you really want some laughs, get a Physicians Desk Reference and look
at the effects medications have on test patients. Then look at what a
placebo does to another group who only =think= they're getting drugs. Man o
man!!! ROTFLMAO!!!! People are amazing!
Bob

>
> ---
> http://lastliberal.org
> Free random & sequential signature changer http://holysmoke.org/sig
>
> "Well Jack, I guess I don't have to floss anymore." --- upon hearing he
> had pancreatic cancer (false diagnosis). -- Edward Abbey

"frederick ploegman" > wrote in message
...
> "...The Wine/Enology-Grape Chemistry Group is currently evaluating the
> impact of accelerated aging, as a means of determining shelf life and
> differences among closures...".
>
> Accelerated aging ???

If you google that term (add wine) you'll get some interesting links, here's
one:
http://corp.wineglobe.com/wg/editori...rl=Articles001

Steve

Even easier, you know the ads for drugs in magazines? Usually on the
next page, you'll see a small-print disclosure of all the information
on the drug. About 60% of the way through the stugg, there'll be a
table comparing side effects of people who use the drug against side
effects of people using placebos. I tell you, reading those, I'd never
take one of those placebo things - they'll kill you!

Rob

Who would have believed that the discussion of a perfectly serious serious
article on winemaking processes (probably one of the more serious postings
in quite some time) would have instantly deteriorated into a discussion of
two misunderstood words and scams.

I suspect the wine industry is moveing to screw caps and short term they are
probably right that they work just as well if not better than traditional
corks. Most comercial wine is designed to be drunk within a year or two of
bottling. A big question is whether wines that are really designed to be
aged in bottle for a number of years are better or as good under a screw
cap. If they had a reliable way of "accelerated aging" they may be able to
determine this in a reasonable time period.

Another question is -- when is there going to be a reliable screw cap
sealing system for the home winemaker. All the comercial devices that I
have seen form the cap on the bottle. These devices are a bit pricey for
home use.

Ray

On Tue, 22 Feb 2005 22:28:18 GMT, "Ray Calvert"
> wrote:

> Who would have believed that the discussion of a perfectly serious serious
> article on winemaking processes (probably one of the more serious postings
> in quite some time) would have instantly deteriorated into a discussion of
> two misunderstood words and scams.
>
> I suspect the wine industry is moveing to screw caps and short term they are
> probably right that they work just as well if not better than traditional
> corks. Most comercial wine is designed to be drunk within a year or two of
> bottling. A big question is whether wines that are really designed to be
> aged in bottle for a number of years are better or as good under a screw
> cap. If they had a reliable way of "accelerated aging" they may be able to
> determine this in a reasonable time period.
>
> Another question is -- when is there going to be a reliable screw cap
> sealing system for the home winemaker. All the comercial devices that I
> have seen form the cap on the bottle. These devices are a bit pricey for
> home use.

Why not use bottle caps, the type that crimp on? I read in "Ther
Alaskan Bootlegger's Bible" that the crimp-on caps are just as
good as corks, and one can make one's own capper.

> Ray

---
http://lastliberal.org
Free random & sequential signature changer http://holysmoke.org/sig
"Well, I think there was a mole in the White House... or maybe a gerbil."
(Bill Maher, speaking of the Republican male prostitute in the White House)

"It is true that some of my fiction was based on actual events. But the
events took place after the fiction was written." -- Edward Abbey

Here's more on this topic:

http://www.vwm-online.com///Magazine...6/28thASEV.htm

"...Leigh Francis returned for another study presentation with "The Effect
of Ascorbic Acid, Closure Type and Storage Conditions on the Composition and
Sensory Properties of a Chardonnay and Riesling Wine." The study used
unoaked riesling, and oaked chardonnay. Francis notes that ascorbic acid is
used exclusively in white wine production, but cannot replace SO2 as a
preservative; in Australia some studies have questioned the efficacy of
ascorbic acid because visible browning was thought to correlate with
ascorbic acid levels; this study wanted to verify if ascorbic acid was a
problem.
At bottling, both wines had 45 mg/ L ascorbic acid, with similar free SO2
levels. A spectrometer was developed which could measure light wavelength in
bottled wines; the 420 nm wavelength is used to correlate with visible
browning in wine and with low free SO2 levels. Storage also affects the 420
nm levels in chardonnay; upright storage increased levels for one of two
natural corks used; synthetics used have more 420 nm levels than do natural
corks.

Chardonnay with ascorbic added actually had less browning visible and with
lower 420 nm levels. Ascorbic acid reduces the 420 nm levels when added at
bottling; high 420 nm levels also correlates with oxidized aroma scores, but
a single wavelength e.g. 420 nm is not as reliable as multi-wavelength
levels for measuring wines with and without ascorbic acid measurement. The
study conclusion was that ascorbic acid addition together with sound free
SO2 levels at bottling contribute significantly to reducing 420 nm levels,
or visible browning..."

This seems to contradict the earlier studies. Anyone ??





"miker" > wrote in message
oups.com...
> Here's more on this topic:
>
> http://www.vwm-online.com///Magazine...6/28thASEV.htm
>