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THE STOMPER
The Monthly Winemaking Newsletter of grapestompers.com
October, 2001 Issue #15
http://www.grapestompers.com 1-800-233-1505
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Welcome to the latest issue of "THE STOMPER", a newsletter
of winemaking hints and other wine-related articles.
You are receiving this newsletter because you requested a
subscription and have an interest in home winemaking.
Unsubscribe instructions are at the end of this newsletter.
Feel free to pass along this newsletter to your winemaking
friends; we only ask that it be sent in its entirety.
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IN THIS ISSUE
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=> Feature Article - How to Rehydrate Yeast
=> New Products
=> Bonnie's Bin - Breaking in the New Warehouse
=> This Month's Specials
=> Tom's Cellar - My Trip to Australian Wine Country
=> Feedback from Our Customers
=> Improved Look for Free Wine Labels
=> Guest Column - Acidity and pH - Whys and Wherefores
=> How to Be Featured as our Guest Columnist
=> Corky's Winemaking Definition
=> Subscribe/Unsubscribe Information
*^* Hot Tips are sprinkled throughout the newsletter
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FEATURE ARTICLE: How to Rehydrate Yeast
By Brant Burgiss, Editor
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Fall has certainly arrived in the mountains of North
Carolina, where early morning frosts and cold winds have
already appeared. It's a great time of year to be inside
making wine!
We had a wonderful time at our 4th Annual Wine Tasting
on October 7th (hence the tardiness of this newsletter)
and all of us at grapestompers.com wanted to thank you
for a great turnout and a wonderful party. We got to meet
a lot of our customers in person; many like Ed Csencsits
came from several states away to attend. We can barely
wait for next year's bash!
Anyway, on with the show...
This month's winemaking article explains how a simple
five-step process can vastly improve your wine's chances
of success.
The rehydration of active dry wine yeast is easy to
do, and when done properly, can help ensure thorough
fermentation.
You can learn how to rehydrate wine yeast, as well as the
reasons for doing so, on the newest page on our web site:
http://www.grapestompers.com/articles/rehydrate_yeast.htm
We hope you'll like this page, and will be able to pick
up a few pointers about taking care of your yeast during
water uptake.
Here's to you... and Happy Winemaking!
You can write to Brant at webmaster@grapestompers.com
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NEW PRODUCTS
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Here is a list of products recently added to our catalog:
- Item # 3168 Sangiovese Cru Select Gold Wine Kit $77.00
- Item # 3170 Amarone Classico CS Platinum Wine Kit $80.66
- Item # 3168 Shiraz (Aust.) CS Platinum Wine Kit $80.66
- Item # 3284 Chardonnay (Aust.) CS Plat Wine Kit $73.32
- Item # 3274 Soave (Italy) Grand Cru Wine Kit $39.60
- Item # 3270 Riesling Grand Cru Wine Kit $45.84
- Item # 2718 Wine Kit Enhancer, Red $1.91
- Item # 2719 Wine Kit Enhancer, White $3.12
- Item # 2688 Buon Vino Automatic Bottle Filler $16.94
- Item # 2680 B. Vino Fill Jet Elec Bottle Filler $293.32
We've added 6 new wine kits this month, all made by the
folks at RJ Spagnols. The Cru Select (CS) line of wine kits
(both Platinum and Gold varieties) contains 16 liters of
juice, while the Grand Cru line has 10 liters of juice.
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BONNIE'S BIN: Breaking in the New Warehouse
By Bonnie Brown, Manager
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Happy October to all of you home winemakers. This IS the
season isn't it? We have sure been busy filling your
orders. Excuse us if we are a bit behind. Lots happening,
AGAIN! Is that a statement I make each month? Sounds like
something I have said a lot over the past few months!
Our new building (warehouse and pack/ship) is under roof
so Tom had them build the shelving. We are now moved in.
It's not as organized as it will be when the building is
done, but certainly usable as long as we stay to one side
out of the builder's way. It is going to be so easy to work
in... soon! We are enjoying it in the rough while
dreaming of the finished product. It's a major step
forward for us. So nice and exciting that we have been
discussing the next addition!!
One positive point here, the Bodega certainly looks
wonderful all cleaned out. I think we should have a wine
tasting every 6 months or so! Ya get a lot done in a short
time! We spent a couple of days last week moving and
rearranging. Where our stock was we now have a wonderful
room in which to make our wines. Nothing is crowded!
There is also a relaxing area in our office where customers
can sit and go over things. Overall, it is more inviting
the minute you walk in the front door.
For those of you who attended our wine tasting on October
7th, THANK YOU! You helped in making it a very enjoyable
day. For those who could not attend, we are sorry to have
missed you. There was a variety of wines: Dandelion, plum,
and Ma Barker's grape for some of the homemade wines. That
was a wonderful experience in itself. I don't usually get
to taste those, I just hear about them in phone calls and
e-mails. It is always fun for us to meet, greet and
converse with other winemakers.
See you next month.
Bonnie
GOD BLESS THE USA AND THOSE WHO DO THEIR PART!
'Tis a wonderful day in the mountains. . .
Life is too short... to drink bad wine... so make your own!
You can write to Bonnie at bonnie@grapestompers.com
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THIS MONTH'S SPECIALS
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grapestompers' specials for the month of October 2001 are:
Save 10% on VDV White Zinfandel Wine Kits
AND
Save 10% on our "Home Stomper" Special
AND
Save over $70 on the purchase of a
Complete Winemaking Starter Kit
which includes a RED or WHITE Concentrate
(see wine kit selection below)
Item # Description Regular Price SPECIAL Price
3229 VDV White Zin Wine Kit 43.95 39.56
2010 Home Stomper Special 33.10 29.79
3200 Complete White Starter Kit 246.68 175.00
3100 Complete Red Starter Kit 259.79 185.00
Here's what you get with the HOME STOMPER special:
+ 3 gallon glass carboy
+ Multi-fit stopper (fits carboy)
+ Airlock (Triple Ripple)
+ Triple Scale Hydrometer
+ Recipe Book (#2801)
+ Packet of yeast (Montrachet)
+ Campden tablets (2 oz. - about 100 tabs)
+ Pectic enzyme (15 ml)
+ Yeast Nutrient (4 oz.)
+ Acid Blend (3 oz.)
+ Bentonite (4 oz.)
The Home Stomper special provides nearly everything you'll
need to create your own homebrew from scratch - except the
juice! So pick your favorite fruit, flower, or edible
plant and start making wine!
Here's what you get with the COMPLETE Starter Kit:
If choosing the Complete WHITE Kit, your choice of either:
Fume Blanc, Piesporter, or Chenin Blanc VDV concentrate
If choosing the Complete RED Kit, your choice of either:
Valpolicella, Shiraz, or Cabernet/Merlot VDV concentrate
PLUS ALL THESE GOODIES:
Tom's Winemaking Video Bottle Rinser
Fermenter Bucket with lid Three-Piece Airlock
6-Gallon Glass Carboy Carboy Brush
Bung (stopper) Bottle Filler
Five feet of vinyl tubing B-Brite Sanitizer
Portuguese Hand Corker FermTech AutoSiphon
2 Cases of 750-ml Bottles Spoon or Paddle (our choice)
Bottle Washer Adapter Brass Bottle Washer
Bottle Drainer, 45 station
AND YOU GET THE FOLLOWING ITEMS FREE ($16.59 value):
- Free Wine Labels (text of your choice)
- Free $5 coupon towards your next concentrate purchase
- Free Corks (30 corks, enough for one batch)
Just think: This complete kit offers EVERYTHING a brand-new
hobbyist would need to begin making his own wine. All you
need to decide is which wine kit you want!
And don't forget... you can always return your winemaking
video and receive a credit for $19.95 on your next
purchase... that's like getting the video for free! All
we ask is that you return it in good condition.
This is the best deal we've ever offered on a complete kit,
so don't miss out... order one for yourself or a friend
today. Ask for RED Complete Kit # 3100 or WHITE Kit # 3200
and be sure to let us know which wine concentrate you want.
NEW! Now you can "personalize" your Complete Kit -
Let's say you don't need or want some of the items that
normally come with the Complete Kit... just give us a call
at 1-800-233-1505 and let us know which items you don't
need, and we will adjust the price of the equipment kit
accordingly. Likewise, if you'd like a different wine kit,
just let us know and we can adjust the price.
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TOM'S CELLAR: My Trip to Australian Wine Country
by Tom Burgiss, Owner
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I would like to share with you my impression of the wines
in Australia from my recent visit to "The Barossa" area of
South Australia.
This was an excellent trip and I highly recommend it! The
folks were very friendly and you can see and appreciate
the loving care the Australians have given their vineyards
through the years. The Barossa area is a concentrated
boundary about 30 miles (50 KM) north of Adelaide (a real
showplace and a well laid out city on the coast of the
Indian Ocean).
There are 51 wineries open to the public for you to visit
in Barossa. These are all very close to each other in
about a 5-mile radius of Tanunda. North of Tanunda there
is Nuriootpa, South is Lyndoch and to the Northeast there
is Angaston. My wife, Nancy, and I stayed near Tanunda on
property that touched "Jacob's Creek"! This area produces
the grape concentrate we handle here at grapestompers.com
in both the Vino del Vida (VDV) and the Cellar Classic (CC)
brands. All grapes are mostly handled by a co-op that runs
24 hours a day with tremendous storage capacity during the
harvest season. There is very little rainfall in this
region, with hot temperatures around 110 degrees F during
their summer months. Water that is driven off during the
concentration process is captured and recycled, so you can
see water is very precious.
*-----------------HOT TIP------------------*
I just discovered a great way to crush
Campden tablets. It is a little device
called the "Pill Pulverizer."
I found this at Wal-Mart in the pharmacy;
it is made by Apex Medical Corporation and
costs just a few dollars. After all the
time I have spent crushing Campden, I now
do it in a matter of seconds!
It also pulverizes must finer than I ever
could. What a time saver! If the "Pill
Pulverizer" is not available locally,
their address is:
Apex Medical Corporation
PO Box 1235
Sioux Falls, SD 57101-1235
Our thanks to Deanna Truran from
Fairfield, IL for this tip.
Have a tip you'd like to submit?
Send it to tips@grapestompers.com
*-----------------HOT TIP------------------*
It was interesting to note that they pay special attention
to the wind when deciding how to plant the rows of their
vineyards. Sunlight is very essential to their producing
a great wine. It has been written that "wine is sunshine
held together by water" and it is certainly true! The
hills are rolling and the soil filters quickly. As you
might have guessed, the sun does set in the west, but
really in the northwest! We visited about 11 of the 51
wineries and ran across some unusual wines. One of our
favorites was a chocolate wine known as "Choc-a-Bloc"!
In closing, I am happy to report with competition of
"Virgin Blue" with "Qantas", air travel inside Australia
was very reasonable (round trips ran $100). August (their
winter) was perfect weather for this mountain man.
The service and accommodations were not crowded, and our
dollar bought 2 Australian dollars.
When I visit a country I like to mix with the natives...
My favorite place to accomplish this on this particular
trip was the pub at Tununda Hotel (my kind of place!). If
you've got about a day to talk, come visit me, and I'll
share with you some other favorite wine places of mine and
Nancy's... for instance, Yamhill County in Oregon, Waiheke
in New Zealand, and Victoria, BC and others!!
See ya! Tom
You can write to Tom at tom@grapestompers.com
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FROM OUR CUSTOMERS
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As you might imagine, our office receives quite a bit of
correspondence - mostly through e-mail - here are some
comments we've recently received:
Bonnie,
Thanks for confirming the order, and tallying the total.
You guys make it very easy to shop online, and your
products are first rate.
Hope Tom is well.
-- Ron Clark
Fairfield, PA
Tom,
I just wanted to thank you for you expertise on fining
wine. I called and so did my husband, fisherman Ralph,
and we used the bentonite and everything came out hunky
dory. With all the work the elderberry wine took, it was
way worth it. I know you'd like us to be more sanitary
and precise, but I'm not going to talk my husband out of
making wine the way he has for 40 years. Believe me, I
tried. This is the first flawed batch, and I hope the
last... but it's nice to know you're there for support.
You are a peach!! Thanks again.
-- Teri Reinhart
Fostoria, OH
Bonnie,
You went above and beyond what anyone should ever expect
in quality customer service. I just had momentary anxiety
and you caught it! Anyway, thanks again - I'm sure this
wine will be a "great year" when it is all said and done!
Yours,
-- Marva Griffith
Clarkesville, GA
Tom and Bonnie,
I received my order promptly and complete! The Vintner
license tag was a very nice gesture, thanks!
-- Don Steberl
Newport News, VA
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Improved Look for Free Wine Labels
by Brant Burgiss
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If you've received free wine labels from grapestompers.com
recently (you get free labels with each wine concentrate
kit you purchase), you may have noticed an improved look.
What happened?
Crazy Tom must have sprung a leak in his pocket, because
we have recently purchased a color laser printer!
We think you'll love the improved look and feel of your
free wine labels. The best things about labels made by
our new printer:
1. The colors won't fade
2. The colors won't run if the label gets wet
3. The colors are more VIVID and CLEAR
4. The labels have a shinier finish to them
Remember - all you have to do to get your free wine labels
is to tell us a couple things when ordering your wine kit:
- The type of label you want. Just make your pick from the
labels shown at http://www.grapestompers.com/cat104.htm
- The name of your winery (i.e. Smith Mountain Cellars)
We'll automatically print the vintage year and type of
wine for you.
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GUEST COLUMN - Acidity and pH - Whys and Wherefores
by Dave Burley, SC
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Summary: Making wine without knowing about pH and acidity
and how to adjust them is a lot like wearing a blindfold
while you drive with no steering wheel. You may get where
you want to go, but not likely.
In this article, the following is discussed:
-pH and Acidity - Who cares?
-So Why Should You Care About Acidity?
-pH and Acidity in must
-Acidity Measurement
-Finding the Endpoint
-Using a pH Meter
-Why Do you care About pH?
-Acidity and pH Recommendations for Wine
-Malo-Lactic Fermentation
-Cold Conditioning
-Chemical Acid Adjustment
-You're Now in Control
pH AND ACIDITY - WHO CARES?
This time of year all the grapes are coming in from
California or your local mid-western vineyard or maybe
from your backyard trellis. Or maybe you have some other
fruits which you want to convert into nectar for those cold
winter nights that may be coming your way. Assuming you
obey all the rules and are careful in your sanitation, one
of the surest ways to not have a good wine is to ignore the
effect of pH and acidity on the final product.
If you have been a winemaker for any time period, you have
probably read at least one explanation of pH and acidity.
Some are confusing, especially if you don't have a
technical background and already know something about it.
Others don't go far enough, especially with fresh fruits.
And you aren't always sure just why you care about these
at all. Many of you just think it is too much trouble to
try to adjust these and just add your lemon juice (even if
you may not need it) and hope for good wine.
Think of pH as an intensity measurement, like temperature,
and think of acidity as a quantity measure, like heat
content. Now you can understand that while they may be
related in a particular substance they are not identical.
The pH is an indicator of the free hydrogen concentration
when you measure it. The total acidity is a measure of the
potential hydrogen ion contribution were it to react with
a base.
Probably the most puzzling thing about pH is that it is
based on a logarithmic scale so that each pH unit is ten
times more or less hydrogen ion concentration than its
adjacent value. Thus a pH of three may be 0.001 M in terms
of hydrogen ion concentration and a pH of 4 is 0.0001 M.
So remember the pH scale is not linear, but treat it like
you would a temperature measurement and you will do just
fine.
Those of you who learned about pH in chemistry class but
didn't go on to study about weak acids, buffers,
simultaneous equilibria and such are often puzzled about
why pH and acidity are not more closely related in wine.
That's another story we can't get into here, but suffice
it to say that the wine system is a complex mixture of
weak acids and acid salts which make pH difficult to
predict, so the most efficient method is to determine the
effect on pH in wine of added acids and bases is to do it
experimentally. Another tricky thing discussed below is
that long term these measurements may not be exact since
insoluble but slow to precipitate salts may precipitate,
changing the pH and acidity. Fun, huh?
SO WHY SHOULD YOU CARE ABOUT ACIDITY?
As far as the taste goes, total or titratable acidity (TA)
is the key factor in whether your wine tastes acidic or
flabby or just right. Sugar content of the wine can modify
this perception somewhat, making higher acid wines more
enjoyable.
pH AND ACIDITY IN MUST
Here are some recommendations for various musts as a
guideline:
White wines: 0.7% - 0.9% total acidity and pH of 3.1 - 3.4
Red wines: 0.6% - 0.8% and a pH of 3.3 to 3.6
For sweet or semi-sweet it is better to have the acidity
in the higher range and the pH in the lower one to help
balance the sweetness.
These are not the recommended levels for the final wines
however (see below) as some changes to these values occur
depending on other winemaking processes, especially yeast
fermentation, malo-lactic fermentation and cold
conditioning (more later).
So how do you determine the total or titratable acidity?
First let's understand that the total acidity and the
titratable acidity expressions are used interchangeably in
the US and refer to the grams of tartaric acid per liter
of solution. This can be expressed as parts-per-million,
ppm, (which is milligrams per liter) or as a % which is
grams per 100 milliliters. We will use % in this
discussion as is the habit of many professional books.
You may find that older books and books not published in
the US may use other standards, particularly sulfuric acid
or citric acid as standards. Be sure to understand what
standard is being used in anything you read.
ACIDITY MEASUREMENT
Now to the measurement of total acidity. In this measure-
ment the acid in the wine sample is reacted with a base
(sodium hydroxide) until exactly all of the acid is
consumed. This is called the "equivalence point" or in
common vernacular the "endpoint" (abbreviated e.p.) when
doing a titration.
A titration is the method in which the acid source is
placed in a beaker or flask, some water added, and an
endpoint indicator (phenolphthalein) added. A known
concentration of sodium hydroxide (typically 0.1 or 0.2N)
is added slowly until the endpoint indicator changes color
and the volume of sodium hydroxide is recorded. This value
is used to determine the titratable acidity (or TA) by a
simple equation which assumes a 5 ml sample of wine:
TA = 1.5 X Vb X Nb
Thus if you used 0.1 N NaOH then the formula would reduce
to TA = 0.15 x Vb, which many of you have seen in a
popular supplier's catalog. Of course, others may have
seen different formulas depending on the conditions of
the titration in terms of sample size and base normality,
but let's stick with this simple formula here.
Oh, if you are wondering whether or not added water will
affect the outcome of this titration, it won't as you are
measuring the total quantity of acid which does not change
with added water. You should use distilled water which you
can buy at the grocery store under "Water". If you don't
have access to distilled water, just take a 50 ml sample
of your tap water and titrate it without added sample and
see where the endpoint is. Usually one drop of base is
sufficient to get an indicator change signaling that you
can use this water. If your water takes several drops, then
this correction can be used by subtracting this from the
total amount of base added before you calculate TA.
FINDING THE ENDPOINT
With white wines the endpoint is easy to see and you
should have no trouble determining the TA. In the case of
phenolphthalein, the proper procedure is to add base until
the solution turns just slightly pink and remains so for
about 20 seconds. Record the mls of NaOH. To check the e.p.
add another drop and the color should become very dark red.
This is how it should be theoretically. In real life there
are some white wines that exhibit color change slightly as
you add sodium hydroxide so be sure not to get fooled.
Always go to the pinkish endpoint and check your mls by
going slightly beyond it to a dark red. Often it is best
to do a quick titration and then repeat it more carefully
once you are in the ball park.
*-----------------HOT TIP------------------*
I almost dropped my carboy after sanitizing
it with cleaner - it was really wet and
slippery!
My solution to prevent dropping slippery
carboys was to carry them using two wet
washcloths - one for each hand.
I grip the top of the carboy around the
neck with one washcloth, and bottom of the
carboy with the other.
Our thanks to Jimmy Phipps from Sparta,
NC for this tip.
Have a tip you'd like to submit?
Send it to tips@grapestompers.com
*-----------------HOT TIP------------------*
Here's how to check the acidity of red/black fruits. It is
tricky since the fruit color is also pH sensitive and
changes to a grey green color at about pH = 5.5.
CHOICE 1
Dilute the 5 ml sample to about 50 - 100 mls with distilled
water (grocery store under water section). Do not add
phenolphthalein until you have added enough NaOH that it
gets to the dark green/grey point at which no red
coloration should remain. Then add phenolphthalein and
titrate to a slight reddish coloration in amongst the
grey/green. Not easy but with practice you will learn.
A side light in a slightly darkened room may help.
CHOICE 2
If you just note the point at which the color of the
solution goes to the grey/green color without any reddish
and this will be close enough for most wine work as this
is a pH of about 5.5 and it only takes a few drops more to
get to the 8.2 at which phenolphthalein changes color.
Many wine labs use this method at least for a quick
analysis at the beginning. The danger here is that this
endpoint is not sharp and inexperienced eyes may miss the
slight rosy color from the unreacted pigment. Such an error
will result in a low TA reading. Be sure you go on to the
point at which no red color is indicated in a grey/green
solution.
CHOICE 3
Often when I am faced with a tricky, highly colored sample
(blackberry, raspberry, elderberry which, unlike grapes,
sometimes keep a slight reddish color all through the
titration) I use a pH meter and plot pH versus mls of NaOH
as the sample is being titrated. I add in increments of
1 ml and near the e.p. around pH = 5 in 0.5 ml increments.
This plot is "s" shaped and where it rises through pH = 8.2
is the traditional endpoint. This is a quick rise so you
may go from pH = 5 to pH = 8 in only a few drops. Don't
worry. Now you know the endpoint, as it is the point at
which the change in the pH is the fastest versus added
NaOH.
USING A pH METER
Remember pH meters have delay in them, so most ones
available do not make for titration "on the run" as an
indicator does. So that's not how a pH meter is used in
this circumstance. The NaOH is added in set increments
of about 1 ml as described above and the pH meter reading
is allowed to stabilize. A plot of the pH vs. NaOH volume
will exactly indicate the end point in even the darkest
inky wine or must. You can also use this to train your eye
to the color changes.
There are lots of suitable pH meters available from various
suppliers including wine hobby stores and by mail order.
Omega has a wide variety. Check out their web address -
www.omega.com. Costs as low as $35 I think, but plan on
less than $50 to get one that reads to two significant
figures. You can pay more, but it is not always worth it.
Be sure to also buy the buffer solutions at pH = 4.0 and
7.0 to calibrate your meter and to store the pH meter wet
in pH 7 buffer and not distilled water. There is also a
special storage solution you can purchase. Clean the probe
with pepsin (a proteinase) periodically. A protein layer
builds up on the glass, especially if it is used for
producing beer also. Also, be sure you replace the buffer
weekly as it is a haven for bacteria.
WHY DO YOU CARE ABOUT pH?
Other than using a pH meter like a thermometer to judge
the actual hydrogen ion concentration, what other use does
it have in winemaking?
The pH of the grape must and wine is the key to the
stability of the final wine and whether or not you get
infection easily during the fermentation. pH determines
the activity of sulfurous acid. At around 3.3 it is the
most active. Higher pHs cause the formation of the sulfite
ion and reduce the activity. Practically speaking you would
like to have the pH below 3.7 in all cases. If you pick
your own grapes then try to pick them at a pH of around 3.5
or lower.
What to do if your pH of the must is too high? You will
need to add acid to adjust the pH. To determine how much
to add, make up a known solution of tartaric acid (say 1%)
and add it to a known volume of wine (say 50 mls) until the
pH drops into the desired region around pH =3.4-3.5 or so
for reds and pH = 3.3- 3.4 or so for whites. Calculate how
much acid is needed to be added to your wine and what the
must's TA will be. Hopefully you will be within the above
guidelines of pH and TA. But now comes a balancing act if
you are in the unfortunate state of high acid wine and high
pH. It does happen. If so, minimize the amount of acid you
will add by sticking to the upper limits of the guidelines.
Don't worry too much about this as you will likely be
adjusting the acidity of the wine as discussed later.
ACIDITY AND pH RECOMMENDATIONS FOR WINE
Phillip Jackish in Modern Winemaking, p 103 (Cornell 1985)
suggests the following range for pH and acidity for wines:
Wine Titratable Acidity pH
Dry White 0.65-0.75% 3.2-3.6
Dry Red 0.60-0.70% 3.2-3.6
Sweet White 0.70-0.85% 3.0-3.5
Semi-Sweet Red 0.65-0.80% 3.0-3.6
Sherries 0.50-0.60% 3.4-3.9
for Sparkling, Ports, Fruit and Flavored wines generally
the same as the corresponding wine in the above table.
MALO-LACTIC FERMENTATION
If your grapes came from a region such as the mid-west
where the acidity is high and the malic acid (green apple
taste) is high, now near the end of the fermentation is the
time to decide to do or not do a malo-lactic fermentation.
In this bacterial fermentation (starters available from
your wine hobby supplier) the malic acid is converted to
lactic acid and the pH rises. To carry out this
fermentation it is necessary to have low sulfite typically
0 to 20 ppm. If you choose to do this it is a good idea
to determine if you have a malic acid problem by doing
paper chromatography with a kit you obtain from your wine
hobby supplier and follow the directions. As the
fermentation progresses you will see the malic acid drop
to zero and then it is time to add sulfite to the wine to
get protection. Remember if you do a malo-lactic
fermentation (MLF) you should not blend this wine with
one which has not undergone MLF as it will eventually
ferment in the bottle with subsequent formation of gas
and reduction of the acidity. Not a nice thing.
COLD CONDITIONING
What if you can't get inside the guidelines? Don't worry
too much about it if you are 0.1 units high or so, as a
third technique will help you drop the acidity and the pH
without much affect on the wine's taste or other
organoleptic properties.
As it turns out, potassium bitartrate, the partially
neutralized salt of tartaric acid, is pretty insoluble in
wine, but it is slow to precipitate. It is also a buffer
and controls the pH to a great extent. Removing a portion
of it will affect the pH and TA. Cold conditioning the
wine by keeping it near to slightly below the freezing
point of water (not the wine) for a week or two will
precipitate cream of tartar (potassium bitartrate crystals)
which will reduce the total acidity and the pH. This will
also ensure that you don't get crystals in your bottled
wine.
Once the wine is cold, add crystals (about 1/8 tsp of
Cream of Tartar per 5 gallons). This addition while not
totally necessary will guarantee a quick and thorough
precipitation as they act as seeds for the potassium
bitartrate to form. Cream of tartar is available in the
spice section of your supermarket. While still cold, rack
the wine off of the crystals. Once it has returned to room
temperature, check the acidity and pH.
CHEMICAL ACID ADJUSTMENT
If you do end up with an acid wine after cold conditioning
then and only then is it time to adjust the acid by
reacting it chemically with potassium bicarbonate/carbonate
(whichever is available) or calcium carbonate or with
proprietary acid modifiers, like Acidex or Sihadex,
typically containing calcium carbonate with crystals of
calcium tartrate and calcium malate. Note that you should
do only one of these chemical treatments, so now is the
time to choose based on how far you need to go and if you
have a malic acid problem.
If the acidity is within 0.3% of the desired value and the
wine does not have a green apple taste from malic acid, you
can likely use potassium carbonate/bicarbonate and simply
neutralize any acid by adding this to get to the desired
TA. Care should be taken as it will fizz. It is best to
do this to a small portion of the wine and then recombine
it with the bulk doing it more than one time so as to avoid
missing the desired level and to avoid getting a salty
taste which can occur at the upper levels of added
potassium. Cold conditioning is again required to reduce
the possibility of cream of tartar formation later in the
wine. This will also reduce any possibility of salty taste
and will often drop the pH a little more.
If the acidity is still too high after cold conditioning
and outside the above 0.3% guideline and you have a malic
acid problem, the use of calcium carbonate is recommended.
But you should do this to only a portion of your wine and
and neutralize all of the acid to remove both calcium
tartrate and calcium malate, which is much more soluble.
Cold condition this treated wine and recombine with the
bulk of the wine. This technique also minimizes the
effect that calcium has on the other components of the
wine as some of them are insoluble in the presence of
calcium as well. Too much calcium may result in a chalky
taste, so do this judiciously.
What do you do if the acidity of your must is too low?
Easy - add tartaric acid but keep an eye on the pH to stay
inside the guidelines. You can always add more acid but it
is difficult to remove it. It is a good idea if you add
more tartaric acid to cold condition again.
YOU'RE NOW IN CONTROL
Well, there you go. Blindfold is off and you have the
steering wheel. You're in control.
Good Winemaking!
Dave Burley
Copyright 2001 David R. Burley
ABOUT THE AUTHOR - Dave Burley has been making wine since
1960 when he started a gallon of "applejack" made from
apple juice, brown sugar and raisins in his Grandpa's barn.
He's maintained his winemaking interest through college,
although information was sparse and supplies non-existent
and made beer in graduate school. He moved to Wales for
post doctoral research in Physical Chemistry and found to
his delight that making wine and beer was legal and
supplies and literature abounded.
He has maintained an interest in both wine and beer making
over the decades by digging into the more technical aspects
of professional literature but has not lost the fun of
fermentation.. He's won two national Gold medals and a
Bronze from an American Wine Society contest for his reds,
Petit Syrah, Pinot Noir and Cabernet Sauvignon.
Recently Dave moved to South Carolina and picked 2000
pounds of vinifera grapes from his new vineyard and made
about 120 gallons of wine from the twenty European
varieties he has planted there. Since Pierce's Disease is
indigenous to this area, he is beginning a program of
grape breeding for P.D. resistant grapes from local grapes.
You can contact Dave at Dave_Burley@charter.net
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