11-20-2005, 06:14 AM
What are the ideal temps and humid levels for wine cellars. In talking with different people I get ranges from 52 to 60 db and 50 to 70 percent
Also how fast could wine "go bad" if the refrigeration system died and the box temp went up to say 70 or 80 deg for a week. Did it realy go bad or can you save it by bringing the temp back down.
The reason I am asking is because I have been to several systems where the refer units have broken down and the customers have said that they "have lost thousands of dollars of wine"
11-22-2005, 12:27 AM
How Temperature Affects the Aging of Wine1
By Alexander (Al) J. Pandell, Ph.D.
There are three storage conditions of concern to collectors and consumers
of fine wine: light, humidity and temperature. The storage area for wine
must be dark because ultraviolet (UV) light will damage wine by causing
he degradation of otherwise stable organic compounds found in wine. Since
these organic compounds contribute to the aroma, flavor and structure of
the wine, the changes caused by UV light result in the deterioration of
the essence of wine. (Note: Fluorescent lights emit a significant amount
of UV light.)
The only reason humidity is an issue in wine storage is because of the use
of the traditional cork seal. The relative humidity of the storage area
(i.e., the amount of gaseous water in the air) can exacerbate the rate of
evaporation of wine from the bottle if the cork is defective. Since corks
are far from perfect in their ability to seal a bottle of wine, ullage
(the space between the bottom of the cork and the wine level in the bottle)
develops in almost all bottles stored for extended periods due to evaporation.
If the cork (seal) is defective, low humidity in the storage area will result
in wine moving out of the bottle faster over time and significant ullage will
develop in less time under these conditions. Thus, the more important issue
is the quality of the cork seal and not the relative humidity in the storage
area. Of course, very low humidity can dry out the cork leading to sealing problems.
Assuming one has good cork seals, and a non-drying (i.e., moderately humid)
and dark storage area, the most important factor in the storage and aging of
wine is temperature. If you ask most anyone associated with wine, from collector
to so-called expert, they will most likely tell you that the ideal storage
temperature is 55° to 60°F. According to conventional wisdom, wine develops
most harmoniously if stored in this temperature range with little or no fluctuation.
So, for example, an excellent storage temperature would be 55°F with a fluctuation
of plus or minus one degree. A well-known wine personality and executive from
Burgundy told me recently that the ideal temperature for wine storage is 13°C
hich is equivalent to about 55°F. Degrees (°) C refers to the Celsius temperature
scale on which water freezes at 0°C and boils at 100°C. This scale is used
throughout Europe and most of the world. The 13°C temperature makes historical
sense since wine storage in France is typically in caves and the natural underground
temperature is around 13°C. Thus, the "ideal" seems to have been the result of
regional custom and practice rather than scientific study.
What will happen to a wine stored at room temperature (73°F) in a dark closet
rather than in a temperature-controlled environment of 55°F, the commonly accepted
"ideal" temperature? This is the question I will attempt to answer in the following
discussion. To do this, we must consider some chemical principles to help us
understand why high temperature is detrimental to wine.
Bottle aging of fine wine is a result of many chemical changes (reactions) taking
place over time. Each of these reactions occurs at a certain speed or rate, and
each reaction is affected differently by temperature changes because each has a
unique energy factor or natural energy barrier, the "hurdle" that must be overcome
("jumped over") for the reaction to occur. Using well founded and accepted chemical
principles that will not be discussed here, one can estimate the effects of
temperature increases above the (assumed) ideal 55°F on the increase in rate or
speed of aging. These calculations are made assuming two different energy barriers,
or hurdles for reaction to occur, (low and high) and three different temperature
changes, 55° to 59°F, 55° to 73°F, and 55° to 91°F. By choosing the low and high
extremes for the energy barrier, one can be fairly certain that the true reaction
barrier lies between these extremes. After examining reactions similar to those that
occur in wine during aging (e.g., oxidation, reduction, esterification, etc.), I am
persuaded that the true reaction barrier lies closer to the high energy barrier than
the low energy barrier. The results are summarized in the TABLE.
The first two columns in the TABLE show the temperature change, and the third and
fourth columns show the increase in the rate of aging associated with each temperature
change based on LOW and HIGH energy barriers. For example, the first row shows a
temperature change of 55°F to 59°F with a calculated increase in the rate of aging
of 1.2 times assuming a LOW energy barrier and an increase of 1.5 times assuming a
HIGH energy barrier. One can conclude from these calculations that the increase in
the rate of aging for a temperature change of 55°F to 59°F is between 1.2 and 1.5
times. This means that if your cellar is at 59°F instead of 55°F, your wine ages 1.2
to 1.5 times faster than if it were at 55°F.
As the data in the TABLE show, going from 55°F to 73°F, an increase in temperature
of 18°F(10°C), doubles the rate of a reaction if it has a LOW energy barrier. If
the reaction has a HIGH energy barrier, the rate of the reaction increases by a
factor of eight for this temperature difference.Translated, this means if your
cellar is at 73°F instead of 55°F, your wine ages 2.1 to 8.0 times faster than if
it were at 55°F. Thus, 3 years at 73°F is equivalent to between 6.3 and 24 years of
aging at 55°F. These differences are very significant.
It gets worse as the temperature difference increases. As seen in the TABLE, a
change from55°F to 91°F increases the rate 56 times for reactions with HIGH energy
barriers and 4.1 times for reactions with LOW energy barriers. So if your storage
is at 91°F instead of 55°F, your wine ages 4.1 to 56 times faster than if it were
stored at 55°F. One month of aging at 91°F is equivalent to between 4 months and
18 years of aging at 55°F. As stated earlier, the "true" situation probably closer
to the 18 year end of the range. These calculations show that higher temperatures
markedly speed up the aging process and result in maturation of a wine over a very
But it doesn’t end there. Another concern is that higher temperatures will result
in undesirable chemical reactions taking place that were either too slow or
nonexistent at the lower temperatures. I think this is as important an issue as
speeding up changes that have a desirable effect on the bouquet of a wine as it
ages. If these undesirable reactions have HIGH barriers to reaction, which is
very likely, then over a moderate aging period for a quality red wine, say 15
years at 55°F, little reaction has occurred and the wine is relatively unaffected.
But, if the storage temperature is 73°F,the undesirable reactions will have
occurred 8 times faster which means the same reactions have occurred in less
than 2 years. Another way to put is that 15 years at 73°F is equivalent to 120
years (8 x 15 years) at 55°F. Of course, very high temperatures for even relatively
short periods can lead to nasty reactions producing compounds with foul odors and
off tastes. This situation undoubtedly prevails at temperatures above 90°F where
the rates of high energy barrier reactions increase by a factor of 56 times or more.
In summary, doubling, tripling or quadrupling the rate of the desirable reactions
is not the only issue in the aging process. Increasing the rates of UNDESIRABLE
reactions that are very slow at lower temperatures may be an equally or more
important issue. Higher storage temperatures make available many new pathways
for desirable AND UNDESIRABLE reactions. Chaos reins in the bottle! Excessively
high temperatures for several hours will surely have a detrimental effect on a
wine’s chemistry with the production of off-flavors resulting from oxidation and
other undesirable reactions whose rates have been dramatically increased by the
higher temperature. It is not going to matter what temperature YOUR cellar is if
somewhere along the distribution line the wine is COOKED on the dock or in a hot
What does one see and taste in a heat damaged wine? One important indicator of
heat damage is color. Pre-mature browning can be an indicator of oxidation due
to heating. A brick edge in a young red wine is a telltale sign of oxidation due
to excessive heat. Since Sherry is an oxidized wine,another indicator of heat
damage in table wines is a sherry-like taste.
If 55°F is better than 73°F for wine storage, why isn’t 49°F better than 55°F?
It may very well be! Clearly, the rates of all reactions will be slowed even more
at the lower temperature. However, 49°F may be too low a temperature to allow some
desirable aging changes to occur at a rate that is comparable to the human life
cycle. Remember from our earlier discussion that different reactions are affected
differently by temperature changes because each has a different barrier to reaction.
Reactions with high barriers are more sensitive to temperature changes and with
decreasing temperature will slow down more than reactions with low barriers.
Since the harmonious aging of wine is due to many different chemical reactions
occurring in a naturally orchestrated manner, the lower temperature may slow down
some reactions to the point where they become non-contributors to desirable
flavors, and, therefore, the wine’s evolution is thrown out of sync. It would
be interesting to carry out research on this, but the time line required is beyond
that of most humans.
As a final thought, and in keeping with the discussion above, be sure to store
your opened bottle of wine in the refrigerator. If you must keep an opened bottle
of wine for a few days, the best place to store it is in your refrigerator which
is typically at a temperature of about 41°F (5°C). The chemical reactions leading
to spoilage (primarily oxidation-reduction) will be slowed down by a factor of 6
to 16 times compared with storage at room temperature (about 73°F). Therefore, a
wine should last 6 to 16 times longer in the refrigerator than at room temperature.
Red wine can be poured in a glass and allowed to slowly warm before consumption or
put in a microwave oven for 15-20 seconds.
11-22-2005, 05:49 AM
One of my thoughts has always been, where were these wines before they got to the customers cellar. Were they in a temp controlled environment before or in some storage warehouse and for how long. If you go to a liquor store to buy wine how long have those pricey bottles been there, because the liquor stores sure don't have temperature and humidity control. I've seen $100.00 plus bottles of wine at a particular store and then a month later I returned to see the same bottle there, with a little mor dust on it.
Kinda makes you wonder.
I think I'll stick to Corona
Poodle Head Mikey
11-24-2005, 05:28 PM
First of all - if the customer has a large cellar, 500 bottles or more, I consider this to be a 'critical service' application, like a blood bank, and strongly suggest redundancy - two completely seperate refrigeration units.
This is just my opinion, but I think that the loss of temperture control if less critical than is the rate of re-cooling. Simple thermal mass in a well stocked cellar will slow the temperature rise for a day or two anyway. But if a cellar has been warm I ALWAYS have the customer reduce the temperature by about two or three degrees MAX per 24 hours - until it's back to 55°, so as not to 'shock'the wine. Especially French reds. California wines seem more tolerant in general. Of course the French would insist that this is because they were not as good to start with. <g>
I fell that the actual temperature is less critical that the Rate Of Change in temperature.
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