MadSci Network: Chemistry

Re: what gives every wine its unique taste?

Date: Tue Mar 7 11:28:09 2000
Posted By: Carl Custer, Staff, Office Public Health & Science, Scientific Research Oversight Staff , USDA FSIS OPHS
Area of science: Chemistry
ID: 949804393.Ch

1) What makes the wines different in taste and color? 
a. Color is easy: Red grapes make red wine; white grapes make some white 
wine.  Red grapes can be used for some white wines -- if the winemaker 
doesn't squeeze the grapes too hard and removes the juice from the skins 
quickly; an example is a "Pinot Blanc.  Rose wine is make from red wines 
where the juice is left on the skins for just long enough to tint it. 
b. The different tastes come from different combinations of chemicals such 
as esters, alcohols, ketones, and aldehydes.  But, you may be more 
interested in what causes these different combinations: 
1. Probably the major taste comes from using different grapes. A Tokay 
grape will make a different wine than a Syrah - just as a Macintosh apple 
tastes different than a Delicious apple and will make a different tasting 
juice.  Thus, most wines are named after the grapes used. 
2. How much sugar is left unfermented in the wine is another factor. For 
instance, Mosel wines are usually left with a little sugar unfermented; 
red Bordeaux wines are usually fermented until no sugar is left (but, 
white Bordeaux are usually sweet).
3.  How the wine was made:  For instance, if a red wine is to be aged for 
a long time, the winemaker will leave the juice fermenting on the skins to 
pick up additional tannins as a preservative.  If the red wine is for 
drinking in a short time, the winemaker will remove the  juice from the 
skins sooner.  Thus, the amount of tannin and the age of the wine affect 
4. Additional differences will come from how the wine is aged. 
For instance, some wines are aged in oak casks to give them an "oaky" 
flavor.  The kind of oak and it's previous use will give more subtle 
Wine is usually aged at a cool (10-15 C) temperature. but Madeira (& 
Sherry) wine is aged at warmer temperatures.  This gives a characteristic 
oxidized flavor named "maderized" which is a "defect" in most wines but 
a "feature" in a few. 
Some Spanish wines, e.g. "reserva" and "Gran Reserva" are aged longer in 
casks to promote their maturity sooner but, evaporation raises the cost of 
making these wines. 
5.  The soil and the climate where the grapes are grown and another factor 
in the tastes of the wine.  For some regions, the vintage year, the year 
the grapes were grown is a critical piece of information.  Some years are 
better than others, because of the amount of sun and when the rains fell.  
The combination of soil and microclimate give some vineyards an advantage 
over another vineyard a few miles away.  Thus, many wines will list not 
only the kind of wine, but also the vineyard from which the grapes 

Whew, I've just skimmed the surface of what gives wines their different 
flavors.  For more information, use your favorite search engine and try 
these combinations:
+"white wine" +"red grapes" +"wine making"
+wine +maderized
+wine +reserva +casks

2) What kind of wine is classified as "good wine"?
The wine you enjoy at the time:
It never hurts to ask a waiter or a wine merchant what they recommend for 
a meal. 
Some people like a light sweet wine; some like an oaky, dry Chardonnay; 
others insist on robust reds.  For instance, with a smoked turkey, I like 
a dry Shiraz Cabernet or a Rioja tinto (reds) but some times I prefer a 
Rhine or Mosel.  My wife usually prefers dry Chardonnays or maybe a 
Cabernet Blanc. Other times, I've enjoyed (free) home made Georgian wine 
or a Portuguese Rose. It depends on the occasion, the circumstance, and 
your budget. 

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