Evaluating Wine for Faults

What to be on the Lookout for in your glass: 

The Good

Sacchromyces, a yeast that lives without air and produces alcohol, these die around 16-18% alcohol yet most die earlier by heat. Choosing strains that live longer or cooling vats can alter future alcohol content.

Lactobacillus, bacteria that convert malic acid into lactic acid. They do this by chopping off an acetyl group, which when in high concentration forms diacetyls and  tastes of  “buttered popcorn”; the stages in between are like cream, custard, butter and butterscotch. This fermentation is  bacterial (not yeasts) and occurs naturally - the wine master must decide on how and when, if at all.

 
The Bad
Acetobacter, bacteria that love to eat sugar but make acetic acid (vinegar)
Trichloranisoles(TCA), a mold that grows on overly bleached barrels, piping and corks
Brettanomyces(dekkera), a yeast that lives in unclean equipment, mostly wood crevices
Zygosacchromyces, a rude form of the good yeast “Sacchomyces”
Mercaptans, the result of additive sulfurs combining with too much oxygen
Ethyl Acetate, those malactic by products exposed to too much oxygen
 
 The Ugly
My Wine Smells Like:                                                            
Butterscotch, Popcorn              Possible Cause:   Malactic went too far
Metallic, Sour, Brown                                                  Oxidation, anytime in process
Band-Aid, Antiseptic, Sweat                                     “Brett”, those dirty barrels
Wet Dog, Musty, Cardboard                                       TCA, the “bleach mold”, a survivor
Vinegar, Sour, Salad dressing                                  Acetobacter
Nail Polish, Varnish                                                      Ethyl Acetate, O2 in the vats
Rotten Eggs, Septic/Sewer                                        Sulfur Dioxide, overdosing the batch
Onion, Skunk, Rubber                                                 Mercaptans, sulfurs with a lot of oxygen
 
Oxidation Fault:
Aldehyde - Shery - Bruised Apple - Wet Paper - Beer - Dullness
Volatile Acidity:
Nail polish remover - Model glue - Vinegar - Pungent - Acetic
Brett Fault:
Band aid - Horsey - Wool - Creosote - Medicinal
Mousy Fault:
Popcorn - Corn chips - Bread crusts - Mouse urine
Cork Taint:
Musty - Moldy - Dank Cellar - Old Books
Sulfide Fault:
Boiled eggs - Garlic - Cabbage - Rubber - Socks - Boiled Potatoes
 
While many of the negative factors will be in most wines, it is a matter of how high in concentration and the taster's profile.  Just as strong cheeses or pet odor may offend some persons, wine is quite subjective.  Often many characteristics "blow off" as the wine begins to open, yet a true fault will not - leaving the wine with a lack of balance - and undrinkable at any level.  Many wines have a touch of Brett, rendering one to believe that it is an Old World style; others with sulfide faults are unforgiveable.  A good rule of thumb is that a wine that cannot pass your eyes or nose should not be thrown into your mouth - enjoyment is not forced!