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Flaws in Wine

The Winemaker’s Think Tank: Vol 12- Common Winemaking Faults and Flaws

Wine expert testing wine silhouette image

What’s the Winemaker’s Think Tank?

Every Thursday we will post about a few frequently asked questions that our winemaker has answered. If you have a winemaking question you would like to have answered, please email us at support@juicegrape.com and we will try to get into next week’s post. Cheers! :)

In this week’s Winemaker’s Think Tank we outline the difference between flaws, faults, and how to identify them.

  • Flaws
    •  Flaws are a mistake made in the winemaking process that leads to a property in the wine that is not characteristic of the varietal
    •  Stylistic Choice vs. Flaw
    •  Imbalance Flaw
      • Acid vs Sugar, Oak Levels, Alcohol Level
    • Visual Flaws
      • Haze, Sediment, Effervescence, TA Crystals, Floaters, Lack of Color Saturation
    • Aroma/Bouquet Flaws
      • Lack of Aroma, Non-varietal aroma, Over-oaking
  • Faults
    • Faults are often a microbial or chemical reaction within the wine in some part of its life that significantly alters a wine, eventually leading to the point of spoilage.
  • Oxidation Faults
    • Acetaldehyde – oxidation of Ethyl Alcohol smells like sherry, or old apples, browning
      • Causes: headspace, low sulfites, poor corks, bacterial contamination
    • Acetic Acid – Vinegar
      • Causes: Acetaldehyde, Acetobacter bacteria react with ethanol, Fruit Flie
    • Ethyl Acetate – Nail Polish Smell
      • Oxidation of Acetaldehyde and Acetic Acid
      • Causes: headspace and bacterial contamination
  • Sulfur Faults
    • Hydrogen Sulfide – Rotten Eggs Smell
      Causes: lack of yeast nutrients, yeast stress, sulfur sprays, yeast bi-product, high temps
    • Sulfur Dioxide – Burnt Match Smell
      Causes: over sulfating, wild yeast
    • Complex Sulfur Faults- Mercaptans, DMS, DES, DMDS, DEDS
      Causes: Hydrogen Sulfide reacting with Ethyl Alcohol
  • Microbial Faults
    • Brettanomyces – Barnyard, Horse Saddle, Antiseptic Ointment, Band-Aids, Bacon, Clove
      • Causes: spoilage yeast cells that are incredibly dangerous and difficult to eliminate. Most often found in contaminated barrels, winery cleanliness, resistant to acid and SO2
    • Geranium Taint – Fresh cut geranium leaves
      • Causes: Reaction of potassium sorbate with Lactic Acid Bacteria in the presence of Ethyl Alcohol
    • Refermentation – Fizzy wine, popped corks
      • Causes: Yeast or microbial fermentation of residual sugar
  • Other Faults
    • Cork Taint – Wet basement, wet old newspaper, mildew
      • Causes: strain of trichloanisole on cork (cork taint); mold that contacts chlorine and wood
    • Heat Damage – Cooked fruit smell, brick red color, similar to oxidation
      • Causes: leaving wine in a hot car, in the sun, etc.

We hope this information helps with your winemaking. If you have any follow up questions or winemaking questions in general, please email us at support@juicegrape.com.