Wine alterations, defects and diseases

Every time we open a bottle of wine, tap wine from the barrel or sniff a cork, we are seized with a performance anxiety that not even Rocco after 50 and 4 blondes in the last hour. "Will I really be able to recognise any faults in the wine we are about to taste?" Confess, you too have asked yourself this question at least once. I can honestly tell you that I ask myself it all the time: sometimes alterations and defects are really subtle and you can almost confuse them with the intrinsic characteristics of that specific wine or grape variety. With this in-depth study, I hope to help you clarify what wine alterations, defects and diseases are, although only lots of practice can give you the confidence to answer this dreaded question with a discreet smile!

One thing that was very useful to me at the time was the box of wine aromas with defects that a colleague of mine bought on Amazon (You can find the link to the one we used HERE). There is little we can do, every scent becomes easier for us to recognise if we have a sample to associate with it in our minds. In aroma recognition, nothing is invented! There are certainly people who are born with a more sensitive and acute nose than others, but in the end it is safe to say that it's all a matter of training!

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What are the alterations in wine?

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• oxidic cases: due to oxygen and oxidative enzymes, it affects white wines, especially those made from somewhat mouldy grapes. Effects in white winesdark colour, chestnut broth, turbidity in white wines. Effects in red winesbrowning, madder odour and cooked taste.
• ferric coffersdue to an excess of iron, affects both white and red wines. Effects in both white and red winesturbidity with bluish precipitate.
• protein cratesdue to compounds between proteins and tannins, affects both white and red wines.Effects in both white and red wines: turbidity with whitish precipitate.
• phosphate boxesdue to an excess of iron, affects white wines. Effects on white wines only: turbidity with greyish-white, milky precipitate.
• coppery cratesdue to an excess of copper, affects white wines. Effects on white wines only: turbidity with reddish-yellow precipitate due to copper-sulphur compounds.

What are the faults of wine?

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• capDue to trichloroanisole and other substances produced by moulds and bacteria, it affects both white and red wines. Effects on both white wines and red winesiunpleasant corky smells and tastes.
• sulphur compoundsDue to an excess of sulphur dioxide, it affects both white wines and red wines provided they have been treated with sulphur dioxide. Effects on both white wines and red winesiunpleasant bitter and pungent odours and flavours of garlic and rotten eggs.
• metaldue to an excess of iron, copper, zinc due to the use of old equipment, affects both white and red wines. Effects on both white wines and red winesibitter and unpleasant smells and tastes.
• dry & drumdue to the use of poorly preserved barrels, affects both white and red wines. Effects on both white wines and red winesiunpleasant smells and tastes reminiscent of cork.
• vanisheddue to racking with excessive aeration, affects both white wines and weak red wines. Effects on both white wines and red winesiunpleasant odour and bitter, flat and soft taste.
• mould & rot: due to the use of old, poorly preserved barrels with mould development, it affects both white and red wines. Effects on both white wines and red winesiunpleasant odours and tastes.
• maderizeddue to oxidation, affects weak wines, especially whites.Effects on both white wines and red winesiunpleasant vinegar odours.

What are the diseases of wine?

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• fiorettadue to yeasts (pinchia, candida, hansenula), affects weak wines. Effects on both white and red wines: superficial whitish veil, vanishing odour, flat taste.
• cue & ascenceDue to anaerobic lactic bacteria, it affects weak and/or low-alcohol wines. Effects on both white and red winesveiled appearance, pungent vinegar odour (oxidised compounds such as acetic acid, aceltaide, ethyl acetate), harsh and sour taste.
• stringyDue to anaerobic lactic bacteria, it affects white and rosé wines with residual sugar, low alcohol and low fixed acidity. Effects on both white and rosé wines: oil-like appearance due to the presence of viscous and mucilaginous substances, rancid smell and sluggish taste.
• lactic/sour cueDue to anaerobic lactic bacteria, it affects wines with residual sugar. Effects on both white and red winesturbidity, smell of overripe fruit, sweet and sour taste.
• shotDue to anaerobic lactic bacteria, it affects wines with low fixed acidity. Effects on both white and red wines: dull colour, turbidity, slight effervescence, pungent odour, flat and very unpleasant taste.
• bitterDue to anaerobic lactic bacteria, it affects old red wines. Effects on red wines only: faded colour with yellowish hues, pungent and very unpleasant odour, bitter taste.

And finally, I will give you a list of resources that will be very useful for studying:

• Let's learn my study method together: 5 techniques to study better in less time and pass the exam!
• How to recognise if a wine tastes corked?
• My sommelier exam: questions and answers, tips and more!

Good luck and good studying!

If you need my help with your study, write me a comment and I'll get back to you in a few minutes... I can handle the comment notifications much better than on the Facebook page because I get too many people writing to me there!

Cheers ❤

Chiara

All my notes on wine and food in one book.