Following quite a few requests by e-mail, this week we will take a look at faulty or out-of-condition bottles of wine.
They do put in an appearance from time to time, so it is just as well to be aware of just what can go wrong, so that we can identify the problem.
Corked wine A good old favourite, this one.
First off, the term corked wine does not mean bits of cork floating on the surface after the wine has been poured out that is simply the result of a dry cork or a hastily opened bottle, if the customer wishes, simply remove them with a clean teaspoon.
With "corked" wine, the villain of the piece is a mould-connected chemical known as trichloroanisole or TCA for short that, when present in a cork, infects the wine to make it undrinkable.
What happens is that when these cells come into contact with the wine, the liquid picks up the foul smell of wet wood and fusty mushrooms, least ways that is how I describe it.
Wines affected in this way are undrinkable and must be exchanged.
Oxidisation An oxidised wine has basically had too much contact with the air.
This may have happened at any time during the wine-making process or during storage.
If the wine has too much contact with oxygen, its condition rapidly deteriorates and becomes flat and stale.
In my experience, they also seem to go darker in colour, an aspect that for obvious reasons is more noticeable in white wines.
Acetic fermentation Instantly recognisable by the smell and/or taste of vinegar.
It is caused by acetic bacteria acetobacter acetaldehyde for the technically minded that can easily spread from cask to cask.
Any wine so affected must be replaced.
Secondary fermentation This is a problem that can occur, not so often these days, with low-strength wines and sweetened white wines.
It is caused by residual yeast in the wine feeding on the sugar, reproducing and releasing carbon dioxide.
Cloudiness and unwanted bubbles form along with an appley, yeasty smell.
The wine must be replaced.
Wine flower This is a biological malady that I have only come across once.
It can be recognised by a white film or skin floating on the surface of the wine.
This is accompanied by a certain amount of haziness, considerable deposit and an oxidised nose.
The wine must be replaced.
Tartrate crystals Sugar-like crystals can sometimes appear in bottles of wine, either settled on the bottom or around the base of the cork.
They are entirely harmless and simply indicate that the wine has not been over-refined.
They can form after some months of shelf life or if the temperature at which the wine is kept fluctuates.
However, too many crystals can be unsightly so if the customer complains, the bottle should be exchanged.
It is also worth noting that some red wines have a tendency to form a deposit in the bottle as they mature.
This is completely natural and is not a fault.
Careful pouring or decanting will solve the problem.
Another point to bear in mind is that if the bouquet or flavour of a wine is disliked, only objective criteria should be used to judge if the wine is faulty.
In this respect, the best test is the nose does the wine smell clean or unclean?
The taste of the wine should confirm the nose so the question to be asked is, does it taste faulty, rather than, do I like it or not?
Finally, if an out-of-condition bottle does occur, don't be peevish about it, it is not the customer's fault.
Exchange it or offer an alternative with good grace and return the bottle in question for credit.