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Top 6 Wine Faults - How To Deal With Them

Most of us enjoy a glass of wine after a busy day at work, it's a great way of winding down and relaxing. We are quite used to appreciating the quality of the wine, but what many of us often don't realise is that there is so much that can go wrong throughout the entire winemaking process, even long before it gets bottled.

When we look at a bottle of white wine we get used to seeing that crystal clear, star bright colour, whether it's pale green or rich yellow, it is still remarkably clear. But ask any winemaker, and he or she will tell you that on occasions they have noticed clarity in the bottle turning opaque. A yeast has got in or more accurately by-passed the filtration at bottling time without being noticed - this is how Dom Perignon discovered Champagne. I guarantee nearly all winemakers at some stage of their careers have created a 'champagne' style like this, quite unintentionally. I certainly have!

Let's look at some wine faults and problems that can happen and how to deal with them...

  1. Before the winemaking stage - Dirty grapes. When the grapes arrive at the winery they must be clean and disease free. If they are not then there is an increased risk of a fault in the form of off-flavours developing later on. Remedy: Extra amounts of SO2 (sulfur dioxide) are required. Clean grapes = clean wine.

  2. During the winemaking process - Bad flavours. Bacteria in the form of yeasts are responsible for much of the character and aroma of the wine. The winemaker wants to allow these to work away for as long as possible as long as they don't get out of control. It's a sort of high risk gambling game in order to extract the maximum flavour. Leave the yeast too long and harmful aromas can develop, which in serious cases can turn the wine into vinegar. These bad flavours can indicate the presence of ethyl acetate in the wine. Remedies:
    • Regular tastings and accurate anti bacterial control are important by inoculating the wine with SO2 at intervals.
    • Some aeration may be necessary.

  3. During fermentation - Stuck ferment. Yeast converts sugar into alcohol which in turn creates heat. The warmer the must (fermenting grape juice) gets, the quicker the yeast works but if the fermentation is allowed to cool down too much, the ferment may not restart and becomes 'stuck'. Remedies:
    • A constant controlled fermentation temperature is vital avoiding any fluctuations.
    • Use high quality yeasts from renowned sources.

  4. All stages of winemaking - Oxidation. This is perhaps the most common wine fault where the presence of oxygen oxidises the anthocyanins and other phenols in the wine. This leads to a colour loss and reduced flavour and aroma making the wine flat or as it is commonly referred to as being 'flattened'. Remedy: The addition of SO2 or erythorbic acid by the winemaker.

  5. Fermentation - Hydrogen sulphide (H2S) This nasty odour is a by-product of the fermenting yeast in a nitrogen reduced environment which is reminiscent of bad eggs. Remedy: Supplement the wine by adding diammonium phosphate as a source of nitrogen to prevent the H2S forming.

  6. Cork taint is another old enemy in the spoilage of wine. This is nothing to do with the wine, but comes from the chlorine treated cork bark. The fault is partly attributed to the compound 2,4,6-trichloroanisole (TCA) which originates as a mould growth on the bark. Not all corks are affected but enough to make this a very major issue in the wine industry. The cork bark is vulnerable to fungus infections and occasionally the fungus can survive the treatment ready to wreak havoc in the wine.

  7. Remedies:
  • Better treatment of the cork to combat TCA.
  • Use of other forms of bottle closure such as plastic corks and screw caps.

Unfortunately there are many more than six faults that can occur in wine. Winemakers go to such a lot of trouble to keep problems at bay in the winery, and treat faults as soon as they are seen. So, grape growers just remember, produce the best quality fruit you can, then at least the winemaker has a better chance of making it into some decent wine.

Like everything, it always comes down to quality and attention to detail. Give the winemaker rubbish grapes, and expect rubbish wine in return!


Article Source: Top 6 Wine Faults - How to Deal With Them

By Rob Hemphill