D1: Faults: Background: Sam Harrop MW on wine faults and reduction
Sam Harrop MW is a winemaker, co-chairman at the International Wine Challenge and an expert on all things wrong with wine. We talk to Sam about his analysis of wine faults at this year's IWC, focusing on reduction and sulphides. As well as tasting and judging all wines entered into the competition Sam also looks after the wine faults clinic. Sam analyses hundreds of wines that get rejected then classifies the faults to come up with trends to help the industry improve its winemaking.
Sam started out as a winemaker in New Zealand. He worked for Villa Maria in an all round role before going overseas to make wine. He then joined Marks & Spencer as a winemaker travelling around the world.
Sam came on board the IWC as a co-chairman 3 years ago. Cork taint was previously the only real fault detected. They now look for brett, sulphides or reduction (sometimes a bigger problem than cork taint) and other faults. In 2005 cork taint rate just over 6%. In 2006, they found this had halved - perhaps previously other faults had been classified as cork taint.
The biggest trend they are seeing is that excessive sulphide H2S (rotten egg smell) in the wine, where you can't pick up any fruit, is a bigger issue than cork taint. In the New World, reductive, hygienic winemaking to produce fruit-driven wines can mean winemakers forget to look after the yeast. If the yeast doesn't get nutrients it becomes stressed and releases sulphides.
When a wine is rejected they look at the closure - screwcap or natural cork. They ask for second bottle and if that is also faulty it means the batch is faulty and the wine gets rejected. With screwcaps reduction is an issue - it is a reductive seal, more so than cork, and sulphides can develop after bottling.
Sulphides H2S are chemicals that occur during fermentation from stressed yeast. The yeast can be stressed because of a lack of nutrients or from the overused of SO2 or Ascorbic Acid (vitamin C) which reduce the level of oxygen the yeast can use causing problems for the yeast.
Sulphides H2S can easily be removed by copper fining. However if it is left in the bottle the sulphides tend to react and form more complex sulphur based chemicals which are very hard to get rid of. These complex sulphides are known as mercaptins which create cauliflower, onion, garlic and even burnt rubber flavours in the wine.
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