Photograph: Jason Lowe

As I have discovered over the past eight years of working in wine education, the answer to nearly every single wine-related question is often (confusingly!) “it depends”. The question of whether or not to decant is no different.

Respected Bordeaux oenologist Émile Peynaud was famous for his opinion that decanting wine, which saturates it with air, should be avoided where possible. According to Peynaud one should only decant in cases where the wine has thrown a sediment, and even then only at the last possible moment before service, since the effects of dissolved oxygen are detrimental to the wine’s sensory attributes.

Among the wider world of wine experts, this is a controversial stance. The accepted view shared by most other wine specialists is that aeration at least two hours in advance of service can improve the experience of drinking certain wine styles, particularly young, tannic reds (aeration is said to mimic the effects of ageing by softening tannins and speeding up the wine’s development). Aeration can also improve the taste of young wines which show a ‘reductive’ character, which in wine-geek language means aromas of volatile sulphur compounds and in ordinary language means the smell of struck match, flint, rubber or smoke. These are characteristics often observed on wines sealed with a screw-cap.

In an attempt to answer the crucial question through experimentation rather than theory alone, I conducted a fascinating tasting here in the Pickering Cellar at No. 3 St James’s Street: The Great Decanting Debate. We tasted four different wines, and three examples of each. The first example had been decanted 24 hours in advance, the second two hours in advance and the third was served straight from the bottle. The wines were served blind and in no particular order. While our sample size (28 guests) was not large enough to yield statistically significant results, the results were nevertheless fascinating.

The wines selected were as follows:
2010 Kumeu River Hunting Hill Vineyard Chardonnay, Auckland, New Zealand – chosen because it is a young white wine sealed under screw-cap and I have previously observed reductive characteristics on wines from this producer. Would decanting improve this?
2010 Ch. Batailley, 5ème Cru, Classé, Pauillac – chosen as an example of a young, tannic red. Would decanting help open up the wine and soften the tannins?
2001 Rioja, Gran Reserva, Bodegas Amézola de la Mora – chosen as an example of an older, oxidatively aged red, meaning it had already been exposed to a significant amount of oxygen during its ageing process – would it benefit from more?
1994 Quarles Harris, Vintage Port – chosen because we always need to decant vintage Port due to its heavy sediment – so this was to explore when exactly we should decant it.

Anyone who regularly tastes wine will know how subjective this activity is. Inevitably, therefore, opinions were to a certain extent split on all the wines as the different preferences and palates in the room emerged. However, there were some clear trends which I have summarised below:

Kumeu River Chardonnay – because this was not as reductive as I had anticipated, the majority of the tasters preferred the just-opened bottle, which was more aromatic and tauter in structure with crisper acidity. However, if you do come across a reductive bottle at home, don’t be afraid to give it some air.

Ch. Batailley – this was perhaps the most surprising, because there was a clear preference for the just-opened bottle, despite received wisdom. This preference is backed up by previous wine school experiments in which the majority of our tasters have always preferred the non-decanted example. Why is this? I feel that it is to do with the aromatic qualities of the wine. The just-opened example had pure and crisp aromas of cassis and a lovely freshness, whereas those which had been decanted had lost that immediacy; the flavours of the wine had evolved more towards the dried fruit end of the spectrum. In addition, even the example decanted 24 hours earlier did not show any signs of softer tannins. Indeed this fits with the comments of some wine scientists who have pointed out that decanting in advance would not mimic the effects of ageing because there would simply not be enough time for the oxygen to change the chemical structure of the tannins; many years in bottle are needed for this to happen. This point remains a controversial one.

Rioja – here, there was a clear preference for the example decanted 24 hours in advance. I had anticipated that because this wine had already been exposed to so much oxygen during its élevage (30 months in barrel with regular racking) it wouldn’t necessarily benefit from more exposure, but I was wrong – the example decanted the day before was the most aromatically complex and the silkiest in texture. It was obviously well used to air and wanted more of it!

Vintage Port – this was very interesting, because the majority of tasters found it nearly impossible to distinguish any nuances between the three samples. I concluded that this must be because, even at 20 years of age, a vintage Port is so firmly structured that the antioxidant properties of its very robust tannins render its defences against the onslaught of oxygen very strong indeed.

One guest said to me on the way out, “Now I’m even more confused about whether or not to decant!” A very valid point, and I could understand his confusion. My advice is this: experiment. If you have a case of a particular wine, each time you open a bottle try a different option for decanting it. Soon your own personal preferences will emerge. There may be no straightforward answer, but let’s face it, the process of experimenting will be a pleasurable one – and at the end of the day, wine is all about pleasure.

To attend the Berry Bros. Wine School, or for more information on the events we run, go to bbr.com.