To decant or not to decant?

How the decanting of a wine influences its organoleptic qualities.

According to the dictionary of the RAE (Royal Spanish Academy), decanting is the action of separating a liquid from the sediment it contains, pouring it gently into another container.

If we consult the definition in Volume IV of El Bulli’s Wine Sapiens, on Sommelier, it defines the term decanting as the operation carried out to favour the contact of the wine with the air and/or eliminate the presence of impurities and undesirable substances with the aim of increasing its aromatic charge as much as possible.

From these two definitions we can deduce that there are at least two reasons for decanting a wine, on the one hand, to separate the lees and, on the other, to oxygenate it. These two objectives are achieved with the same instrument (the decanter) but must be carried out in different ways.

But when is decanting necessary? Do the wine characteristics vary when decanting?  How? Why do decanters come in different sizes and shapes, do they really influence the organoleptic qualities of the wine. Is aerating, oxygenating or eliminating the sediment essential before serving a wine, or is it more a liturgical act?

The aim of this decanting study carried out by the Vila Viniteca Tasting Panel is to try to answer three questions related to decanting:

  1. Are there sensory or organoleptic differences between a wine that has been decanted and one that has not? How? To what extent?
  2. Does the shape of the decanter influence the final perception of the wine, or is it just an aesthetic aspect?
  3. Does a half-full bottle act the same as a decanter, and are there differences with non-decanted wine?


To carry out this study we have used 5 different conditions. Firstly, all the wines were evaluated at the moment of opening the bottle, a variable we called A0′. After 90 minutes in 3 Riedel decanters of different shapes and capacities, the Cabernet (1440/13) which we call Cab90′, the Cornetto (1977/13) which we call Corn90′ and finally the Ultra (2400/14) which we call Ult90′, the last variable evaluated is the bottle opened after 90 minutes, denoted A90′. This last condition aims to study whether a half-empty bottle can be considered as a decanter itself.

All the bottles in the project were of large format, three were 3-litre bottles and one was a 5-litre bottle. In this way, the bottle effect was avoided, always evaluating the same wine. In each decanter, 75 cl of wine was transferred, the same amount that remained in the 3-litre bottle for 90 minutes. In the 5-litre bottle, 1.5 litres remained, in order to respect the proportion with the other samples.

Each decanting was carried out very delicately and slowly, avoiding a violent racking of the wine, trying to minimise the oxygenation of the liquid.

All samples were evaluated at the same temperature of 22°C, although a difference of two degrees positive or negative, i.e. between 20 and 24°C, was accepted.

Four different red wines with the following characteristics were used:

The project was carried out in two sessions on the following dates and conditions:

The panellists conducted the sessions in a standardised facility according to ISO 8589:2012 and had approximately 10 minutes to evaluate each cup individually.

In each session 2 wines were evaluated with the 5 different conditions, so in the 1st session Red Wine 1 and Red Wine 2 were evaluated, and in the 2nd session Red Wine 3 and Red Wine 4 were evaluated.

Each panellist evaluated these attributes for each sample:

Olfactory phase: (more information here)

  • The intensity of the flavour in a still glass (continuous scale from 0 to 10)
  • The intensity of the flavour in a swirled glass (continuous scale from 0 to 10)
  • Presence of defects and intensity (slight/medium/intense) if detected
  • Presence of flavours: 48 flavours that may be present in a wine and for which the panellists have been trained.

Taste phase (in the mouth): 

  • Sweet (continuous scale from 0 to 10):(more information here)
  • Acid (continuous scale from 0 to 10):(more info here)
  • Bitter (continuous scale from 0 to 10)
  • Alcoholic sensation (continuous scale from 0 to 10)
  • Alcohol integration (Yes:0 / No:1)
  • Intensity of aroma in the mouth (continuous scale from 0 to 10)
  • The overall persistency of the detected flavourings (continuous scale from 0 to 10)

Tactile sensations (in the mouth): (more information here).

  • Astringency (continuous scale from 0 to 10)
  • Fluency (discrete 5-point scale: Low/Low-Medium/Medium/Medium-High/High)
  • Volume (discrete 5-point scale)
  • Weight (discrete 5-point scale)
  • Greasy feeling (Yes:0 / No:1)

Summary of results

After evaluating and comparing the results, we have observed differences between the different variables. In the following, we present the results in response to the three questions we asked at the beginning. All the data obtained has been subject to a statistical study that allows us to extract the following results reliably:

  • Are there sensory or organoleptic differences between a wine that has been decanted and one that has not? How? To what extent?

When we compared the results obtained from the just opened bottle (A0′) with those obtained from the wine decanted for 90 minutes in the three decanters (Cab90′, Corn90′ and Ult90′), we observed significant differences in the following attributes, which allow us to affirm that when we decanted the wine, we were able to obtain this results:

  • The aromatic intensity (both when smelling and on the palate) is diminished.
  • The wines become more astringent.
  • The feeling of weight
  • Acidity, bitterness, alcoholic sensation, aromatic persistence and volume vary, but not in all wines in the same way.
  • Sweetness and fluidity remain more stable in all cases and do not change after decanting.

On the aromatic level, we can see that in 3 of the 4 wines evaluated there are flavours that only appear if the wine has not been decanted, even though they do not belong to the same aromatic family: in Red Wine 1 these flavours belong to the caramelised family, in Red Wine 2 to balsamic and wood, and in Red Wine 3 to animal.

Concerning the aromatic expressivity or variability of the wines according to the variable applied (decanting or not and decanter format), we observed the following results:

In graph 1, we can see how aromatic variability (we understand variability as the number of flavours mentioned in the same wine for each variable studied) is not related to the parameter applied to the wine. We cannot speak, for example, of a decanter favouring the aromatic variability of wines repeatedly.

  • Does the shape of the decanter influence the final perception of the wine, or is it just an aesthetic aspect?

After comparing the results of the different decanters, we have observed that they increase:

  • The Cabernet Decanter (Cab90′): the bitterness of wines (especially those that are not aged for a long time in wood).
  • The Cornetto Decanter (Corn90′): the aromatic intensity, both in still and swirled glass, in most cases. (In all wines that have not undergone long ageing in wood).
  • The Ultra Decanter (Ult90′): the feeling of weight of the wine, in most cases.

No relationship has been observed between the decanter and the increase or decrease in intensity between the attribute’s sweetness, bitterness, astringency, alcoholic sensation, aromatic intensity in the mouth, aromatic persistence and fluidity. We can conclude that they do not behave in the same way depending on the shape of the container in which they are decanted.

After carrying out the study, it is clear that there is a decanter effect and that some attributes such as bitterness, aromatic intensity (still or swirled glass) and weight increase or decrease.

Aromatically, in all three decanters, the wines repeatedly express flavours of berry fruit, spices and lactic flavours. In addition to the flavours mentioned above, different families of flavours were observed depending on the decanter.

  • The Cabernet Decanter (Cab90′): has a tendency to show more of the toasted and earthy notes of the wines evaluated, flavours that do not appear in the other two decanters.
  • The Cornetto Decanter (Corn90′): no different flavours are found when compared to the results of the other two decanters.
  • The Ultra Decanter (Ult90′): unlike the other two, animal notes were identified in some of the wines evaluated, which did not appear in the other decanted samples.

3) Does a half-full bottle act the same as a decanter, and are there differences with non-decanted wine?

In this case we have evaluated the results in two ways:

We first compared the results of the wine after 90 minutes in the bottle (A90′) with those obtained in the three decanters (Cab90′, Corn90′ and Ult90′), and observed differences in these attributes:

When the wine has not been decanted, the aromatic intensity in the swirled glass and in the mouth is slightly higher in most cases, the astringency is lower and no variations in sweetness or bitterness have been observed.

All other parameters vary, but not linearly in all cases, so we have not been able to draw any conclusions.

On the aromatic level, when we compare the overall results of the decanted wines with the 90-minute bottle, we observe more flavours of berry fruit, spices and wood, but only the floral and balsamic aromatic families have been identified in the 90-minute bottle.

Secondly, we compared the results obtained from the 90-minute bottle (A90′) with the undecanted bottle (A0′) (evaluated immediately after opening) and observed a decrease in aromatic intensity on smelling and alcoholic sensation, and an increase in fluidity, astringency and bitterness.

Neither acidity nor volume are altered if we compare them between the bottle and the wine without decanting. The rest of the parameters vary, but not linearly in all cases, so we cannot draw any conclusions.

On the aromatic level, if we compare the results obtained between the just opened bottle (A0′) and after 90 minutes in the bottle (A90′), we observe that, in this second variable, the wines with long ageing or more traditional wines (Red Wine 1 and Red Wine 4) express a greater variability of flavour families.

If we compare the flavours mentioned between the two variables, we observe that in the bottle with 90 minutes (A90′), the wines show flavours from the following families: balsamic, berry fruit, floral and wood. On the other hand, in the bottle just opened (A0′) the wines show more flavours of cooked fruit, dry vegetable and toasted.


– Aromatic intensity does not increase with decanting

We have observed that if we compare the aromatic intensity of the wines evaluated (at swirled glass or still glass, and in some cases even in the mouth), they have been more aromatic when the bottle have just been opened compared to the three decanters (especially the Cornetto) and also compared to the 90-minute bottle.

– Wines become more astringent when they are decanted

It was observed that the tested wines showed a more astringent sensation when decanted and even when they had been in the bottle for 90 minutes. The results obtained for the astringency of the samples from the bottle that had just been opened were always less astringent than the other samples.

Many studies show the opposite trend to the one we have experienced. One of the possible explanations we give for this phenomenon is related to an experience lived by the expert Ferran Centelles, which he describes in the article “How and why to decant” published in September 2013 on the Jancis Robinson website, in which he explains how a wine decanted without removing the sediment with a filter, can be particularly astringent, with a slight aromatic intensity and marked by aromas of the earthy family (dry earth or mushroom). We must specify that, in our case, when decanting all the wines, no filter was used, and although the decanting was carried out with great care, it is possible that the sediment was transferred to each decanter.

This fact would also give us a possible explanation for the results obtained for aromatic intensity.

– Wines are perceived as less bitter in a bottle that has just been opened

We observed that when we compared the results for the bitter attribute between the 90-minute bottle variable (A90′) and the bottle that had just been opened (A0′), the wine was perceived as less bitter in the latter case. Similarly, if we compare the results between decanters, it was observed that the Cabernet decanter accentuated the bitterness compared to the other two.

– Decanting reduces the sensation of weight of the wines.

We have observed that non-decanted samples have a greater sensation of weight than decanted wines.

– Decanting does not change the volume of the wines.

We observed no significant differences in the analysis of this tactile sensation. It showed similar results regardless of the variable.

– Acidity and sweetness do not change with decanting

These taste attributes have shown uniform results in all the variables applied, with no significant differences in any case.

– Wines that have been decanted or have remained in the bottle show greater aromatic variability.

The wines showed a wider range of aromas after decanting or after 90 minutes in the bottle. In addition, the aromas belonged to the berry fruit and floral families, whereas in the freshly opened bottle the aromas were more animal, wood, cooked fruit, dried vegetable, caramelised and toasted.

After carrying out this study, we can conclude that decanting affects the sensory perception of the wines, and that the shape of the decanter or the way of decanting (removing the sediment or not) can also have an influence. We can consider that the bottle can act as a decanter, as the sensory perception of the wine varies in comparison to the bottle without decanting, but it does not do so in the same way as in the decanters studied, as no similar tendencies have been observed in any of the three.

It is important to note that the study has been carried out with wines aged between 3 and 8 years and, therefore, the results would be different for wines aged a few decades.

Wines used for this decanting project:

Red Wine 1: Álvaro Palacios Gratallops 2017 (3 L)

Red Wine 2: L’Equilibrista 2017 (5 L)

Red Wine 3: Venta las Vacas 2018 (3 L)

Red Wine 4: Muga Reserva Selección Especial 2012 (3 L)


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