Analyzing Sediment

This month, a grouping of questions was posed on FTLOP’s Forum by Monique Heinemans, who is from Geleen, The Netherlands. She asked some specifics about the sediment found in bottles of Vintage Port. Appealing more to the serious Port enthusiast, but it should be of interest to anybody who appreciates Port. It wasn’t as easy to obtain as many responses as usual due to the Easter holiday, but I thank the members of the trade who did take the time to share their insight into this complex and fascinating topic.

Q:  Is there a relationship between the amount of sediment in the younger years or even the moment the sediment begins to form and the development or aging of vintage port?

Can anything be determined by the quantity or type of sediment, when it comes to the quality or development of the Port?

Lastly, is there a difference between the types of sediment that is flaky vs. dusty particulate?

From David Fonseca Guimaraens, Director and Portmaker, The Fladgate Partnership:

The question raised by Monique Heinemans about the sediment in Vintage Port shows a keen interest and good observation on her part, and deserves to have a complete explanation.

When we compare Vintage Port with other fine wines of the world which are expected to have ageing potential in the bottle, most are bottled between 18 and 30 months after being made. Vintage Port is generally bottled 22 months after the harvest. Many of the table wines are fined before bottling and some are also filtered.

With Vintage Port, we neither fine nor filter prior to bottling. The tannins in combination with anthocyanins make up the phenolic content of red wine and Port. The complex that is formed when these two components combine gives both the colour and astringency, and are crucial to the ageing capacity of a Vintage Port. By not fining or filtering a Vintage Port prior to bottling, the astringency is more pronounced when they are young; however, no compromise is made to its ageing capacity.

The other consequence of this minimal handling to Vintage Port prior to bottling is that the natural process of red wine/port of throwing a sediment as they age starts relatively soon after they are bottled. This sediment is the settling of the tannin/anthocyanin complexes that grow into a size that they are no longer dissolved in the wine.

Regarding the type of sediment, a younger vintage Port will have a finer/dusty sediment, and requires much greater care in the handling and decanting of the Vintage. The sediment in older bottles of Vintage Port tends to combine and becomes more flaky and solid. The sediment in older vintage Ports can vary between being more solid and between being more flaky.

Regarding taking conclusions as to the relationship between the type or dynamics of the sediment and the quality of a particular Vintage/Year, I do not believe there is any. In the same way that the style of a Vintage Port will vary depending on if it comes from a very hot, concentrating year or from a cooler, ripening year, the variation between years (and sediment type) are part of the interest and enjoyment of every Vintage Port that is produced.

Discovering the features of each Vintage year is what makes Vintage port so interesting, and also a key attribute when drinking a bottle, or tasting it blind.

I hope the above comments help add to the knowledge and appreciation of what we make. If you have any further questions, please do not hesitate to ask.

From Manuel Lobo, Oenologist, Quinta do Crasto:

For Monique’s first question … There is a direct relationship between wine concentration and the amount of sediment. In the case of Vintage Port, where there is no filtration, only natural stabilization of the wine; it’s to be expected to have sediment along the process of ageing in the bottle. The sediment is the result of a natural combination between anthrocyanins and tannins that naturally will precipitate in time. It is normal to expect from this precipitation, that with time, wines will be smoother and less vibrant in colour, and also have a greater amount of sediment.

For her second question ... The quantity of sediment is directly related to the initial concentration in the wine that was the result of the extraction during the fermentation process. Regarding quality, in my opinion, it is difficult to assure there is a relation with the quantity and type of sediment, because each winery has different winemaking techniques, and of course different extraction methods. Anyway we believe that every Vintage Port wine needs to reach the natural balance in bottle, and that is only possible with time and natural precipitation of sediments.

Lastly, a good sediment should have solid particles, and these particles should be more dense than wine. Bottle storage conditions are crucial to the proper ageing of a bottle of Vintage Port.

From Paulo Coutinho, Oenologist, Quinta do Portal:

First of all, we have to remember that Port wine, even if in a bottle … is still alive! It is a natural thing and I don’t believe anyone can predict exactly what will happen, or what is happening inside the bottle. For me, the presence of sediment, only tells me one thing … the wine is alive and it is better that it occurs.

Especially for those wines that aren’t filtered, like Vintage Port, the sediment is definitely natural. I believe those sediments (in small proportion) are something that will increase the complexity of the Vintage Port. In terms of the type of sediment … the powder could be a signal of microbiological problems (not common) … the uncolored sediment that looks like sugar … is a sign that the wine was submitted at lower temperatures. It is best to have colored and well defined sediment.

From João Nicolau de Almeida, General Manager and Winemaker, Ramos Pinto:

Both of the principle parameters for the Port Wine to be considered a vintage are:
- Opaque colour
- Create deposit/sediment in the bottle

The quantity of deposit/sediment depends on various factors:
- Specificity of the year
- Concentration and ripening of the grapes
- Varieties of the grapes. There are varieties with polyphenols (tannins and anthocyanins) which are more or less stables in the bottle.
- The type of extraction used during the fermentation.
- The quantity of stalk/stem used in the fermentation.
- The stalk or stem’s tannins precipitate faster than the skin’s tannins which are more stable.
- The oxidation suffered during the bottling; the stronger the oxidation is during this period, the faster the precipitation in the bottle will be.
- The precipitation conditioned by all these factors may be more or less rapid.
- The stowage of the bottles in a constant temperature extend the period of sediment precipitation which is favourable for the quality of the wine. Inconstant temperatures speed up the precipitation process, which is prejudicial for the quality of the wine.
- The size of the bottle is also influential; the bigger the bottle, the faster the precipitation.
- The sediment’s quantity by itself is not fundamental for a wine to be considered good or no good.
- The ideal would be to taste the sediment. If it is not oxidized and if it does not taste like fruit of good quality, it means that all the factors were good from the beginning and thus that they maintained throughout time. That wine should be a great vintage. Obviously, this tasting should be done after a period of aeration.
- In the case of vintages with some suspended or not suspended sediment, I would not say that this might be a fundamental factor to establish its quality. There are wines whose structural constitution is different depending very much on the terroir and of the physicochemical composition of the wine, as well as of the ph level and the potential redox (reduction-oxidation).
- The sediment may be conditioned by all these circumstances.
To conclude I think that tasting the wine or the sediment is what reveals the quality of the wine.

From Carlos Flores, General Manager, J.H. Andresen:

Monique’s question is not an easy one, and I have discussed it with Alvaro (as you know I am not a winemaker …), and my conclusion is as follows:

Is there a relationship between the amount of sediment in the younger years or even the moment the sediment begins to form and the development or aging of vintage port?

No. Some Vintage Ports start to form sediment early, but they can get very stable during the ageing process and stop throwing more sediment.

Can anything be determined by the quantity or type of sediment, when it comes to the quality or development of the Port?
We know that with some Vintages, right before bottling, the sediment in the wood vat (there is no filtration) where it is stored, mixes with the wine. It is in fact hard to predict anything concerning the amount and type of sediment.

Is there a difference between the type of sediment that is flaky vs. dusty particulate?

Sure there is. During the ageing process there are two main types of instability that cause the formation of sediment: tartrate and polyphenolic instability. The tartrate instability creates more instability in the wine during the ageing process due to the change in the wine’s pH.

However, I believe you can say that, first, you have the tartrate precipitation (red crystal sediment). The wine is bottled very soon and you still have tartrates to precipitate. Then, you will have the polyphenolic precipitations (color and tannins) in conjunction with some polysaccharides, but, it is very hard to predict the amount of precipitation of these elements because the variables are still not controlled by science. We pray a lot while bottling a Vintage and we do rely a lot on the historical experience and tradition.

From Jorge Alves, Port & Winemaker, Quinta do Tedo:

As you well know the Vintage Ports are, without any doubt, wines with higher concentrations of  polyphenolic compounds - i.e. condensed tannins and anthocyanins.

2 to 3 years of aging in tonel of Vintages are not sufficient for polymerization to happen (formation of larger compounds by repetition of structural units of the tannins and anthocyanins). Polymerization ends up happening inside the bottle leading to the formation of small scales. The non-filtering and no tartaric stabilization Vintage Ports lead to some instability that occurs during aging in the bottle.

a) The formation of polymeric compounds like tannin / anthocyanin (direct condensation) or tannin / ethanol / tannin or tannin / ethanol / anthocyanin in the cylinder, is normal during the first 2 to 3 years.
If the formation of these compounds exceed 35 structural units, sediment will be very large and tend to precipitate out and deposit in the bottle.

b) The instability of tartaric acid (natural wine) in the presence of potassium cation and low temperatures leads to the formation of crystals of potassium bitartrate that rush in and create a characteristic deposit – colorless red crystals,

c) The junction of these two precipitates leads to the formation of a deposit scaly and red color.
The deposit is characteristic of early aging in the bottle, the experience we have leads us to think that this occurs with greater intensity between 5 and 10 years of bottle aging.

Another type of deposit - dusty - basically consists of precipitates of monomeric anthocyanins and polysaccharides, are colloidal particles (smaller than 10 microns) hence the difficulty in forming a consistent deposit. The “flake” type of deposit is the most characteristic for Vintage Port. It is natural and synonymous with quality.

From Jorge Moreira, Port & Winemaker, Quinta de la Rosa and Quinta das Carvalhas:

The quantity and type of sediment is related to the level of stability the port has before it is bottled. The instability is basically the colour matter or the crystals (coming from acids) and the correlation between colour matter and these ´bitartrate` crystals determine the type of sediment that appears in the bottle. So the sediment is not related to the quality of the port. It is related to the degree of stabilisation that the port has before it is bottled. Flaky is more the combination of the two types of sediment whilst dusty comes from the colour matter – generally speaking as to have a good assessment you have to look at the sediment with a microscope.

There can be a relationship between the concentration and quality of the port and the amount of sediment, but you cannot say that if a port has more sediment it will be of better quality.

From Paul Symington, Joint Managing Director, Symington Family Estates:

Port is naturally a very full-bodied wine and with the traditional practice of giving no fining or filtration to our Vintage Ports (as well as to our Traditional LBV’s and Crusted Ports), it is normal that a substantial deposit be formed over time. Incidentally, it is worth pointing out that very few wines from anywhere in the world reach the consumer in such a natural state. Virtually all wines have either a fining or a filtration, often both. Vintage Port has neither.

Before answering the questions in detail, I would also like to point out that because Vintage Port is bottled in its natural state; the sediment over time becomes very substantial, making decanting a relatively easy task. Many times I have personally served a Vintage Port straight from the bottle (when a second bottle has been required at short notice or another wine to compare was called for) and it is perfectly possible to pour carefully direct into a glass without disturbing the sediment. This is difficult with an old Burgundy or Bordeaux, where the sediment is a very light dust and is easily disturbed and dispersed through the wine.

The amount of sediment in Vintage Port is related to the levels of pigments present in the wine at bottling and to the storage conditions. Temperature is a major factor; there will be greater precipitation at lower temperatures. Vintage Port contains various families of macromolecules which include: polymeric pigments (grape origin); mannoproteins (yeast origin) carbohydrate polymers (grape and yeast origin); etc. The polymeric pigments increase in size with time, resulting from condensation reactions between pigments. After reaching a critical point, precipitation occurs, resulting is sediment at the lower side of the bottle.

Ageing profiles depend upon many factors including the initial levels of pigments (anthocyanins, proanthocyanidins, etc.,), the level of acetaldehyde, maturation temperature, wine pH, etc.

Clearly the more full-bodied the wine, the greater the potential level of deposit.

Each wine will have its own sedimentation rate based on many of the factors mentioned above. In general terms the highest rate of deposit begins sometime between the 5th year and continues to roughly the 20th year, after which the rate of deposit slows down considerably, although it will continue for many years after. One important variable is the cork. No two corks are the same and will permit different levels of oxygen transfer and associated wine aging. Hence the bottle variation found in old wines (oxidation produces acetaldehyde leading to further polymerization).

With regard to the question about the quantity or type of sediment, it is clear that the quality of the wine depends on achieving a fine balance between the tannins, the natural sugars and acidity. This is critical to the wine’s quality. So a balanced deposit will reflect a well made

wine and the best drinking time for a Vintage Port will depend upon the initial wine structure and the storage conditions, as well of course on individual preference.

Finally a flaky deposit is likely to be a polymeric precipitation and a dusty or crystal deposit is likely to be tartrates.

But perhaps the most important point to remember is in my opening remarks above; with Vintage Port, we have a wine which has minimal interference and reaches your cellar in its purest possible form, straight from our Douro vineyards and our Douro lagares to your cellar. Vintage Port brings its own in-built aging mechanism that will function slowly and naturally in your cellar until such time that you decide to open it. The elegance of a great bottle-matured Port evolves over years of gentle bottle aging, there are no short cuts and the slow development of the deposit, or crust, is an absolute fundamental factor in creating these unique wines.

From Dirk van der Niepoort, Proprietor & winemaker, Niepoort Vinhos S.A.:

All of Monique’s questions do make a lot of sense.

Is there a relationship between the amount of sediment in the younger years or even the moment the sediment begins to form and the development or aging of vintage port?

The amount of sediment depends really on how the wine was aged before being bottled. More racking (aeration) means less sediment: aging in smaller barrels also means less sediment, the earlier the port is bottled the more sediment it will have.

I don’t really think that there is a relationship between sediment and aging of the port.

Can anything be determined by the quantity or type of sediment, when it comes to the quality or development of the Port?

No, I don’t think so, but the style of sediment can tell a lot about how the port was aged.

It is very interesting to note the difference between the sediment of an old tawny (with a lot of bottle age) and a vintage port. The sediment of vintage port usually drops quite quickly and is a heavy sediment.

The tawny usually gets cloudy and takes a lot of time to drop. The sediment of tawnies interferes a lot with the wine while the sediment of vintage almost doesn’t interfere (visually it does interfere a lot).

A Question for the Port Trade appears in every other FTLOP newsletter, sharing this space with Port Personalities: In Focus.

By | 2016-11-18T10:24:03+00:00 May 10th, 2011|Categories: Port, Questions for the Trade|Tags: |0 Comments

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