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Steel – Stone – Wood; an Experiment in Fermentation at Weingut Andreas Schmitges

The Sixpack: Two Bottles Each of SteelStone, and Wood

Have you ever thought about what affects the taste of the wine you drink? Have you ever considered what influence is exerted by the soils in which the vines grow? Have you pondered the changes effected in a wine by the sulphur that has been used (or not used)?

Well what about the influence of the container used to ferment and age that precious grape must?

I love wine, and I am endlessly fascinated by the myriad variables that must be considered in the creation of it. There are literally hundreds of options, inputs and considerations, each with a larger or smaller impact on the finished product and, naturally, every choice that is made – or event which takes place that is beyond the control of the winemaker or viticulturalist – has a cumulative effect on the wine that ends up in your glass. Even we, as consumers, are making choices that influence how a wine is experienced every time we open a bottle or enjoy a glass. You need do nothing more than drink a wine over several consecutive days to see this at work firsthand.

Here is just a simple list of only the largest factors lying in the control of the person or people that plan to make a wine before it even gets to the cellar:

  • Vineyard site (including soils, exposure, climate, precipitation, latitude, etc.)
  • Grape varieties
  • Viticulture (including vine training, agricultural practices such as organic production, soil treatments and so forth)
  • Harvest date and time (as well as the number of passes through the vineyard that will be undertaken)

Once at the winemaking facility, there are many more choices:

  • Pressing (including what kind of press and the pressure at which this will take place)
  • Maceration (yes/no, and if so, how long etc.)
  • Fermentation (length of time, temperature, what kind of vessel)
  • Ageing (how long and in what kind of vessel? Oak, steel, terracotta etc.)
  • Filtration and Fining

…and so on. You get the idea. This was the briefest of lists containing only the most basic of options – each of which will, nevertheless, have a significant effect on the finished wine. So how interesting would it be to make a concerted study where all variables are controlled but one? What happens if we only change one element? What would be most interesting, or what would be the most informative? What have you always wanted to test?

Weingut Andreas Schmitges has run a little experiment for one of those variables: the container used to ferment and age the wine. And they want to know what their customers prefer among the options that have been considered, with the result of the experiment (that is, the preference of their customers) dictating how the wine will be made in the future. As soon as I read about it, I wanted to try the wines – and not just because I love the idea and don’t often get the opportunity to taste the results of such a project. Their experiment has several unusual elements that contribute to the excitement!

The Elements of Excitement

The Raw Material: Ungrafted Riesling

Riesling is one of the world’s great wine grapes. It reflects soils, climate, aspect and viticulture more clearly than perhaps any other white grape – and at least as well as those two great red grapes: Pinot Noir and Nebbiolo. So it seems a good candidate for illustrating small differences in vinification as well.

Furthermore, Weingut Andreas Schmitges (hereafter just “Schmitges”) is in the Mosel; Gemany’s most important and best-known Riesling wine region. Producers are generally small-scale here, working oft-vertiginous slopes by hand – it is back-breaking labour to begin with, and not particularly profitable. Along the Mosel there remain some parcels of ungrafted Riesling vines. In this particular case, the vines are about 25 years old, planted from cuttings taken from the Wehlener Sonnenuhr and Zeltinger Sonnenuhr vineyards. These are vines with pedigree, and come from very, very old vinestock.

Mosel from the Erdener Treppchen
Mosel beauty.

The wines could be exciting based only on that – at least if you are interested in what Riesling tastes like when planted on its own roots – but there’s more!

The Vineyard: Erdener Treppchen

Looking up the incline through the vines of the Erdener Treppchen at Weingut Schmitges
The Erdener Treppchen
A view of a vineyard staircase cut into the Erdener Treppchen site.
This is probably not the staircase for which the vineyard is named.

So we are in Germany’s foremost Riesling zone – and it has been considered so for a long time. The Erdener Treppchen has been recognized as a top vineyard for well over a hundred years according to our records, but in fact the history and appreciation of this nearly-vertical slice of the Mosel goes back well into Roman times. The ruins of several Roman wineries have been discovered here, one of which is the oldest example of its kind in all of Germany.

Consider the fact that Schmitges has used 5500 m² of their four-hectare parcel of the Erdener Treppchen to make these wines. Now I‘ve written about another important Mosel vineyard, The Brauneberger Juffer and Brauneberger Juffer-Sonnenuhr before; the Erdener Treppchen is just one bend of the Mosel away from there. Schmitges grows their Riesling on gray slate, but there is both red and grey slate found in the Erdener Treppchen, and they are the foundation of some truly great wines, often yielding exotic fruit and incandescent minerality in equal measure. And this site stands proudly among the great vineyard sites of the Mosel.

If you are interested, Erdener Treppchen literally means “the Little Staircase of Erden”. If you see the terraces carved into the 60% grade slopes of the vineyard site, you will not have difficulty imaging why it would be named this way…but Treppchen is not an altogether rare component in the vineyard names of the Mosel. Sometimes it also relates to actual staircases cut into the slate to facilitate the passage of vineyard workers.  For a refresher on German vineyard labelling, check out my post on the topic.

Grey slate.
Grey slate is the “soil” for the vines. And these flowers.

The Vinification

Let’s start with the harvest, which was done by hand on October 29 once the grapes had reached 93° Oechsle (a measure of grape ripeness and sugar level), which would have allowed Schmitges to declare the wine as an Auslese  (or to declassify it as a Spätlese or even Kabinett), had they desired to do so. Check here for a refresher on Germany’s Official Classifications. The grape must was fermented with indigenous yeasts in one of the three vessels after a short maceration and very gentle pressing at just 0.4 bar. After pressing the must was transferred into a 1050-litre oak Stück (second-fill), a 1000-litre steel tank and a 1000-litre granite barrel for fermentation, which took place without temperature controls.  Temperature remained between 15° and 20°C, with the lowest temperatures in the granite barrel. The wines were filtered once with diatomaceous earth before filling, and went into the bottle unfined. There was only one application of sulphur throughout the entire process; it took place on April 15. Finally, on May 21 the wines were bottled.

The Vessels: Steel Tank, Granite Barrel and Oak “Stück

These containers were used for the fermentation and brief ageing:

The steel tank, granite barrel and oak barrel used by Weingut Schmitges to create the "Sixpack: Steel - Stone - Wood" wines
There can be only one… Photo: Weingut Schmitges

Steel Tank – 1,000 Litre

These can be seen in virtually all “modern” wineries with enough capital to buy them. Why? Steel is airtight, allowing the winemaker to control how much air (and, therefore, oxygen) is in contact with the wine. This permits “reductive” winemaking, where there is little or no oxygen present to lead to oxidation and such. Steel is non-porous, which makes them easy to clean, thus preventing unwanted microbial colonisation. Steel is very conductive, allowing the heat that builds up during fermentation to dissipate more easily than with wood or concrete, even without temperature controls – which are very often also built-in to the barrels. Those temperature controls, however, can also be a major advantage for other reasons, such as warming a grape must that is too cold to ferment. And, of course, steel is non-reactive, so it will not directly influence the taste of the wines being made. All this adds up to more control, more options for the winemaker.


Granite – 1,000 Litre

Now here’s a thing. Granite fermentation/ageing barrels are starting to create some buzz in the wine world. There are a few things to be said for it, after all – despite the difficulty of working with the raw material to create the vessel. Perhaps surprisingly, It is exceptional for stabilising temperature, tempering the heat generated by the fermenting must, but also storing the heat built up and returning it slowly when external temperatures sink. The molecular structure of granite makes it extremely easy to clean, as nothing binds to it – including tartaric acid, which simply sloughs off. That being said, the material is not completely impermeable. Fluids will soak into the stone and air will come into contact with the wine. So it is not as reductive a container as steel, but not quite as oxidative as a wood barrel or even a clay amphora. This just means that there will be a little more wine development during fermentation/ageing as compared with steel, but the stone does not add flavour to the wine, like a new or newer oak barrel would.

The process of creating such a vessel is, unsurprisingly, both very challenging and extremely interesting. To have a look at what goes into such a feat, check out the website of the producer: Steinfass, a German company located in Deggendorf, Bavaria.

Oak Barrel – 1,050 Litre

We’ve all seen them. Oak barrels. The most famous is, of course, the barrique: a 225-liter oak barrel beloved across the world. But oak barrels are made in nearly any size and for a variety of reasons. Furthermore, many old wine regions have their own traditional barrel shapes and sizes – the Mosel is no different. In this case we are dealing with a very traditional, oval barrel called a “Stück. The word indicates a larger barrel, but, honestly, many regions of Germany used the word and they all meant something different by it. In this case the barrel is 1050 Litres, and has been used once before. Fermenting in a wood barrel allows some oxygen to work on the wine, since the oak is watertight but not completely airtight. Having oxygen present during fermentation and ageing generally softens a wine, knocking off the sharp corners; the wine has already undergone a little bit of development while in barrel.

The Producer

With a history going back to the 18th century, Weingut Andreas Schmitges, like many other Mosel-Saar-Ruwer wine producers, can lay claim to a lengthy pedigree. But it wasn’t until 1990 that Andreas Schmitges and his wife Waltraud took over the family holdings from his father. Andreas was fresh from his studies, eager to apply his knowledge, passion and sweat to bringing the family’s vineyards into the vanguard of producers along the Mosel. It wasn’t easy and, as so often, their ideas and innovations were not generally accepted in the beginning.

But of course those ideas and innovations have paid off. Working on a foundation of sustainability, they use no herbicides, harvest mostly by hand, and have made a name for producing high-quality – and high-value – wines from generally ungrafted rootstocks, and from two of the most important Riesling vineyards in all of Germany. No small feat.

But How are the Wines?

The wines were filled quite recently, so I am conducting the tasting in two rounds. The first round took place a couple weeks ago, and you can read about it below:

Steel – Stone – Wood Round I

The second round has now taken place, after having allowed the wines a bit of time to settle down in the bottles. Read about it here:

Steel – Stone – Wood Round II

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