"Mineral-tasting wines contain few minerals"

But we know that minerals cannot be tasted. How do you detect them?

Fischer: It is a misunderstanding to assume that minerality comes from dissolved minerals in the wine. They cannot volatilise, they cannot be smelled and tasted. But there are other attributes with which minerality correlates: acidity, citrus aromas, sulphurous substances. The latter is often described with the term flint. However, the correlation of aromatic substances and minerality has not yet been found. There are more factors at play.

The correlation between aromatic substances and minerality has not yet been established.

Which factors of the terroir can be smelled or tasted?

Fischer: Mineral-tasting wines contain few minerals. Wines with many minerals, on the other hand, buffer the acidity better and have a softer effect on the palate. When I add tartaric acid to the must, the potassium in the must precipitates as tartrate. This reduces its mineral content. So I get a wine that is low in minerals, but more present in the acidity. In short: I can create minerality in the taste by acidifying the wine. This leads to a certain astringency. However, it is not created by phenols - but only by higher tartaric acid values.

Why are some wines described as more mineral than others?

Fischer: If the usual aromatic substances are rather discreetly pronounced in the wine, the minerality comes out better. So it comes from the absence of other aromatic substances. Personally, I find minerality more in poor soils like red sandstone, granite and porphyry. These are soils that are old and washed out, as opposed to limestone or slate, which weather more easily. But the expression of minerality does not necessarily have to do with the proportion of components such as calcium, magnesium and potassium.

So could a winegrower in Rheinhessen produce a slate-scented Riesling like the one from the Mosel?

Fischer: If I wanted to produce a slate-scented wine in Rheinhessen, I would work with more lees and ferment warmer so that the aromas come out more, possibly in used barriques. I would work more reductively. If I add sulphur dioxide to the wine, it is absorbed by the yeast and released again as hydrogen sulphide. This creates thiols and benzenes, which signal minerality on the palate. I still can't get the radiant acidity of the Mosel and the slate that way. However, good oenologists can bring out pronounced minerality in wines even from rich soils.

One of your publications says that wines from slate and basalt are less mineral than from sandy and "softer" soils. One would expect the opposite...

Fischer: You can't generalise that. The winemaker plays a role there, because the biggest influencing factor is the human being. As a winemaker, you are active at the mash and must stage. During fermentation, I have to take a back seat. Today, I would even recommend neutral pure yeasts such as sparkling wine base yeasts, and ageing in stainless steel with as few accents as possible so that the subtle element of the terroir can come across.

I can bring about minerality in the taste by acidifying the wine.

What is the relationship between spontaneous fermentation and terroir imprinting?

Fischer: Spontaneous fermentations can, depending on the nutritional status of the must and other factors, contribute to the formation of hump, which overlays the wine aroma. There are vintages that are more transparent, so that I can see through to the bottom, figuratively speaking. I would prefer the cooler vintages with a longer growing season, as 2021 is likely to be. Warm vintages like 2005 and 2007 are more difficult. I like the fact that local wines often express the terroir even better, because they don't have to bring so much pressure.

Doesn't that contradict the expectations and wishes of many winemakers and customers?

Fischer: With higher-quality wines like Erste Lagen and Grosse Gewächse, you want to get as much complexity as possible. But to do that, you have to set other accents. In any case, the winemaker is the biggest factor if he doesn't take a back seat. In a trial, we harvested the grapes from six vineyards ourselves and microvinified them. In the process, we tried not to introduce any microorganisms onto the grapes and to work only with the vineyards' own yeasts. To do this, we worked with hygienic gloves, brought our own press and fermented in our own refrigerated containers. Everything was disinfected with 70 percent alcohol beforehand. We fermented all the musts and compared them with the wines fermented in the winery cellars. It was the same harvest, the same harvest time. The wines with their own micro-grown grapes tasted much leaner and more mineral, the terroir was more pronounced. Unlike the winery wines, they did not undergo acid reduction. We know that part of the winery style comes from the cellar because there is always its own cellar flora.

Can we conclude from this that the cellar flora reduces the mineral impression?

Fischer: If the winemaker does not take a step back, he overlays the terroir and the minerality with the cellar management.

The biggest influencing factor is man

Could you distinguish grapes sensory according to their origin?

Fischer: No. At most, I could distinguish the acidity, the aromatic substances are bound. This means that they cannot be perceived retronasally. I don't think it is possible to distinguish terroir grapes. We have already done sensory experiments with grapes, with a Sauvignon Blanc, a Riesling and a Pinot Noir from three harvest dates each, and compared them with the wines produced from them. It was somewhat disappointing how small the differences and poor the correlations were, although our results were reproducible. The ripeness and sugar content were distinguishable, but not the aromas of the wine. Many winemakers put it differently. I cannot confirm it.

Nevertheless, many wine lovers are fascinated by how location factors shape wine.

Fischer: With our terroir study, we want to give vintners a feeling and a reason why they should continue on this path. A grape variety, a yeast and a wine style are interchangeable. I can make shockingly good wines around the world that are quite similar. But the terroir - bedrock, soil, slope, orientation, grape variety - cannot be copied. But interchangeable wines do not achieve higher added value. The acid test is the wine in the glass. I recommend to the regions and the wine industry as a whole to individually adapt cellar management so that they produce well-distinguishable regional wines.

So minerality must be detached from the soil?

Fischer: The perception of minerality is not triggered by the presence of certain volatile or non-volatile components in the wine. It is promoted by the lack of distinct varietal aromas, wood or off-flavours. Fresh, lemony and green aromas and a pronounced acidity with its slightly astringent perception on the tongue support the impression of minerality. Although their description varies, many consumers recognise minerality and appreciate its expression.

Photo: © Weincampus-Neustadt

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