Week 7, was one of the final really technical sessions of the WSET Diploma Unit 2 Wine Production module. This week we put ourselves in the shoes of a winemaker and made decisions on the wine making techniques and technologies we would employ to create three very different styles of wine; a medium-dry Riesling, a classic Paulliac and a high volume branded red wine.
I’ll take you through some of the decisions we considered to make a medium-dry Riesling.
So with a medium dry Riesling we are looking to create a fresh, aromatic style of wine with plenty of varietal character and enough acidity to balance the sweetness. Any winemaking techniques must protect and encourage the purity of fruit and aromatic style of this wine.
After deciding whether or not to destem the grapes, we’ll ensure a little skin contact, between the grape juice and the grape skins in order to absorb more of the varietal character into the grape must.
At this time, we will add a pectolytic enzyeme to aid juice extraction and improve aromatics. Enzymes make the juice more viscous and have the added benefit of speeding up the cold settling process, one of the most effective ways to clarify a wine.
Next fermentation, we chose a stainless steel tank for fermenting this medium-dry Riesling. It is easier to control the temperature in stainless steel tanks, which is important for preserving the key aromatics of the Riesling, and it is easy to keep clean and hygienic.
Concrete vats are cheaper but can absorb heat created during the fermentation process, which is a problem when you want to create pure, aromatic white wines – as higher temperatures can kill the delicate fruit aromas. Traditionally, concrete vats have been harder to keep clean, but with a good lining this is less of a problem, today’s tanks are lined with an epoxy resin, replacing the traditional glass tiles.
We will use an inoculated yeast which will ferment in exactly the way we want which is important when we have a very clearly defined flavour profile. We don’t want the potential random, quirky characteristics of an uninnoculated yeast to impact on the purity of fruit.
We will control the fermentation at between 13-14°C, a safe option for an aromatic wine, cool temperatures help preserve the varietal fruit flavours, we could go as low as 11°C but there is a risk of developing synthetic flavours. Below 10°C, you’ll get synthetic flavours developing of over ripe banana, pear drops and boiled sweets.
In order to create this medium-dry style we could stop fermentation by chilling, racking and filtering or ferment to dryness and then add unfermentated juice, i.e. süssreserve, to create the sweetness required for a medium-dry style.
The first option, would require chilling the juice to zero, and filtering out solid yeasts, this technique is used by small scale producers of medium dry wine. There is a danger that if the wine comes in contact with yeast again it will start refermenting and there may be problems with bacteria spoilage as there is plenty of sugar in the wine for bacteria to feed on. For small producers working on small batches refermenting barrels is an inconvenience, but for larger producers using huge big vats it represents a major problem.
Chilling, racking and filtering is preferred by small scale producers as it best preserves the purity of fruit and terroir character and there’s something to be said for the sweetness in the finished wine coming from the vineyard not from sugars added in afterwards.
However, fermenting to dryness creates a wine that is inherently more stable and adding süssreserve in to create the required sweetness is a preferred option for many large scale producers because it is a less risky and more reliable process.
After the intital fermentation, unlike with the oak aged Chardonnay we discussed in Week 6, we want to avoid malo-lactic fermentation in order to protect the fruit purity. To do this, we will keep the wine at a cool temperature and ensure sufficient SO2 levels to inhibit the development of lactic bacteria.
Winemaking as ever is full of decisions with no one right way of doing things. The style of wine you want to create, the budget you have available and the quality you are looking to achieve will all impact on the decisons you make as a wine maker and that’s what makes the world of wine so interesting.
Travelling today seems to be simultaneously fast and slow due to COVID-19 requiring rapid change of plans and jumping on planes with