How Aszú is made
Aszú is a sweet wine produced in Central Europe primarily in North Eastern Hungary and Southern Slovakia. It obtains its sweetness as a consequence of a beneficial fungus which causes the skins to split and water to evaporate. This process concentrates the sugars, acids and flavours creating a full bodied, rich, and complex wine with high sugar and acid levels. Wines are characterised by dried fruit, apricot, orange marmalade, honey, ginger and beeswax aromas and flavours. It is thought that the best examples can comfortably age well over 100 years.
Aszú is a white wine made only from white grape varieties. Due to the fungus required to produce an Aszú wine, all of the grape varieties are ones which are suseptible to this fungus. They are also varieties which accumulate good levels of sugar, while also retaining sufficient acidity to provide balance. Over centuries, growers discovered that these grapes complement each other in a way that’s particularly suited to noble rot and long-lived sweet wines. The remarkable thing about Tokaj is that its signature style isn’t based on a single grape, although there are single varietal bottles.
Picking the grapes
As we discovered in the previous article, Aszú berries all experience noble rot, but it affects berries at different rates. This means that all Aszú berries have to be picked individually, there is no whole bunch harvesting and no machinery used. Affected berries shrivel and begin to look like Raisins. Those berries are picked one by one which means that multiple passes of picking will take place between September and November, only harvesting those which are ready. An experienced picked can pick around 8 to 10Kg of berries a day. Care needs to be taken when going through the vineyard so as not to damage other grapes which may be picked later.
Unlike in other areas of the world, berries are not usually harvested by students or foreign workers, because there is a need to be familiar with the grapes which comes from experience. Generally the demographic is people over 50 years old and also predominantly female. To harvest 1Kg of berries, it will typically take around 5Kg of healthy pre-botrytis affected grapes. The berries were traditionally harvested into 27 litre wooden containers called Puttons. Once picked the berries are stored in vats until the harvest is over. The high sugar and acid levels in the berries means they are naturally preserved for a few months.
Not every vintage produces a full Aszú worthy harvest, and producers such as Royal Tokaj typically produce 3-4 vintages every 10 years. Berries which are not affected by noble rot can be utilised in other styles of wine made from those grape varieties, including sparkling, still whites and other types of sweet wines made using different methods.
The paste and base wines
While the berries are awaiting processing, a small quanity of juice will be produced (c. 2-3 litres per 100Kg). This is free run juice which is produced purely by the weight of the grapes at the top of the vat, pressing on the grapes lower down. This free run juice is generally split into two parts. The most concentrated juice is taken away and stored in a cool cellar for many years. It ferments very slowly and only achieves around 1-4% of alcohol due to the concentrated sugars. This becomes known as Eszencia or ‘the essence’. Eszencia is highly concentrated, very sweet (600+g/L of sugar) wine and good examples fetch extremely high prices. I have written about this in more detail here. The less concentrated free run juice is sometimes added to the pressed juice used for the Aszú.
The berries which have been stored in vats while the harvest is completed are eventually transferred and soaked in must. The must is made of grapes which have been harvested and crushed. The must can either be fresh and unfermented, partially fermented or already fermented into a base wine. The type of must, the proportion of berries to must and the length of maceration is determined depending on the type of Aszú and the origin of the berries. Once the must is ready, the Aszú berries are then crushed into a paste (aszútészta) which is then macerated in the must for hours or days in order to extract the sugar, acidity, flavour compounds and noble rot characteristics. Once complete the mixture is pressed slowly and wine is then run off into a maturation container to age.
How sweet?
Remeber the Puttons we discussed earlier, which were the collection baskets? Historically, the number of Puttons utilised in the blend which was added to 136 litre casks, indicated the sweetness level of the wine. As such, the scale used to run from 3 to 6 Puttonyos, but since 2013 this is now determined by the sugar levels. Only three official levels now remain:
- 5 Puttonyos must have a minimum of 120g/L of residual suagr
- 6 Puttonyos must have a minimum of 150g/L of residual sugar
- Eszencia must have a minimum of 450g/L of residual sugar
Aging
The minimum aging requires for Tokaj wine is 18 months, and this must take place in wooden barrels. The regulations also state that the wine cannot be released for sale until at least 1st January of the third year after the harvest has taken place. In practice this means most Tokaj wine age longer than 18 months.
The cellars in the Tokaj region are famous for being carved into the volcanic rock. They typically maintain a temperate of 10-12°C and a humidity above 85%. In the cellars a black mould, known as Cladosporium cellare often develops. This mould feeds on alcohol vapours and contributes to regulation of humidity. The mould can grow several inches thick.
Oxidative and reductive development
Many producers ensure a controlled exposure to oxidation during aging. The oxidation process generally supports the winemaker in balancing fresh fruit and acidity with the complexity and tertiary aromas and flavours from aging. With age wines will develop a Amber-Gold colour, nutty and dried fruit characteristics, complexity and texture. During the aging process water slowly evaporates meaning sugar, acid and flavour compounds become more concentrated. Due to the loss of liquid barrels must be topped up periodically.
Special barrels are used to age Aszú wines. Rather than the typical 225 litre french or American Oak barrels, winemakers opt for Gönci casks which hold 136 litres. These will be almost exclusively Hungarian oak. As a result these barrels add only small amount of overt oak flavour. The aim is to assist oxidation rather than adding wood flavours.
Noble rot continues
The impact of the noble rot does not end in the vinyeard. During ageing, compounds which have been created by the fugus continue to evolve. Over time they can produce saffron, beeswax, ginger and spice characteristics.
In the rest of this series we will uncover the distinctive features of Aszú. Hopefully you will discover why Aszú is so beloved in Hungary. And in the meantime, keep on exploring this beautiful planet we live on, one glass at a time.