The Tokaji region can be very humid and this humidity promotes the spread of Noble Rot. Noble Rot is caused by the special fungus Botrytis Cinerea. The fungus shrivels grapes as they hang on the vine, reducing the water content and concentrating the sugars. The grapes turn very dark, moldy and look incredibly unappetizing. Grapes bunches affected by this fungus are often referred to as having Botrytis Bunch Rot.
Harvest can take two or even more months to complete as the Botrytis works its magic unsystematically through the vineyards. Grapes for the sweet wines of Tokaji are picked in multiple passes through the vineyards selecting only the perfect shriveled grapes, often one small berry at a time.
Historically, wines were classified by using the traditional system of Puttonyos. A Puttony is a basket containing 25 kilograms of grapes. To make the sweet wines of Tokaji a number of Puttonyos of shriveled grapes are added to the must or finished wine. This new must is fortified by high sugar in the Botrytis effected grapes and is allowed to macerate for several days. The higher number of Puttonyos, the sweeter the final wine. Aszú and Eszencia wines are made entirely from berries and grape bunches that have been infected with Botrytis Bunch Rot.
Eszencia is the rarest of all the wines made in Tokaji and possibly one of the most rare wines in the entire world. Eszencia is an elixir made from the drippings of the crushed Botrytis infected berries that are stored in a vat, while additional Botrytis berries are hand-harvested. The weight of the berries gently presses the berries and intensely concentrated grape juice trickles out from a drain in the bottom of the barrel. Fermentation takes so long Eszencia rarely reaches 5 degrees of alcohol, many are only 1 to 2% after 10 years of slowly fermenting.
This wine is very rare, very expensive and is often served by the spoonful.
A vast system of underground cellars were constructed throughout the region in the 1400s through the 1600s . These cellars are very high in humidity. Some cellars will keep a steady level of 95 to 100% humidity. Many of the wines of Tokaji are aged slowly in barrel. Although recently a trend towards fresh, un-oaked dry wines for early consumption have seen an increase in production due to consumer demand. The sweet wines of Tokaji are very special. There is no other wine growing region that has the combined aspects of terroir and environment that the Tokaji region has. Tokaji has a northern location, the two rivers, sloping foothills, indigenous grape varieties, old vines, deep cellars with high humidity and volcanic soils.