The essential base material of the famous Tokaji sweet wines are the botrytised grapes attacked by Botrytis cinerea. Botrytis occurs only when the climate is right for it, and dries and shrivels the over-ripe grapes, turning them into raisin-like “Aszú berries”. During botrytisation, flavours, acidity and sugar content concentrate and turn into unmistakeable complex flavours, a honeyed character wine with high amounts of residual sugar. In the process of botrytisation sugar is not produced, but the water content in the berry decreases, so the content becomes more concentrated.