Süssreserve (German: Süßreserve, literally meaning "sweet reserve") is a wine term referring to a portion of selected unfermented grape must, free of microorganisms, to be added to wine as a sweeting component. This technique was developed in Germany and is used with German style wines such as semi-sweet Riesling or Müller-Thurgau.[1] The technique not only raises the sugar level of the wine, but also lowers the amount of alcohol. Under German law, no more than fifteen percent of the final wine's volume may be the reserved juice.[2] This practice is allowed also for Prädikatswein, the highest level in the German wine classification. It is often used for semi-sweet Kabinett and Spätlese but more rarely for Auslese and upward.
The use of Süssreserve gives a different composition of sugars in the wine in comparison to arrested fermentation. Grape must contains mainly the sugars glucose and fructose. When wine ferments, glucose is fermented at a higher rate than fructose. Thus, arresting fermentation when a significant portions of the sugars have fermented gives a wine where the residual sugar consists mainly of fructose, while the use of Süssreserve will give a wine where the sweetness comes from a mixture of glucose and fructose.
