Better with Age
It’s often a surprise that some white wines have greater ageability than many red wines. Riesling wines have, for the most part, great aging potential. The aging potential comes from the naturally low pH (and high acidity) of Riesling wines as well as from Riesling’s mineral aspect, 
or at least, that is what is theorized. The aging potential is accentuated as the sugar level increases. Some dessert-style Rieslings have the longest ageability of any wines, reaching up to 100 years. Proper storage (50-55°F) will help to age the wine gracefully and to the longest extent.
In fact, the town hall of Bremen, Germany, stores various German wines, including Riesling wines, in barrel back to the 1653 vintage.
August 1st, 2008 at 3:40 pm
Another fact to consider is the reduction is the actual sensation of sweetness in Riesling wines as they get older. This is due to a polymerisation of the smaller sugar molecules into large ones that are less sweet to the palate. This same phenomenon contributes to an increase in viscosity of sweeter wines over time.