In my introduction to the Basics of Dessert Wines, Ice Wines and my review on Alvear Pedro Ximénez De Anada 2003, I briefly mentioned late harvest, raisin wines, and The Noble Rot. Now it is time to delve a bit deeper into these subjects to explain why dessert wines are so sweet and luscious. Late Harvest Wines- This is exactly what it sounds like. The grapes are left on the vines for an extended period of time. They grow sweeter and riper, first becoming swollen, and then slowly dehydrate, losing moisture and partially drying out until they start to get slightly shriveled in appearance. As this happens the sugar levels slowly increase to higher, and yet higher levels as the weeks and sometimes months go by.
Sometimes the dehydration process is helped along by workers going through the vineyards and twisting the bunches of grapes, forcing the vines to crush and squeeze shut so that very little or no moisture can get into the grapes. This causes concentrating of the sugars and complex chemical changes and compounds being developed within the grapes, which the French call passerillage.



