August 6, 2006
It's finally happening - grapes turning purple! Veraison signifies the change from berry growth to berry ripening in grapevines. In red varietals, this is evident as the berries change from bright green to light purple and eventually to dark purple or almost black. Other notable aspects of veraison are:
- increase in sugar
- decrease in acidity (due to dilution)
- softening of the skin
Now when I pick a berry to taste it I don't have to spit it right out before it makes me gag.
As we would expect, the viognier is ripening faster than the cab franc, and a quick test on the refractometer supports this. The viognier is currently around 15 Brix and the cab franc around 13. The Brix scale is the measurement of soluble solids in grapes at harvest, taken with a refractometer and expressed in degrees. In unfermented grapes, degrees of Brix are approximately the same as percent of sugar. After fermentation, the alcohol concentration is roughly half the sugar concentration (actually .55) of the juice. Thus, grapes harvested at 22.5 degrees Brix will produce a wine with an alcohol content between 12.5 to 13.5%.
Have a look at veraison - view image.
Posted by Stephen at August 6, 2006 10:17 PM