Unfortunately for me, it doesn’t feel much like summer in Napa, but our activities in the cellar keep on going all year long. We have been following the Su’skol Chardonnay’s journey from barrel to bottle and today we are going to continue along that path. Last we spoke I talked about blending the Su’skol in our cellar. This time we will talk about what we do in the winery to get the bottle ready for enjoyment.

There are two things that wineries need to do to get any variety of white wine ready to put in the bottle. These two activities are making sure that it is both heat and cold stable. These are processes that get rid of excess protein and excess tartrate in the wine.

When you pump out any wine there is a slight haze from lees. Lees are essentially proteins such as yeast cell walls and long chains of certain wine chemicals (like color compounds and tannin compounds). To make a wine heat stable it is necessary to add purified clay which will bind with all of the proteins in the wine. Thus leaving the wine clarified. If there are any remaining proteins in suspension, the wine is susceptible to hazing in extreme heat. The haze does not affect the flavor of the wine, but it is visually unappealing.

Have you ever had a bottle of wine with “glass” in it? Tartrate crystals are commonly mistaken for “glass”. This is one of the main reasons why we cold stabilize our wine prior to bottling. The tartrate crystal that becomes the “glass” comes from one of the main acids in the grape, tartaric acid.  Tartrate typically drops out of wine when there is an abrupt temperature change. These two reasons are why white wines are more susceptible to this process. In the winery, we seed tanks with cream of tartar, which is tartrate crystals that have been purified. In fact it is the same substance you have in your pantry. Chilling and seeding the wine work to push the equilibrium of tartaric acid from suspension to crystallization. This relatively easy process allows us to bottle wine that will not throw crystals while in your refrigerator.

Julie Murrell
Assistant Winemaker