Gewürztraminer: from grapes to juice

 

White wines are never fermented on the skins and seeds. The grapes are first pressed and the resulting juice is settled to remove most solids (a process the French call débourbage). These days, we have the good fortune to start most of our whites wines from settled juice that we get directly from winery tanks. However, we still get Gewürztraminer directly as grapes and we have to produce settled juice before we can begin to make wine.

It also happens that the juice from winery tanks may come with more solids than we like (the target is about 2% solids), in which case we may have to settle it again before starting our wine. So, some of this information in this note has relevance beyond Gewürztraminer. 

Getting to juice

When the Club gets its Gewürztraminer grapes, it brings out its motorized destemmer-crusher and its compressor-powered bladder press. A few people take their grapes home whole to deal with themselves, but most people have their grapes put through the destemmer-crusher into pails. Most people add about 50 ppm SO2 to their pails at this point. If there is much bunch rot or you suspect possible VA problems, use 100 ppm. This can be added just before the crushed grapes go into the pail or you can add it to the top of the pails and stir it in. The idea is to protect the crushed grapes as soon as possible.    

Some of those who crush their grapes will put their crushed grapes through the bladder press before they leave the crush site (you have to do this if you are freezing your juice). This is certainly convenient. But probably most people now take their crushed grapes home in pails and will press them later themselves using their own basket presses or other methods.

There are two main issues when pressing your Gewürztraminer.

The skin contact issue

Most white grapes are pressed immediately after crushing. Indeed, cluster pressing is the preferred method for most commercial wineries (but their presses get more out of the skins than most home winemakers can manage with their methods).

Gewürztraminer is different, especially for home winemakers, because many prefer to have their crushed grapes sit for a while before pressing in order that the juice can have contact with the skins and pick up some of the color and flavor of the skins. Seven or eight years ago, only a few members preferred this extra skin contact, but today it is the norm in the Club. Therefore, at a Gewürztraminer crush, you will see only a few people using the bladder press. Most people take their crushed grapes home in pails and will press these themselves later.

There is no agreement about the optimum amount of skin contact contact to maximize varietal character. Everything between a couple of hours and a couple of days has been tried, but probably the most typical skin contact times are between 12 and 24 hours.  If you have experience, you keep tasting the juice. You want to be enhancing the flavor of the juice, not picking up bitterness or harshness. Keep your juice as cool as you can during this period of skin contact.

The free run/press run issue

However many hours you wait to press your grapes, you then have to decide whether to keep your free run and press run juice separate. (Note: This is more of an issue for those getting lots of grapes. Given the possible benefits, it is just too much trouble to keep small quantities separate, especially when you increase your risk of spoilage problems.)

"Free run" juice is the juice that flows out of the press with no or only very minimal pressure, while the rest that comes off under pressure is called "press run."  If you have the volume you can even keep juice pressed off a low pressure separate from juice pressed off at high pressure.

The reason for keeping these fractions separate is that the higher the pressure, the more likely you are to extract bitterness, astringency and other unwanted elements from the skins and seeds. With the separate fractions, you then proceed to make separate wines.  You can then decide on the optimum amount of  press run wine to add to your free run wine before bottling.  In general, free run juice is reputed to provide superior wine, but it is often a case that a blend of free run and press run is better than either alone. 

Settling white juice

Once you have your juices (free run, press run, or a combination), you will see they are cloudy with skin and cell wall debris. This juice MUST be settled and clarified before you begin fermentation.  This is the normal procedure :

If your juice does not begin to clarify quickly, consider an addition of bentonite.

It is not necessary or even desirable to get the juice perfectly clear. Some solids are inevitable and the fermentation process benefits from them.  And don’t worry about the browning of some solids and the juice. This is normal oxidation and actually assists the fermentation. The brown will disappear as the yeast use the oxygen. (If you have ever had Peter Brehm juice, you will know it is often very brown when it comes from the pail, and the juice is far from perfectly clear.) However, the "new world" style of winemaking is to get get juice as clear as possible, minimize oxidation, and ferment very cool in the hope of more fruit flavor.

Warning: If you see turbulence in your settling juice, wild yeast activity has started and you have a major problem. You can try getting the juice really cold to stop the yeast action, or you can make the best of a bad situation and start with the juice as clear as you can get it. Juice that is not adequately clarified is likely to produce wine with off flavors.

Secondary juice recovery

The sludge or dregs left after you rack off the settled juice still contains juice. The standard way to recover some of this is to freeze the sludge, preferably in something clear and tall (one popular option is the 2L plastic container for soft drinks). Remember to leave space for the expansion on freezing. If you don’t, you will be very sorry. Cleaning syrup out of a freezer is no fun.

 

Note prepared by Rod Church. This is a revision of material that was first presented in educational sessions and published on this website in 2004 and 2005.