A grape with spice
Many of the long-time readers of this column know of my tenure with the Department of Viticulture and Enology at UC-Davis. The department is one of the oldest and most storied departments in the University of California system, being established in the 1880s by the California State Legislature for a research institution that would promote outreach in the wine industry to further improve the quality of California grapes in the wake of the phylloxera epidemics in both Europe and California in the 1860s and 1870s. There were many individuals that contributed to the department’s achievements, and I am humbled and honored to be part of that legacy. I never met Dr. Maynard Amerine, but we shared an office, albeit he was long since retired when I took over the same space. I have heard that one of his statements about making great Gewürztraminer wines is that you must “sleep in the vineyard.” I did not understand what this meant until I had the opportunity to make wine from this grape when I came to the University in 2006.
At the time, the grape demonstration block had a total of 50 individual rows of grapes. Each row was short, with only 14 vines per row. That was just enough for about 50 gallons (190 L) of wine to use in classes. Many of these varieties were not suited for the hot climate in Davis and usually wound up sunburned or severely raisined, but for some reason the Gewürztraminer always held out. The first year I worked with these particular grapes, as I walked the vineyard making picking decisions, I liked the spice flavor coming up at about 19 °Brix, but I held off picking as it just didn’t seem right.
I was a young winemaker on the quest of achieving 24 °Brix, assuming I needed alcohol to balance the wine. With the lower sugars, I was thinking how low the alcohol would be and the wine would not be balanced. Alas, I waited until the “magic” Brix of 24 and picked. The wine was good, exhibited some typical flavor profiles, but just didn’t seem complete. Then a good friend told me what Dr. Amerine had said, and it clicked. That was the day a light bulb went off between my ears and started opening the world to the diversity of grapes, their unique profiles, and the wines you can make from them.
As the name implies, Gewürztraminer is part of the Traminer family of grapes. It’s an extremely diverse family that seems to have originated in the Franche-Compté region of eastern France. It’s a very old variety. In doing the research for this piece, many references point back to Savagnin Blanc, not to be confused with Sauvignon Blanc from the Bordeaux region. Among the 100+ synonyms of Gewürztraminer listed in the Vitis International Variety Catalog (www.vivc.de) are listings of Traminer Aromatique, Savagnin Rose, and Red Traminer. The database officially lists its pedigree as a Savagnin Rose mutation.
Gewürztraminer is classified as a white grape; however, it has pink to red skin tones. None of these pigments translate into the wine, even with some incidental skin contact. The variety has a characteristic spice tone for which the “gewürz” in its name refers to. But according to Jancis Robinson, she says the spice character is more of a catchall descriptor for the multitudes of aromatics in the grape. She goes on to state that there is “no single spice that is particularly like the smell of Gewürz.” The grape is rich in terpenes, which when not bound to various sugar moieties in solution, play an important role in the aromatic characters for which the wine is known. Incidentally, terpenes are also responsible for the varietal character you would find in Muscat grapes. Muscat is often blended into Gewürztraminer to enhance the aromatics.
The main aromatic compounds in the grape are in the skins, so therefore employing a series of treatments to enhance their extraction are the initial keys to boosting the aromatics. Terpenes in wine can be both free and bound. By “bound,” this refers to the chemical bonding that takes place between the terpene and a mono or disaccharide sugar moiety, such as glucose (monosaccharide) or arabinose, rhamnose, or apiose, (all disaccharides). Bound terpenes are non-volatile, thus not contributing to the aroma profile. However, these bound forms are flavor precursors and the aroma profile of the wine is largely due to the free forms of the terpenes in solution.
Some winemakers choose to add enzymes to terpene-rich wines toward the end of fermentation. These enzymes cleave the sugar moiety, releasing the free form that can contribute to enhanced varietal character. It is important to use the correct enzyme as they all have a specific function. The right enzymes will have alpha and beta glycosidase activities as well as pectinase to assist in breaking down the grape skins and releasing the free and bound forms. Follow the manufacturer’s instructions when working with enzymes. The pH and the temperature of the wine must be just right to get the optimal effect. When the desired effect is obtained, the enzyme action can be halted with the addition of 5–10 g/hL (190–380 mg/gallon or 50–100 mg/L) bentonite addition. Allow to settle and rack.
On another note, regarding extracting these aromatics from the skins is a technique I learned from some of the visiting students from Germany. That technique is up to 24 hours of skin contact after destemming and crushing. This can also bring out some of the astringent phenolic compounds also located in the skins. As you look at the concept of skin contact, if done carefully, use less time for a dry version of Gewürztraminer and more time for an off-dry version where the sweetness will mask any astringency.
I have also always been intentional with my yeast choice with not just Gewürztraminer, but aromatic whites in general. Lallemand recommends Cross Evolution specifically for this varietal, but my experience is with QA23 and CY3079. QA23 has beta-glycosidase activity and is a good thiol converter. CY3029 is slow to finish, can have some mouthfeel enhancements through some early autolysis, and in my experience leaves a little residual sugar. Be sure to follow the proper hydration procedures and feed them properly. I find that QA23 needs a little more nutrients than what is recommended.
Acidity in the juice and wine is important for balance. From our basic grapevine physiology we know that the acidity decreases and the sugar accumulates in the grape via photosynthesis. Warm-climate Gewürztraminer accumulates sugar too fast at the expense of acidity and lack of time to properly develop the aromatics. So cool-weather climates are best suited for this variety.
Its home territory is Alsace and Lorraine in the northeastern part of France and then across the Rhine River in the Baden and Pfalz regions in Germany. These regions are actually very close to the Franche-Compté region where the Savagnin story most likely originated. Good examples exist in the Alto Adige in northern Italy, northern Spain, southern Australia, New Zealand, and Chile. In North America, Canada, New York, Oregon and California’s Anderson Valley work well.
I really do not think my wife, Polly, would appreciate me sleeping in the vineyard at this point in our life. Although I have been known to do it when I was much younger after a long day of harvesting and the thought that an hour’s drive home in the dark was probably not the smartest thing to do. But what I learned from those years at UC-Davis was to appreciate the varieties we worked with and maximize their potential by following the expertise of veteran winemakers.
Yield 5 gallons (19 L)
- 100 lbs. (45 kg) Gewürztraminer fruit or 6 gallons (23 L) commercially available juice (clarified)
- Distilled water
- 10% potassium metabisulfite (KMBS) solution (Weigh 10 grams of KMBS, dissolve into about 75 milliliters (mL) of distilled water. When completely dissolved, make up to 100 mL total with distilled water.)
- 5 g Lallemand QA23
- 5 g Fermaid K (or equivalent yeast nutrient)
- 5 g Diammonium phosphate (DAP)
- Freeze dried malolactic bacteria (Chr Hansen)-optional
- 5-gallon (19-L) carboy
- 6-gallon (23-L) carboy
- 6-gallon (23-L) plastic bucket
- Airlock and stopper
- Racking hoses
- Equipment cleaning and sanitizing agents (Bio-Clean, Bio-San)
- Inert gas (nitrogen, argon, or carbon dioxide)
- Refrigerator (~45 °F/7 °C) to cold settle the juice. (Remove the shelves so that the bucket will fit.)
- Ability to maintain a fermentation temperature of 55 °F (13 °C). TIP: Use a 33-gallon (125-L) plastic can as a water bath. Place ice blocks in the water to maintain a relatively constant temperature. This will be your refrigeration system for peak fermentation. If you have other means to keep things cool, of course use that. TIP: If you have a need to keep it warm, in this case wrapping the bucket/carboy with an electric carboy wrap (available at most home winemaking outlets) works well.
- Thermometer capable of measuring between 40–110 °F (4–43 °C) in one-degree increments
- Pipettes with the ability to add in increments of 1 mL
- Ability to test or have testing performed for sulfur dioxide
Step by Step
1. Crush and press the grapes. Consider some light skin contact or enzymes to enhance the aromatic flavors. Scott Labs Rapidase Revelation Aroma is a good one. For other choices, scottlab.com/scott-labs-enzyme-choosing-guide. Follow the directions.
2. Move the must directly to the press and press lightly.
3. Transfer the juice to a 6-gallon (23-L) bucket. During the transfer, add 16 milliliters of 10% KMBS solution (This addition is the equivalent of 40 mg/L or ppm SO2). Move the juice to the refrigerator.
4. Let the juice settle at least overnight. Layer the headspace with inert gas and keep covered.
5. Measure the Brix and acidity.
6. Adjust the acidity to 6-7 g/L. (If the acidity is greater than 7 g/L, consider the option of inoculating for the malolactic fermentation near the completion of the alcoholic fermentation described later.)
7. When sufficiently settled, rack the juice off the solids into the 6-gallon (23-L) carboy.
8. Prepare yeast. Heat about 50 mL distilled water to 108 °F (42 °C). Measure the temperature. Pitch the yeast when the suspension is 104 °F (40 °C). Sprinkle the yeast on the surface and gently mix so that no clumps exist. Let sit for 15 minutes undisturbed. Measure the temperature of the yeast suspension. Measure the temperature of the juice. You do not want to add the yeast to your cool juice if the temperature of the yeast and the must temperature difference exceeds 15 °F (8 °C). To avoid temperature shock, acclimate your yeast by taking about 10 mL of the juice and adding it to the yeast suspension. Wait 15 minutes and measure the temperature again. Do this until you are within the specified temperature range. Do not let the yeast sit in the original water suspension for longer than 20 minutes. When the yeast is ready, add it to the fermenter.
9. Add Fermaid K or equivalent yeast nutrient.
10. Initiate the fermentation at room temperature (~65–68 °F/18–20 °C) and once fermentation is noticed, (~24 hours) move to a location where the temperature can be maintained at 55 °F (13 °C).
11. Two days after fermentation starts, dissolve the DAP in as little distilled water required to completely go into solution (usually ~20 mL). Add directly to the carboy.
12. Normally you would monitor the progress of the fermentation by measuring Brix. One of the biggest problems with making white wine at home is maintaining a clean fermentation. Entering the carboy to measure the sugar is a prime way to infect the fermentation with undesirable microbes. At this point, the presence of noticeable fermentation is good enough. If your airlock becomes dirty by foaming over, remove it, clean it, and replace as quickly and cleanly as possible. Sanitize anything that will come in contact with the juice.
13. Leave alone until bubbles in the airlock are about one bubble per minute. Usually about two to three weeks. Measure the Brix every 2–3 days at this point.
14. The wine is considered dry, or nearly dry, when the Brix reaches -1.5 or less. As an option, inoculate with your malolactic bacteria.
15. Monitor the progress of the malolactic fermentation (MLF) using thin layer chromatography.
16. If you chose not to inoculate for MLF, then add 3 mL of fresh KMBS (10%) solution per gallon of wine (0.8 mL per L of wine) or when the MLF is complete, add that same dosage of fresh KMBS (10%) solution. This is the equivalent to ~40 ppm addition. Transfer the wine to the five-gallon (19-L) carboy and lower the temperature to 38–40 °F (3–4 °C).
17. After two weeks, test for pH and SO2 and adjust as necessary to attain 0.8 ppm molecular SO2. (There is a sulfite calculator on our website at winemakermag.com/sulfitecalculator). Check the SO2 in another two weeks, prior to the next racking and adjust while racking. HINT: Rack to another sanitized 5-
gallon (19-L) carboy or your bucket. In the case of the latter, clean the original carboy and transfer the wine back to it. This is done at about 4–6 weeks after the first SO2 addition. Once the free SO2 is adjusted, maintain at the target level by monitoring every 3–4 weeks.
18. Consult winemakermag.com for tips on fining and filtration if a haze is noted in the wine.
19. At about three months you are ready to bottle. Be sure to maintain sanitary conditions while bottling. Once bottled, you’ll need to periodically check your work by opening a bottle to enjoy with friends.