When I first came to UC-Davis’ Department of Viticulture and Enology in 2006, one of the first tasks I undertook was a thorough review of the campus vineyards. There was a block of vines that contained about 50 different varieties; the purpose of this block was to evaluate different cultivars and how well they did on this site. Ultimately, we found that a majority of the cultivars here did not belong in the hot climate of the southern Sacramento Valley of California. While most of the block has been removed, two notable varieties did stand out, and they remain in the block; Verdelho (which was featured in the August-September 2010 WineMaker “Varietal Focus”) and Torrontés. I was particularly drawn to Torrontés because of the Muscat-like flavors, but another reason was because of the challenge it presents from a winemaking perspective; something I have been chasing ever since that first vintage. Another thing I did not know at the time was what a rare privilege it was to be working with such a unique grape. Unique in that it has a flavor profile of Muscat, Gewürztraminer and Riesling, but also that it is not easy to come by domestically.
Torrontés is a white grape that is widespread and increasingly planted throughout the major wine regions of Argentina. Torrontés was originally thought to be native to Spain, specifically Galicia, where a similar grape is grown and known locally as Albillo Mayor as well as Torrontés. Over the years, Galician workers have immigrated to Argentina so it is natural as to how this notion came about; but once again, DNA evidence proved to be the spoiler. What is somewhat confusing, and at the same time came as a surprise to researchers, is that Torrontés is not a single grape but rather three different varieties all genetically closely related; Torrontés Riojano, Torrontés Sanjuanino, and Torrontés Mendocino. These varieties are all separate crossings of Muscat of Alexandria and the Mission grape and are referred to as belonging to the Criolla group of grape varieties, which loosely defined, means that they are the “American-born” cultivars of the European grapevine vitis vinifera. The Mission grape was one of the first varieties of vitis vinifera to make it across the Atlantic, arriving with the Catholic missionaries in both South and North America. As the influx of European settlers continued in to the late 1800s, more varieties of vitis vinifera were introduced to the new world.
To explain a little of how three different varieties can come about from the cross of these two cultivars, it is as simple as looking at how the DNA is read during the pollination process. Each grape flower produces seeds that are unique to the pollen used to pollenate it, and those seeds, when planted, produce three different cultivars. Hence, these three varieties of Torrontés are essentially siblings of each other. It is not clear whether this cross was a random cross or by design. There is also a similar white cultivar called Torontel, but it is not the same, and to confuse us just a little more, there is also a red grape known as Torrontés (aka Tarrantes or Turrundos).
Torrontés Riojano is reported to create the wines of the highest quality and thus encompasses twice the area of acreage planted in Argentina over Torrontés Sanjuanino. The former is also the variety that is most widely exported to the United States and United Kingdom under the common name “Torrontés.” Just to confuse us, you will also find the Galician Torrontés exported to the same markets even though they are probably not the same grape as that in South America. Nevertheless, they are all enjoying success in the marketplace as an alternative to the common white wines such as Chardonnay and Sauvignon Blanc. It is a welcome alternative given Torrontés has a quite different flavor profile than we are used to in white wines. Torrontés wines are moderately acidic, highly aromatic, and are generally all stainless steel fermented. Oak aging tends not to be of any advantage and the wines are best consumed when young. Sometimes the grapes are made into sparkling wines using the méthode champenoise.
The acreage dedicated to growing Torrontés is steadily increasing in Argentina. It is widely grown in the La Rioja and Salta provinces in the north, sometimes at altitudes exceeding 5,000 feet, where crisp, acidic wines are the result. Outside of Argentina, you can also find the grape grown widely in Chile, where most of its production is distilled into brandy.
California wineries reported a whopping 35.2 tons crushed in 2012, which was just more than double that from 2011. Over 30 tons were produced in the Northern San Joaquin Valley — quite close to home, so there is hope it may catch on here in Sacramento as well because it seems to do quite well based on what I see in our campus vineyards!
The clusters I am familiar with tend to weigh in the range of two pounds or more. On the large clusters are relatively large berries that are very pulpy. It seems to crop heavy even in years when fruit set is generally poor. Poor fruit set, leading to shatter (where the clusters take on an uneven appearance), tend to be compensated for by producing even larger berries, filling the clusters out so that at harvest one would never guess that set was poor. The berries turn yellow at veraison, and then as the sugar accumulates closer to harvest they take on more of a golden hue. As the berries mature, I look for more Muscat characteristics to base my harvest decision on rather than strictly sugar accumulation. In fact, this block is typically harvested when the sugar is 22 to 23 °Brix.
It is widely reported that Torrontés can be a difficult grape to produce wine from, and I will attest to those reports based on my personal experiences. I am fortunate to have the luxury of working with this grape from a teaching perspective, as I would have lost my fortune long ago given my trials and tribulations. From a winemaking perspective, the mesocarp of the berries from the Torrontés vine is very dense, which makes it reluctant to give up its juice easily. My first attempts to extract the juice via whole cluster were dismal, often yielding less than 100 gallons per ton of fruit. Muscling more yield via harder press pressures only caused issues with the pH climbing to sky-high levels and watching the titratable acidity drop in the three to four gram per liter range; resulting in rather dull flavors in the juice despite the nice Muscat flavors I had tasted in the unharvested berries. As the years progressed, I experimented with crushing and de-stemming, but I still could not get the yields in the press that I wanted. Two years ago, I modified my automated press program by increasing the length of the cycle, pressing at much lower pressures for shorter press intervals. Then I experimented with my small basket press with smaller quantities using rice hulls as a pressing aid and soon began to find more success in getting better yields using both press types. This experimentation paid off as I started getting upwards of 130 to 140 gallons of juice per ton.
Juice yields aside; there were additional challenges once it came to the winemaking. I was faced with higher than desired pH (3.8 to 3.9) and low starting titratable acidities (4 to 5 g/L). Being picky in how I like my white wines to taste, notably with crisp acidity from a long-term wine stability aspect as well as mouthfeel, tartaric acid supplements of upwards to 2 grams per liter were made. When it came to yeast, with so many choices of designer yeast in the marketplace, I began to make this variety my “yeast trial” wine every season, so students could see how different yeasts performed in the same juice under identical nutrient supplementation and fermentation conditions. In a typical season I may ferment with up to four different yeasts, so I have tried at least 20 different yeasts with this grape and have finally decided that Lallemand QA23 produces the most consistent wine that preserves the Muscat flavors and is enhanced by other fermentation bouquet aromas.
All of my challenges aside, in reality, the biggest challenge to producing your own Torrontés domestically is sourcing the fruit. The report compiled by the National Agricultural Statistics Service division of the United Sates Department of Agriculture does not even list it by name. I am fortunate to have this small block at my disposal. With hope — as I am a major fan of uncommon grape cultivars — Torrontés will catch on and you will also have the opportunity to work with this grape. The opportunity, unless you can spend a season in the southern hemisphere, is indeed a rare one.
(yield: 5 gal/19 L)
• 100 lbs. (45 kg) Torrontés fruit
• 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.
• Lallemand QA23 yeast or 5 grams Premier Cuvée
• 5 grams Fermaid K (or equivalent yeast nutrient)
• 5 grams Di-ammonium Phosphate (DAP)
• Rice Hulls
• Tartaric acid (if acidity adjustment is needed)
Other equipment or needs
• 5-gallon (19-L) carboy
• 6-gallon (23-L) carboy
• 6-gallon (23-L) plastic bucket
• Racking hoses
• Equipment cleaning and sanitizing agents (Bio-Clean, Bio-San)
• Inert gas (nitrogen, argon or carbon dioxide will do)
• Refrigerator (~45 °F/7 °C) to cold settle the juice. (Remove the shelves so the bucket will fit.)
• Ability to maintain a fermentation temperature of 55 °F (13 °C).
• 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 milliliter.
• Clinitest® tablets to measure residual sugar at the end of fermentation.
• Ability to test or have testing performed for sulfur dioxide.
Step by Step
1. Crush and press the grapes. Do not delay between crushing and pressing. Crush to a bucket and mix in rice hulls. The ratio of must to rice hulls should be about 70% must to 30% rice hulls. The rice hulls aid in pressing by creating juice channels. Your juice yields will increase significantly with their use. Move the must/rice hull slurry directly to the press and press.
2. 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 (ppm) SO2. Move the juice to the refrigerator.
3. Measure the Brix and acidity.
4. Adjust the acidity to 6.0-7.0 g/L, if necessary, with tartaric acid.
5. Let the juice settle at least overnight. Layer the headspace with inert gas and keep covered.
6. When sufficiently settled, rack the juice off of the solids into the 6-gallon (23-L) carboy.
7. Prepare yeast. Heat about 50 mL distilled water to 104 °F (42 °C). Sprinkle the yeast on the surface of the water 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 disparity in the temperatures exceed 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 15 °F (8 °C). Do not let the yeast sit in the original water suspension longer than 20 minutes. When the yeast is ready, add it to the fermenter.
8. Add Fermaid K or equivalent yeast nutrient and stir.
9. 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).
10. 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 and stir.
11. 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. So at this point, the presence of noticeable fermentation is good enough. If your airlock becomes dirty by foaming over, remove it and clean it and replace as quickly and cleanly as possible. Sanitize anything that will come in contact with the juice.
12. Leave alone until bubbles in the airlock are about one bubble per minute. Usually about two to three weeks. Then measure the Brix every 2-3 days.
13. The wine is considered dry, or nearly dry when it reaches -1.5 °Brix or less. Measure the residual sugar using the Clinitest®.
14. When the fermentation is complete, add 3 mL of fresh KMBS (10%) solution per gallon (3.8 L) of wine.
15. Transfer the wine to the 5-gallon (19-L) carboy and lower the temperature to 38-40 °F (3-4 °C). If you have leftover wine, you might as well have this for dinner.
16. After two weeks, test for pH and SO2 and adjust as necessary to attain 0.8 ppm molecular SO2. (There is a simple SO2 calculator at www.winemakermag.com/guide/sulfite). 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.
17. At about three months you are ready to bottle. Be sure to maintain sanitary conditions while bottling.
• Yields are assumed based on 120 gallons (454 L) of juice per ton of grapes using a crusher/destemmer and basket press. Your actual yields may vary based on equipment used.
• The recipe calls for specific additions of sulfur dioxide at specified intervals. Once these scripted additions are made, you must monitor and maintain 30–35 ppm, adjusting as necessary using the potassium metabisulfite solution previously described or by methods of their own choosing. Testing can be done at a qualified laboratory, or in your home cellar using various commercially available kits.