Article

The ABCs of Making Z

It’s difficult to walk through a wine aisle in the supermarket, or to browse through the kit section in your favorite winemaking store, without coming across a wide selection of Zinfandels. Red, robust and fruity, Zinfandel is one of the most popular grapes for winemaking (and wine drinking) in North America. Typically made into a dry, red table wine that carries an alcohol content between 13 to 15 percent, “Zin” is also a grape that lends itself to any number of wine styles, ranging from light red “picnic wines” to chewy, Port-style dessert wines. In fact, the so-called “White Zinfandel,” a rosé made from the just-pressed juice of the red Zinfandel grape, was until recently the best-selling wine on the market. It was only in 1997 that Chardonnay eclipsed it in popularity.

That said, when most people think “Zin” they envision a fruit-forward, tannic dry red wine that’s a pleasure to drink young, due to its fresh and fruity-spicy character, but that also can handle at least a few years of aging. Well-made Zinfandel should have a good balance of color and tannin, alcohol and acidity and should be neither perceptibly sweet nor perceptibly oaky.

Zinfandel’s exodus from Europe is swathed in shadow. What’s known for certain is that Zin first made its appearance on the East Coast of the United States around 1820. One theory is that Zin was brought to our shores by Italian immigrants. Most Vitis vinifera grape species don’t do well on the cold and damp East Coast, and thanks to the willing hands of westward-moving immigrants, Zinfandel debuted on the West Coast around the year 1850.

In the early days of the California wine industry, growers found that Zinfandel was a good “workhorse” grape that did well in a variety of climates and that could, under hot and dry conditions, be forced to accrue a high concentration of sugar. This discovery added to Zinfandel’s popularity in the wine business, and it became a key ingredient in the sweet red wine that was popular with the American drinking public in the 1940s and 1950s. For this reason, Zinfandel was widely grown in the hot valleys of inland California, where it essentially was exploited as an abundant source of grape sugar for the region’s large factory-scale wineries and distilleries.

The White Zinfandel craze, which helped create a new interest in Zinfandel in recent years, ironically started out as an attempt to make a better dry red table wine out of a grape that had long been dismissed as a “hot climate” and uninteresting varietal. Bob Trinchero, the winemaker at Sutter Home Winery in the Napa Valley, decided in 1972 that he would try to make a rich, dry red table wine from Zin grapes grown in the cooler Amador County region in the Sierra Nevada foothills. To make the wine even more concentrated, he decided to bleed off a portion of the juice from the crushed grapes and allow the must to ferment normally. He noticed that the juice he had drawn off had a lovely pink color and a nice flavor, so he decided to ferment it like a white wine. He created a dry, tart rosé that turned out to be popular with winery employees and a few locals. During a subsequent harvest, the Zinfandel juice didn’t entirely ferment to completion and that year’s rosé was left with a little bit of residual sugar. The resulting product became a tasting room sell-out as well as an international success.

As the wine boom of the 1970s hit California, and as the collective palate of North America became more sophisticated, it was time for dry, red Zinfandel to take precedence in the minds and cellars of consumers. Though some wineries in the Napa and Sonoma valleys had been making a dry, red Zinfandel table wine for years, it took an infusion of energetic vision and young talent, by Zin pioneers such as Joel Peterson of Ravenswood and Paul Draper of Ridge Vineyards, to bring Zinfandel to the fore of the fine-winemaking movement in California. Throughout the 1980s, as Zin from cooler-climate vineyards reached full maturity, and as more winemakers began to gain experience dealing with its formidable sugar and tannin levels, Zin established a place for itself among the fine red table wines of the world.

Today Zinfandel is more popular than ever. And its legions of fans seem to be an especially outspoken bunch. Through organizations like Zinfandel Advocates and Producers (ZAP), which hosts the largest varietal-specific wine tasting in the world every year in San Francisco, Zin diehards champion their cause and win new devotees.

UC-Davis plant geneticist Dr. Carole Meredith recently discovered that Zin and a Croatian grape called Crljenak the same. Perhaps because it has such humble roots, Zin — called Primitivo in Italy — is a simple grape to get to know. It’s a bright, fruit-forward red wine that is easy to like, easy to drink and easy to pair with many kinds of foods. Luckily, Zinfandel is also relatively easy to make. It’s vinified like any other dry, red table wine … but with a few twists and turns.

A note on the chemistry and additive parlance that we’ll be using in this article. Most winemakers talk about adding things like yeast or sulfur dioxide in parts per million (otherwise known as milligrams per liter). This common term allows us to talk about adding a certain amount of anything to our projects, whether we’re talking about a juice or finished wine. When it comes to fresh grape musts, however, it gets a little bit more complicated. Many commercial winemakers assume that post-press they’ll get around 165 gallons of wine per ton of fresh grapes. Therefore, when talking about making additions to fresh grapes or must, we can still talk about ppm or mg/L (or even pounds per thousand gallons, or grams per 5-gallon carboy), because we assume we’ll get 165 gallons for every fresh ton of grapes crushed. (This will change if we add water or take out some of the juice to make White Zinfandel.)

How to make a standard Zin table wine

As the saying goes, “Wine is made in the vineyard.” Commercial wineries invest a lot of time, effort and money in either tending their own vineyard or establishing a strong relationship with grape growers. Most home winemakers lack those resources, so finding great grapes can sometimes be tough.

Depending upon where you live, you may have more fresh-grape options than others. If you happen to live in an area where Zinfandel is grown, try calling up some local wineries and vineyards to see if anyone’s selling. Be sure to call well in advance of harvest. If you haven’t talked to a winery at least a few months in advance, be prepared to be brushed off in the rush and bustle of the season. Sometimes wineries and vineyards are willing to let people pick “second crop” clusters for a discount. These are the smaller, weaker clusters that are often left hanging on the vine. Due to their weaker color, flavor and sugar levels they won’t make the best wines of that region, but many home winemakers have made satisfying wines from second crop grapes.

Even if you don’t live in a Zin-growing area, you can still get fresh grapes. Surf the Internet (or read the WineMaker ads) to find companies that ship boxes of just-picked grapes to home hobbyists. You can also call your favorite winemaking supply store; many shops order shipments of grapes that arrive in refrigerated trucks.

When buying fresh grapes, make sure you’re buying from someone who knows how to farm Zinfandel. Talking to local wineries, fellow home winemakers and grape-growers can give you a good sense of who’s reputable. Be sure to talk to your supplier about when you want the fruit picked.

For a full-bodied red table wine that will ferment to dryness, you want the grapes to be around 24 to 26° Brix. Hot, dry climates can lead to rapid sugar accumulation in Zin, while the grapes have a hard time ripening in cooler climates. Similarly, fertile soils can lead to vigorous green growth with little sugar concentration in the fruit. Look for sandy, rocky or “poor” soil, which will keep vine vigor low. To get appropriate flavor development, seed ripening, stem lignification and even cluster ripeness, some people are tempted to let the grapes hang too long on the vine. Zin can fool people into thinking it’s less ripe than it is. For all of these reasons, vineyard sampling is very important.

Zinfandel wines sometimes have high total acidity in the face of relatively high final pH, so it’s not unheard-of to see a pH level of 3.6 or 3.7 and a TA of 0.90. When in doubt, go by taste and by Brix. You can always acidulate, but watering down a must of 29° Brix so that the yeast can survive will only dilute flavor and concentration.

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The Seven Deadly Sins of Zin:

1. Grapes not ripe enough……..Try to pick (or buy) between 24-26° Brix

2. Grapes too ripe……….Add water to get below 26° Brix ………..Check and adjust TA and pH

3. Stuck or sluggish fermentation………Pick in the correct sugar target ………..Feed your yeast! ………..Stay within temperature bounds

4. High alcohol………..Make sure Brix is within bounds

5. High volatile acidity………..Avoid stuck or sluggish fermentations ………..Add SO2 at the crusher………..Don’t let cold soak or extended maceration get infected with spoilage organisms

6. Too much oak………..Be conservative and keep tasting during aging

7. Too much tannin………..Monitor fermentations and taste often………..Don’t press too hard

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A Caveat for Kits

Zinfandel concentrate is also widely available. Well-stocked home winemaking supply stores should always be able to sell you a red Zinfandel kit that will make the kind of wine we’re talking about here. Follow the directions if you’re a first-timer, but after that, feel free to use a different yeast strain or add a little more acid or concentrate. As long as you pay attention to the numbers and stick to sound winemaking practice, using a kit doesn’t mean you’re locked in to someone else’s idea of the ideal wine. My directions for making Zinfandel assume the reader is using fresh fruit, but the majority of the kinetics, chemistry and processing still apply to the kit user. One caveat: Do not inoculate a kit wine with a commercial malolactic culture. Your wine will be flabby.

Processing the fruit

Most home winemakers begin the winemaking process by crushing and/or destemming the grapes. Crushing releases the juice, while de-stemming takes away most of the “green” stem tannins that can sometimes make whole-cluster musts taste harsh or overly tannic. Feel free to include some stems in the fermenting vessel if you like how the stems taste (give them a chew just to see). If the grapes were properly ripened, the stems should be somewhat brown and lignified (woody). If added back to the must in the 5-20 percent range, stems can contribute to the tannin structure.

Additives

Many winemakers add sulfur dioxide in the form of potassium metabisulfite powder to the crusher at the rate of anywhere between 25 to 45 parts per million (ppm). Zinfandel has a propensity to produce a lot of acetic acid, due to the activity of acetobacter spoilage bacteria, so a little pre-emptive sulfite in the crusher is usually a good idea.

Let the must sit overnight or for at least eight hours. Then agitate thoroughly to mix, and measure the Brix, pH and TA of the must. If the Brix is over 26°, add water to get it below that point. If you don’t, the yeast might have a hard time fermenting the must to dryness. This also is the time to acidulate the must if necessary. If the pH is over 3.6 at this early stage or if the TA is under 0.55, you’re definitely going to want to add a little tartaric acid to bring the wine back into the realm of sensory and stability sanity. Dissolve your acid in water and add to your must while mixing in order to incorporate it thoroughly into the juice in your fermenter, aiming for a starting pH between 3.45-3.6 and a TA between 0.55-0.75. I add acid in increments no great than 0.5 g/L, measuring as I go along. Keep in mind that the pH will end up a bit higher at the end of a wine’s life due to malolactic fermentation. Also, a little of the TA will drop out in the form of tartrate crystals.

When it comes to Zin, home winemakers have a wide variety of yeast choices. The most important thing is to buy a yeast strain that will finish the fermentation to dryness and that is suited to a dry, red wine. My favorite strains are D80, SYR, BM45 and D254. (These commercial strains may be hard for home winemakers to find; for information, go to www.scottlab.com). Other recommended (and widely available) yeast strains include Lalvin’s Bourgovin RC-212 and Red Star’s Pasteur Red. Prise de Mousse is always a great workhorse and will often plow happily through high-sugar fermentations when no other strain will.

Always pitch yeast according to the package directions, paying special attention to the recommended temperature of the water used for hydration. Dehydrated yeast are delicate, tempermental beings that are very put out by hydration water that is too hot or too cold. Use filtered water if you can, as heavy metals can wreak havoc on the delicate cellular membranes. Yeast nutrients will help your yeast get off to the best start possible. Two commercial names are Superfood and Fermaid-K, both of which contain a mix of nitrogen, amino acids and vitamins that will help your yeast conduct a healthy and complete fermentation.

A note of caution: Zin is susceptible to stuck fermentations. As I mentioned, this grape can accumulate high sugar levels, and high sugar levels translate to high alcohol levels. This can compromise the yeasts’ cell membranes. The yeast cells die, leaving residual sugar behind. Stressed-out yeast also may produce undesirable volatile acids during a difficult fermentation.

Fermentation kinetics

Some Zinfandel winemakers like to start out with an initial must temperature around 65 °F (18 °C), or even colder if a “cold soak” is desired. A cold soak is sometimes employed pre-inoculation as a way to extract extra complexity and color from the grapes. This is not usually necessary when making Zin. If you want to try it, start out with an initial must temperature of 55–60 °F (13–15 °C) and let the must sit, well covered, for 24–48 hours. You could even gas the container with carbon dioxide to make the environment less hospitable to spoilage organisms. Smell the top of the fermenter as you go along and be prepared to inoculate at the first sign of any off-odors. Agitate the fermenter frequently to submerge the grapes floating on the surface. If you don’t, mold can easily develop.

Zinfandel can handle a warm fermentation. A good goal is to let the fermentation get going and then try to keep the must warmer than 75° F (24° C) but no warmer than 95° F (35° C). You will have an even greater chance of a stuck fermentation if the temperature of the ferment gets greater than 95° F (35° C). Try to finish out the fermentation at a minimum of 80° F (27° C). This nice, warm environment will help the yeast finish their job.

Maceration

It’s necessary to completely turn over your must at least twice a day during the active fermentation stage, when appreciable levels of carbon dioxide are still evolving from the must. The goal is to completely submerge the cap in the fermenting juice. If you’re dealing with the popular “trash can” fermenter, you can easily punch down the cap, either with your hands or by using a 2×4 with a round disk nailed to one end. (Sanitize the utensil in a sulfite solution first.) When the wine is almost dry, you can punch down only once a day.

Extended maceration is a popular technique among Zinfandel makers. This fancy term simply means letting the grapes sit on the skins after primary fermentation is over. (Primary fermentation should take about ten days.) Extended maceration helps to extract and fix color and tannin in the wine. Because carbon dioxide is no longer actively coming off the wine during extended maceration, it’s unprotected, to a certain degree, from many spoilage bacteria, namely acetobacter. So keep your fermenter well-covered and continue to wet the cap at least once a day. This discourages bacteria. Extended maceration lasts from five to ten days.

Malolactic Fermentation

As with any red wine, it’s important that malolactic fermentation (MLF) goes to completion. Grapes carry a significant amount of malic acid, which serves as a carbon source for the many ambient bacteria, collectively called the “ML bacteria,” that are found in musts, juices and wines. If a wine is bottled without undergoing malolactic fermentation — which describes the digestion of malic acid by ML bacteria and its subsequent transformation into lactic acid — then these reactions will probably take place in the bottle, which leads to cloudy and fizzy wines. For this reason, malolactic fermentation is encouraged by all red Zinfandel makers. It’s possible to buy commercial ML bacteria strains and inoculate the must, but this is usually not necessary. If the must is in the proper pH and temperature range, the ambient bacteria often will take care of it themselves. This usually happens during, or immediately after, primary fermentation. MLF can also go to completion during the bulk-aging process — winemakers just need to keep an eye on it, which is easily accomplished with a paper chromatography testing kit (see “Malolactic Magic” in the Winter 2001 issue of WineMaker). If MLF doesn’t happen on its own, use a commercial culture. Be sure to adjust the free sulfur dioxide to 15–20 ppm once the wine is through malolactic fermentation and is dry.

Pressing, Racking and Aging

Once the wine is dry — or nearly dry; some people press reds when they still carry 1–2% residual sugar — Zinfandel can be pressed just like any other red must. A wine is considered dry when it contains 0.2 to 0.3 percent residual sugar. Monitor the sugar level with a hydrometer until it drops below -1° Brix (0.995 specific gravity), and then use a test kit to confirm the results.

Pay special attention to the press wine coming out at the higher pressures. These later press fractions can be extremely tannic. You may want to do what professional winemakers do and take “press cuts,” separating the free run and the press wine for blending later. Whether you take cuts or not, you can press directly into barrels, carboys or a stainless-steel tank. Make sure there is no headspace in your containers, and if the wine is still going through MLF, anticipate additional carbon dioxide production. Let the wine settle for a few weeks and then rack off the gross lees into another vessel. Watch for signs of stinkiness — smelling slightly like hydrogen sulfide, garlic or onions — in this stage. Sitting on the gross lees can sometimes make a wine turn down this path and it will need to be racked.

Zinfandel can handle quite a bit of oak (much more than, say, Syrah or Pinot Noir) and it benefits from early oaking. So be sure to get your Zin to barrel sooner rather than later. If you use oak chips, add them immediately after pressing. Watch out for over-oaking and be prepared to rack your wine one more time to remove the chips.

Make sure that during the aging process you keep your containers topped up. Keeping containers topped is essential in the battle against spoilage organisms and oxidation.

Most Zinfandels are aged for 12–18 months before being bottled. During this time, if they are settling well, they may need to be racked only once before bottling. Zinfandels are rarely filtered. They traditionally are bottled in dark-colored “claret” (sharp-shouldered) bottles and finished with natural corks. Happy Zinning!

Ten Steps to Making White Zin

1. Crush grapes.

2. Press off juice after 2-8 hours skin contact time, depending upon how dark you want the juice.

3. Acidulate juice to pH 3.20 to 3.35.

3. Pitch any yeast you would use for white wine that is relatively easy to stop with a little residual sugar (Lalvin 71B-1122, Red Star Côte des Blancs).

4. Shoot for a longer, cooler ferment, around 60–65° F (15–18° C). Aim for 1-2° Brix drop per day.

5. Stop fermentation when there is still 0.5–1.0% residual sugar by chilling, adding 50 ppm SO2, and adding 2 g/gallon bentonite to clear the wine.

6. Keep chilled and rack off gross lees when bentonite has settled.

7. Keep free SO2 levels at least at 20 ppm to retard re-fermentation caused by residual sugar.

8. Sterile filter.

9. Adjust free SO2 to 32 ppm, add potassium sorbate to prevent re-fermentation (1 tsp per 5-gallon/19 L batch) and bottle.

10. Chill to 50 °F (10 °C) to serve.

Wisdom from the Zin Master Joel Peterson, Ravenswood Winery

Joel Peterson, long considered one of the most talented and influential makers and ambassadors of Zinfandel table wine, started Ravenswood Winery in 1976 with a production of 327 cases of dry, red Zinfandel. Today, he and a team of managers and winemakers have grown the brand to produce an impressive 500,000 cases of premium California table wines, of which almost two-thirds is Zinfandel. Joel’s wines are stylish, expressive and always a joy to drink. He is a tireless advocate for Zindandel and has managed to win many converts by consistently showing both winemakers and wine drinkers that Zinfandel is a grape capable of producing truly great wines. This interview was conducted by Alison Crowe, an enologist at Bonny Doon Vineyards and a WineMaker contributing editor.

WM: What do you like so much about Zinfandel as a wine?

Joel: I think I really enjoy the sensuous aspects of Zinfandel — it’s got to be one of the most satisfying wines you can drink. Zinfandel has great body and nice flavors. It has a number of different incarnations depending on what part of California it came from. It makes a very flavorful beverage with lots of blackberry, pepper and spice character. I have always found it fun to consume and very pleasing.

WM: What do you see as particular challenges to growing and making great Zinfandel?

Joel: Well, the challenges are myriad. First of all, you have the vineyard issue of uneven ripening in the cluster. The grapes also tend to have a thin skin. Then there are a lot of location issues. In California we’re still trying to find the best places to grow the best grapes, and as a result, a lot of vines get planted in the wrong places. And this is before you even get to the production issues. Worrying about stuck fermentations is very relevant. Getting the right balance of color and tannin is important, too, as is the issue of style.

WM: What do you think about the various styles of Zinfandel out there?

Joel: Zin is just so versatile. The winemaker can make an incredibly wide variety of styles, and they are all delightful beverages.

White Zinfandel — that pink, juicy, slightly sweet wine that is so popular these days — is a really pleasing drink of an afternoon, if it’s not too sweet. Zin can also make a really nice, very satisfying dry rosé.

Then there’s a “picnic style” red wine. It has lower alcohol and tannin levels than a typical table wine, and it’s made in that really approachable, juicy, almost Beaujolais Nouveau style. Following these are the classic mid-table wines. These are wines in the 13-15 percent alcohol range. They are barrel-aged, fruit-driven wines that also have a complex tannin structure underneath.

Finally, there’s the esoteric high-ripeness, naturally-fermented Zin. This has some residual sugar and an alcohol level of 17–18 percent. These wines have that deep, port-like, raisin aroma and flavor, but also retain the fresh-fruit character that makes Zin quite unique.

People used to say Zin had no style of its own. That’s because it is so versatile. Many other grapes have versatility, but winemakers focus on the styles that they think are the best and the most satisfying.

As Zin has become more popular and as more wineries and more winemakers have gotten involved, you see people focusing on the big table wine that is more comparable to Rhone-style wines than anything else. This style has slightly higher alcohols and the density is based on fruit and spice. That’s the style that most winemakers have settled on.

That said, I think that with Zin sometimes it can be a case of TMO — too many options. Dry and red, sweet and red, sweet and pink — it’s a very versatile grape.

WM: Do you think in the public’s mind that Zinfandel means red Zinfandel or White Zinfandel?

Joel: (Laughs) It definitely wants to be red. You have to practically force it to be pink!

WM: So do you see that mostly as a marketing and sales issue?

Joel: I suppose. We should be thankful for pink Zinfandel giving Zinfandel a name at all. It’s just up to us now to pervert it.

WM: So do you have any cardinal rules of Zinfandel making?

Joel: Definitely. The first one is to get your grapes ripe, but not too ripe. That may mean, for the home winemaker, to look at the Brix when the grapes come in and to do some water modification if necessary. You need to get the Brix under 26° to allow them to get through the fermentation. Choosing a grape source wisely will help as well — it’ll make a huge difference. Location is important.

You also want to make sure that your Zin vineyard isn’t carrying more than 4 tons an acre. If it is, you’ll lose a lot of intensity. Zinfandel grapes, as opposed to other varietals, tend to fall apart faster with regard to the intensity of color and flavor. We’ve done a lot of experiments and have found without fail that the break point is always between 4 and 5 tons an acre. Over that level, the concentration of fruit and spice character drop off substantially.

Do a moderately warm fermentation, keeping it between 80 and 90 °F (27 to 32 °C) for as long as you can.

Be sure to agitate (punch down or pump over or otherwise mix) the skins with the wine frequently during active fermentation. It’ll help with the stuck fermentation issue.

Don’t be afraid to extend your macerations as long as the ferment smells clean.

Use good oak and use it soon after pressing your wine. You want to get the wine into oak early. You need that tannin to complex with the anthocyanins to get the color fixed. Zin marries really well with oak character. Don’t over-oak, though!

Avoid the VA (volatile acidity) monster by adding 45 ppm sulfur dioxide at the crusher just to knock down wild yeasts and unwanted bacteria. It keeps down the population of the bad boys, so that the Saccharomyces (wine yeast) are free to take over. Also, keeping your barrels and containers topped will help to avoid the VA issue. Maintaining adequate levels of free sulfur dioxide with an eye on the pH of the wine is something I don’t think home winemakers pay enough attention to. It’s a pretty important issue.

Avoid brett (Brettanomyces spoilage yeast) by finishing the fermentation and not leaving any food (residual sugar) around for them. With any residual sugar left in a fermentation, I’m much more concerned with Brettanomyces spoilage than I am with VA.

WM: Thanks! Those are some pretty thorough tips. We certainly don’t want you to feel like you have to reveal any trade secrets, but I know our readers will appreciate it. Getting back to Ravenswood as a winery, and your Zinfandel styles specifically, what do you see on the horizon for Ravenswood Zin?

Joel: Well, we pretty much have our styles dialed in, though we’re obviously always trying to improve them. We’re now focusing on regional Zins to try to get more regional vineyard flavors and character to come through. There are some real differences that you see in the vineyard from place to place around California. Many people wouldn’t think that Zin would show terroir as much as some of the “classic” traditional grapes like Pinot Noir or Cabernet Sauvignon, but Zinfandel does show those differences and it’s really quite interesting.

With our wide selection of vineyards from various counties in the state, but especially with our “Vineyard Designated” series of wines, we really have the opportunity to look at a lot of regional differences, so it’s great. I find that making Zinfandel is an ever-expanding horizon and I try to keep busy and keep the winery moving forward.