NW Winemaking Notes

Making White Wines

September 2005 revision

Overview—choosing a style

The most important step in white wine making is choosing a style.  The basic choice (with a number of intermediate possibilities) is between:

• Light-bodied aromatic whites. Riesling and Gewürztraminer are the classic examples, but this is also the usual style with Chenin Blanc and Pinot Gris. Almost any white grape can be (and has been) made in this style. The style has higher acid levels, uses no oak, and avoids MLF. It usually uses some residual sugar and it does not aim for high alcohol levels.
• Full-bodied wooded whites. Chardonnay and Sauvignon Blanc are the classic examples, but the style can be used with other grapes including Semillon, Viognier and white Pinots. The style is characterized by ML fermentation, oak treatment (including barrel fermentation), and sur lie aging. It seldom uses much residual sugar and high alcohol levels are common.

Some grapes are made in either style. Sauvignon Blanc is a classic example. Compare the high-acid, aromatic New Zealand style with its tart gooseberry, cat's pee flavors and the Fumé Blanc of California, with its mellow, light tropical fruit and oak. Both are distinctively Sauvignon Blanc and wonderful wines, but the California grapes were riper, with more sun exposure, and they aged on their lees in oak.

This note covers the following topics. Some topics apply to both styles, but even then there are important differences according to style.

1. Starting with settled juice

White wines are never fermented on the skins and seeds. The grapes are pressed and the resulting juice is settled to remove most solids (a process the French call débourbage). If you do not have the good fortune to start with settled juice thanks to the efforts of someone else, you will have to press the grapes and settle the juice yourself. In general, you can expect about 1L of juice per 5 lbs. of grapes, or a bit more depending on the grape variety and the efficiency of your pressing and settling operations.

Skin contact and pressing

The Club uses a destemmer to crush and destem white grapes and then our pneumatic bladder presses to squeeze out the juice. besides the extra work involved, there are two related issues involving how many of the ingredients you want from the grapes skins:

• Skin Contact. There is a fair bit of debate about the optimum amount of contact between a crushed grape and its skin before pressing. Some people like to move as quickly as possible to the press in order to minimize skin contact; others like some skin contact because they think it increases varietal flavor. Often there is a backlog to get to the press, which means some skin contact is almost inevitable.  Some people deliberately wait 24 or more hours before pressing.
  Most makers of the finest white wines seem to try to minimize skin contact. They do this by cluster pressing their grapes (no crushing and destemming). This reduces yield but can increase quality. However, these commercial operations use much more efficient presses than we do, so it is possible they are getting more out of the skins than we do.
• Free run and press run. After you have moved your crushed grapes to the press, the juice that flows off with little or no pressure is known as "free run," while the rest that comes off under pressure is called "press run."  Commercial wineries will often keep free-run juice separate from juice pressed off at low pressure and also keep this separate from the last juice pressed off at high pressure.  If you are making a significant amount of a particular white wine, it may also be feasible to keep “free run" and “press run” juice separate and to make wine from them separately.  You can then blend them before bottling to get the optimum wine.  Free-run juice is generally thought to make a superior wine, but again it depends on how much of the various ingredients in the skin.

Unfortunately, over the years, the Club has been able to develop no good guidelines on whether our white wines are better with more skin extra or less.  It may depend in part on the grapes (if you are not getting much fruit flavor, try more skin contact; if you are getting any bitterness, try less skin contact), but it probably also depends on the tastes of the winemaker.

Settling white juice

• Sulfite juice immediately after pressing—50 ppm is standard. If there is much bunch rot or you suspect possible VA problems, use 100 ppm.
• Add pectic enzyme.
• If you want to avoid malolactic fermentation or make sure it is delayed until after the yeast fermentation, add Lysozyme now—0.1 grams per liter.
• Move juice to carboys or other tall, narrow (preferably clear) containers. Keep as cold as possible. A fridge is ideal.
• In one to two days, there will be a clear separation of juice (on top) from the solids (on the bottom, although sometimes there is a secondary layer on the top.) Rack off the clear juice to begin making your wine. Freeze the dregs in plastic containers.

Note: It is not necessary or even desirable to get the juice perfectly clear. Some solids are inevitable. 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 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 is something thin, 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.

• Standard recovery method. When you take your frozen containers of dregs from the freezer and let them stand and thaw, there will be a new separation of juice and sludge. Rack or pour off the juice. Add this to your ferment. Because this newly recovered juice will be cold, it will help to lower the temperature of your ferment (which is usually what you want). Or, if you are planning to back sweeten your wine, you could refreeze some portion of this juice to keep as your “sweet reserve.”
• Duane Lukyn’s recovery method. Instead of thawing completely to let the sludge and the juice separate, Duane upends the frozen container in a funnel over another container. As the sludge thaws, the clear juice is released first. You just have to watch that you don’t let everything unfreeze and slide through the funnel. This process is not unlike that used to get a higher sugar juice for “ice” wine, so it is wise to be aware that the sugar content of the juice recovered this way could be higher than your original juice. The advantage of Duane’s method is that it seems to result in a higher proportion of recovered juice.

2. Acid levels and other fermentation parameters

White wines always have higher acid levels than red wines. This is because red wines have significantly higher tannin levels. Acid and tannin “fight” one another, and high acid in combination with high tannin make a wine almost undrinkable. But full-bodied whites do have some tannin from the oak and they therefore will have lower acid levels than aromatic whites. Full-bodied whites also usually aim for higher alcohol and therefore start with more sugar (Brix) than aromatic whites. Aromatic whites often have some residual sugar to offset the higher acid levels.

The standard recommendations for starting a white wine are:

• TA: 7.5-8.5. The aromatic style commonly has a higher acid level, especially if you are going to have some residual sugar. If your TA is below 7.0 or above 9.0 make acid adjustments before you ferment.
• pH: 3.1.-3.5. For fruity wines, you need a low pH (3.1 or below) to prevent MLF. Otherwise, you should use Lysozyme. If your pH is above 3.5 you should consider adding tartaric acid to drop it, even if this takes you above the recommended TA levels. You can reduce this tartaric acid later.
• Sugar: SG 1080 (19 Brix) to 1100 (23.6 Brix).
Some makers of full-bodied wines (especially Chardonnay) will accept (even seek) very high sugar levels. If you are going to add water to reduce the Brix, do it now (use acidulated water unless you also have high acid). If you are going to add sugar, calculate the amount now, but add it later (in solution), as the fermentation is winding down (this helps to prolong the fermentation and is supposed to enhance flavor and body).

3. Yeasts and fermentation temperatures

There are yeasts specifically selected for white wines. White wines are always fermented at cooler temperatures than red wines. Light-bodied aromatic whites are usually fermented at lower temperatures than full-bodied whites.

Choosing a yeast

Club members commonly use only a small selection of the total number of yeasts available. The full list, with descriptions, is available elsewhere ("Yeasts commonly used by Nanaimo Winemakers").  You can click on the names of the yeast below and go to these descriptions.

There seem to be no right answers when it comes to yeast.  Club members certainly have different experiences and preferences. 

Some general comments on the above table:

• There is lots of experience with Chardonnay, and several yeasts have been specially identified for it.
• Semillon is often combined with Chardonnay (the Australian approach) and with Sauvignon Blanc (the Bordeaux approach).  Yeasts suitable for these other varieties should also work with Semillon.
• Peter Brehm prefers VL1 or R2 for his German whites. Vin 13 has also well for these grapes in the experience of Club members. In theory, VL3 should work better than VL1 for aromatic varieties.  A Club taste panel almost unanimously preferred VL3 over VL1 in a tasting of two otherwise identical 2004 Chenin Blancs.
• There seems to be no special attention given to Pinot Gris yeast choices. The two-star choices in the chart are Peter Brehm's recommendations for his Oregon Pinot Gris.
• Viognier is usually made in the fruity style, but it can also be made like a Chardonnay.  The two-star choices in the table are Peter Brehm's recommendations for his Suisun Valley Viognier, which always has high sugar.
• EC-1118 is the old warhorse yeast for whites.  It can be used almost anywhere with satisfactory results.  Paul Kirschmann (who grows our Gewürztraminer and Pinot Gris) uses 1118 routinely because it is readily available and has few complications.  Club members tasted Paul's wine and it was a match for our wines made with more specialized yeasts.  However, Lallemand now recommends DV10 over EC-1118 as an all-purpose, no-problem yeast.
• The closest things to better quality, general purpose white wine yeasts are D47, Vin 13, VL1, and (perhaps) DV10.  You probably won't go terribly wrong using any of these in almost any white wine situation.  All of them also have a reputation of being relatively forgiving and easy to use. D47, Vin 13 and DV10 have low nitrogen requirements.

As a general rule, if you are fermenting a significant amount (say 200 lbs and up) of the same grape, there are usually advantages to fermenting in smaller lots and using a different yeast on each one. This rule is probably truer for full-bodied whites than it is for the aromatic style.

Read the instruction on the “Care and Feeding of Yeast.” Do not automatically add yeast nutrient before the start of your fermentation.

Fermentation temperatures

White wines are almost always fermented cooler than reds, in large part because cooler temperatures are thought to produce better fruit flavors (they also produce more alcohol from the same amount of sugar). Lower temperatures are particularly important for aromatic whites.

The usual strategy is to get your must started at close to room temperature and then, after about 24 hours, to get the temperature down by whatever means possible.  See the FAQ section of this website for a note on the different ways Club members manage this task ("How do I keep my white ferments cool?").

In general the desirable temperature ranges are as follows:

• Aromatic whites: 10-15°C.  This will make for a very slow ferment—probably several weeks.  Make sure your yeast can handle low temperature; not all yeasts can.
• Full-bodied whites: 15-20°C.  Some yeast work best in the 18-20°C range.  These ferments will take about two weeks or less. 

Warm up the fermentation as it nears completion. This helps the fermentation go to dryness.

Some discussions of white wine making distinguish a European style of fermentation and a New World style. The European style uses a warmer fermentation (15-20°C). The New World style tends to be as cool as possible, with a view to maximizing fruit flavor.

4. Oak treatment for white wine

Full-bodied whites wines usually get some oak treatment. This is especially true of Chardonnay, but is also common for Semillon, Sauvignon Blanc (in the Fumé style), Semillon, Pinot Blanc, Viognier, and even Pinot Gris

The preferred way to get oak flavors and effects into wine is to ferment and age sur lie in a barrel. You can start your ferment outside the barrel if you want to make sure it is going properly, but put it into a new or white-wine-only barrel soon after. (Watch you don't overfill; the fermentation needs room.) With barrel fermentation, you can leave the wine in the barrel for the subsequent MLF and sur lie aging. With a new barrel one must be careful, however, not to pick up too much oak flavor. Once you have enough oak flavor, you can move the wine to carboys for additional sur lie aging. Wineries typically use a mix of newer and older barrels to ensure not too much oak flavor comes through.

Alternatives to barrel fermentation

1. Add oak chips to the fermentation. This seems to work quite well.
2. Aging new wine in a barrel. This is not as good as fermenting in the barrel. Oak flavors usually are not as well integrated.

5. ML fermentation

Almost all red wines undergo an ML fermentation (which reduces malic acid to a milder lactic acid). With whites it is an option that almost defines white wine style. MLF is almost never used with fruity whites, because it reduces and and sometimes spoils fruit flavor. MLF is common with full-bodied whites, especially those like Chardonnay and Sauvignon Blanc which get oak treatment and sur lie aging and which benefit from the softening that comes from MLF.

Because ML (wooded) wines and non-ML (aromatic) wines have very different characteristics, some wineries like to blend the two to get the best of both worlds. They accomplish this by using sterile filtration—an option that is not open to the home winemaker. The home winemaker has to use Lysozyme (see below). In general, home winemakers take one of two courses of action: they either try to prevent MLF (for aromatic whites) or they encourage it (with wooded whites). Accidental MLF (there are many different ML bacteria) is often bad news. And MLF in the bottle is always bad news.

Note: The "geranium" fault in some off-dry white wines comes from 2,3 ethoxy, 3,4 hexadiene that is produced by ML bacteria working on sorbate that has been added to prevent the fermentation of the residual sugar. If you have residual sugar you must take efforts to control ML bacteria by maintaining an adequate SO₂ level. Using Lysozyme is also a good idea. The use of MLF with full-bodied white wines partially complements the tendency to leave them completely dry—no residual sugar, therefore no sorbate, and therefore no risk of geranium taint.

Preventing MLF—using Lysozyme

The task with a light-bodied aromatic white wine is to prevent MLF. This is not easy, because the bacteria are everywhere, just waiting for an opportunity.  Previously, those who wanted to discourage MLF were urged to keep their wine in conditions inhospitable for ML bacteria. The standard conditions which prevent ML are:

• Temperature below 15C.
• pH 3.1 or lower.
• Free SO₂ above 35 ppm.

Today, Lysozyme is the preferred way to prevent an MLF. Lysozyme is an a enzyme that works by killing ML bacteria. The effect does not last forever, but judicious treatment with Lysozyme reduces the bacteria population below the threshold necessary for activity. More than one treatment of Lysozyme may be necessary during the winemaking process. (For more details, see the note “Using Lysozyme.”)  To prevent MLF, the standard strategy is to add 0.1 g/L Lysozyme before the fermentation starts and another 0.2 g/L after the fermentation is finished and before you fine.

Advice: Some very good Club-member 2004 wines (they won high medals in February 2005) eventually went wrong because the winemakers did not use Lysozyme.  Later, these wine began an unwanted MLF (the very worst kind), which pretty much ruined the wines.  The best strategy if you are not planning on introducing your own MLF is to use Lysozyme.

Encouraging MLF

To ensure you have a MLF, and the kind you want, you introduce ML bacteria into your white wine, just as you would with red wine.  In white wines always introduce your ML bacteria at the end of the alcohol fermentation,

There are a couple of special consideration, however, with MLF in white wines.

• Introduce your ML bacteria only at the end of the regular fermentation, when you bring the wine back up to room temperature.  Some of the yeasts most favored for white wine do not like a concurrent MLF. Also, when ML bacteria are active in the presence of sugar, they act on the sugar rather than the malic acid, leading to an increase in “buttery” flavor and acetic acid (which is more noticeable in whites than reds).
• Remember to bring your wine to room temperature. You will not get a decent MLF at temperature much below 20ºC.
• Consider feeding your ML fermentation with nutrients, especially if you are not aging sur lie, (with aging on the lees, the spent yeast cells can provide the nutrients).
• Make sure your MLF runs to completion. Use chromatography to test for the completion of the MLF. See "Malolactic Chromatography Testing."
• If you are going to be back-sweetening your wine and using sorbate, consider using Lysozyme to kill off the lactic acid bacteria when the MLF is complete in order to help avoid geranium off-flavors.

6. Sur lie aging

"Sur lie" is French for "on the lees," but only the fine lees of spent yeast, not the gross lees or other organic matter. Aging on the lees is a practice than can be used with any wine (and increasingly is) but it is most commonly associated with full-bodied whites, especially, Chardonnay, Sauvignon Blanc and Semillon. Sur lie aging is often accompanied by malolactic fermentations. There are several advantages of sur lie aging:

• Lees contact encourages the malolactic fermentation because it provides the micronutrients needed by the ML bacteria.
• Lees contact is thought to contribute to a richer mouthfeel.
• Lees contact can add some complexity to flavor. Fine champagnes develop yeasty, bready flavors after several years on the lees in the bottle. Normal full-bodied white wines are not aged on the lees anywhere close to that long (a few months to a year is the usual range), but the champagne-effect hints at what can happen to flavor with more limited lees contact.

How to do it:

• Either carboy or barrel can be used. You want the lees to form a sediment an inch or two in depth. You can introduce fresh yeast if you do not have enough after racking your wine, but that can be expensive.
• Stir  (what the French call bâtonnage) regularly (every one or two weeks). If you don't, you run the risk, especially with a deeper sentiment, of producing H₂S, mercaptans, or various other sulfides and disulfides. This happens when the yeast autolyse (digest themselves) in the absence of enough oxygen. The amino acids in yeast and other compounds in wines can be reduced to foul-smelling sulfur compounds.
• Along with stirring, taste and smell your wine. Don't let the process go on too long.

7. Residual sugar

For most people, the flavor and body of white wines, especially aromatic whites is often enhanced by a bit of sweetness. There are two main ways to achieve this :

• Stop the fermentation as it nears completion, by chilling it and racking several times. This eliminates most of the yeast population—enough with SO₂, you hope, to prevent the fermentation restarting.  This is risky but it can work with yeasts that are less tolerant of high alcohol levels (these low-alcohol yeasts are hard to come by these days). Sometime you end up with a stuck fermentation, in which case you can make a virtue of necessity and claim the residual sugar as intentional.
• The more common and more predicable method is to ferment to dryness, add sorbate to stop yeast activity, and then back-sweeten with some reserved juice or a sugar syrup. (The “wine conditioner” sold in stores is simply a sugar syrup and potassium sorbate.)

Observe these principles in wines with residual sugar.

• Don’t over-sweeten. George Gibson thinks a sugar addition of 0.4g/L (and an eventual SG of about 0.997) is about right, but partly this will depend on your acid level. The more acid, the more sugar you can use to “balance” the wine. The most common mistake is to add too much sugar. This can taste find for a few sips, but soon grows tiresome. Also, young whites may still have a fair bit of dissolved CO₂, which may make the wine taste less sweet than it will later.
• Use potassium sorbate. In the absence of sterile filtration, which is not really possible for the home winemaker, the only way to guarantee that your wine won't re-ferment in the bottle is to use potassium sorbate. Use 0.10-0.20g/L depending on your alcohol level. A higher level of SO₂ is also wise. For more on sorbate, see the note on "Potassium Sorbate (Sorbic Acid)."

 

8. Handle gently and bottle early

White wines must be handled much more carefully than reds because they do not have the tannin to protect them from oxidation. This is especially true of  light-bodied, aromatic wines, which do not even have oak tannins. You want to get the SO₂ into your wine as soon as possible after the fermentations. White wines require a higher level of SO₂ than red wines do for a similar pH. See the FAQ: "How much sulfite (SO₂) should I add?"

White wines, especially the aromatic ones, are also bottled as soon as possible in order to capture as much fruit flavor as possible. There is nothing to be gained in fruit flavor by holding a white wine in bulk (except for aging on the lees).

Early bottling means fining, cold stabilizing, and filtration are much more common with white wines than they are with reds (where many of the clarifying processes happen naturally over the course of a couple of years in bulk). White wines not being aged sur lie typically go through the following processes as quickly as possible:

• SO₂ addition: 50 ppm (or as appropriate for pH).
• Temporary warming of wine and/or stirring to help release CO₂.
• Residual sugar adjustment (if wanted) and protection with sorbate—together with final acid adjustment.
• Fining first with gelatin and then with Kieselsol (or a similar negatively-charged agent). See FAQs on "What is protein haze and how do I prevent it?"
• Cold stabilization (which can be combined with the settling of the finings). See FAQs: "Should I fine my wine before cold stabilization?"
• Bottling, with free SO₂ of at least 25 ppm, adjusted upwards for higher pH wines and wines with residual sugar (you do not need the higher SO₂ level with residual sugar if you have used Lysozyme to limit the ML bacteria).

 

 

Sources

Johnson, Hugh, and James Halliday (1992). The Vintner's Art: How Great Wines are Made. New York: Simon & Schuster.

Has separate chapters on light-bodied aromatic and and full-bodied wooded whites. Good reading and informative.

Martin, Jeff (2001). "Building Bigger Okanagan Chardonnays." Home Winemaking and Beyond. Proceedings of the 5th Annual Vancouver Island Amateur Winemakers Association, pp. 16-24.

A very desirable re-read for anyone making Chardonnay.

 

 

Originally prepared by Rod Church for a Nanaimo Winemakers educational session in August 2004. This revised version is for a similar educational session in September 2005.