There are competing images in the story of fine wine. One version goes something like, “get the best grapes you can and get out of the way.” It’s great advice and it often makes excellent wine. On the other hand, not every lot of grapes is wonderful and we now have techniques and products that are offered to improve, enhance, or correct an imperfect wine. Old World winemakers decry the use of “New World” manipulations, but those techniques are quietly applied behind the scenes throughout Europe every day. Some American and Australian winemakers openly acknowledge modern tools and techniques. So what’s a home winemaker to do? Are the products even available to us? Is there home-scale equipment for advanced processes? Let’s take a quick survey through the current (and emerging) state of the art.
Some of these tools and techniques have been around for a number of years but may not have been available in every region. Others have been introduced by home winemaking suppliers through distribution of commercial-grade products and equipment. Some are still available only at the commercial level, but wine clubs or other groups may be able to get together to take advantage of them. In our sidebar on the facing page, we have a few that — as far as I know — are not available at all to us hobbyists. Since this is a “when to apply” article, it necessarily involves some opinion. I will include as much factual material as I can, but I freely acknowledge that other home winemakers may strongly disagree with my approach. It’s not uncommon for winemakers to disagree, after all. For what it’s worth, I start from the position of intervening as little as you can to make that wonderful wine. I don’t bar any procedure or product, though, if it is demonstrated (or highly likely) to make an improvement. My review here encompasses the following:
Whole cluster pressing
Basic pectic enzyme products have been available to home winemakers for many years. Relying primarily on pectinases as active ingredients, these products help break down the polysaccharide pectin in fruit, allowing the release of more juice during maceration and fermentation. Especially useful for fruit wines, they have also been applied to grape wines. These days, much more tailored enzyme preparations have been developed for winemaking. For red wines, in addition to pectinases, the products include hemicellulases. These components break down hemicellulose, a structural component of plant matter. In macerating red grapes, they help release more of the native anthocyanin color compounds, improving color extraction in the wine. White wine products often emphasize beta-glucosidases that help free aroma precursor molecules from bonds with sugar in the native fruit material. The released aroma compounds then remain in the juice and, eventually, the wine and are not lost to the pomace when the wine is pressed.
When to apply: Any time you want darker color in reds or more aroma in whites. In other words, in almost any winemaking project with other than perfect grapes — and maybe even then.
Beyond the decision to use a wild fermentation or to add a winemaking yeast, there are now many more choices available. While old standbys like Pasteur Red or Champagne may make perfectly acceptable wines, modern home winemakers have access to yeasts that can respond to difficult conditions in the ferment or enhance the final product in particular ways. With particular emphasis on any individual batch of grapes, my April-May 2014 WineMaker magazine “Tech-niques” column addressed pairing with available yeast strains. For instance, very high sugar must will suggest the use of an alcohol-tolerant yeast if you want the wine to finish dry. To achieve a highly aromatic result, you may wish to choose a strain that naturally produces some of the same sorts of enzymes as described above, leading to enhanced varietal character. The degree to which you can control temperature, up or down, may influence your choice as each strain has an optimum range in which it works best. If you anticipate particular problems based on the variety or on history with the vineyard, you can intervene early by making an appropriate yeast choice. Some strains are listed as helping to stabilize color and may improve a pale red wine. Others strains are noted for reducing vegetal character and may help if the grapes have been over-cropped or grown in shady conditions. Figure out what you want to get in your finished wine and it is likely that you can find a yeast strain to help you get there.
When to apply: Every fermentation. Wild fermentation is too risky and is just one step over from “spoilage.” So, if you are adding yeast anyway, you might as well do a little homework and make an optimum choice for your situation.
These products are very special-purpose materials that are just barely available for home use. The smallest package I have seen offered at retail treats 30 gallons (114 L), so you are clearly a serious home winemaker to get into this area. The encapsulated yeasts are various strains of conventional Saccharomyces winemaking yeast, but they are uniquely bound into alginate beads and are pretreated to improve tolerance for high sugar or high alcohol. The beads are contained in a mesh bag during use. The yeast can be introduced to a tank or barrel of wine and then removed when its job is over. Three applications are common: Restart-ing a stuck fermentation, making sweet dessert wine, and bottle fermentation for making sparkling wine. For a stuck fermentation, a vigorous yeast strain is used and the mesh bag is simply removed when the job is done. For a sweet dessert wine, the encapsulated yeast is used for the primary fermentation. When the desired sugar level is reached, the bag is removed. Nearly all of the yeast is still in the beads in the bag, but some may have escaped into the wine. Typical procedures of chilling, sulfiting, and filtering may be required but may not need to be as aggressive as when trying to stop a conventional fermentation. For sparkling wine, the encapsulated yeast is much more compact and easier to remove from the bottle after carbonation develops.
When to apply: Any time you are making 30 gallons or more and experience a stuck fermentation or want to stop one with residual sugar.
You should already be using a balanced yeast nutrient in your home winery like Superfood or Fermaid K, possibly boosted with diammonium phosphate (DAP) if your yeast nutrient demand and must nitrogen content suggest it. This category is another group of specialized nutrients, also called specific inactivated yeasts. Derived from yeast and therefore permitted in winemaking, they are prepared in special ways for particular outcomes. For red wines, the preparation of the inactivated yeast emphasizes retention of yeast cell-wall polysaccharides. These compounds help in color retention and in rounding out mouthfeel. They react with polyphenols as soon as they are released during maceration, improving color stability. They also help reduce harshness and “green” character in a red must. For white wines, the products are manufactured to contain similar polysaccharides, supplemented with high levels of glutathione. In combination, these molecules act to inhibit development of brown oxidation colors and to preserve the presence of esters in the grapes responsible for aromas like passion fruit and grapefruit (if the grape variety has those esters present to start with, of course).
When to apply: For white wines when you want to enhance the aroma profile or minimize later browning. The white-wine products are also useful in rosé wines to delay development of orange hues. Apply red wine products when you suspect harsh or green character or when color retention may be problematic.
Oak barrels and their alternatives — sticks, staves, spirals, cubes and the like — have been used to modify the tannin profile of wines for a long time. More recently, wine industry suppliers have been developing and producing a series of powdered tannin products aimed at specific purposes and specific times of addition. For use in must, Quebracho wood tannins are formulated to contribute soft, round mouthfeel and help stabilize color in red wines. For white wines, oak gall nut tannins may be added during fermentation to help prevent oxidation and enhance mouthfeel. Later in the cycle, further oxidation resistance and mouthfeel improvement may come about from use of Quebracho tannins, untoasted oak tannins, or toasted oak tannins. The toasted oak also adds barrel-like aroma components to the wine.
When to apply: Use the fermentation tannins in whites that are at risk for oxidation or where a thin or astringent body might otherwise be expected. Apply the red wine fermentation tannins if you anticipate difficulty with color retention or thin mouthfeel. Use untoasted oak tannins for a light oak character and improved freshness in cellared wines. Use toasted oak tannins as late as three weeks before bottling to give an oak boost to otherwise bland or boring wine.
The many choices of fining agents cover a range of needs. Bentonite and Sparkolloid are focused mostly on clarity and stability. Polyvinylpolypyrrolidone (PVPP) is for removal of color and reduction of bitterness. The whole range of protein fining agents — gelatin, egg white, isinglass, plus milk and its derivatives (casein or potassium caseinate should also be considered) — act on polyphenols in the wine to reduce harshness and astringency.
When to apply: Some winemaking authorities recommend fining every wine, but I don’t. Fining also depends on whether you will be filtering and bottling the wine early. If you have a problem to solve or a possible improvement to be made, or if you want to hurry a wine along to bottle early, do a fining trial. Select your best guess as to what might help; treat a small sample; then observe, smell, and taste the result. Scale up the addition for your entire batch if the
bench trial reveals the improvement you are after.
To achieve many benefits similar to enzyme use, you can instead use a cold soak on red must. Destem (or crush and destem) the grapes, then chill the must to below 46 °F (8 °C). If you have a jacketed stainless steel tank with glycol cooling or if you have a walk-in refrigerator, this may be fairly easy. Most home winemakers lack such equipment and need to improvise. If the grapes are shipped to you cold or you pick very early in the morning while they are still chilled from the night air, an improvised method has a good chance of working. If the grapes are already hot on a sunny afternoon, you may not be able to get the temperature down to a stable level. If you try to soak at too warm a temperature, fermentation may start or rot may set in. To improvise, add sanitized plastic jugs of ice or double-sealed plastic bags of ice to the must and stir. Alternatively, scatter pellets of dry ice on the must (Warning! Do this only in a well-ventilated area! Dry ice releases carbon dioxide, which is an asphyxiant gas). You will need to renew the ice or dry ice as long as you want to keep the must cold. The period may be as little as a day or two for light wines up to a week or so for big, heavy reds.
When to apply: When you want to get more flavor complexity and color from a red wine must and you do not want to use macerating enzymes. While cold soaking and enzymes are not mutually exclusive, they are duplicative and may not be a good use of time and money if applied together.
Whole cluster pressing
To get adequate juice yield when making white wine with a small basket press you will typically need to crush (or crush and destem) the grapes before pressing. Small basket presses are not always powerful enough to produce a good juice yield from most whole clusters. Many commercial winemakers favor whole cluster pressing, especially for more delicate and aromatic whites or for making sparkling wine, for minimizing harshness and vegetal notes. Water bladder presses and hydraulic piston presses are available for home winemaking use and can readily press whole clusters.
When to apply: Use this technique for the most delicate production of white juice. Especially suited to aromatic, light-bodied varieties. You will need access to a press that is more robust than a small ratcheting basket press.
Also known as rack-and-return, this technique is much favored by commercial producers of Pinot Noir. From the fermenting tank, the fermenting juice is drained out, allowing the cap to settle to the bottom. As the juice drains, it is run through a strainer and seeds are removed. After resting for an hour or two, the cap is gently flooded by use of a large-volume pump to return the juice over the top. Since home winemakers rarely have a pump with the 1.5 to 2 inch connections (3.8 to 5 cm) that would be recommended, the pumping approach may not be available. In Techniques in Home Winemaking, and at http://winemakermag.com/story237 Daniel Pambianchi details a method involving juice in carboys to be poured back over the must.
When to apply: If you are making a red wine where you want a lower tannin profile and a higher estery aroma complexity than would be produced by traditional punch-down methods. If you want to use a pump, one capable of moving juice rapidly should be applied — they may cost from $800 to $3,000 or more with the large connections recommended. Alternatively, use the poured-carboy method to return the juice.
Introduction of a very small amount of oxygen during aging helps to soften the tannin profile and round out flavors in red wine. Traditionally, this gentle addition of oxygen was achieved naturally during barrel aging as small amounts of air entered through the wood, at the barrel-head joints, or through the bung hole during topping. Commercial wineries now have available systems for metering a controlled addition of compressed oxygen into a tank via a stainless steel diffuser in the bottom of the tank. Oak adjuncts are used along with the process for microox to work properly. If it
goes well, results similar to barrel aging are achieved in a shorter time and at lower cost.
When to apply: Use microox when barrel-aging results are desired without barrels or in a short time period. This will probably not be cost effective, however, unless you can improvise a system, since manufactured flow controllers start at about $2,500.
This refers to the process of leaving a red wine on the skins after primary fermentation is complete. It is also called “post fermentation maceration.” As with enzymes or cold soaks, the objective is to extract additional skin components into the wine. Because of the higher alcohol content in wine as compared with juice, the fraction of polyphenolics that can be extracted will shift. Extended maceration rounds out and mellows tannins and may improve dark color. The period of post fermentation maceration may be from one week to one month. It is not without risks, however. During active primary fermentation, the must is protecting itself from oxidation by producing large volumes of carbon dioxide. After fermentation, the winemaker must actively exclude oxygen by sealing the tank, blanketing with inert gas, or both.
When to apply: If your history with a particular wine shows that it produces a harsh tannin profile or inadequate color extraction, give this technique a try.
Small, basic filtration units have been around for home winemakers for many years. The debate about the effects of filtration has been around just as long. Filtration advocates point to better clarity and improved bottle stability. Those who rarely filter cite loss of color in red wines and possible loss of aromas and flavors in any wine. Some people fine but do not filter, others do neither. Some high-end commercial winemakers avoid filtration entirely in their top-tier reds, accepting a bit of sediment in the bottle as a mark of quality and “naturalness.” Meanwhile, mass-market wines are almost always filtered for improved stability. The range of filtration equipment and media available to home winemakers has expanded greatly. In many cases, a simple single-plate or cartridge type filter will work perfectly well for clarifying a small lot of wine. Three-plate and even six-plate filters from about $400 to about $1,000 are also available. Currently, home winemakers have access to commercial-grade plate and frame filters with as many as forty plates for upwards of $1,000. These units can process multiple-barrel volumes.
When to apply: A wine produced over a short period of time and intended for early drinking may not have time to stabilize naturally. Such a wine is a good candidate for filtration. Wines with extended aging, particularly in barrels, are often stable just as they are and may be blended and bottled immediately after aging. Your objectives for the wine, and its condition, should guide your decision.
Winemakers make decisions
With so many materials and processes now available to home winemakers, decision making about your wine and when to intervene can seem very complex. It will be simplified if you become comfortable with your own approach to intervention and technology, whatever that approach is. Find your balance. I work with winemakers on both sides of the spectrum: Some who practice very minimal hands-off winemaking and with others who use every winemaking product and process they can find. For my own winemaking, I use a simple question before I make a move: Do trials or experience give me a strong likelihood of better wine? If the answer is yes, I apply the treatment. If not, I let nature take its course. In your home winery, you as the winemaker are in control and must decide when you should — or should not — intervene.
SIDEBAR – You Can’t Do This at Home
The following are some products and processes available to commercial winemakers that are not yet feasible or accessible for home winemakers. Availability is a dynamic situation, so it may well be that one or more of these has appeared in your neighborhood winemaking supply store. If you’ve tried it, write WineMaker a note or email and tell us how it worked on the hobby winemaking level.
No Brett Inside. This product from Lallemand is a chitosan material derived from Aspergillus niger. Although chitosan finings, often of shellfish origin, have been available for general clearing of wine, this product is formulated specifically to kill off populations of spoilage yeast Brettanomyces. While it has no effect on the odors already produced in the wine, it prevents them from getting any more pronounced. It is packed in a 100 g packet and the recommended use rate is 4 to 8 g per hectoliter. At that rate, a package treats at least 12 HL or over 300 gallons. Not ready for the home cellar yet!
Malic Acid Reducing Yeast. A GMO (genetically modified organism) yeast strain has been developed by inserting genetic material from malolactic bacteria into a yeast. That way, if a winemaker is faced with very high malic acid levels, the primary fermentation itself can be used to significantly cut down the concentration. The product was available as the ML01 yeast strain for a while, but seems to have disappeared. Market rejection of GMO products may be responsible.
Crossflow Filtration. Most filtration practiced by winemakers can be characterized as “dead end filtration.” That is, the product you want (clear wine) goes through a filter and what you don’t want (solids, debris) is retained in or on the filter material. In cross-flow filtration, though, the material to be separated flows under pressure parallel to the filtration barrier, usually a membrane of some kind. What goes through is called “permeate” and what stays in the flow is called “retentate.” The technique can be used to concentrate desirable materials or remove undesirable ones. A familiar example is home reverse osmosis systems for water purification. Minerals stay in the retentate and go down the drain while pure water is stored in a pressure tank as the permeate. In winemaking, one application uses a semipermeable membrane to force alcohol and water through as the permeate. That permeate stream can then be distilled to separate ethanol and water. As needed to produce higher or lower alcohol than in the original wine, water or alcohol can be mixed back in with the retentate. A variation of the method is used to remove acetic acid when volatile acidity is excessive. The acetic acid is in the permeate stream with the alcohol and water. That stream is run through an ion exchange column to remove the acetic acid, with the alcohol and water returned to the wine. A company that provides such services recommends a minimum batch size of 100 gallons (379 L)!
Spinning Cone. This is an alternate process for removing alcohol. Wine flows down through a column with a series of spinning cones that spread the flow into very thin layers. A portion of the wine at the bottom of the column flash evaporates in the vacuum atmosphere and flows upward, carrying alcohol with it. The alcohol is condensed and captured. For this method, complete dealcoholization of a small portion of the wine lot is generally carried out, then that no-alcohol wine is mixed back in with the larger batch as needed. The smallest column at one service provider is 2 meters tall and 0.5 meters in diameter.
Rotary Fermenter. Looking something like a stainless steel cement mixer, these large horizontal tanks are used to ferment red wine with lower labor costs and in a shorter time. A computer controls the movement, allowing the cap to rise inside the tank for some period of time, then gently rolling over to mix the cap back in. They are very efficient, but are made in sizes for 7.5 to 100 tons of grapes. Not your backyard winemaking tool! Maybe an industrious reader could try converting a stainless-steel front-load washing machine into the first home-size rotary fermenter!