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General Guide to Making Wine from Grapes

You can make bad wine from great grapes, but you cannot make great wine from bad grapes.

This guide covers the basic principles of making wine from grapes. There are some more advanced steps and procedures that can be included in your method of winemaking, but with that being said, if you follow the process outlined below you will be able to craft very pleasant and enjoyable wines at home.

Equipment: Primary fermenter, stirring spoon, hydrometer, siphon tubing kit, 6 gallon carboy, airlock and bung. A thermometer and brewing belt may be used to monitor and control temperature. A grape crusher/destemmer, a wine press, and a filter can be used decrease time and labor.

***Be sure to clean and sanitize anything that your grapes and/or must comes in direct contact with.


The Grapes

The first thing you need to do to make wine from grapes is to source your grapes. Begin at a reputable vendor that takes the proper care in the handling and storage of the grapes. They should be able to tell you about where the grapes are from and the average Brix, pH, and acidity. If possible, inspect the grapes to select the best looking cases that they have availabl for the style of wine that you would like to make.

After purchasing and receiving your grapes the first step is to remove any foreign and undesirable vineyard material, such as insects and other types of vegetation, and remove any leaves still present in your boxes of grapes.

Try and sort the grapes to remove any moldy bunches, or rotten and spoiled berries. Discard any grapes that look damaged or unhealthy. This can be time consuming, however, it minimizes the risk of some problems down the road in the vinification process.

After sorting your grapes the next step is the crushing and destemming. This is not a required step for white winemaking, although it does make the pressing easier. Crushing and destemming is required for red winemaking, as it plays a major role in what is known as phenolic extraction.

***Phenols; often referred to as polyphenolics, polyphenols, or simply phenols, are compounds including many natural color pigments, tannins, and flavor compounds that are present in fruits and vegetables.

 

Crushing and Destemming

Crushing is the first operation where tannins are extracted. When whole bunch clusters of grapes are crushed, tannins are extracted from the grape skins, seeds, and stems. Of these, the stems are the only tannin imparting component that can be removed prior to crushing.

Destemming is the removal of stems from grape bunches and may be done before or after crushing. If done after, there is more mess and time required, and more tannin will be extracted. The decision on when to destem depends on your equipment at hand, time, and patience. There are various machines on the market that can be used to crush and destem your grapes. Both crushing and destemming can be done by hand without the use specialized equipment, but the process will be very labor intensive and time consuming.

***Stems; especially green, non-woody stems; increase pH, which will reduce color intensity, fruitiness, and freshness. Stems add bitter and harsh tannins, that will require longer aging and maturation to become balanced and drinkable.

 

Maceration

After crushing and destemming the grapes, a red wine will need to be macerated. Maceration is the process of letting the crushed grape berries soak in the juice before, during, and after fermentation. The process of maceration is to extract phenolics (flavor and aroma compounds) and intensify color. It is during this period that red wines acquire part of their structure, color and flavors, and that wine’s aging potential can be influenced.

Macerating enzymes, such as Pectic Enzyme, may be added to the must at the crush to increase juice yield, tannin extraction and to prevent possible pectin-related problems, such as haze, at bottling time.

White wines do not benefit from maceration, since no color extraction is required and in general tannins are not desirable.

***As a general rule of thumb, the longer the maceration/fermentation period, the more tannins, color, and flavors will be extracted and the more full-bodied and colored a red wine will be.

 

Pressing

In white winemaking, either whole (uncrushed) grape bunches, or pre-crushed must, may be pressed. In white winemaking, pressing always takes place prior to fermentation and within a few hours of being crushed. Pressing is the process of extracting the juice from the grapes through pressure. There are several styles and sizes of presses available, choose a size and style that fits your needs. Pressing may also be done by using a nylon straining bag and squeezing the juice out by hand.

***In red winemaking, grapes are first crushed and destemmed, macerated, and fermentation begins. Just before or after fermentation is complete, grape solids (skins, seeds, pulp, and stems) are transferred to the winepress for pressing.

 

Yeast

Alcoholic fermentation is the conversion of must into wine, it is the single most vital and critical winemaking procedure. Constant care and supervision during fermentation is a mandatory practice. One of the critical factors, however, is yeast selection. Yeast is more than just a fermentation agent, yeast shapes the style of the wine, influences the wine’s qualities, and reduces the risk of fermentation problems.

Fermentation can start on its own from wild yeasts, which have formed on the grape skins and in the winery. Wild yeast fermentations must be monitored because they are prone to microbial spoilage and the results are not predictable. Controlling wild yeast is easily done with the addition of campden tablets or potassium metabisulfite.

Cultured wine yeast strains are genetically identified, cleaned, and grown in isolated laboratory conditions. Each type has been selected to work best for particular styles of wine or situation during fermentation. When choosing a yeast, consider the following fermentation factors:

  • The style of wine being made
  • The temperature of fermentation
  • Alcohol tolerance of the yeast
  • Rate of fermentation
  • Foam production
  • Flocculation
  • Volatile acid (VA) production
  • Sulfur dioxide (SO2) production
  • Malolactic (ML) compatibility
  • Hydrogen sulfide (H2S) production
  • Nutrient requirements


***See our Wine Yeast Guide to help determine the best yeast for your wine.

Red Wine Fermentation

***Before beginning fermentation test the must for Brix (SG), titratable acid (TA), pH, and sulfur dioxide (free SO2). Record these measurements and make any adjustments necessary. Testing would be done with a refractometer or hydrometer for sugar content; an acid test kit for TA; acid test paper or a pH meter to check the pH; and a Titrets kit for the sulfite levels.

In red winemaking, following crushing and any cold soak maceration, the initial vigorous fermentation takes place in a large open fermenter, and in order to minimize oxidation, reduce the risk of spoilage, and to keep dust and fruit flies (a major source of acetobacter, mother of vinegar) out, a heavy plastic sheet or tarp is kept over the vessel; which also traps a protective layer of carbon dioxide (a byproduct of fermentation) on the surface of the must. To begin fermentation warm the must to at least 68*F, but not much higher as heat is generated by yeast during fermentation, and add your selected yeast. Twice a day during fermentation the cap (residue of skins and grape particles that float on the must during primary fermentation) needs to be punched down. To do this, remove the cover and using a sanitized spoon, paddle, or plunger, to stir the cap back down into the juice. Continue this until the wine has finished fermenting, which will typically last 7-14 days, depending on fermentation temperature.

When vigorous fermentation has subsided and the Brix (SG) is below -1.3B* (0.995), rack the wine and transfer it to another fermenter, and press the pomace (residual grape skins, solids, stems, and seeds). At this point test the wine, at a minimum for TA, pH, and free SO2. These values will be different from the pre-fermentation test, as fermentation can decrease TA, and raise pH and SO2 levels. Make any adjustments that are needed to balance the wine to the intended style. At this point you can clarify and stabilize the wine; however it will improve greatly if allowed to age for up to 6 months in a cool dark place. During the aging period, change the sanitizer in the air lock monthly. Monitor the level of wine in the vessels and top up as needed. Rack the wine again before clarification if the wine has been aged.

***Caution: Fermentation of large volumes of must will release asphyxiating quantities of carbon dioxide gas. To eliminate any potential health hazards, properly ventilate the fermentation area to the outside. And never conduct fermentation in a closed container without the use of a properly functioning air lock, otherwise, the consequences of an exploding fermenter can be disastrous.

 


White Wine Fermentation

***Before beginning fermentation test the must for Brix (SG), titratable acid (TA), pH, and sulfur dioxide (free SO2). Record these measurements and make any adjustments necessary. Testing would be done with a refractometer or hydrometer for sugar content; an acid test kit for TA; acid test paper or a pH meter to check the pH; and a Titrets kit for the sulfite levels.

In white winemaking, must should be fermented in a properly air locked fermenter. In most cases there is no requirement for color or tannin extraction, therefore there is rarely a pre- or post-fermentation maceration, and there is no need for a hot fermentation. In fact, a cooler fermentation in conjunction with an appropriate yeast strain is most beneficial for optimal flavor and aroma development, and has a number of benefits essential to making fruit-forward wines. Fermentation for white wine is usually carried out between 55*F and 65*F, this slows it down allowing for slower aromatic development and may take several weeks, depending on temperature and Brix. The cool temperature and slower fermentation also preserves the more subtle and delicate flavors and aromas that may be volatilized with an otherwise vigorous fermentation. Once the wine reaches a Brix (SG) of -1.3B* (0.995) the fermentation is complete and the wine may be racked and transferred to another vessel. At this point the wine should be tested for TA, pH, and free SO2. After making any necessary adjustments the wine may be clarified and stabilized.

***Caution: Fermentation of large volumes of must will release asphyxiating quantities of carbon dioxide gas. To eliminate any potential health hazards, properly ventilate the fermentation area to the outside. And never conduct fermentation in a closed container without the use of a properly functioning air lock, otherwise, the consequences of an exploding fermenter can be disastrous.

 

Clarification

Clarification is the general class of physical and chemical stabilization processes used to achieve and maintain clarity throughout the wine’s life, and includes racking, fining, and filtration.

Wine is clarified throughout the winemaking and vinification by several rackings or transfers, and if desired, by fining following fermentation, and optionally by filtration prior to bottling. You can rack a wine as little or as often as you deem necessary, but be cautious of the negative effects of over processing and extended exposure to air. A clear wine requires a minimum racking schedule of:

  • Following alcoholic fermentation.
  • Post fermentation, when the Brix (SG) has stabilized at -1.3B* (0.995) or lower for at least 2 weeks.
  • After fining and stabilization.
  • After aging and the wine is ready for bottling.


Racking will always results in a smaller volume of clear wine as the sediment volume is separated and discarded. This lost volume should always be replaced immediately, with a wine of similar style. Testing for free SO2 should be done throughout the aging and racking process to be certain that the wine is still protected against spoilage bacteria and to protect against unwanted oxidation.

Stabilization through fining and filtration is the clarification of a wine through chemical or mechanical means. There are many chemical fining agents available; including bentonite, isinglass, kieselsol, gelatin, Sparkaloid, and SuperKleer. These products aid in the binding of suspended solids in the wine into larger clumps that then precipitate out, leaving a film on the bottom of the vessel, of which the clear wine will need to be racked off.  Fining can be the last step prior to bottling, and should always be done prior to filtration, to avoid clogged filtration pads. Filtration is done by forcing the wine through a filter pad by gravity or the use of a pump. There are typically three levels of filtration: coarse, polish, and sterile. Coarse filtration removes any particulate larger than 8 microns. Polish filters remove anything larger than 2.5 micron. The sterile filters remove anything larger than 0.5-1 micron, which includes yeast and bacteria.

Once your wine has been clarified, stabilized, and aged to the where you would like the wine it's time to bottle. Once bottled your wine will need additional time to mature in a cool dark place.

 

Flow Chart for Red Winemaking

 

Flow Chart for White Winemaking