Winemaking Terms Defined: Chemicals and Additives

Here are some definitions for chemicals and other supplies used by winemakers. Note that these definitions are for home winemak­ing only, though similar items may be used by commercial wineries.

acid  a powder containing either tartaric, malic, or citric acid or a blend of the three, used when needed to raise the acid level and therefore lower the pH of a wine. Acid is needed for fermentation, for taste, and to prevent spoilage.

Campden tablet  sulfite in the convenient form of a tablet for kill­ing unwanted microbes in wine. Use one tablet per gallon of wine and crush before stirring in.

fining agent  a substance that clarifies cloudy wine or removes compounds such as proteins that could cause problems during aging. Most fining agents work by binding to the particles that are causing the cloudiness, causing the particles to fall to the bottom of the container where they can be removed by racking. Specific types of fining agents remove specific causes of cloudiness. Examples include bentonite, egg white, milk, casein, gelatin, isinglass, Kieselsol and Sparkolloid, and sometimes pectic enzyme.

pectic enzyme  a substance that breaks down pectin in fruit, mak­ing it easier to extract flavor from the fruit skin and pulp and to pre­vent cloudiness in the wine. Also used as a fining agent to remove cloudiness caused by pectin in finished wine.

potassium sorbate  a chemical sometimes used to stop fermenta­tion because it prevents wine yeast from reproducing. Never use in a wine with malolactic fermentation. Also called sorbate or stabilizer.

sanitizer  a sulfite solution used to sterilize equipment.

sulfite  a chemical (either potassium metabisulfite or sodium metabi­sulfite) used both to sanitize equipment and to kill unwanted microbes in wine, superior to other sterilizing agents because it does not kill wine yeast. Also called sulfur dioxide, SO₂ or meta.

tannin  a chemical compound that contributes to taste by giving wine an astringent quality, and aids in preservation of finished wine. Found in the skins, seeds and stems of red grapes, it is naturally present in red wines, but is available as a brown powder if needed for white or fruit wines. Can also be imparted to wine from oak.

yeast  microorganisms used in winemaking to ferment sugar into alco­hol. Wine yeast, known scientifically as Saccharomyces cerevisiae, is not the same as bread yeast, brewer’s yeast or other types of yeast. Comes dried in pre-measured packets or as a liquid.

yeast energizer  a nutritional supplement for yeast used mostly for unusual circumstances, such as a stuck or difficult fermentation. Do not confuse with yeast nutrient.

yeast nutrient  a nutritional supplement for yeast (usually di-ammo­nium phosphate, or DAP) used routinely in winemaking.

yeast starter  a mixture of wine yeast and a small amount of water or juice, prepared ahead to allow the yeast time to activate (rehydrate and start reproducing) before adding to the must.

Some resources were used from winemaking.jackkeller.net and Techniques in Home Winemaking by Daniel Pambianchi (2008 version).