Acetic acid The main acid in vinegar.
Acetification The formation of acetic acid (vinegar).
Aroma Wine odors derived from grapes.
Balling A measurement of sugar in fermenting wine.
Bentonite A type of clay used for heat stability.
Bound SO2 Sulfur dioxide that combines with other compounds.
Bouquet Wine odors derived from processing, such as fermentation and oak aging.
Brix Measurement of sugar in juice.
Cap The skins and pulp of crushed grapes that separate from the juice and float to the top during fermentation.
Carbon dioxide
A gas formed during fermentation.
Carboy A glass container
Cold stabilization The removal of tartrates in wine to prevent precipitation in bottled wine.
Crusher A device that breaks grapes skins to allow for juice extraction. Often re- moves grapes from their stems as well.
Deacidify To reduce the total acidity in wine or juice.
Dry A wine with no fermentable sugar.
Ethyl acetate A compound smelling like nail polish remover.
Ethyl mercapton A compound smelling like cooked asparagus.
Fermentation The conversion of grape sugar by yeast to alcohol and carbon dioxide.
Fermenter A container for fermenting wine.
Fermentation lock A device that allows CO2 to escape and prevents air from entering a container of wine.
Finish The taste of wine that remains in the mouth after swallowing.
Free run Juice or wine that flows from grapes without pressing.
Free SO2 Sulfur dioxide actively available to protect wine.
Heat stabilization The removal of excess proteins to prevent cloudiness in bottled wine.
Hydrogen sulfide A compound smelling like rotten eggs.
Hydrometer A device used for measuring sugar in juice or must.
Lactic acid An organic acid produced from malic acid by bacteria.
Lactobacillus A spoilage bacteria that can carry out malolactic fermentation.
Lees Sediment from wine fermentation.
Leuconostoc oenus The desired bacteria for carrying out malolactic fermentation.
Malic acid One of the organic acids found in grapes.
Conversion of malic acid into lactic acid and CO2 gas.
Mercapton A compound smelling like cooked green beans.
Must The crushed juice, skins, and pulp of grapes.
Oxidation Browning and undesirable changes in a wine’s flavor resulting from contact with oxygen.
pH A measurement of hydrogen ions in solution used as an indicator for wine production.
A compound that can reduce acidity when added to wine or juice.
ppm Parts per million
Press A device that extracts juice or wine from grapes.
Press juice That fraction of juice or wine separated from the grapes by pressure.
A test to measure the progress of  malolactic fermentation.
Punching down Pushing the cap down into the juice during fermentation.
Racking Moving juice or wine from one container to another.
Refractometer A device to measure the sugar content of juice
Sulfur dioxide
An antiseptic that inhibits the growth of bacteria, acts as an antioxidant, and can be used as a wine preservative and sanitizing agent.
Stuck fermentation When a fermentation stops before all of the sugar is converted to alcohol.
Tannins Compounds responsible for astringency and bitterness in wine, but also thought to contribute to a wine’s ability to age.
Tartaric acid The main organic acid found in grapes.
Tartrates Crystals that can form naturally in chilled wine.
Topping up Keeping containers of wine filled to the top to help prevent oxidation.
Total acidity
A measurement of the acid level in wine or juice.
Total SO2 The concentration of SO2 in juice or wine that includes both free and bound SO2.
Yeast Converts grape sugar to alcohol and CO2 gas.