Autolysis in

winemaking Winemaking or vinification is the production of wine, starting with the selection of the fruit, its fermentation into alcohol, and the bottling of the finished liquid. The history of wine-making stretches over millennia. The science of wine and ...

relates to the complex chemical reactions that take place when a wine spends time in contact with the lees, or dead

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...

cells, after

fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...

. While for some

wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...

s - and all beers - autolysis is undesirable, it is a vital component in shaping the flavors and mouth feel associated with premium Champagne production.J. Robinson (ed) ''"The Oxford Companion to Wine"'' Third Edition pg 54 Oxford University Press 2006 The practice of leaving a wine to age on its lees (or ''

sur lie Lees are deposits of dead yeast or residual yeast and other particles that precipitate, or are carried by the action of " fining", to the bottom of a vat of wine after fermentation and aging. The same while brewing beer at a brewery is known as ...

'' aging) has a long history in winemaking dating back to Roman winemaking. The chemical process and details of autolysis were not originally understood scientifically, but the positive effects such as a creamy mouthfeel, breadlike and floral aromas, and reduced

astringency An astringent (sometimes called adstringent) is a chemical that shrinks or constricts body tissues. The word derives from the Latin ''adstringere'', which means "to bind fast". Calamine lotion, witch hazel, and yerba mansa, a Californian plant ...

were noticed early in the

history of wine Wine has been produced for thousands of years, with evidence of ancient wine production in Georgia from BC (the earliest known traces of wine), West Azerbaijan province of Iran from BC, Armenia from BC (large-scale production), and Sicil ...

Jancis Robinson Jancis Mary Robinson OBE, ComMA, MW (born 22 April 1950) is a British wine critic, journalist and wine writer. She currently writes a weekly column for the ''Financial Times'', and writes for her website JancisRobinson.com, updated daily. She ...

(ed), '' The Oxford Companion to Wine'' Third Edition pg 399

Oxford University Press Oxford University Press (OUP) is the university press of the University of Oxford. It is the largest university press in the world, and its printing history dates back to the 1480s. Having been officially granted the legal right to print books ...

2006

History

Ancient Roman In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 BC ...

writers, such as

Marcus Porcius Cato Marcus Porcius Cato can refer to: *Cato the Elder (consul 195 BC) *Cato the Younger (praetor 54 BC) *Marcus Porcius Cato (consul 118 BC) * Marcus Porcius Cato (consul 36) *Marcus Porcius Cato (father of Cato the Younger) *Marcus Porcius C ...

, observed that wine that was left on its lees (or sediment as they knew it) exhibited different characteristics than wine that was quickly separated from its sediment. While the Romans did not understand the full chemical process or details behind the autolysis that took place, they were able to perceive the results of this autolysis in the creamy mouthfeel, reduced astringency and unique flavors and aromas that developed. With modern day understanding of autolysis, winemaking in the Champagne have strict regulation regarding the time Champagne must spend in contact with its lees in order to receive some benefit from autolysis. Under ''

Appellation d'origine contrôlée An appellation is a legally defined and protected geographical indication primarily used to identify where the grapes for a wine were grown, although other types of food often have appellations as well. Restrictions other than geographical boun ...

'' (AOC) regulations, wines from Champagne cannot legally be sold until it has gone through autolysis in the bottle for at least 15 months with non-

vintage Vintage, in winemaking, is the process of picking grapes and creating the finished product—wine (see Harvest (wine)). A vintage wine is one made from grapes that were all, or primarily, grown and harvested in a single specified year. In certa ...

Champagne. Vintage Champagne must have a minimum of 3 years aging; some

Champagne house The listing below comprises some of the more prominent houses of Champagne. Most of the major houses are members of the organisation ''Union de Maisons de Champagne'' (UMC),K. MacNeil ''The Wine Bible'' pg 653 Workman Publishing 2001

Process

During fermentation, yeast cells convert the

sugar Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double ...

in the grape

must Must (from the Latin ''vinum mustum'', "young wine") is freshly crushed fruit juice (usually grape juice) that contains the skins, seeds, and stems of the fruit. The solid portion of the must is called pomace and typically makes up 7–23% of t ...

into

ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...

. When the sugar food source for the yeast and necessary nutrients such as nitrogen run out, or the alcohol level of the wine reaches such a point to where it is

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

for the yeast, the cells die and sink to the bottom of the fermentation vessel. These dead cells, or "lees", are normally removed by

racking Racking, often referred to as Soutirage or Soutirage traditionnel (meaning racking in French), also filtering or fining, is the process of moving wine or beer from one container to another using gravity rather than a pump, which can be disruptiv ...

the wine into a clean vessel. If the wine is left in contact with the lees,

enzymes Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...

start to break the cells down producing mannoproteins (

mannose Mannose is a sugar monomer of the aldohexose series of carbohydrates. It is a C-2 epimer of glucose. Mannose is important in human metabolism, especially in the glycosylation of certain proteins. Several congenital disorders of glycosylation ...

-containing glycoproteins) and polysaccharides that are released into the wine. In

sparkling wine production Sparkling wine production is the method of winemaking used to produce sparkling wine. The oldest known production of sparkling wine took place in 1531 with the ''ancestral method''. Pressure and terminology In popular parlance and also in the ...

, a wine is made "sparkling" or "bubbly" because a secondary fermentation is introduced when the wine is contained within a sealed wine bottle. During this time the wine is deliberately kept in contact with its lees inside the bottle for a period ranging from a couple of months to several years. Studies have shown that the chemical reaction of autolysis, and its impact on the wine, starts to become noticeable after 18 months and will continue to impart traits for at least 5 years. The sparkling wine is eventually separated from its lees through a technique known as

riddling The traditional method is the process used in the Champagne region of France to produce Champagne. It is also the method used in various French regions to produce sparkling wines (not called “Champagne”), in Spain to produce Cava, in Port ...

and

disgorgement Disgorgement is defined by ''Black's Law Dictionary'' as "the act of giving up something (such as profits illegally obtained) on demand or by legal compulsion." Overview Disgorgement is a remedy or penalty used in US securities law. For exampl ...

Influences on the wine

The effects of autolysis on wine contributes to a creamy mouthfeel that may make a wine seem to have a fuller body. The release of enzymes inhibits

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

which improves some of the

aging potential The aging of wine is potentially able to improve the quality of wine. This distinguishes wine from most other consumable goods. While wine is perishable and capable of deteriorating, complex chemical reactions involving a wine's sugars, acids and ...

of the wine. The mannoproteins improve the overall stability of the proteins in the wine by reducing the amount of tartrates that are precipitated out. They may also bind with the

tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner'', ...

s in the wine to reduce the perception of bitterness or astringency in the wine. The increased production of

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

s leads to the develop of several flavors associated with premium Champagne including aromas of

biscuit A biscuit is a flour-based baked and shaped food product. In most countries biscuits are typically hard, flat, and unleavened. They are usually sweet and may be made with sugar, chocolate, icing, jam, ginger, or cinnamon. They can also be ...

s or

bread Bread is a staple food prepared from a dough of flour (usually wheat) and water, usually by baking. Throughout recorded history and around the world, it has been an important part of many cultures' diet. It is one of the oldest human-made f ...

dough Dough is a thick, malleable, sometimes elastic paste made from grains or from leguminous or chestnut crops. Dough is typically made by mixing flour with a small amount of water or other liquid and sometimes includes yeast or other leavening ag ...

nut Nut often refers to: * Nut (fruit), fruit composed of a hard shell and a seed, or a collective noun for dry and edible fruits or seeds * Nut (hardware), fastener used with a bolt Nut or Nuts may also refer to: Arts, entertainment, and media Com ...

tinessBeverage Industry Factsheet '
Autolysis
"'' Accessed Dec. 20th, 2008 and

acacia ''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus na ...

. As the wine ages further, more complex notes may develop from the effects of autolysis.

Potential faults

If not properly managed, wine faults can potentially develop from autolysis. If the layer of lees begins to exceed 4 inches (10 centimeters), the enzymes released from the process of the yeast digesting themselves creates reducing conditions and promotes the development of

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The unde ...

and

mercaptan In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl gro ...

odors. The process of stirring the lees or ''bâttonage'' can help prevent a thick layer of lees forming and promote a smoother autolysis. Poor hygiene of the winemaking equipment or wine made from grapes that had residue from

fungicide Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...

can create off odors smelling of

sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...

References

External links