Autolysis in

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

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 (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are est ...

cells, after

fermentation Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic molecules, such as glucose or other sugars, are catabolized and reduce ...

. While for some

wine Wine is an alcoholic drink made from Fermentation in winemaking, fermented fruit. Yeast in winemaking, Yeast consumes the sugar in the fruit and converts it to ethanol and carbon dioxide, releasing heat in the process. Wine is most often made f ...

s - and all beers - autolysis is undesirable, it is a vital component in shaping the flavors and mouth feel associated with premium

Champagne Champagne (; ) is a sparkling wine originated and produced in the Champagne wine region of France under the rules of the appellation, which demand specific vineyard practices, sourcing of grapes exclusively from designated places within it, spe ...

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'' 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". Astringency, the dry, puckering or numbing mouthfeel caused by th ...

were noticed early in the

history of wine The oldest evidence of ancient wine production has been found in Georgia from BC (the earliest known traces of grape wine), Greece from BC, Armenia from BC (large-scale production), and Sicily from BC. The earliest evidence of fermente ...

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 ''The Oxford Companion to Wine'' (''OCW'') is a book in the series of Oxford Companions published by Oxford University Press. The book provides an alphabetically arranged reference to wine, compiled and edited by Jancis Robinson, with contributio ...

'' Third Edition pg 399

Oxford University Press Oxford University Press (OUP) is the publishing house of the University of Oxford. It is the largest university press in the world. Its first book was printed in Oxford in 1478, with the Press officially granted the legal right to print books ...

2006

History

Ancient Roman In modern historiography, ancient Rome is the Roman people, Roman civilisation from the founding of Rome, founding of the Italian city of Rome in the 8th century BC to the Fall of the Western Roman Empire, collapse of the Western Roman Em ...

writers, such as Marcus Porcius Cato, 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

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 In France, the ''appellation d'origine contrôlée'' (, ; abbr. AOC ) is a label that identifies an agricultural product whose stages of production and processing are carried out in a defined geographical area – the ''terroir'' – and using ...

'' (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 In winemaking, vintage is the process of picking grapes to create wine. A vintage wine is one made from grapes that were all, or primarily, grown and harvested in a single specified year. In certain wines, it can denote quality, as in Port wine ...

Champagne. Vintage Champagne must have a minimum of 3 years aging; some Champagne houses extend the time for autolysis to 7 years or more.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 Glucose is a sugar with the Chemical formula#Molecular formula, molecul ...

in the grape

must Must is freshly crushed Juice, 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 the total weight of the must. Making must ...

into

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

. 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 disrupti ...

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

enzymes An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as pro ...

start to break the cells down producing mannoproteins (

mannose Mannose is a sugar with the formula , which sometimes is abbreviated Man. It is one of the monomers of the aldohexose series of carbohydrates. It is a C-2 epimer of glucose. Mannose is important in human metabolism, especially in the glycosylatio ...

-containing

glycoproteins Glycoproteins are proteins which contain oligosaccharide (sugar) chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known a ...

) and

polysaccharides Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long-chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wat ...

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 A wine bottle is a bottle, generally a glass bottle, that is used for holding wine. Some wines are fermentation (wine), fermented in the bottle while others are bottled only after fermentation. Recently the bottle has become a standard unit of ...

. 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 for producing sparkling wine is the process used in the Champagne wine region, Champagne region of France to produce Champagne. It is also the method used in various French regions to produce sparkling wines (not called " ...

and

disgorgement Disgorgement is the act of giving up something on demand or by legal compulsion, for example giving up profits that were obtained illegally. In United States regulatory law, disgorgement is often a civil remedy imposed by some regulatory agenci ...

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

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 an ...

of the wine. The mannoproteins improve the overall stability of the proteins in the wine by reducing the amount of

tartrate A tartrate is a salt or ester of the organic compound tartaric acid, a dicarboxylic acid. The formula of the tartrate dianion is O−OC-CH(OH)-CH(OH)-COO− or C4H4O62−. The main forms of tartrates used commercially are pure crystalline ...

s 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 Precipitation (chemistry), precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widel ...

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 over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...

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

biscuit A biscuit is a flour-based baked food item. 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 savoury, similar to crackers. ...

s or

bread Bread is a baked food product made from water, flour, and often yeast. It is a staple food across the world, particularly in Europe and the Middle East. Throughout recorded history and around the world, it has been an important part of many cu ...

dough Dough is a malleable, sometimes elastic paste made from flour (which itself is 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 ...

nut Nut often refers to: * Nut (fruit), fruit composed of a hard shell and a seed * Nut (food), a dry and edible fruit or seed, including but not limited to true nuts * Nut (hardware), fastener used with a bolt Nut, NUT or Nuts may also refer to: A ...

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

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

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

Potential faults

If not properly managed,

wine fault A wine fault is a sensory-associated (organoleptic) characteristic of a wine that is unpleasant, and may include elements of taste, smell, or appearance, elements that may arise from a "chemical or a microbial origin", where particular sensory expe ...

s 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 toxic, corrosive, and flammable. Trace amounts in ambient atmosphere have a characteristic foul odor of rotten eggs. Swedish chemist ...

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 grou ...

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 pesticides used to kill parasitic fungi or their spores. Fungi can cause serious damage in agriculture, resulting in losses of yield and quality. Fungicides are used both in agriculture and to fight fungal infections in animals, ...

can create off odors smelling of

sulfide Sulfide (also sulphide in British English) 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 large families o ...

References

External links