The process of fermentation in wine is the catalyst function that turns grape juice into an alcoholic beverage. Fermentation is the process of deriving energy from the oxidation of organic compounds such as carbohydrates using an endogenous electron acceptor which is Wine is an Alcoholic beverage made from the fermentation of Grape juice Catalysis is the process in which the rate of a Chemical reaction is increased by means of a Chemical substance known as a catalyst Grape juice is a Juice obtained from crushing Grapes The juice is often fermented and made into Wine, Brandy, or Vinegar During fermentation yeast interact with sugars in the juice to create ethanol, commonly known as ethyl alcohol, and carbon dioxide (as a by-product). Yeasts are a growth form of eukaryotic Microorganisms classified in the kingdom Fungi, with about 1500 Species currently described Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single A by-product is a secondary or incidental product deriving from a Manufacturing process a Chemical reaction or a biochemical pathway and is not the primary product In winemaking the temperature and speed of fermentation is an important consideration as well as the levels of oxygen present in the must at the start of the fermentation. Winemaking, or vinification, is the production of Wine, starting with selection of the Grapes and ending with bottling the finished wine Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the MUST may refer to Militära underrättelse- och säkerhetstjänsten, the Swedish Military Intelligence and Security Service Misr University The risk of stuck fermentation and the development of several wine faults can also occur during this stage which can last anywhere from 5 to 14 days for primary fermentation and potentially another 5 to 10 days for a secondary fermentation. Fermentation in Food processing typically refers to the conversion of Sugar to Alcohol using Yeast under Anaerobic conditions A wine fault or defect is an unpleasant characteristic of a Wine often resulting from poor Winemaking practices Fermentation may be done in stainless steel tanks, which is common with many white wines like Riesling, in an open wooden vat, inside a wine barrel and inside the wine bottle itself like in the production of many sparkling wines. Riesling is a white Grape variety which originates in the Rhine region of Germany. The use of Oak in Wine plays a significant role in Winemaking and can have a profound effect on the resulting wine impacting the color flavor A wine bottle is a Bottle used for holding wine generally made of Glass. There are three main methods of sparkling wine production The first is simple injection of Carbon dioxide (CO2 the process used in Soft drinks, [1][2]
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History
- See also: History of wine
While there may never be evidence to pinpoint the moment when fermentation was first observed-the natural occurrence of fermentation, with little need for human interaction, makes it likely that fermentation was observed quite early in human history. The history of Wine spans thousands of years and is closely intertwined with the history of Agriculture, Cuisine, Civilization and [3] The earliest uses of the word "Fermentation" in relation to winemaking was in reference to the appearance "boiling" within the must that came from the anaerobic reaction of the yeast to the sugars in the grape juice and the release of carbon dioxide. See also Fermentation (biochemistry Anaerobic respiration (anaerobiosis refers to the Oxidation of molecules in the absence of Oxygen to produce The Latin fervere means, literally, to boil. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. In the mid-19th century, Louis Pasteur noted the connection between yeast and the process of the fermentation in which the yeast act as catalyst and mediator through a series of a reaction that convert sugar into alcohol. Louis Pasteur (27 December 1822 – 28 September 1895 a French Chemist and Microbiologist, is best known for remarkable breakthroughs in the causes and The discovery of the Embden–Meyerhof–Parnas pathway by Gustav Embden, Otto Fritz Meyerhof and Jakub Karol Parnas in the early 20th century contributed more to the understanding of the complex chemical processes involved the conversion of sugar to alcohol. See also Gluconeogenesis, which carries out a process wherein glucose is synthesized rather than catabolized Gustav Georg Embden ( November 10, 1874 - July 25, 1933) was a German chemist who conducted studies on Carbohydrate Otto Fritz Meyerhof ( April 12, 1884 &ndash October 6, 1951) was a German -born Physician and Biochemist. Jakub Karol Parnas, also known as Yakov Oskarovich Parnas (Яков Оскарович Парнас ( January 16, 1884 &ndash January 29, [4]
Process
- See also: Ethanol fermentation and Glycolysis
In winemaking there are distinctions made between ambient yeasts which are naturally present in wine cellars, vineyards and on the grapes themselves (sometimes known as a grape's "bloom" or "blush") and cultured yeast which are specifically isolated and inoculated for use in winemaking. The most common genus of wild yeasts found in winemaking include Candida, Klöckera/Hanseniaspora, Metschnikowiaceae, Pichia and Zygosaccharomyces. A genus (plural genera from Γένος Latin genus "descent family type gender" is a low-level Taxonomic Candida is a Genus of Yeasts Many species of this genus are Endosymbionts Metschnikowiaceae is a family of Yeasts in the order Saccharomycetales that reproduce by budding Pichia is a genus of teleomorphic Yeasts in the family Saccharomycetaceae. Zygosaccharomyces is a Genus of Yeast in the family Saccharomycetaceae. Wild yeasts can produce high-quality, unique-flavored wines; however, they are often unpredictable and may introduce less desirable traits to the wine, and can even contribute to spoilage. Traditional wine makers, particularly in Europe, advocate use of ambient yeast as a characteristic of the region's terroir; nevertheless, many winemakers prefer to control fermentation with predictable cultured yeast. Terroir (/t̪εʁwaʁ/ in French (terruño pago was originally a French term in Wine, Coffee and Tea used to denote the special characteristics The cultured yeasts most commonly used in winemaking belong to the Saccharomyces cerevisiae (also known as "sugar yeast") species. Saccharomyces cerevisiae is a Species of Budding Yeast. It is perhaps the most useful Yeast owing to its use since ancient times Within this species are several hundred different strains of yeast that be used during fermentation to affect the heat or vigor of the process and enhance or suppress certain flavor characteristics of the varietal. In biology strain is a low-level Taxonomic rank used in three related ways Varietal describes Wines made primarily from a single named Grape variety. The use of different strains of yeasts are a major contributor to the diversity of wine, even among the same grape variety. [5]
The addition of cultured yeast normally occurs with the yeast first in a dried or "inactive" state and is reactivated in warm water or diluted grape juice prior to being added to the must. To thrive and be active in fermentation, the yeast needs access to a continuous supply of carbon, nitrogen, sulfur, phosphorus as well as access to various vitamins and minerals. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 A vitamin is an Organic compound required as a Nutrient in tiny amounts by an Organism. Dietary minerals are the Chemical elements required by living Organisms other than the four elements Carbon, Hydrogen, Nitrogen, and These components are naturally present in the grape must but their amount may be corrected by adding nutrient packets to the wine, in order to foster a more encouraging environment for the yeast. Oxygen is needed as well but in wine making the risk of oxidation and the lack of alcohol production from oxygenated yeast requires the exposure of oxygen to be kept at a minimum. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state [6]
Upon the introduction of active yeasts to the grape must, phosphates are attached to the sugar and the six-carbon sugar molecules begin to be split into three-carbon pieces and go through a series of rearrangement reactions. A phosphate, an Inorganic chemical, is a salt of Phosphoric acid. In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by A rearrangement reaction is a broad class of Organic reactions where the carbon skeleton of a Molecule is rearranged to give a Structural isomer of the original During this process the carboxylic carbon atom is released in the form of carbon dioxide with the remaining components becoming acetaldehyde. Carboxylic acids are Organic acids characterized by the presence of a Carboxyl group, which has the formula -C(=OOH usually written -COOH or -CO2H Acetaldehyde, sometimes known as ethanal, is an organic chemical compound with the formula C[[Hydrogen H]]3CH O or MeCHO The absence of oxygen in this anaerobic process allows the acetaldehyde to be eventually converted, by reduction, to ethanol. During the conversion of acetaldehyde a small amount is converted, by oxidation, to acetic acid which, in excess, can contribute to the wine fault known as volatile acidity (vinegar taint). Acetic acid, also known as ethanoic acid, is an organic chemical compound, giving Vinegar its sour taste A wine fault or defect is an unpleasant characteristic of a Wine often resulting from poor Winemaking practices After the yeast has exhausted its life cycle they fall to the bottom of the fermentation tank as sediment known as lees. Lees refers to deposits of dead Yeast or residual yeast and other particles that precipitate or are carried by the action of " Fining " to the bottom of [7]
Other compounds involved
The metabolism of amino acids and breakdown of sugars by yeasts has the affect of creating other biochemical compounds that can contribute to the flavor and aroma of wine. Metabolism is the set of Chemical reactions that occur in living Organisms in order to maintain Life. In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this These compounds can be considered "volatile" like aldehydes, ethyl acetate, ester, fatty acids, fusel oils, hydrogen sulfide, ketones and mercaptans) or "non-volatile" like glycerol, acetic acid and succinic acid. This article describes a highly specialized aspect of its subject in the "Terminology and legal definitions" section An aldehyde is an organic compound containing a terminal Carbonyl group. Ethyl acetate ( systematically, ethyl ethanoate commonly abbreviated EtOAc or EA is the Organic compound with the formula CH3COOCH2CH3 Esters are a class of Chemical compounds and Functional groups Esters consist of an inorganic or organic Acid in which at least In Chemistry, especially Biochemistry, a fatty acid is a Carboxylic acid often with a long unbranched Aliphatic tail ( chain) which Fusel alcohols, also sometimes called fusel oils, or potato oil in Europe are higher order (more than two carbons Alcohols formed by fermentation Hydrogen sulfide (or hydrogen sulphide) is the Chemical compound with the formula H 2 S. A ketone (pronounced as key tone) is either the Functional group characterized by a Carbonyl group (O=C linked to two other Carbon atoms or In Organic chemistry, a thiol is a compound that contains the functional group composed of a Sulfur atom and a Hydrogen atom (-SH Succinic acid ( IUPAC Systematic name: butanedioic acid; historically known as spirit of amber) is a Dicarboxylic acid. Yeast also has the effect during fermentation of releasing glycoside hydrolase which can hydrolyse the flavor precursors of aliphatics (a flavor component that reacts with oak), benzene derivities, monoterpenes (responsible for floral aromas from grapes like Muscat and Traminer), norisoprenoids (responsible for some of the spice notes in Chardonnay), and phenols. Glycoside hydrolases (also called glycosidases) catalyze the Hydrolysis of the Glycosidic linkage to generate two smaller Sugars They Hydrolysis is a Chemical reaction during which one or more water molecules are split into hydrogen and hydroxide ions which may go on to participate in further reactions In Organic chemistry, compounds composed of Carbon and Hydrogen are divided into two classes Aromatic compounds which contain Benzene rings The use of Oak in Wine plays a significant role in Winemaking and can have a profound effect on the resulting wine impacting the color flavor Benzene, or benzol, is an organic Chemical compound and a known Carcinogen with the molecular formula C 6 H 6 Monoterpenes are a class of Terpenes that consist of two Isoprene units and have the molecular formula C10H16 Savagnin or Savagnin Blanc is a variety of white Wine Grape with green-skinned berries Terpenes are a large and varied class of Hydrocarbons, produced primarily by a wide variety of plants particularly Conifers though also by some insects such Chardonnay is a green-skinned Grape variety used to make white Wine. In Organic chemistry, phenols, sometimes called phenolics, are a class of Chemical compounds consisting of a Hydroxyl group (- Some strains of yeasts can generate volatile thiols which contribute to the fruity aromas in many wines such as the gooseberry scent commonly associates with Sauvignon blanc. In Organic chemistry, a thiol is a compound that contains the functional group composed of a Sulfur atom and a Hydrogen atom (-SH The gooseberry Ribes uva-crispa ( syn R grossularia) is a species of Ribes, native to Europe, northwestern Africa Sauvignon blanc is a green-skinned Grape variety which originates from the Bordeaux region of France. Brettanomyces yeasts are responsible for the "barnyard aroma" characteristic in some red wines like Burgundy Pinot noir. Brettanomyces is a non-spore forming genus of Yeast in the family Saccharomycetaceae, and is often colloquially referred to as " Burgundy wine ( is wine made in the Burgundy region in eastern France. Pinot noir ('pino nwar is a red Wine Grape variety of the species Vitis vinifera. [8]
Winemaking considerations
During fermentation there are several factors that winemakers take into consideration. The most notable is that of the internal temperature of the must. The biochemical process of fermentation itself creates a lot of residual heat which can take the must out of the ideal temperature range for the wine. In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature Typically white wine is fermented between 64-68 °F (18-20 °C) though a wine maker may choose to use a higher temperature to bring out some of the complexity of the wine. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 The Celsius Temperature scale was previously known as the centigrade scale. Red wine is typically fermented at higher temperatures up to 85 °F (29 °C). Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 Fermentation at higher temperatures may have adverse effect on the wine in stunning the yeast to inactivity and even "boiling off" some of the flavors of the wines. Some winemakers may ferment their red wines at cooler temperatures more typical of white wines in order to bring out more fruit flavors. [7]
To control the heat generated during fermentation the winemaker has to choose a suitable vessel size or to use cooling devices of various sorts from the ancient Bordeaux traditions of placing the fermentation vat on top of blocks of ice to today's modern use of sophisticated fermentation tanks with built in cooling rings. A Bordeaux wine is any Wine produced in the Bordeaux region of France. [9]
A risk factor involved with fermentation is the development of chemical residue and spoilage which can be corrected with the addition of sulfur dioxide (SO2), although excess SO2 can lead to a wine fault. A winemaker who wishes to make a wine with high levels of residual sugar (like a dessert wine) may stop fermentation early either by dropping the temperature of the must to stun the yeast or by adding a high level of alcohol (like brandy) to the must to kill off the yeast and create a fortified wine. Dessert wines (or pudding wines BrE) are sweet Wines typically served with Dessert, such as Sauternes and Tokaji Brandy (from brandywine, derived from Dutch brandewijn — “burnt wine” is a spirit produced by distilling Wine Fortified wine is Wine to which alcohol (usually Brandy) has been added [7]
Other types of fermentation
In winemaking there are different processes that fall under the title of "Fermentation" but might not follow the same procedure commonly associated with wine fermentation.
Bottle fermentation
Bottle fermentation is a method of sparkling wine production originating in the Champagne region where after the cuvee has gone through a primary yeast fermentation the wine is then bottled and goes through a secondary fermentation where sugar and additional yeast known as liqueur de tirage is added to the wine. There are three main methods of sparkling wine production The first is simple injection of Carbon dioxide (CO2 the process used in Soft drinks, The Champagne wine region ( archaic Champany is a historic province within the Champagne administrative province in the northeast of France. Cuvée (or Cuvee on some English language labels is a French Wine term derived from cuve, meaning Vat or Tank. This secondary fermentation is what creates the carbon dioxide bubbles that sparkling wine is known for. [10]
Carbonic maceration
The process of carbonic maceration is also known as whole grape fermentation where instead of yeast being added to grape must fermentation is encouraged to take place inside the individual grape berries. Carbonic maceration is a Winemaking technique often associated with the French wine region of Beaujolais, in which whole Grapes are fermented This method is common in the creation of Beaujolais wine and involves whole clusters of grapes being stored in a closed container with the oxygen in the container being replaced with carbon dioxide. Beaujolais is a French Appellation d'Origine Contrôlée (AOC Wine generally made of the Gamay Grape which has a thin [11] Unlike normal fermentation where yeast converts sugar into alcohol, carbonic maceration works by enzymes within the grape breaking down the cellular matter to form ethanol and other chemical properties. The resulting wines are typically soft and fruity. [12]
Malolactic fermentation
Instead of yeast, bacteria plays a fundamental role in malolactic fermentation which is essentially the conversion of malic acid into lactic acid. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Malolactic fermentation (or sometimes malolactic conversion) is a process of a change used in Winemaking where tart-tasting Malic acid, naturally present Malic acid is an Organic compound with the formula HO2CCH2CHOHCO2H Lactic acid ( IUPAC Systematic name: 2-hydroxypropanoic acid) also known as milk acid, is a Chemical compound that plays a role This has the benefit of reducing some of the tartness and making the resulting wine taste softer. Depending on the style of wine that the winemaker is trying to produce, malolactic fermentation may take place at the same time as the yeast fermentation. [13]
References
- ^ J. Robinson (ed) "The Oxford Companion to Wine" Third Edition pg 267-269 Oxford University Press 2006 ISBN 0198609906
- ^ J. Robinson Jancis Robinson's Wine Course Third Edition pg 74-84 Abbeville Press 2003 ISBN 0789208830
- ^ H. Johnson Vintage: The Story of Wine pg 16 Simon and Schuster 1989 ISBN 0671687026
- ^ J. Robinson (ed) "The Oxford Companion to Wine" Third Edition pg 267 Oxford University Press 2006 ISBN 0198609906
- ^ J. Robinson (ed) "The Oxford Companion to Wine" Third Edition pg 778-779 Oxford University Press 2006 ISBN 0198609906
- ^ J. Robinson (ed) "The Oxford Companion to Wine" Third Edition pg 779 Oxford University Press 2006 ISBN 0198609906
- ^ a b c J. Robinson (ed) "The Oxford Companion to Wine" Third Edition pg 268 Oxford University Press 2006 ISBN 0198609906
- ^ J. Robinson (ed) "The Oxford Companion to Wine" Third Edition pg 780 Oxford University Press 2006 ISBN 0198609906
- ^ J. Robinson Jancis Robinson's Wine Course Third Edition pg 82 Abbeville Press 2003 ISBN 0789208830
- ^ K. MacNeil The Wine Bible pg 168-169 Workman Publishing 2001 ISBN 1563054345
- ^ K. MacNeil The Wine Bible pg 33-34 Workman Publishing 2001 ISBN 1563054345
- ^ D. Bird "Understanding Wine Technology" pg 89-92 DBQA Publishing 2005 ISBN 1891267914
- ^ K. MacNeil The Wine Bible pg 35 Workman Publishing 2001 ISBN 1563054345
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