A wine fault is a sensory-associated (
organoleptic
Organoleptic properties are the aspects of food, water or other substances as apprehended via the senses—including taste, sight, smell, and touch.
In traditional U.S. Department of Agriculture meat and poultry inspections, inspectors p ...
) 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 experiences (e.g., an off-odor) might arise from more than one wine fault. Wine faults may result from poor
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 ...
practices or
storage conditions that lead to ''wine spoilage''.
In the case of a chemical origin, many compounds causing wine faults are already naturally present in wine, but at insufficient concentrations to be of issue, and in fact may impart positive characters to the wine; however, when the concentration of such compounds exceed a
sensory threshold, they replace or obscure desirable
flavors and
aromas that the winemaker wants the wine to express. The ultimate result is that the quality of the wine is reduced (less appealing, sometimes undrinkable), with consequent impact on its value.
[M. Baldy: ''"The University Wine Course"'', Third Edition, pp. 37-39, 69-80, 134-140. The Wine Appreciation Guild 2009 .]
There are many underlying causes of wine faults, including poor
hygiene
Hygiene is a set of practices performed to preserve health.
According to the World Health Organization (WHO), "Hygiene refers to conditions and practices that help to maintain health and prevent the spread of diseases." Personal hygiene refer ...
at the winery, excessive or insufficient exposure of the wine to
oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
, excessive or insufficient exposure of the wine to
sulphur
Sulfur (American spelling and the preferred IUPAC name) or sulphur (English in the Commonwealth of Nations, Commonwealth spelling) is a chemical element; it has Symbol (chemistry), symbol S and atomic number 16. It is abundance of the chemical ...
, overextended
maceration of the wine either pre- or post-
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 ...
, faulty
fining, filtering and stabilization of the wine, the use of dirty
oak barrels, over-extended barrel aging and the use of poor quality corks. Outside of the winery, other factors within the control of the retailer or end user of the wine can contribute to the perception of flaws in the wine. These include poor
storage of the wine that exposes it to excessive heat and temperature fluctuations as well as the use of dirty
stemware
Stemware is drinkware where the bowl stands on a ''stem'' above a ''foot'' (base that allows to put the vessel down onto a table). It is usually made from glass, but may be made from ceramics or metals. The stemware is intended for cool bever ...
during
wine tasting
Wine tasting is the sensory examination and evaluation of wine. While the practice of wine tasting is as ancient as its production, a more formalized methodology has slowly become established from the 14th century onward. Modern, professional w ...
that can introduce materials or aromas to what was previously a clean and fault-free wine.
[D. Bird: ''"Understanding Wine Technology"'', pp. 31-82, 155-184, 202-222. DBQA Publishing 2005 .]
Differences between flaws and faults
In wine tasting, there is a big distinction made between what is considered a ''flaw'' and a ''fault''. Wine flaws are minor attributes that depart from what are perceived as normal wine characteristics. These include excessive
sulfur dioxide
Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...
,
volatile acidity
Volatility or volatile may refer to:
Chemistry
* Volatility (chemistry), a measuring tendency of a substance or liquid to vaporize easily
** Volatile organic compounds, organic or carbon compounds that can evaporate at normal temperature and p ...
, ''
Brettanomyces'' or "Brett aromas" and
diacetyl or buttery aromas. The amount to which these aromas or attributes become excessive is dependent on the particular tastes and
recognition threshold of the wine taster. Generally, a wine exhibiting these qualities is still considered drinkable by most people. However, some flaws such as volatile acidity and ''Brettanomyces'' can be considered a fault when they are in such an excess that they overwhelm other components of the wine. Wine faults are generally major attributes that make a wine undrinkable to most wine tasters. Examples of wine faults include
acetaldehyde
Acetaldehyde (IUPAC systematic name ethanal) is an organic compound, organic chemical compound with the chemical formula, formula , sometimes abbreviated as . It is a colorless liquid or gas, boiling near room temperature. It is one of the most ...
(except when purposely induced in wines like
Sherry
Sherry ( ) is a fortified wine produced from white grapes grown around the city of Jerez de la Frontera in Andalusia, Spain. Sherry is a drink produced in a variety of styles made primarily from the Palomino grape, ranging from light versio ...
and
Rancio),
ethyl acetate
Ethyl acetate commonly abbreviated EtOAc, ETAC or EA) is the organic compound with the formula , simplified to . This flammable, colorless liquid has a characteristic sweet smell (similar to pear drops) and is used in glues, nail polish removers, ...
and
cork taint
Cork taint is a broad term referring to an off-odor and off-flavor wine fault arising from the presence of 2,4,6-trichloroanisole (TCA), a chemical compound that represents one of the strongest off-flavors, and one "generated naturally in foods/b ...
.
Detecting faults in wine tasting

The vast majority of wine faults are detected by the nose and the distinctive aromas that they give off. However, the presence of some wine faults can be detected by visual and taste perceptions. For example, premature oxidation can be noticed by the yellowing and
browning of the
wine's color. The sign of gas bubbles in wines that are not meant to be
sparkling can be a sign of
refermentation or
malolactic fermentation
Malolactic conversion (also known as malolactic fermentation or MLF) is a process in winemaking in which Tart (flavor), tart-tasting malic acid, naturally present in grape must, is converted to softer-tasting lactic acid. Malolactic fermentation ...
happening in the bottle. Unusual breaks in the color of the wine could be a sign of excessive
copper
Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...
,
iron
Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...
or
proteins
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, re ...
that were not removed during fining or filtering. A wine with an unusual color for its variety or wine region could be a sign of excessive or insufficient maceration as well as poor temperature controls during fermentation. Tactile clues of potential wine faults include the burning, acidic taste associated with
volatile acidity
Volatility or volatile may refer to:
Chemistry
* Volatility (chemistry), a measuring tendency of a substance or liquid to vaporize easily
** Volatile organic compounds, organic or carbon compounds that can evaporate at normal temperature and p ...
that can make a wine seem out of balance.
Oxidation
The
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 ...
of wine is perhaps the most common of wine faults, as the presence of
oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
and a
catalyst
Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...
are the only requirements for the process to occur. Oxidation can occur throughout the winemaking process, and even after the wine has been bottled.
Anthocyanin
Anthocyanins (), also called anthocyans, are solubility, water-soluble vacuole, vacuolar pigments that, depending on their pH, may appear red, purple, blue, or black. In 1835, the German pharmacist Ludwig Clamor Marquart named a chemical compou ...
s,
catechin
Catechin is a flavan-3-ol, a type of secondary metabolite providing antioxidant roles in plants. It belongs to the subgroup of polyphenols called flavonoids.
The name of the catechin chemical family derives from ''catechu'', which is the tannic ...
s, epicatechins and other
phenols
In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of one or more hydroxyl groups (− O H) bonded directly to an aromatic hydrocarbon group. The simplest is phenol, . Phenolic compounds ar ...
present in wine are those most easily oxidised,
[duToit, W.J. (2005)]
Oxygen in winemaking: Part I
WineLand, accessed on 2 April 2006. which leads to a loss of colour, flavour and aroma - sometimes referred to as ''flattening''. In most cases compounds such as
sulfur dioxide
Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...
or
erythorbic acid are added to wine by winemakers, which protect the wine from oxidation and also bind with some of the oxidation products to reduce their organoleptic effect.
[Goode, Jamie (06/25/19)]
Oxidation in wine
. ''internationalwinechallenge.com'', accessed on 10 February 2021. Apart from phenolic oxidation, the
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 ...
present within wine can also be oxidised into other compounds responsible for flavour and aroma taints. Some wine styles can be oxidised intentionally, as in certain
Sherry
Sherry ( ) is a fortified wine produced from white grapes grown around the city of Jerez de la Frontera in Andalusia, Spain. Sherry is a drink produced in a variety of styles made primarily from the Palomino grape, ranging from light versio ...
wines and
Vin jaune
is a special and characteristic type of white wine made in the Jura (wine), Jura region in eastern France. It is similar to dry fino Sherry and gets its character from being matured in a barrel under a film of yeast (wine), yeast, known as the ...
from the Jura region of France.
Acetaldehyde
Acetaldehyde
Acetaldehyde (IUPAC systematic name ethanal) is an organic compound, organic chemical compound with the chemical formula, formula , sometimes abbreviated as . It is a colorless liquid or gas, boiling near room temperature. It is one of the most ...
is an intermediate product of
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 ...
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 ...
; however, it is more commonly associated with
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 ...
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 ...
catalysed by the enzyme
ethanol dehydrogenase. Acetaldehyde production is also associated with the presence of surface film forming yeasts and bacteria, such as
acetic acid bacteria
Acetic acid bacteria (AAB) are a group of Gram-negative bacteria which Oxidation, oxidize sugars or ethanol and produce acetic acid during Aerobic fermentation, fermentation. The acetic acid bacteria consist of 10 genus, genera in the family Acet ...
, which form the compound by the
decarboxylation
Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2). Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is ...
of
pyruvate
Pyruvic acid (CH3COCOOH) is the simplest of the alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate base, CH3COCOO−, is an intermediate in several metabolic pathways throughout the cell.
Pyruvic ...
. The
sensory threshold for acetaldehyde is 100–125
mg/
L. Beyond this level it imparts a ''
sherry
Sherry ( ) is a fortified wine produced from white grapes grown around the city of Jerez de la Frontera in Andalusia, Spain. Sherry is a drink produced in a variety of styles made primarily from the Palomino grape, ranging from light versio ...
'' type character to the wine which can also be described as ''green apple'', ''sour'' and ''metallic''. Acetaldehyde
intoxication is also implicated in
hangover
A hangover is the experience of various unpleasant physiological and psychological effects usually following the consumption of alcohol (beverage), alcohol, such as wine, beer, and liquor. Hangovers can last for several hours or for more than ...
s.
Acetic acid
Acetic acid
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...
in wine, often referred to as volatile acidity (VA) or ''vinegar taint'', can be contributed by many wine spoilage
yeasts
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 constitu ...
and
bacteria
Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...
. This can be from either a
by-product
A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced.
A by-product can be useful and marketable or it can be cons ...
of fermentation, or due to the spoilage of finished wine. Acetic acid bacteria, such as those from the genera ''
Acetobacter
''Acetobacter'' is a genus of acetic acid bacteria. Acetic acid bacteria are characterized by the ability to convert ethanol to acetic acid in the presence of oxygen. Of these, the genus ''Acetobacter'' is distinguished by the ability to oxidiz ...
'' and ''
Gluconobacter'' produce high levels of acetic acid. The
sensory threshold for acetic acid in wine is >700 mg/L, with concentrations greater than 1.2-1.3 g/L becoming unpleasant.
There are different opinions as to what level of volatile acidity is appropriate for higher quality wine. Although too high a concentration is sure to leave an undesirable, 'vinegar' tasting wine, some wine's acetic acid levels are developed to create a more 'complex', desirable taste. The renowned 1947
Cheval Blanc is widely recognized to contain high levels of volatile acidity.
Ethyl acetate
Ethyl acetate commonly abbreviated EtOAc, ETAC or EA) is the organic compound with the formula , simplified to . This flammable, colorless liquid has a characteristic sweet smell (similar to pear drops) and is used in glues, nail polish removers, ...
is formed in wine by the
esterification
In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...
of ethanol and acetic acid. Therefore, wines with high acetic acid levels are more likely to see ethyl acetate formation, but the compound does not contribute to the volatile acidity. It is a common microbial fault produced by
wine spoilage yeasts, particularly ''
Pichia anomala
''Wickerhamomyces anomalus'' is a species of ascomycete and teleomorphic fungi of the genus '' Wickerhamomyces''. It is used as a preventive (biocontrol agent) for undesirable fungi or mold, nevertheless it may spoil food in large quantities. ...
'' or ''
Kloeckera apiculata''. High levels of ethyl acetate are also produced by
lactic acid bacteria
Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical ( cocci) bacteria that share common metabolic and physiological characteristics. These bact ...
and
acetic acid bacteria
Acetic acid bacteria (AAB) are a group of Gram-negative bacteria which Oxidation, oxidize sugars or ethanol and produce acetic acid during Aerobic fermentation, fermentation. The acetic acid bacteria consist of 10 genus, genera in the family Acet ...
.
Sulfur compounds
Sulfur
Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...
is used as an
additive
Additive may refer to:
Mathematics
* Additive function, a function in number theory
* Additive map, a function that preserves the addition operation
* Additive set-function see Sigma additivity
* Additive category, a preadditive category with fin ...
throughout the winemaking process, primarily to stop oxidation as mentioned above but also as
antimicrobial
An antimicrobial is an agent that kills microorganisms (microbicide) or stops their growth (bacteriostatic agent). Antimicrobial medicines can be grouped according to the microorganisms they are used to treat. For example, antibiotics are used aga ...
agent. When managed properly in wine, its presence there is often undetected, however when used recklessly it can contribute to flavour and aroma taints which are very volatile and potent. Sulfur compounds typically have low sensory thresholds.
Sulfur dioxide
Sulfur dioxide
Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...
is a common wine additive, used for its
antioxidant
Antioxidants are Chemical compound, compounds that inhibit Redox, oxidation, a chemical reaction that can produce Radical (chemistry), free radicals. Autoxidation leads to degradation of organic compounds, including living matter. Antioxidants ...
and
preservative
A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or ...
properties. When its use is not managed well it can be overadded, with its perception in wine reminiscent of ''matchsticks'', ''burnt rubber'', or ''mothballs''. Wines such as these are often termed ''sulfitic''.
Hydrogen sulfide
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 ...
(H
2S) is generally thought to be a metabolic by-product of yeast fermentation in
nitrogen limited environments. It is formed when yeast ferments via the
sulfate reduction pathway. Fermenting wine is often supplemented with
diammonium phosphate
Diammonium phosphate (DAP; IUPAC name diammonium hydrogen phosphate; chemical formula (NH4)2(HPO4)) is one of a series of water- soluble ammonium phosphate salts that can be produced when ammonia reacts with phosphoric acid.
Solid diammonium ph ...
(DAP) as a nitrogen source to prevent H
2S formation. The sensory threshold for hydrogen sulfide is 8-10 μg/L, with levels above this imparting a distinct ''rotten egg'' aroma to the wine. Hydrogen sulfide can further react with wine compounds to form mercaptans and
disulfide
In chemistry, a disulfide (or disulphide in British English) is a compound containing a functional group or the anion. The linkage is also called an SS-bond or sometimes a disulfide bridge and usually derived from two thiol groups.
In inorg ...
s.
Mercaptans
Mercaptans (thiols) are produced in wine by the reaction of hydrogen sulfide with other wine components such as ethanol. They can be formed if finished wine is allowed prolonged contact with the
lees. This can be prevented 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. Mercaptans have a very low sensory threshold, around 1.5
μg
In the metric system, a microgram or microgramme is a Physical unit, unit of mass equal to one millionth () of a gram. The unit symbol is μg according to the International System of Units (SI); the recommended symbol in the United States and Uni ...
/
L,
[Technical Bulletin - Sulfides in Wine]
. ''etslabs.com'', accessed on 12 March 2006. with levels above causing ''onion'', ''rubber'', and ''skunk'' type odours. Note that dimethyl disulfide is formed from the oxidation of methyl mercaptan.
Dimethyl sulfide
Dimethyl sulfide
Dimethyl sulfide (DMS) or methylthiomethane is an organosulfur compound with the formula . It is the simplest thioether and has a characteristic disagreeable odor. It is a flammable liquid that boils at . It is a component of the smell produc ...
(DMS) is naturally present in most wines, probably from the breakdown of sulfur containing amino acids. Like ethyl acetate, levels of DMS below the sensory threshold can have a positive effect on flavour, contributing to ''fruityness'', ''fullness'', and ''complexity''. Levels above the sensory threshold of >30 μg/L in white wines and >50 μg/L for red wines, give the wine characteristics of ''cooked cabbage'', ''canned corn'', ''asparagus'' or ''truffles''.
Environmental
Cork taint
Cork taint is a wine fault mostly attributed to the compound
2,4,6-trichloroanisole (TCA), although other compounds such as
guaiacol
Guaiacol () is an organic compound with the formula C6H4(OH)(OCH3). It is a phenolic compound containing a methoxy functional group. Guaiacol appears as a viscous colorless oil, although aged or impure samples are often yellowish. It occurs wid ...
,
geosmin
Geosmin ( ) is an irregular sesquiterpenoid with a distinct earthy or musty odor, which most people can easily smell. The geosmin odor detection threshold in humans is very low, ranging from 0.006 to 0.01 micrograms per liter in water. Geosmin, a ...
,
2-methylisoborneol
2-Methylisoborneol (MIB) is an irregular monoterpene derived from the universal monoterpene precursor geranyl pyrophosphate. MIB and the irregular sesquiterpene geosmin together account for the majority of biologically-caused taste and odor outbr ...
,
1-octen-3-ol
1-Octen-3-ol, octenol for short and also known as mushroom alcohol, is a chemical that attracts biting insects such as mosquitoes. It is contained in human breath and sweat, and it is believed that insect repellent DEET works by blocking the i ...
,
1-octen-3-one
Oct-1-en-3-one (CH2=CHC(=O)(CH2)4CH3), also known as 1-octen-3-one or amyl vinyl ketone, is the odorant that is responsible for the typical "metallic" smell of metals and blood coming into contact with skin. Oct-1-en-3-one has a strong metallic mus ...
,
2,3,4,6-tetrachloroanisole,
pentachloroanisole, and
2,4,6-tribromoanisole are also thought to be involved.
[LaMar, Jim (09/25/02)]
Cork Taint
accessed on 12 March 2006. TCA most likely originates as a
metabolite
In biochemistry, a metabolite is an intermediate or end product of metabolism.
The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...
of
mould
A mold () or mould () is one of the structures that certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi ...
growth on
chlorine
Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...
-bleached wine corks and barrels. It causes ''earthy'', ''mouldy'', and ''musty'' aromas in wine that easily mask the natural fruit aromas, making the wine very unappealing. Wines in this state are often described as ''"corked"''. As cork taint has gained a wide reputation as a wine fault, other faults are often mistakenly attributed to it.
Heat damage
Heat damaged wines are often casually referred to as ''cooked'', which suggests how heat can affect a wine. They are also known as maderized wine, from
Madeira wine, which is intentionally exposed to heat. The ideal storage temperature for wine is generally accepted to be 13 °C (55 °F). Wines that are stored at temperatures greatly higher than this will experience an increased aging rate. Wines exposed to extreme temperatures will
thermally expand, and may even push up between the cork and bottle and leak from the top. When opening a bottle of wine, if a trace of wine is visible along the length of the cork, the cork is partially pushed out of the bottle, or wine is visible on the top of the cork while it is still in the bottle, it has most likely been heat damaged. Heat damaged wines often become oxidized, and red wines may take on a brick color.
Even if the temperatures do not reach extremes, temperature variation alone can also damage bottled wine through oxidation. All corks allow some leakage of air (hence old wines become increasingly oxidized), and temperature fluctuations will vary the pressure differential between the inside and outside of the bottle and will act to "pump" air into the bottle at a faster rate than will occur at any temperature strictly maintained.
Reputedly, heat damage is the most widespread and common problem found in wines. It often goes unnoticed because of the prevalence of the problem, consumers don't know it's possible, and most often would just chalk the problem up to poor quality, or other factors.
Lightstrike
Lightstruck wines are those that have had excessive exposure to
ultraviolet
Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...
light, particularly in the range 325 to 450 nm.
[Drouhin, R.J. (01/23/98]
Bottle Glass
, accessed 3 April 2006. Very delicate wines, such as
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 ...
s, are generally worst affected, with the fault causing a ''wet cardboard'' or ''wet wool'' type flavour and aroma. Red wines rarely become lightstruck because of the phenolic compounds present within the wine that protect it. Lightstrike is thought to be caused by sulfur compounds such as
dimethyl sulfide
Dimethyl sulfide (DMS) or methylthiomethane is an organosulfur compound with the formula . It is the simplest thioether and has a characteristic disagreeable odor. It is a flammable liquid that boils at . It is a component of the smell produc ...
. In France lightstrike is known as "''goût de lumière''", which translates to ''a taste of light''. The fault explains why wines are generally bottled in coloured glass, which blocks the ultraviolet light, and why wine should be stored in dark environments.
Ladybird (pyrazine) taint
Some insects present in the grapes at harvest inevitably end up in the press and for the most part are inoffensive. Others, notably the
Asian lady beetle, release unpleasant-smelling nitrogen heterocycles as a defensive mechanism when disturbed. In sufficient quantities, these can affect the wine's odor and taste. With an olfactory detection threshold of a few ppb, the principal active compound is
isopropyl methoxypyrazine; this molecule is perceived as rancid
peanut butter
Peanut butter is a food Paste (food), paste or Spread (food), spread made from Grinding (abrasive cutting), ground, dry roasting, dry-roasted peanuts. It commonly contains additional ingredients that modify the taste or texture, such as salt, ...
, green
bell pepper
The bell pepper (also known as sweet pepper, paprika, pepper, capsicum or, in some parts of the US midwest, mango) is the fruit of plants in the Grossum Group of the species ''Capsicum annuum''. Cultivars of the plant produce fruits in diff ...
, urine, or simply bitter. This is also a naturally occurring compound in Sauvignon grapes, and so
pyrazine
Pyrazine is a heterocyclic aromatic organic compound with the chemical formula C4H4N2. It is a symmetrical molecule with point group D2h. Pyrazine is less basic than pyridine, pyridazine and pyrimidine. It is a ''"deliquescent crystal or wax-lik ...
taint has been known to make
Riesling
Riesling ( , ) is a white grape variety that originated in the Rhine region. Riesling is an aromatic grape variety displaying flowery, almost perfumed, aromas as well as high acidity. It is used to make dry, semi-sweet, sweet, and sparkling ...
s taste like
Sauvignon blanc
Sauvignon blanc () is a green-skinned grape variety that originates from the city of Bordeaux in France. The grape most likely gets its name from the French words ''sauvage'' ("wild") and ''blanc'' ("white") due to its early origins as an ind ...
.
Microbiological
''Brettanomyces'' (''Dekkera'')
The yeast ''
Brettanomyces'' produces an array of
metabolite
In biochemistry, a metabolite is an intermediate or end product of metabolism.
The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...
s when growing in wine, some of which are volatile
phenol
Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile and can catch fire.
The molecule consists of a phenyl group () ...
ic compounds. Together these compounds are often referred to as ''phenolic taint'', ''"Brettanomyces character"'', or simply "Brett". The main constituents are listed below, with their sensory threshold and common sensory descriptors:
*
4-ethylphenol (>140 μg/L): Band-aids, barnyard, horse stable, antiseptic
*
4-ethylguaiacol (>600 μg/L): Bacon, spice, cloves, smoky
*
isovaleric acid: Sweaty, cheese, rancidity
Geosmin
Geosmin
Geosmin ( ) is an irregular sesquiterpenoid with a distinct earthy or musty odor, which most people can easily smell. The geosmin odor detection threshold in humans is very low, ranging from 0.006 to 0.01 micrograms per liter in water. Geosmin, a ...
is a compound with a very distinct ''earthy'', ''musty'', ''beetroot'', even ''turnip'' flavour and aroma and has an extremely low sensory threshold of down to 10 parts per trillion. Its presence in wine is usually derived as metabolite from the growth of filamentous
actinomycetes
The Actinomycetales is an Scientific classification, order of Actinomycetota. A member of the order is often called an actinomycete. Actinomycetales are generally Gram-positive bacteria, gram-positive and anaerobic and have mycelia in a filamento ...
such as ''
Streptomyces
''Streptomyces'', from στρεπτός (''streptós''), meaning "twisted", and μύκης (''múkés''), meaning "fungus", is the largest genus of Actinomycetota, and the type genus of the family Streptomycetaceae. Over 700 species of ''St ...
'', and
mould
A mold () or mould () is one of the structures that certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi ...
s such as ''
Botrytis cinerea
''Botrytis cinerea'' is a necrotrophic fungus that affects many plant species, although its most notable hosts may be wine grapes. In viticulture, it is commonly known as "botrytis bunch rot"; in horticulture, it is usually called "grey mould" ...
'' and ''Penicillium expansum'', on grapes. Wines affected by but not attributed to geosmins are often thought to have earthy properties due to
terroir
(; ; from ''terre'', ) is a French language, French term used to describe the environmental factors that affect a crop's phenotype, including unique environment contexts, farming practices and a crop's specific growth habitat. Collectively, th ...
.
[Kennel, Florence (14/12/05)]
Bordeaux boffin solves geosmin conundrum
''Decanter.com'', accessed on 2 April 2006. The geosmin fault occurs worldwide and has been found in recent vintages of red wines from
Beaujolais
Beaujolais ( , ) is a French ''Appellation d'Origine Contrôlée'' (AOC) wine in the Burgundy wine, Burgundy region. Beaujolais wines are generally made of the Gamay grape, which has a thin skin and is low in grape tannins, tannin, but like most ...
,
Bordeaux
Bordeaux ( ; ; Gascon language, Gascon ; ) is a city on the river Garonne in the Gironde Departments of France, department, southwestern France. A port city, it is the capital of the Nouvelle-Aquitaine region, as well as the Prefectures in F ...
,
Burgundy
Burgundy ( ; ; Burgundian: ''Bregogne'') is a historical territory and former administrative region and province of east-central France. The province was once home to the Dukes of Burgundy from the early 11th until the late 15th century. ...
and the
Loire
The Loire ( , , ; ; ; ; ) is the longest river in France and the 171st longest in the world. With a length of , it drains , more than a fifth of France's land, while its average discharge is only half that of the Rhône.
It rises in the so ...
in France. Geosmin is also thought to be a contributing factor in
cork taint
Cork taint is a broad term referring to an off-odor and off-flavor wine fault arising from the presence of 2,4,6-trichloroanisole (TCA), a chemical compound that represents one of the strongest off-flavors, and one "generated naturally in foods/b ...
.
Lactic acid bacteria
Lactic acid bacteria
Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical ( cocci) bacteria that share common metabolic and physiological characteristics. These bact ...
have a useful role in winemaking converting
malic acid
Malic acid is an organic compound with the molecular formula . It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms ( ...
to lactic acid in
malolactic fermentation
Malolactic conversion (also known as malolactic fermentation or MLF) is a process in winemaking in which Tart (flavor), tart-tasting malic acid, naturally present in grape must, is converted to softer-tasting lactic acid. Malolactic fermentation ...
. However, after this function has completed, the bacteria may still be present within the wine, where they can metabolise other compounds and produce wine faults. Wines that have not undergone malolactic fermentation may be contaminated with lactic acid bacteria, leading to refermentation of the wine with it becoming
turbid
Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of both water clarity and wate ...
, ''swampy'', and slightly
effervescent or ''spritzy''. This can be avoided by sterile filtering wine directly before bottling. Lactic acid bacteria can also be responsible for other wine faults such as those below.
Bitterness taint

Bitterness taint or ''amertume'' is rather uncommon and is produced by certain strains of bacteria from the genera ''
Pediococcus
''Pediococcus'' is a genus of gram-positive lactic acid bacteria, placed within the family of Lactobacillaceae. They usually occur in pairs or tetrads, and divide along two planes of symmetry, as do the other lactic acid cocci genera '' Aerococc ...
'', ''
Lactobacillus
''Lactobacillus'' is a genus of gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically div ...
'', and ''
Oenococcus''. It begins by the degradation of
glycerol
Glycerol () is a simple triol compound. It is a colorless, odorless, sweet-tasting, viscous liquid. The glycerol backbone is found in lipids known as glycerides. It is also widely used as a sweetener in the food industry and as a humectant in pha ...
, a compound naturally found in wine at levels of 5-8 g/L, via a
dehydratase enzyme to ''3-hydroxypropionaldehyde''. During ageing this is further dehydrated to
acrolein which reacts with the
anthocyanin
Anthocyanins (), also called anthocyans, are solubility, water-soluble vacuole, vacuolar pigments that, depending on their pH, may appear red, purple, blue, or black. In 1835, the German pharmacist Ludwig Clamor Marquart named a chemical compou ...
s and other phenols present within the wine to form the taint.
[duToit, M., Pretorius, I.S. (2000). "Microbial spoilage and preservation of wine: Using weapons from nature's own arsenal - A review". South African Journal of Enology and Viticulture 21: 74-96.] As red wines contain high levels of anthocyanins they are generally more susceptible.
Diacetyl
Diacetyl in wine is produced by
lactic acid bacteria
Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical ( cocci) bacteria that share common metabolic and physiological characteristics. These bact ...
, mainly ''
Oenococcus oeni''. In low levels it can impart positive ''nutty'' or ''caramel'' characters, however at levels above 5 mg/L it creates an intense ''buttery'' or ''
butterscotch'' flavour, where it is perceived as a flaw. The sensory threshold for the compound can vary depending on the levels of certain wine components, such as sulfur dioxide. It can be produced as a metabolite of
citric acid
Citric acid is an organic compound with the formula . It is a Transparency and translucency, colorless Weak acid, weak organic acid. It occurs naturally in Citrus, citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, ...
when all of the
malic acid
Malic acid is an organic compound with the molecular formula . It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms ( ...
has been consumed. Diacetyl rarely taints wine to levels where it becomes undrinkable.
[Gibson, George; Farkas, Mik]
Flaws and Faults in Wine
accessed on 12 March 2006.
Geranium taint
Geranium taint, as the name suggests, is a flavour and aroma taint in wine reminiscent of
geranium
''Geranium'' is a genus of 422 species of annual, biennial, and perennial plants that are commonly known as geraniums or cranesbills. They are found throughout the temperate regions of the world and the mountains of the tropics, with the gre ...
leaves. The compound responsible is ''
2-ethoxyhexa-3,5-diene'', which has a low sensory threshold concentration of 1 ng/L. In wine it is formed during the
metabolism
Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...
of
potassium sorbate
Potassium sorbate is the potassium salt of sorbic acid, structural formula CH3CH=CH−CH=CH−CO2K. It is a white salt that is very soluble in water (58.2% at 20 °C). It is primarily used as a food preservative (E number 202). Potassium ...
by
lactic acid bacteria
Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical ( cocci) bacteria that share common metabolic and physiological characteristics. These bact ...
. Potassium sorbate is sometimes added to wine as a
preservative
A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or ...
against yeast, however its use is generally kept to a minimum due to the possibility of the taint developing. The production of the taint begins with the conversion of
sorbic acid
Sorbic acid, or 2,4-hexadienoic acid, is a natural organic compound used as a food preservative. It has the chemical formula and the structure . It is a colourless solid that is slightly soluble in water and sublimes readily. It was first iso ...
to the alcohol ''
sorbinol''. The alcohol is then
isomerised in the presence of acid to ''
3,5-hexadiene-2-ol'', which is then esterified with ethanol to form ''
2-ethoxy-3,5-hexadiene''. As ethanol is necessary for the conversion, the geranium taint is not usually found in
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 ...
.
Mannitol
Mannitol
Mannitol is a type of sugar alcohol used as a sweetener and medication. It is used as a low calorie sweetener as it is poorly absorbed by the intestines. As a medication, it is used to decrease pressure in the eyes, as in glaucoma, and to l ...
is a
sugar alcohol
Sugar alcohols (also called polyhydric alcohols, polyalcohols, alditols or glycitols) are organic compounds, typically derived from sugars, containing one hydroxyl group attached to each carbon atom. They are white, water-soluble solids that c ...
, and in wine it is produced by
heterofermentative lactic acid bacteria, such as ''
Lactobacillus brevis
''Levilactobacillus brevis'' is a gram-positive, rod shaped species of lactic acid bacteria which is heterofermentative, creating CO2, lactic acid and acetic acid or ethanol during fermentation. ''L. brevis'' is the type species of the genus ''L ...
'', by the
reduction of
fructose
Fructose (), or fruit sugar, is a Ketose, ketonic monosaccharide, simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and gal ...
. Its perception is often complicated as it generally exists in wine alongside other faults, but it is usually described as
viscous
Viscosity is a measure of a fluid's rate-dependent resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for example, syrup h ...
,
ester
In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...
-like combined with a sweet and irritating finish.
[ Mannitol is usually produced in wines that undergo malolactic fermentation with a high level of ]residual sugar
The subjective sweetness of a wine is determined by the interaction of several factors, including the amount of sugar in the wine, but also the relative levels of alcohol, acids, and tannins. Sugars and alcohol enhance a wine's sweetness, while ...
s still present. Expert winemakers oftentimes add small amounts of sulfur dioxide during the crushing step to reduce early bacterial growth.
Ropiness
Ropiness is manifested as an increase in viscosity
Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for e ...
and a ''slimey'' or ''fatty'' mouthfeel of a wine. In France the fault is known as "''graisse''", which translates to ''fat''. The problem stems from the production of dextrin
Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch and glycogen. Dextrins are mixtures of polymers of D-glucose units linked by α-(1→4) or α-(1→6) glycosidic bonds.
Dextrins can be produced fro ...
s and polysaccharide
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 ...
s by certain lactic acid bacteria, particularly of the genera ''Leuconostoc
''Leuconostoc'' is a genus of gram-positive bacteria, placed within the family of Lactobacillaceae. They are generally ovoid cocci often forming chains. ''Leuconostoc'' spp. are intrinsically resistant to vancomycin and are catalase-negative (w ...
'' and ''Pediococcus
''Pediococcus'' is a genus of gram-positive lactic acid bacteria, placed within the family of Lactobacillaceae. They usually occur in pairs or tetrads, and divide along two planes of symmetry, as do the other lactic acid cocci genera '' Aerococc ...
''.
Mousiness
Mousiness is a wine fault most often attributed to ''Brettanomyces'' but can also originate from the lactic acid bacteria
Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical ( cocci) bacteria that share common metabolic and physiological characteristics. These bact ...
''Lactobacillus brevis
''Levilactobacillus brevis'' is a gram-positive, rod shaped species of lactic acid bacteria which is heterofermentative, creating CO2, lactic acid and acetic acid or ethanol during fermentation. ''L. brevis'' is the type species of the genus ''L ...
'', '' Lactobacillus fermentum'', and '' Lactobacillus hilgardii,''[ and hence can occur in ]malolactic fermentation
Malolactic conversion (also known as malolactic fermentation or MLF) is a process in winemaking in which Tart (flavor), tart-tasting malic acid, naturally present in grape must, is converted to softer-tasting lactic acid. Malolactic fermentation ...
. The compounds responsible are lysine
Lysine (symbol Lys or K) is an α-amino acid that is a precursor to many proteins. Lysine contains an α-amino group (which is in the protonated form when the lysine is dissolved in water at physiological pH), an α-carboxylic acid group ( ...
derivatives, mainly;
* 2-acetyl-3,4,5,6-tetrahydropyridine
* 2-acetyl-1,4,5,6-tetrahydropyridine
* 2-ethyltetrahydropyridine[Marais, Johan]
Flavourful nitrogen containing wine constituents
. ''Wynboer.co.za'', accessed on 12 March 2006.
* 2-acetyl-1-pyrrolene
The taints are not volatile at the pH of wine, and therefore not obvious as an aroma. However, when mixed with the slightly basic pH of saliva they can become very apparent on the palate,[Gawell, Richar]
Somellier, A Mouse Must Have Wee'd in My Wine!
''aromadictionary.com'', accessed on 12 March 2006. especially at the back of the mouth, as ''mouse cage'' or ''mouse urine''.
Refermentation
Refermentation, sometimes called secondary fermentation, is caused by yeasts refermenting the residual sugar
The subjective sweetness of a wine is determined by the interaction of several factors, including the amount of sugar in the wine, but also the relative levels of alcohol, acids, and tannins. Sugars and alcohol enhance a wine's sweetness, while ...
present within bottled wine. It occurs when sweet wines are bottled in non-sterile
Sterile or sterility may refer to:
*Asepsis, a state of being free from biological contaminants
* Sterile (archaeology), a sediment deposit which contains no evidence of human activity
*Sterilization (microbiology), any process that eliminates or ...
conditions, allowing the presence of microorganisms. The most common yeast to referment wine is the standard wine fermentation yeast ''Saccharomyces cerevisiae
''Saccharomyces cerevisiae'' () (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungal microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have be ...
'', but has also been attributed to ''Schizosaccharomyces pombe
''Schizosaccharomyces pombe'', also called "fission yeast", is a species of yeast used in traditional brewing and as a model organism in molecular and cell biology. It is a unicellular eukaryote, whose cells are rod-shaped. Cells typically meas ...
'' and '' Zygosaccharomyces bailii''.[ The main issues associated with the fault include ]turbidity
Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of both water clarity and wa ...
(from yeast biomass
Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how ...
production), excess ethanol production (may violate labelling
Labelling or using a label is describing someone or something in a word or short phrase. For example, the label "criminal" may be used to describe someone who has broken a law. Labelling theory is a theory in sociology which ascribes labelling ...
laws), slight carbonation
Carbonation is the chemical reaction of carbon dioxide to give carbonates, bicarbonates, and carbonic acid. In chemistry, the term is sometimes used in place of carboxylation, which refers to the formation of carboxylic acids.
In inorganic che ...
, and some coarse odours. Refermentation can be prevented by bottling wines dry (with residual sugar levels <1.0g/L), sterile filtering wine prior to bottling, or adding preservative chemicals such as dimethyl dicarbonate. The Portuguese wine
Portuguese wine was mostly introduced by the Romans (wine), Romans and other ancient Mediterranean peoples who traded with local coastal populations, mainly in the South. In pre-Roman Gallaecia-Lusitania times, the native peoples only drank beer ...
style known as " vinhos verdes" used to rely on this secondary fermentation in bottle to impart a slight spritziness to the wine, but now usually uses artificial carbonation.
Bunch rots
Organisms responsible for bunch rot of grape berries are filamentous fungi, the most common of these being ''Botrytis cinerea
''Botrytis cinerea'' is a necrotrophic fungus that affects many plant species, although its most notable hosts may be wine grapes. In viticulture, it is commonly known as "botrytis bunch rot"; in horticulture, it is usually called "grey mould" ...
'' (gray mold) However, there are a range of other fungi responsible for the rotting of grapes such as ''Aspergillus
' () is a genus consisting of several hundred mold species found in various climates worldwide.
''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Miche ...
'' spp., ''Penicillium
''Penicillium'' () is a genus of Ascomycota, ascomycetous fungus, fungi that is part of the mycobiome of many species and is of major importance in the natural environment, in food spoilage, and in food and drug production.
Some members of th ...
'' spp., and fungi found in subtropical climates (e.g., ''Colletotrichum
''Colletotrichum'' (sexual stage: ''Glomerella'') is a genus of fungi that are symbionts to plants as endophytes (living within the plant) or phytopathogens. Many of the species in this genus are plant pathogens, but some species may have a mu ...
'' spp. (ripe rot) and '' Greeneria uvicola'' (bitter rot)). A further group more commonly associated with diseases of the vegetative tissues of the vine can also infect grape berries (e.g., Botryosphaeriaceae, '' Phomopsis viticola''). Compounds found in bunch rot affected grapes and wine are typically described as having mushroom, earthy odors and include geosmin, 2-methylisoborneol
2-Methylisoborneol (MIB) is an irregular monoterpene derived from the universal monoterpene precursor geranyl pyrophosphate. MIB and the irregular sesquiterpene geosmin together account for the majority of biologically-caused taste and odor outbr ...
, 1-octen-3-ol
1-Octen-3-ol, octenol for short and also known as mushroom alcohol, is a chemical that attracts biting insects such as mosquitoes. It is contained in human breath and sweat, and it is believed that insect repellent DEET works by blocking the i ...
, 2-octen-1-ol, fenchol and fenchone.[Grapevine bunch rots: impacts on wine composition, quality, and potential procedures for the removal of wine faults. Steel CC, Blackman JW and Schmidtke LM, J Agric Food Chem., 5 June 2013, volume 61, issue 22, pp. 5189-5206, .]
See also
*Oenology
Oenology (also enology; ) is the science and study of wine and winemaking. Oenology is distinct from viticulture, which is the science of the growing, cultivation, and harvesting of grapes. The English word oenology derives from the Greek word ' ...
*Acids in wine
The acids in wine are an important component in both winemaking and the finished product of wine. They are present in both grapes and wine, having direct influences on the color, balance and taste of the wine as well as the growth and vitality of ...
* Browning in red wine
* Storage of wine
References
External links
Organoleptic defects in wine
(PDF
Portable document format (PDF), standardized as ISO 32000, is a file format developed by Adobe Inc., Adobe in 1992 to present documents, including text formatting and images, in a manner independent of application software, computer hardware, ...
document) Link Not Working
How to Spot Faulty Wine
from The Wine Doctor Link Not Working
in ''Enobytes Wine Online''
{{DEFAULTSORT:Wine Fault
Oenology
Wine chemistry
Wine tasting
Product expiration