dimethyl sulphide
“DMS , like sweetcorn or tomato sauce”
dimethyl sulphide
225 µg per capsule
Technical specification
Assessment
The best way to detect DMS character in wine is as follows. Without covering the glass, swirl the sample to release the aroma. Take a single short sniff. Repeat as necessary. Amount of flavour per capsule
225 µg per capsule Threshold
The flavour threshold of dimethyl sulphide in wine is 25 - 75 µg / l. Origins
Dimethyl sulphide is formed during ageing of wine in ways that are not yet fully understood. The flavour can potentially arise as a result of microbiological growth during wine fermentation. Importance
At low concentrations DMS can contribute to the body and mouthfeel of white wines. In red wines, it contributes to fruitiness, reminiscent of quince or truffles. At higher concentrations it may present itself as an off-flavour, imparting cooked corn, tomato or asparagus notes to affected wines. CAS registry number
The CAS registry number of dimethyl suphide is 75-18-3. Other names
DMS
dimethyl monosulfide
methylsulfanylmethane
methyl monosulfide
methane thiomethane
methyl sulfide
methyl thioether
methylsulfanylmethane
2-thiapropane
thiobis(methane)
thiobismethane
Remarks
The perception of dimethyl sulphide is influenced by the presence of aromatic higher alcohols such as 2-phenylethanol which can be present at high concentrations in some wines. Threshold distribution
Capsules per pot
10
4-ethyl phenol
“Band aid , like a Brettanomyces -contaminated wine”
4-ethyl phenol
1.7 mg per capsule
Technical specification
Assessment
The best way to detect ethyl phenol and the signs of Brettanomyces activity in wine is as follows. Cover the sample with your hand and swirl the glass to release the aroma. Remove your hand and take a single long sniff. Repeat as necessary. Amount of flavour per capsule
1.7 mg per capsule Threshold
The flavour threshold of 4-ethyl phenol in wine is 300 - 550 µg / l. Origins
4-Ethyl phenol is a flavour defect of red wine produced by contaminant Brettanomyces (Dekkera ) during barrel ageing, and occasionally after bottling. Wines which are low in sulphur dioxide are particularly sensitive to this problem. Importance
Ethyl phenol Imparts an unpleasant band aid-like character, described as barnyard, medicinal or horsey. The flavour tends to mask more subtle varietal notes in the wine. Insufficient sulphuring of grapes and poor winery hygiene predispose wines to this problem. CAS registry number
The CAS registry number of 4-ethyl phenol is 123-07-9. Other names
p-ethyl phenol
para-ethyl phenol
1-ethyl-4-hydroxybenzene
4-ethylphenol
1-hydroxy-4-ethyl benzene
4-hydroxyethyl benzene
4-hydroxyphenyl ethane
Remarks
Ethyl phenol is the characteristic odour of Brettanomyces contamination of wine. It occurs in combination with other Brettanomyces end-products including acetic acid, ethyl acetate, isovaleric acid, and ethyl guaiacol, which smells of smoked bacon or smoked cheese. Threshold distribution
Capsules per pot
10
ethyl phenylacetate
"Honey , like sweet mead or sherry”
ethyl phenylacetate
900 µg per capsule
Technical specification
Assessment
The best way to evaluate honey flavour in wine is as follows. Cover the sample with your hand and swirl the glass to release the aroma. Remove your hand and take a single long sniff. Repeat as necessary. Amount of flavour per capsule
900 µg per capsule Threshold
The flavour threshold of ethyl phenylacetate in wine is 150 - 300 µg / l. Origins
Ethyl phenylacetate is produced by yeast from phenolic precursors during maturation of wine. Concentrations of ethyl phenylacetate may increase after packaging of wine as a result of non-enzymic reactions. Importance
At low concentrations ethyl phenylacetate imparts a pleasant sweet, ‘honey-like’ note to wine. The presence of this note is associated with high quality white wines, such as Sauternes and Tokaji in vintage years. The compound has been confirmed as a cause of a sweet flavour detect in Italian Aglianico del Vulture reds. CAS registry number
The CAS registry number of ethyl phenylacetate is 101-97-3. Other names
benzene acetic acid ethyl ester
ethyl 2-phenyl ethanoate
ethyl 2-phenylacetate
ethyl alpha-toluate
ethyl benzene acetate
ethyl phenyl ethanoate
phenyl acetic acid ethyl ester
alpha- toluic acid ethyl ester
Remarks
Ethyl phenylacetate is also responsible for the sweet, honey-like note found in top class sweet white wines. This flavour is slow to develop on the palate. Threshold distribution
Capsules per pot
10
hydrogen sulphide
“H2 S , like boiled or rotten eggs”
hydrogen sulphide
60 µg per capsule
Technical specification
Assessment
The best way to evaluate hydrogen sulphide in wine is as follows. Without covering the glass, swirl the sample to release the aroma. Take a single short sniff. Repeat as necessary. Amount of flavour per capsule
60 µg per capsule Threshold
The favour threshold of hydrogen sulphide in wine is 1 - 20 µg / l. Origins
Hydrogen sulphide (H2 S) is a normal metabolic product of yeast which is produced during fermentation. Excessive levels of H2 S are caused by non-optimal concentrations of amino acids in the must and, occasionally, as a result of the use of elemental sulphur on vines. Importance
H2 S is present in all wines. It is an off-flavour at high concentrations when it can mask varietal characters. Supplementation of must with ammonium salts can help minimize formation of H2 S. Use of oxidizing agents, micro-aeration and copper treatment can be used to eliminate any H2 S formed. CAS registry number
The CAS registry number for H2 S is 7783-06-4. Other names
H2 S
hydrogen sulfide
dihydrogen monosulfide
dihydrogen monosulphide
hydrogen sulfuric acid
hydrogen sulphuric acid
sulfur hydride
Remarks
Hydrogen sulphide is often found in association with other sulphur compounds. Be careful not to overexpose yourself to samples with H2 S. The more you look for it the less likely you are to find it. Threshold distribution
Capsules per pot
10
β-ionone
“Violets , like Turkish delight”
β-ionone
1.1 mg per capsule
Technical specification
Assessment
The best way to detect beta-ionone in wine is as follows. Without covering the glass, swirl the sample to release the aroma. Take a single short sniff. Repeat as necessary. Amount of flavour per capsule
1.1 mg per capsule Threshold
The flavour threshold of beta-ionone in wine is 5 - 360 µg / l. Origins
Although β-ionone is present in all grape varieties, the distinctive flavour develops only in some wine styles. The compound is derived from grape carotenoids. Importance
β-Ionone plays a negligible role in the flavour of white wines but plays a more important role in the flavour of reds wines. The flavour imparted to wine by β-ionone is a component of fruity / floral character of some of the most sought-after red wines of Bordeaux, Burgundy and the Rhone Valley. CAS registry number
The CAS registry number of beta-ionone is 14901-07-6. Other names
ionone
beta-cyclocitrylidene acetone
beta-irisone
4-(2,6,6-trimethyl cyclohex-1-ene-1-yl) but-3-ene-2-one
4,2,6,6-trimethyl-1-cyclohexen-1-yl-3-buten-2-one
4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-3-buten-2-one
4-(2,6,6-trimethyl-1-cyclohexenyl)-3-buten-2-one
(E)-4-(2,6,6-trimethyl-1-cyclohexenyl)but-3-en-2-one
Remarks
β-Ionone together with β-damascenone represent a class of isoprenoid varietal wine flavours. Threshold distribution
Capsules per pot
10
isovaleric acid
“Isovaleric , like stale cheese or sweaty socks”
isovaleric acid
7.5 mg per capsule
Technical specification
Assessment
The best way to assess isovaleric flavour in wine is as follows. Cover the sample with your hand and swirl the glass to release the aroma. Remove your hand and take a single long sniff. Repeat as necessary. Amount of flavour per capsule
7.5 mg per capsule Threshold
The flavour threshold of isovaleric acid in wine is 1 - 2.5 mg / l. Origins
Isovaleric acid is formed by contaminant Brettanomyces during maturation of wine or as a result of spoilage in bottle. Importance
Isovaleric acid Imparts an odour of stale cheese or sweaty socks. Growth of Brettanomyces can add complexity to the product. Excessive growth leads to spoilage, imparting a distinctive and undesirable ‘Brett’ character. CAS registry number
The CAS registry number for isovaleric acid is 503-74-2. Other names
3-methylbutanoic acid
isobutyl formic acid
delphinic acid
dephinic acid
3-methyl butanoic acid
3-methyl butyric acid
beta-methyl butyric acid
3-methylbutanoic acid
isopentanoic acid
isopropyl acetic acid
isovalerianic acid
Remarks
When produced by Brettanomyces isovaleric acid often occurs together with other compounds, including acetic acid, ethyl acetate, and 4-ethyl phenol. A significant proportion of the population is relatively insensitive to this flavour. Threshold distribution
Capsules per pot
10
2-isobutyl-3-methoxypyrazine
“Earthy , like green pepper”
2-isobutyl-3-methoxypyrazine
50 ng per capsule
Technical specification
Assessment
The best way to detect 2-isobutyl-3-methoxypyrazine in wine is a s follows. Without covering the glass, swirl the sample to release the aroma. Take a single short sniff. Repeat as necessary. Amount of flavour per capsule
50 ng per capsule Threshold
The flavour threshold of 2-isobutyl-3-methoxypyrazine in wine is 10 - 16 ng / l. Origins
2-Isobutyl-3-methoxypyrazine is contributed by certain grapes to wine as a varietal character. Higher levels of methoxypyrazines are associated with under-ripe grapes and the presence of vine stem material during extraction of juice. Importance
At low levels 2-isobutyl-3-methoxypyrazine imparts a desirable herbaceous, bell pepper, varietal character. The presence of too much 2-isobutyl-3-methoxypyrazine suggests insufficient maturity of the grapes. It is regarded as an off-flavour at higher concentrations or in some wine styles. Isobutyl methoxypyrazine is one of several methoxypyrazines found in grapes and wine. CAS registry number
The CAS registry number of 2-isobutyl-3-methoxypyrazine is 24683-00-9. Other names
2-methoxy-3-(2-methylpropyl)pyrazine
isobutyl methoxypyrazine
3-isobutyl-2-methoxypyrazine
galbanum pyrazine
2- methoxy-3-(2-methyl propyl) pyrazine
2-methoxy-3-(2-methylpropyl)pyrazine
2-methoxy-3-isobutyl pyrazine
2-2-methyl propyl-3-methoxypyrazine
Remarks
Methoxypyrazines have remarkably low flavour thresholds. They represent a varietal characteristic in Sauvignon Blanc, Cabernet Sauvignon, Cabernet Franc and, sometimes, Merlot. They are regarded as a spoilage characteristic in red Bordeaux wines. Threshold distribution
Capsules per pot
10
sotolon
“Botrytis-infected , nutty, sweet and burnt”
sotolon
120 µg per capsule
Technical specification
Assessment
The best way to evaluate Botrytis character in wine is as follows. Cover the sample with your hand and swirl the glass to release the aroma. Remove your hand and take a single long sniff. Repeat as necessary. Amount of flavour per capsule
120 µg per capsule Threshold
The flavour threshold of sotolon in wine is 1 - 100 µg / l. Origins
Sotolon is contributed to wine by grapes infected with Botrytis cinerea , so-called noble rot. It can also be derived in ways that are not yet fully understood in reactions which lead to premature ageing of some white wines. Importance
Sotolon imparts a nutty, toasted aroma to wine, reminiscent of raw sugar, in the case of wines made with grapes which have undergone noble rot. In prematurely-aged white wine sotolon is often found together with 2-aminoacetophenone. In such wines the overall flavour impression can resemble polish. CAS registry number
The CAS registry number of sotolon is 28664-35-9. Other names
4,5-Dimethyl-3-hydroxy-2(5H)-furanone
caramel lactone
dimethyl oxyfurone
4,5- dimethyl-3-hydroxy-2,5-dihydrofuran-2-one
2,3-dimethyl-4-hydroxy-2,5-dihydrofuran-5-one
fenugreek lactone
2-hydroxy-3-methyl-2-penten-4-olide
2- hydroxy-3,4-dimethyl-2-buten-1,4-olide
3- hydroxy-4,5-dimethyl furan-2(5H)-one
3- hydroxy-4,5-dimethyl-2(5H)-furanone
3- hydroxy-4,5-dimethyl-5H-furan-2-one
sotolone
sugar lactone
Remarks
This flavour standard contains a mixture of (R) and (S) stereoisomers. of sotolon The (S) form of sotolon contributes to the characteristic odour of prematurely aged wines. Threshold distribution
Capsules per pot
10
2,4,6-trichloroanisole
“Musty , like corked wine or a damp cellar”
2,4,6-trichloroanisole
580 ng per capsule
Technical specification
Assessment
The best way to evaluate cork taint in wine is as follows. Without covering the glass, swirl the sample to release the aroma. Take a single short sniff. Repeat as necessary. Amount of flavour per capsule
580 ng per capsule Threshold
The flavour threshold of 2,4,6 trichloranisole in wine is 5 - 100 ng / l. Origins
2,4,6 Trichloranisole (TCA) is associated with use of contaminated corks bottle closures. It can also be picked up from the winery environment. Formation of TCA is linked to growth of mould on wooden structures, especially those to which chlorophenol insecticides have been applied. Importance
2,4,6 Trichloranisole suppresses varietal character in wine when present at low concentrations. It imparts an unpleasant musty, mouldy odour to wine. Trichloranisole is derived from methylation of chlorophenols by moulds. This is one of the few flavours that can taint wine through airborne contamination during production. CAS registry number
The CAS registry number for 2,4,6 trichloranisole is 87-40-1. Other names
methyl 2,4,6-trichlorophenyl ether
1,3,5-trichloro-2-methoxybenzene
TCA
Remarks
Cork taint is caused by a number of different chemicals. 2,4,6-Trichloranisole is one of several chloranisoles associated with such problems. It can be often detected at concentrations well below the published recognition flavour threshold. Threshold distribution
Capsules per pot
10
vanillin
“Vanilla , like ice cream, or oak-aged wine”
vanillin
4.0 mg per capsule
Technical specification
Assessment
The best way to assess vanilla flavour character in wine is as follows. Cover the sample with your hand and swirl the glass to release the aroma. Remove your hand and take a single long sniff. Repeat as necessary. Amount of flavour per capsule
4.0 mg per capsule Threshold
The flavour threshold of vanillin in wine is 0.2 - 1.3 mg / l. Origins
Vanilla notes in wine arise in several ways. Ageing on wood; the action of certain yeasts; and the breakdown of certain phenolic compounds during storage. Importance
Vanillin is a positive flavour note in oaked wines. It imparts a creamy aroma and smooth mouthfeel when present at low levels in both red and white wines. It can also develop during aging of wines which are rich in certain phenolic compounds such as 4-vinyl guaiacol. Formation of vanillin during ageing on oak can be stimulated by malo-lactic bacteria. CAS registry number
The CAS registry number of vanillin is 121-33-5. Other names
4-formyl-2-methoxyphenol
4-hydroxy-3-methoxybenzaldehyde
4-hydroxy-5-methoxybenzaldehyde
4-hydroxy-meta-anisaldehyde
para-hydroxy-meta-methoxybenzaldehyde
2-methoxy-4-formyl phenol
3-methoxy-4-hydroxybenzaldehyde
methyl protocatechuic aldehyde
protocatechualdehyde-3-methyl ether
vanillaldehyde
vanillic aldehyde
para-vanillin
p- vanillin
Remarks
The amount of vanillin formed during barrel ageing is a function of the wine, choice of oak, and age of the wood. Threshold distribution
Capsules per pot
10
