acetic acid
"acetic , like vinegar or spoiled beer"
x 1
acetic acid
Number of capsules
acetic acid
275 mg per capsule
Technical specification
Assessment
The best way to evaluate acetic flavour in beer is as follows. Without covering the glass, swirl the beer to release the aroma. Take a single short sniff. Repeat as necessary.
Amount of flavour per capsule
275 mg per capsule
Threshold
The flavour threshold of acetic acid in beer is approximately 90 mg / l. The precise figure depends on the pH value of the beer.
Origins
Acetic acid is produced by yeast during fermentation. Too much yeast growth, contaminating bacteria and wild yeasts can all result in production of excessive levels of acetic acid.
Confusions
Professional beer tasters sometimes confuse acetic flavour with the following:
Citric acid
Lactic acid
Acetaldehyde
Importance
Acetic acid is present in all beers. It is the characteristic flavour of some beer styles, eg Lambic beer. It is present in all lagers, ales, stouts and wheat beers as a normal component of a balanced flavour. It becomes and off-flavour when present at high concentrations. Acetic flavour is a common problem in draught-dispensed beers, where it results from growth of contaminating acetic acid bacteria or wild yeasts.
CAS registry number
The CAS registry number of acetic acid is 64-19-7.
Other names
ethanoic acid
ethylic acid
methanecarboxylic acid
vinegar acid
acetasol
acide acetique
shotgun
vinegar
Remarks
The intensity of acetic flavour increases with decreasing beer pH value.
Threshold distribution
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
US Patent no. D679900
European Community Trade MarkRegistration no. 009937574
European Community Trade MarkRegistration no. 009856527
US Trade Mark Registration no. 4345057
US Trade Mark Registration no. 4345056
butyric acid
“Butyric“ , rancid, like baby vomit”
x 1
butyric acid
Number of capsules
butyric acid
9.0 mg per capsule
Technical specification
Assessment
The best way to evaluate butryic notes in beer is as follows. Cover the beer 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
9.0 mg per capsule
Threshold
The flavour threshold of butyric acid in beer is 3 mg / l. The threshold is lowered by the presence of diacetyl.
Origins
Butyric acid is produced by bacteria during mashing and sweet wort separation, or during sugar syrup production or storage. It is occasionally formed as a result of bacterial spoilage of packaged beer by strictly anerobic bacteria such s Pectinatus and Megasphaera . .
Confusions
Butryric acid can be confused by professional tasters with the following flavours in beer:
Isovaleric acid
Ethyl butyrate
2,3-Butanedione
Importance
Butyric acid is an off-flavour in beer. The flavour of affected beers can be worsened by the presence of 2,3-butanedione (diacetyl), or improved by ethyl butyrate derived from metabolism of butyric acid by yeast.
CAS registry number
The CAS registry number of butyric acid is 107-92-6.
Other names
butanoic acid
butanic acid
n-butanoic acid
1-butyric acid
n-butyric acid
ethyl acetic acid
1-propane carboxylic acid
propyl formic acid
Remarks
The intensity of butyric acid flavour increases with decreasing beer pH value.
Threshold distribution
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
US Patent no. D679900
European Community Trade MarkRegistration no. 009937574
European Community Trade MarkRegistration no. 009856527
US Trade Mark Registration no. 4345057
US Trade Mark Registration no. 4345056
dimethyl trisulphide
“Onion , like fried onion or garlic”
x 1
dimethyl trisulphide
Number of capsules
dimethyl trisulphide
130 ng per capsule
Technical specification
Assessment
The best way to detect onion character arising from dimethyl trisulphide is as follows. Cover the beer 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
130 ng per capsule
Threshold
The flavour threshold of dimethyl trisulphide in beer is 40 ng / l.
Origins
Although produced from amino acids during wort boiling most dimethyl trisulphide is formed during storage of packaged beer. Some hops impart this character when used post-fermentation.
Confusions
Professional beer tasters can confuse dimethyl trisulphide with the following flavour compounds:
Methanethiol
Ethanethiol
Dimethyl sulphide
Importance
Onion flavour from dimethyl trisulphide is a desirable hop-derived flavour note in some ales. As an off-flavour it is formed during ageing in package of pale lager beers. It can also be found in fresh lager beer as a result of wort boiling practices (specifically, lack of boil vigour in all-malt worts).
CAS registry number
The CAS registry number of dimethyl trisulphide is 3658-80-8.
Other names
DMTS
1,3-dimethyl trisulfane
methyl trisulfide
methyl trithiomethane
methylsulfanyldisulfanylmethane
methyltrithiomethane
2,3,4-trithiapentane
methylsulfanyldisulfanylmethane
Remarks
Dimethyl trisulphide is recognized as an important contributor to the aged character of pale lager beers.
Threshold distribution
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
US Patent no. D679900
European Community Trade MarkRegistration no. 009937574
European Community Trade MarkRegistration no. 009856527
US Trade Mark Registration no. 4345057
US Trade Mark Registration no. 4345056
ethyl phenylacetate
“Honey , like sweet mead or sherry”
x 1
ethyl phenylacetate
Number of capsules
ethyl phenylacetate
480 µg per capsule
Technical specification
Assessment
The best way to evaluate honey flavour in beer is as follows. Cover the beer 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
480 µg per capsule
Threshold
The flavour threshold of ethyl phenylacetate in beer is 160 µg / l.
Origins
Ethyl phenylacetate is formed during ageing of beer. It tends to develop after the appearance of papery, tobacco and leathery notes, and after the loss of banana and bitter notes.
Confusions
Importance
Ethyl phenylacetate off-flavour formed during ageing in pack from precursors which are formed during fermentation. It is a positive flavour note in Honey beers.
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 off-flavours which develop in some white wines. This flavour note is slow to develop on the palate.
Threshold distribution
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
US Patent no. D679900
European Community Trade MarkRegistration no. 009937574
European Community Trade MarkRegistration no. 009856527
US Trade Mark Registration no. 4345057
US Trade Mark Registration no. 4345056
guaiacol
“Smoky , like smoked fish or cheese”
x 1
guaiacol
Number of capsules
guaiacol
100 µg per capsule
Technical specification
Assessment
The best way to evaluate guaiacol flavour in beer is as follows. Without covering the glass, swirl the beer to release the aroma. Take a single short sniff. Repeat as necessary.
Amount of flavour per capsule
100 µg per capsule
Threshold
The flavour threshold of guaiacol in beer is 33 µg / l.
Origins
Guaiacol is contributed to brewing raw materials (malt, rice etc ) by intentional or non-intentional exposure to smoke. It is occasionally formed by bacteria during fermentation.
Confusions
Professional tasters can confuse guaiacol in beer with the following flavours:
4-Vinyl guaiacol
Eugenol
2,6-Dichlorophenol
Importance
Guaiacol is an off-flavour in pale lager beers. It is a desirable character in some ales, in which it is imparted by speciality malts. Guaiacol is the signature flavour character of Rauchbier (smoked beer).
CAS registry number
The CAS registry number for guaiacol is 90-05-1.
Other names
2-methoxyphenol
anastil
guajacol
guajol
guasol
1-hydroxy-2-methoxybenzene
2-hydroxyanisole
ortho-hydroxyanisole
1-oxy-2- methoxybenzene
ortho- methoxyphenol
methyl catechol
ortho- methyl catechol
pyrocatechol methyl ester
pyrocatechol monomethyl ether
Remarks
Guaicol is a s flavour which tends to polarize consumers – they either love it or hate it.
Threshold distribution
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
US Patent no. D679900
European Community Trade MarkRegistration no. 009937574
European Community Trade MarkRegistration no. 009856527
US Trade Mark Registration no. 4345057
US Trade Mark Registration no. 4345056
trans,trans -2,4-heptadienal
“Rancid oil , like cod liver oil”
x 1
trans,trans -2,4-heptadienal
Number of capsules
trans,trans -2,4-heptadienal
450 µg per capsule
Technical specification
Assessment
The best way to for tasters to detect rancid oil flavours in beer is as follows. Without covering the glass, swirl the beer to release the aroma. Take a single short sniff. Repeat as necessary.
Amount of flavour per capsule
450 µg per capsule
Threshold
The flavour threshold of 2,4-heptadienal in beer is 150 µg / l.
Origins
2,4-Heptadienal is formed in adjuncts, such as maize, during storage as a result of enzymic or non-enzymic lipid oxidation. Use of such materials can lead to development of this rancid oil flavour note in beer.
Confusions
Importance
2,4-Heptadienal is an off-flavour in beer associated with ageing. Beers made with oil-rich adjuncts are most susceptible to development of this flavour.
CAS registry number
The CAS registry number for 2,4-heptadienal is 4313-03-5.
Other names
(2E,4E)-hepta-2,4-dienal
(2trans,4trans)- hepta-2,4-dienal
(E)-2,(E)-4-heptadien-1-al
(E,E)-2,4-heptadien-1-al
trans-2,trans-4-heptadien-1-al
trans,trans-2,4-heptadien-1-al
(E,E)-2,4- heptadienal
Remarks
2,4-Heptadienal is a common fault in high adjunct pale lager beers made in warm climates. The flavour develops during the early stages of oxidation, before the appearance of papery and leathery notes.
Threshold distribution
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
US Patent no. D679900
European Community Trade MarkRegistration no. 009937574
European Community Trade MarkRegistration no. 009856527
US Trade Mark Registration no. 4345057
US Trade Mark Registration no. 4345056
hydrogen sulphide
“H2 S , like boiled or rotten eggs”
x 1
hydrogen sulphide
Number of capsules
hydrogen sulphide
18 µg per capsule
Technical specification
Assessment
The best way to detect hydrogen sulphide in beer is as follows. Without covering the glass, swirl the beer to release the aroma. Take a single short sniff. Repeat as necessary.
Amount of flavour per capsule
18 µg per capsule
Threshold
The flavour threshold of H2 S in beer is 4 µg / l
Origins
Hydrogen sulphide is produced by both ale and lager yeasts during fermentation and maturation. The amount of H2 S produced and retained depends on wort composition, yeast strain and fermentation conditions.
Confusions
Professional beer tasters can confuse H2 S with the following flavours:
Sulphur dioxide
Ethanethiol
Methanethiol
Importance
H2 S is present in all beers. Concentrations vary considerably from beer to beer. H2 S is an off-flavour in most beer styles. It is a signature flavour character in Burton ale.
CAS registry number
The CAS registry number of 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
H2 S can contribute to a perception of ‘freshness’ in beer when present at low levels.
Threshold distribution
Capsules per pot
10
isobutyraldehyde
“Grainy , like germinating malt”
x 1
isobutyraldehyde
Number of capsules
isobutyraldehyde
80 µg per capsule
Technical specification
Assessment
The best way to detect grainy flavour notes in beer from isobutyraldehyde is as follows. Without covering the glass, swirl the beer to release the aroma. Take a single short sniff. Repeat as necessary.
Amount of flavour per capsule
80 µg per capsule
Threshold
The flavour threshold of isobutyraldehyde in beer is 10 - 25 µg / l. The precise threshold is influenced by the sulphur dioxide concentration of the beer.
Origins
Isobutyraldehyde and related compounds can arise in beer through use of pale malts and certain brewhouse procedures. Yeast strain and vigour is also important drivers of isobutyraldehyde levels..
Confusions
Professional beer tasters can confuse isobutyraldehyde with the following flavours
Acetaldehyde
trans -2-Nonenal
trans,trans -2,4-Heptadienal
Importance
Isobutyraldehyde is present in all beers. Concentrations vary from beer to beer. It is a key flavour impact character in some lagers and ales and an off-flavour in low and non-alcoholic beers. Isobutyraldehyde is a signature flavour character in some stouts.
CAS registry number
The CAS registry number of isobutyraldehyde is 78-84-2.
Other names
2-methylpropanal
isobutanal
isobutyl aldehyde
isobutyral
isobutyric aldehyde
2-methyl propanal
2-methyl propionaldehyde
alpha-methyl propionaldehyde
2-methyl-1-propanal
2-methylpropanal
isopropyl aldehyde
valine aldehyde
Remarks
Several compounds, closely related to isobutyraldehyde also impart grainy notes to beer. The flavour impact of such aldehydes is influenced by the sulphur dioxide concentration of the beer.
Threshold distribution
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
US Patent no. D679900
European Community Trade MarkRegistration no. 009937574
European Community Trade MarkRegistration no. 009856527
US Trade Mark Registration no. 4345057
US Trade Mark Registration no. 4345056
isovaleric acid
“Isovaleric , like stale cheese or sweaty socks”
x 1
isovaleric acid
Number of capsules
isovaleric acid
3.0 mg er capsule
Technical specification
Assessment
The best way for assessors to evaluate isovaleric flavour in beer is as follows. Cover the beer 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
3.0 mg er capsule
Threshold
The flavour threshold of isovaleric acid is 1 mg / l.
Origins
Isovaleric acid is derived from breakdown of alpha-acids in hops. It is imparted to beer by use of high hopping rates or degraded hops or hop extracts. Isovaleric acid can occasionally be produced by wild yeasts, specifically Brettanomyces spp which may be present either as contaminants or introduced into beer for conditioning purposes.
Confusions
Professional beer tasters can confuse isovaleric acid with the following flavours:
Butyric acid
Ethyl butyrate
2,3-Butanedione
Importance
Isovaleric, sweaty, cheesy flavour notes are characteristic flavours of some beer styles, eg India Pale Ale. Typical ‘cheesy’ characters are often associated with beers of very high bitterness. In pale lager beers, isovaleric character is regarded as an off-flavour.
CAS registry number
The CAS registry number of 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
The intensity of isovaleric flavour increases with decreasing beer pH value.
Threshold distribution
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
US Patent no. D679900
European Community Trade MarkRegistration no. 009937574
European Community Trade MarkRegistration no. 009856527
US Trade Mark Registration no. 4345057
US Trade Mark Registration no. 4345056
methional
“Methional , like mashed potato or autolysed yeast”
x 1
methional
Number of capsules
methional
17 µg per capsule
Technical specification
Assessment
The best way to detect methional in beer is as follows. Without covering the glass, swirl the beer to release the aroma. Take a single short sniff. Repeat as necessary.
Amount of flavour per capsule
17 µg per capsule
Threshold
The flavour threshold of methional in beer is 5 µg / l.
Origins
Methional is produced in the brewhouse from the breakdown of the sulphur-containing amino acid methionine. It can also be released during beer ageing. In some breweries it can be associated with re-use of beer recovered from yeast and with over-pasteurization of beer.
Confusions
Methanethiol
Dimethyl disulphide
Hydrogen sulphide
Importance
Methional is an important ageing character of lager, ales and stouts. It is a sulphury off-flavour of fresh lager beer. Methional is also a signature ‘worty’ note in many low- and non-alcoholic beers.
CAS registry number
The CAS registry number of methional is 3268-49-3.
Other names
beta-methiopropionaldehyde
beta-(methyl mercapto) propionaldehyde
methyl mercaptopropionaldehyde
3-methyl mercaptopropionaldehyde
beta-methyl mercaptopropionaldehyde
methyl mercaptopropionic aldehyde
3-methyl mercaptopropyl aldehyde
3-(methyl thio) propanal
3-(methyl thio) propionaldehyde
beta-(methyl thio) propionaldehyde
3-methyl thiopropionaldehyde
beta-methyl thiopropionaldehyde
3-methylsulfanylpropanal
Remarks
The flavour impact of methional is influenced by both the alcohol and sulphur dioxide concentrations of the beer. Higher concentrations of both compounds suppress its flavour.
Threshold distribution
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
US Patent no. D679900
European Community Trade MarkRegistration no. 009937574
European Community Trade MarkRegistration no. 009856527
US Trade Mark Registration no. 4345057
US Trade Mark Registration no. 4345056
trans -2-nonenal
“Papery , like cardboard or oxidized beer”
x 1
trans -2-nonenal
Number of capsules
trans -2-nonenal
730 ng per capsule
Technical specification
Assessment
The best way to detect trans-2-nonenal in beer is as follows. Without covering the glass, swirl the beer to release the aroma. Take a single short sniff. Repeat as necessary.
Amount of flavour per capsule
730 ng per capsule
Threshold
The flavour threshold of trans-2-nonenal in beer is 50 – 250 ng / l.
Origins
Nonenal is formed during malt and wort production. After being formed, it binds to malt proteins. It is carried through the brewing process in this bound form before being released during storage of finished beer in bottles, cans or kegs.
Confusions
Nonenal is sometimes confused wth:
2,4,6-Trichloroanisole
2-Ethyl fenchol
Isobutyraldehyde
Importance
Nonenal is an off-flavour in beer associated with ageing. Formation of this flavour is more pronounced when precautions have not been taken in relation to minimizing process oxidation.
CAS registry number
The CAS registry number for nonenal is 18829-56-6.
Other names
(E)-heptylidene acetaldehyde
(E)-3-hexyl acrolein
(E)-3-hexyl-2-propenal
(E)- non-2-enal
trans-non-2-enal
(E)-2-nonen-1-al
trans-2-nonen-1-al
(E)-2- nonenal
trans-2- nonenal
Remarks
Sulphur dioxide in beer reversibly reacts with trans-2-nonenal to reduce its flavour impact.
Threshold distribution
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
US Patent no. D679900
European Community Trade MarkRegistration no. 009937574
European Community Trade MarkRegistration no. 009856527
US Trade Mark Registration no. 4345057
US Trade Mark Registration no. 4345056
styrene
“Plastics , like polystyrene”
x 1
styrene
Number of capsules
styrene
65 µg per capsule
Technical specification
Assessment
Te best way to detect plastic-like notes in beer is as follows. Cover the beer 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
65 µg per capsule
Threshold
The flavour threshold of styrene in beer is 20 µg / l.
Origins
Styrene is produced by contaminant wild yeasts during fermentation. It can also be introduced into beer as a taint through use of contaminated packaging materials or defective carbon dioxide gas.
Confusions
Professional tasters can confuse plastic-like flavours in beer resulting from styrene with the following:
Acetaldehyde
4-Vinyl guaiacol
Eugenol
Importance
Styrene can be both an off-flavour and a taint in beer. It is associated with a moderate degree of consumer rejection in beer. It can be described by consumers as ‘chemical’, ‘plasticy’ or ‘contaminated’.
CAS registry number
The CAS registry number of styrene is 100-42-5.
Other names
ethenylbenzene
phenyl ethene
phenyl ethylene
styrol
styrolene
vinyl benzene
vinyl benzol
Remarks
Other compounds can impart a plastic-like note to beer. Samples containing this standard are best tasted in glass, rather than in plastic, to avoid loss of odour.
Threshold distribution
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
US Patent no. D679900
European Community Trade MarkRegistration no. 009937574
European Community Trade MarkRegistration no. 009856527
US Trade Mark Registration no. 4345057
US Trade Mark Registration no. 4345056