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beer off-flavours kit


Beer flavour standards kit used to train professional tasters to recognize and scale the intensity of 12 different off-flavours found in lagers, ales, stouts and wheat beers.

Use this flavours kit to deliver up to 20 hours of taster training to up to ten people. The kit comes in a presentation case together with one set of informative beer flavour cards. AROXA™ beer flavour standards are: food grade | free from sensory impurities | extensively tested | safe to smell and taste. Unsure whether this kit is right for you? Don't forget about our 100% satisfaction guarantee.

Flavours in this kit:

Flavour cards

Flavour standard information

AROXA off-flavours kit for beer
earn 90 points
£899.00
OR

"acetic, like vinegar or spoiled beer"

Number of capsules x 1
Sub-product image
  • Sub-product label imageacetic acid
  • acetic acid beer flavour standard capsulesNumber of capsules
  • Chemical structure

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
Graph
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
  • US Patent no. D679900
  • European Community Trade Mark
    Registration no. 009937574
  • European Community Trade Mark
    Registration no. 009856527
  • US Trade Mark Registration no. 4345057
  • US Trade Mark Registration no. 4345056

“Butyric“, rancid, like baby vomit”

Number of capsules x 1
Sub-product image
  • Sub-product label imagebutyric acid
  • capsules for butyric acid beer flavour standardNumber of capsules
  • Chemical structure

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
Graph
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
  • US Patent no. D679900
  • European Community Trade Mark
    Registration no. 009937574
  • European Community Trade Mark
    Registration no. 009856527
  • US Trade Mark Registration no. 4345057
  • US Trade Mark Registration no. 4345056

“Onion, like fried onion or garlic”

Number of capsules x 1
Sub-product image
  • Sub-product label imagedimethyl trisulphide
  • capsule for dimethyl trisulphide beer flavour standard - onionNumber of capsules
  • Chemical structure

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
Graph
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
  • US Patent no. D679900
  • European Community Trade Mark
    Registration no. 009937574
  • European Community Trade Mark
    Registration no. 009856527
  • US Trade Mark Registration no. 4345057
  • US Trade Mark Registration no. 4345056

“Honey, like sweet mead or sherry”

Number of capsules x 1
Sub-product image
  • Sub-product label imageethyl phenylacetate
  • capsule for ethyl phenylacetate beer flavour standardNumber of capsules
  • Chemical structure

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
  • Not yet known
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
Graph
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
  • US Patent no. D679900
  • European Community Trade Mark
    Registration no. 009937574
  • European Community Trade Mark
    Registration no. 009856527
  • US Trade Mark Registration no. 4345057
  • US Trade Mark Registration no. 4345056

“Smoky, like smoked fish or cheese”

Number of capsules x 1
Sub-product image
  • Sub-product label imageguaiacol
  • capsule for guaiacol beer flavour standardNumber of capsules
  • Chemical structure

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
Graph
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
  • US Patent no. D679900
  • European Community Trade Mark
    Registration no. 009937574
  • European Community Trade Mark
    Registration no. 009856527
  • US Trade Mark Registration no. 4345057
  • US Trade Mark Registration no. 4345056

“Rancid oil, like cod liver oil”

Number of capsules x 1
Sub-product image
  • Sub-product label imagetrans,trans-2,4-heptadienal
  • capsule for rancid oil beer flavour standardNumber of capsules
  • Chemical structure

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
  • Not yet known
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
Graph
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
  • US Patent no. D679900
  • European Community Trade Mark
    Registration no. 009937574
  • European Community Trade Mark
    Registration no. 009856527
  • US Trade Mark Registration no. 4345057
  • US Trade Mark Registration no. 4345056

“H2S, like boiled or rotten eggs”

Number of capsules x 1
Sub-product image
  • Sub-product label imagehydrogen sulphide
  • Capsule for hydrogen sulphide beer flavour standardNumber of capsules
  • Chemical structure

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 H2S in beer is 4 µg / l
Origins
Hydrogen sulphide is produced by both ale and lager yeasts during fermentation and maturation. The amount of H2S produced and retained depends on wort composition, yeast strain and fermentation conditions.
Confusions

Professional beer tasters can confuse H2S with the following flavours:

  • Sulphur dioxide
  • Ethanethiol
  • Methanethiol
Importance
H2S is present in all beers. Concentrations vary considerably from beer to beer. H2S 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 H2S is 7783-06-4.
Other names
  • H2S
  • hydrogen sulfide
  • dihydrogen monosulfide
  • dihydrogen monosulphide
  • hydrogen sulfuric acid
  • hydrogen sulphuric acid
  • sulfur hydride
Remarks
H2S can contribute to a perception of ‘freshness’ in beer when present at low levels.
Threshold distribution
Graph
Capsules per pot
10

“Grainy, like germinating malt”

Number of capsules x 1
Sub-product image
  • Sub-product label imageisobutyraldehyde
  • Capsule for isobutyraldehyde beer flavour standardNumber of capsules
  • Chemical structure

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
Graph
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
  • US Patent no. D679900
  • European Community Trade Mark
    Registration no. 009937574
  • European Community Trade Mark
    Registration no. 009856527
  • US Trade Mark Registration no. 4345057
  • US Trade Mark Registration no. 4345056

“Isovaleric, like stale cheese or sweaty socks”

Number of capsules x 1
Sub-product image
  • Sub-product label imageisovaleric acid
  • Capsule for isovaleric beer flavour standardNumber of capsules
  • Chemical structure

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
Graph
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
  • US Patent no. D679900
  • European Community Trade Mark
    Registration no. 009937574
  • European Community Trade Mark
    Registration no. 009856527
  • US Trade Mark Registration no. 4345057
  • US Trade Mark Registration no. 4345056

“Methional, like mashed potato or autolysed yeast”

Number of capsules x 1
Sub-product image
  • Sub-product label imagemethional
  • Capsule for mercaptan beer flavour standardNumber of capsules
  • Chemical structure

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
Graph
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
  • US Patent no. D679900
  • European Community Trade Mark
    Registration no. 009937574
  • European Community Trade Mark
    Registration no. 009856527
  • US Trade Mark Registration no. 4345057
  • US Trade Mark Registration no. 4345056

“Papery, like cardboard or oxidized beer”

Number of capsules x 1
Sub-product image
  • Sub-product label imagetrans-2-nonenal
  • Capsule for papery beer flavour standardNumber of capsules
  • Chemical structure

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
Graph
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
  • US Patent no. D679900
  • European Community Trade Mark
    Registration no. 009937574
  • European Community Trade Mark
    Registration no. 009856527
  • US Trade Mark Registration no. 4345057
  • US Trade Mark Registration no. 4345056

“Plastics, like polystyrene”

Number of capsules x 1
Sub-product image
  • Sub-product label imagestyrene
  • Capsule for styrene beer flavour standardNumber of capsules
  • Chemical structure

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
Graph
Capsules per pot
10
Legal notices
This product is protected by the following trade marks and patents:
  • US Patent no. D679900
  • European Community Trade Mark
    Registration no. 009937574
  • European Community Trade Mark
    Registration no. 009856527
  • US Trade Mark Registration no. 4345057
  • US Trade Mark Registration no. 4345056