acetaldehyde
“Acetaldehyde , like emulsion paint or green apples”
acetaldehyde
15 mg per capsule
Technical specification
Assessment
The best way to assess the flavour of acetaldehyde in cider 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
15 mg per capsule Threshold
The flavour threshold of acetaldehyde in cider is 5 mg / l. The threshold increases as the sulphur dioxide concentration of the cider increases. Origins
Acetaldehyde is produced by yeast during fermentation. High levels of acetaldehyde are indicative of fermentation problems, poor control of dissolved oxygen during maturation or packaging or spoilage by Zymomonas bacteria. Importance
Acetaldehyde is present in all ciders. Low levels of acetaldehyde contribute to apple character, cleanness and complexity of cider. Acetaldehyde is an off-flavour at high concentrations when the note resembles emulsion paint. CAS registry number
The CAS registry number of acetaldehyde is 75-07-0. Other names
acetic aldehyde
ethanal
ethyl aldehyde
acetaldehyd
aldehyde acetique
aldeide acetica
octowy aldehyd
Remarks
Apple character in cider is dominated by ethyl-2-methyl butyrate. The flavour impact of acetaldehyde is reduced as the sulphur dioxide concentration of the product increases. Threshold distribution
Capsules per pot
8
2,3-butanedione
“Diacetyl , like butter, or butter popcorn”
2,3-butanedione
130 µg per capsule
Technical specification
Assessment
The best way to detect diacetyl character in cider 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
130 µg per capsule Threshold
40 µg / l in cider Origins
Produced in cider from a precursor formed by yeast during fermentation. Diacetyl can also be formed by contaminant lactic acid bacteria including Lactobacillus and Pediococcus . Importance
Diacetyl is a desirable flavour in some ciders, and an off-flavour in others. In traditional ciders it arises from secondary fermentation with malo-lactic bacteria. Such ciders have higher levels of 2,3-butanedione compared with those produced more rapidly, without a malo-lactic fermentation. CAS registry number
The CAS registry number of 2,3-butanedione is 431-03-8. Other names
diacetyl
biacetyl
2,3-butane dione
butane-2,3-dione
2,3-diketobutane
dimethyl diketone
dimethyl glyoxal
2,3-dioxobutane
Remarks
2,3-Butanedione is one of two vicinal diketones found in cider. The ratio of butanedione to pentanedione can be used as an indicator of the source of the diacetyl flavour, since bacteria produce diacetyl and no pentanedione, while yeast produces the precursors of both diacetyl and pentanedione. Threshold distribution
Capsules per pot
10
citric acid
“Sour , like lemon juice, acidic”
Technical specification
Amount of flavour per capsule
457 mg CAS registry number
77-92-9 Other names
3-carboxy-3-hydroxypentane-1,5-dioic acid
citretten
2-hydroxy-1,2,3-propane tricarboxylic acid
2-hydroxypropane tricarboxylic acid
2-hydroxypropane-1,2,3-tricarboxylic acid
2-hydroxytricarballylic acid
beta-hydroxytricarboxylic acid
Threshold distribution
Capsules per pot
10
ethyl acetate
“Ethyl acetate , like nail varnish remover”
ethyl acetate
15 mg per capsule
Technical specification
Assessment
The best way to evaluate solvent-like estery flavours in cider caused by ethyl acetate 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
15 mg per capsule Threshold
The flavour threshold of ethyl acetate in cider is 10 mg / l. Origins
Ethyl acetate is roduced by yeast during fermentation. The amount of ethyl acetate formed depends on juice composition, yeast strain and fermentation conditions. Some wild yeasts produce very high levels of ethyl acetate. Importance
Ethyl acetate is present in all ciders, and the ester found in greatest amounts in cider. It imparts a solvent-like note to cider which at low levels contributes to flavour balance. Excessive levels of acetic acid, in combination with the presence of acetic acid, contribute to ‘volatile acidity’. CAS registry number
The CAS registry number for ethyl acetate is 141-78-6. Other names
acetic acid ethyl ester
acetic ether
acetoxyethane
methyl trithiomethane
methylsulfanyldisulfanylmethane
methyltrithiomethane
2,3,4-trithiapentane
methylsulfanyldisulfanylmethane
Remarks
Use two capsules of this flavour standard in each litre of cider to achieve a similar flavour intensity to that achieved using other flavour standards. Threshold distribution
Capsules per pot
8
ethyl hexanoate
“Ethyl hexanoate , like apple or aniseed”
ethyl hexanoate
600 µg per capsule
Technical specification
Assessment
The best way to detect estery notes from ethyl hexanoate in cider 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
600 µg per capsule Threshold
The flavour threshold of ethyl hexanoate in cider is 200 µg / l. Origins
Ethyl hexanoate is produced by yeast during fermentation. The amount formed depends on juice composition, yeast strain and fermentation conditions. Some wild yeasts produce high levels of ethyl hexanoate. Importance
Ethyl hexanoate is an ester which is present in all ciders and a contributor to the complexity of apple flavour character. Concentrations of ethyl hexanoate vary from cider to cider. CAS registry number
The CAS registry number for ethyl hexanoate is 123-66-0. Other names
butyl acetic acid ethyl ester
capronic ether
ethyl caproate
ethyl hexoate
hexanoic acid ethyl ester
Remarks
Apple character in cider is dominated by ethyl-2-methyl butyrate. Excessive concentrations of ethyl hexanoate are indicative of poor yeast handling or excessive growth of wild yeasts. Threshold distribution
Capsules per pot
10
4-ethyl phenol
“Band aid , like a cider contaminated with Brettanomyces ”
4-ethyl phenol
1.0 mg per capsule
Technical specification
Assessment
The best way to evaluate band aid, horsey flavour notes caused by growth of Brettanomyces in cider 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
1.0 mg per capsule Threshold
The flavour threshold of 4-ethyl phenol in cider is 300 µg / l. Origins
4-Ethyl phenol is produced by contaminant Brettanomyces (Dekkera ) yeasts and, occasionally by lactic acid bacteria, during cider production. Ciders which are low in sulphur dioxide are particularly sensitive to growth of such microorganisms. Importance
4-Ethyl phenol imparts an unpleasant band aid-like character to cider, described by some as ‘barny’ or ‘horsey’. At low levels the odour resembles that of leather. In traditional ciders, growth of Brettanomyces can add complexity to the product, helping to differentiate it from other ciders. CAS registry number
The CAS registry number for 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 often occurs in combination with other compounds produced by Brettanomyces , including acetic acid, ethyl acetate, isovaleric acid, and other phenolic compounds such as ethyl guaiacol. Threshold distribution
Capsules per pot
10
hydrogen sulphide
“H2 S , like boiled or rotten eggs”
hydrogen sulphide
18 µg per capsule
Technical specification
Assessment
The best way to detect sulphury, sulphidic flavour notes in cider 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
18 µg per capsule Threshold
The flavour threshold of hydrogen sulphide in cider is 4 µg / l. Origins
Hydrogen sulphide is a normal fermentation product of yeast - excessive levels of H2 S are caused by non-optimal concentrations of amino acids in juice. Hydrogen sulphide can be also be introduced through use of insufficiently-purified carbon dioxide for carbonation and by microbiological spoilage of cider. Importance
Hydrogen sulphide is present in all ciders. Concentrations of H2 S vary considerably from one cider to another. H2 S is an off-flavour at high concentrations but contributes positively to cider flavour complexity when present in low amounts. Supplementation of juice with ammonium salts prior to fermentation can help minimize formation of H2 S. Copper treatment of finished cider can eliminate any H2 S formed. CAS registry number
The CAS registry number for hydrogen sulphide 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 when evaluating samples containing it. The more you look for it the less likely you are to find it. Threshold distribution
Capsules per pot
10
methanethiol
“Mercaptan , like drains or rotting garbage”
methanethiol
4.5 µg per capsule
Technical specification
Assessment
The best way to detect mercaptan odours in cider 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
4.5 µg per capsule Threshold
The flavour threshold of methanethiol in cider is 1.5 µg / l. Origins
Methanethiol arises in cider production through yeast autolysis at the end of fermentation or during maturation. Formation of high levels of mercaptans by yeast can be indicative of a deficiency of amino acids in the apple juice. Importance
Methanethiol is a component of the sulphury flavour character of cider. It is found in all ciders to a degree. Methanethiol is an off-flavour when present in cider in excess. Supplementation of juice with ammonium salts prior to fermentation can help control formation of mercaptans in ciders. CAS registry number
The CAS registry number for methanethiol is 74-93-1. Other names
methyl mercaptan
mercaptomethane
methane thiol
methyl sulfhydrate
thiomethanol
thiomethyl alcohol
Remarks
Methanethiol is the main thiol found in cider. Other thiols give similar flavour notes which have subtle differences in relation to their flavour associations. Threshold distribution
Capsules per pot
10
