Important Synthetic Flavor Compounds - Part 2 (trans-2-Nonenal, trans-2,cis-6-Nonadienal, trans-2, trans-4-Decadienal, 2-Heptanone, 2-Octen-4-one, Diacetyl, Acetyl methyl carbinol, Acetic acid, Butyric acid, 2-Methyl butyric acid)

Editor

07 Mar 2026 • 8 min read

trans-2-nonenal trans-2,cis-6-nonadienal trans-2, trans-4-decadienal 2-heptanone 2-octen-4-one diacetyl acetyl methyl carbinol acetic acid butyric acid 2-methyl butyric acid

These are part of the 128 flavor compounds John Wright suggests, in his book Flavor Creation, every flavorist should know.

Below is the basic information for the individual flavor compound, including its FEMA number, flavor notes, similar compounds, complementary compounds, potential applications, and regulatory constraints.

trans-2-Nonenal

FEMA Number: 3213
Flavor Note(s): Fatty, green, cucumber, aldehydic, citrus. At low concentrations, it has a distinct cucumber-like and melon rind character with a fatty undertone . Gerard Mosciano described the odor as green, cucumber, aldehydic, fatty with a citrus nuance .
Compounds That Render Similar Flavor Note: Other cucumber-like compounds such as trans-2,cis-6-nonadienal (more intense, fresh cucumber) and cis-6-nonenol (softer, melon-cucumber). It also shares fatty-aldehydic aspects with other 2-alkenals like 2-octenal and 2-decenal.
Compounds Often Used Together With: Used with other green melon and cucumber compounds (e.g., cis-6-nonenol, trans-2,cis-6-nonadienal) to build complex rind and fresh vegetal notes. It can also be paired with fatty aldehydes and other green notes to add realism to fruit and vegetable profiles .
All Potential Applications: Melon flavors (cantaloupe, honeydew), cucumber, citrus peel nuances, and in some savory applications where a fatty-green note is desired . It is also found naturally in many foods including cucumber, melon, fish, roasted peanut, and potato chips .
General Usage Levels: Very potent. Recommended smelling at 1.00% solution or less . In finished flavors, levels would typically be in the very low ppm range (0.01-5 ppm).
Important Considerations for Flavorists: This α,β-unsaturated aldehyde is highly reactive and prone to oxidation and polymerization. It must be stored under inert atmosphere (nitrogen) in tightly sealed containers, protected from light and heat. JECFA concluded "no safety concern at current levels of intake when used as a flavouring agent" . FEMA GRAS.

trans-2,cis-6-Nonadienal

FEMA Number: 3377
Flavor Note(s): Extremely powerful, fresh cucumber, violet leaf, green, melon. It is the primary character-impact compound of fresh cucumber and is often referred to as "cucumber aldehyde" . The odor is intensely green and watery-fresh.
Compounds That Render Similar Flavor Note: trans-2,cis-6-Nonadienol (softer, more attractive, and natural cucumber character) and cis-6-nonenol (melon-cucumber, less intensely cucumber-specific). Other cucumber notes like trans-2-nonenal are less potent and more fatty.
Compounds Often Used Together With: Used almost exclusively to build cucumber flavors. It can be used with cis-6-nonenol to add depth and with other green notes to create a full cucumber profile including peel and flesh . Outside of cucumber, its use is limited by its highly specific profile .
All Potential Applications: Primarily cucumber flavors. It can also find limited use where a subtle cucumber note is desirable, such as in some melon or vegetable complexes .
General Usage Levels: Extremely potent. The dose rate in a flavor intended for use at 0.05% in a finished product would be carefully controlled, typically at very low levels .
Important Considerations for Flavorists: This is a highly reactive dienal, susceptible to isomerization and oxidation. It must be stored at room temperature in airtight containers, protected from light . It is a known skin sensitizer. Meets FG specifications and is KOSHER certified . FEMA GRAS.

trans-2, trans-4-Decadienal

FEMA Number: 3135
Flavor Note(s): Powerful, fatty, fried, oily, chicken fat, citrus rind, green. The main use is to impart a fried character to flavors that include an element of heated fat or oil . It has a dichotomy of being both savory/fatty and melon rindy.
Compounds That Render Similar Flavor Note: Other aliphatic dienals like trans-2,trans-4-nonadienal and trans-2,trans-4-undecadienal. For fried notes, it is quite unique and potent.
Compounds Often Used Together With: Works well when used in conjunction with other similar aliphatic dienals to build complex fried profiles . In nut flavors (hazelnut, peanut), it is paired with pyrazines to create an excellent roasted character . It is also used in chicken flavors with other chicken/meat ketones and sulfur compounds.
All Potential Applications: Nut flavors (hazelnut, peanut, walnut) , savory flavors (chicken with roasted skin note, French fries, roast beef, lamb, bacon) , and dairy flavors (butter, at varying levels for subtle to pungent character) . Also finds application in cucumber, melon, and citrus rind authenticity .
General Usage Levels: Dose rates vary significantly by application. For example, in flavors intended for use at 0.05% in a finished product: Hazelnut flavor ~200 ppm, Roasted peanut ~50 ppm, Chicken with skin note ~200 ppm, Boiled chicken ~30 ppm, Butter ~10-300 ppm . In taste tests, it is noticeable at 1-2 ppm .
Important Considerations for Flavorists: This dienal is highly reactive and sensitive to oxidation and heat, though it is "reasonably, but not ideally, stable in heat processes" . Storage under inert gas, away from light and heat, is essential. JECFA has evaluated it as safe for use as a flavoring agent. FEMA GRAS.

2-Heptanone

FEMA Number: 2544
Flavor Note(s): Fruity, spicy, cinnamon-like, banana-like, with a slight creamy, cheesy, and musty nuance. It provides a sweet, ethereal top note.
Compounds That Render Similar Flavor Note: Other methyl ketones like 2-pentanone (fruity, ethereal) and 2-nonanone (fruity, floral, fatty). For the banana aspect, it is related to isoamyl acetate but is less sweet and more chemical.
Compounds Often Used Together With: Used in banana, blue cheese, and other dairy flavors. In blue cheese, it is combined with other methyl ketones (e.g., 2-nonanone) and lower fatty acids. In fruit flavors, it can be used with esters to add depth and a ripe nuance.
All Potential Applications: Fruit flavors (banana, berry), dairy flavors (cheese, cream), and spice nuances. It is also approved for food use by the FDA.
General Usage Levels: Typical usage levels in finished products range from 1 to 20 ppm, depending on the application and desired intensity.
Important Considerations for Flavorists: Flammable liquid. It is a skin and eye irritant. JECFA concluded "no safety concern at current levels of intake when used as a flavouring agent" . Store in a cool, well-ventilated area away from ignition sources. FEMA GRAS.

2-Octen-4-One

FEMA Number: 3603
Flavor Note(s): While specific flavor notes were not detailed in search results, as a ketone with an unsaturated chain, it likely contributes creamy, fatty, mushroom, or earthy notes with a possible fruity or vegetable nuance.
Compounds That Render Similar Flavor Note: Potentially similar to other unsaturated ketones like 1-octen-3-one (metallic-mushroom) or 3-octen-2-one (earthy, fruity), though specific comparisons require organoleptic testing.
Compounds Often Used Together With: No information found in search results. Would depend on target profile, but likely with other ketones, esters, or green notes.
All Potential Applications: Flavoring agent for food and beverage applications . Specific applications not detailed.
General Usage Levels: No information found in search results.
Important Considerations for Flavorists: This compound is a pale-yellow mobile liquid that requires refrigeration. Keep containers tightly closed in a dry, cool, and well-ventilated place. Keep away from heat, sparks, and flame. It is free from animal products, formaldehyde, and nanomaterials . Store in accordance with national regulations. FEMA GRAS.

Diacetyl

FEMA Number: 2370
Flavor Note(s): Intense, buttery, creamy, sweet, pungent. It is the classic and powerful character-impact compound for butter and other dairy products.
Compounds That Render Similar Flavor Note: Acetyl methyl carbinol (acetoin) which is softer and more milky-buttery, and pentane-2,3-dione which has a deeper, more substantive, and slightly caramel-like buttery note .
Compounds Often Used Together With: In dairy flavors, it is traditionally used with acetoin, butyric acid, and delta-lactones. In brown flavors (butterscotch, caramel), it is used with vanillin, maltol, and other caramelic compounds.
All Potential Applications: Butter, margarine, milk, cream, cheese, yogurt, butterscotch, caramel, coffee, and many baked goods.
General Usage Levels: Extremely potent. Usage levels are very low, often in the range of 1-10 ppm in the finished product.
Important Considerations for Flavorists: Diacetyl is highly volatile and flammable. It has come under significant regulatory scrutiny in recent years due to respiratory hazards associated with inhalation of vapors in industrial settings (popcorn worker's lung). It must be handled with extreme care, using proper ventilation and personal protective equipment. It is subject to specific safety regulations and handling guidelines in many countries.

Acetyl Methyl Carbinol (Acetoin)

FEMA Number: 2008
Flavor Note(s): Buttery, creamy, milky, fatty. It has a much softer, milder, and more subtle buttery note than diacetyl, with a pleasant yogurt-like quality .
Compounds That Render Similar Flavor Note: Diacetyl (much more intense, sharp buttery) and pentane-2,3-dione (deeper, more substantive, with brown notes) .
Compounds Often Used Together With: In some respects, acetoin is actually more authentic than diacetyl in some dairy flavors . It is often used as a base for butter flavors, with small amounts of diacetyl or pentane-2,3-dione added for impact. It is also used in brown, fruit, and nut flavors to add creaminess and depth.
All Potential Applications: Dairy products (butter, yogurt, cream, milk), baked goods, brown flavors (caramel, butterscotch), and fruit flavors (strawberry, raspberry) to add a creamy mouthfeel . It is also used in fragrances and cosmetics .
General Usage Levels: Used at significantly higher levels than diacetyl. In flavors intended for use at 0.05% in a finished product, levels can range from 400 ppm in fresh butter flavors to much higher levels in other applications.
Important Considerations for Flavorists: Acetoin can exist as a monomer (liquid) or dimer (solid). It is important to know which form is being used, as this affects handling and solvation. It is flammable and can be an irritant. It meets FG specifications and is KOSHER certified . FEMA GRAS.

Acetic Acid

FEMA Number: 2006
Flavor Note(s): Pungent, sour, vinegar-like, sharp. At low dilutions, it provides a clean, sharp acidity and sourness.
Compounds That Render Similar Flavor Note: Other short-chain volatile acids like propionic acid (pungent, slightly cheesy) and butyric acid (rancid, cheesy). For sourness, non-volatile acids like citric and lactic acid are used but lack the volatile pungency.
Compounds Often Used Together With: Used extensively with other fatty acids (butyric, propionic) in cheese, vinegar, and dairy flavors. It is a key component in sourdough, brown sugar, and many fruit flavor complexes to provide lift and sourness.
All Potential Applications: Vinegar flavors, cheese flavors, sourdough, brown sugar, fruit flavors (to enhance sourness), and as an acidulant in many processed foods.
General Usage Levels: Usage levels vary widely depending on application, from trace amounts in complex flavors to higher levels in sour or vinegar-type flavors.
Important Considerations for Flavorists: Corrosive in its concentrated form. It is flammable and a strong irritant to skin, eyes, and mucous membranes. It must be handled with care using appropriate PPE. FEMA GRAS.

Butyric Acid

FEMA Number: 2221
Flavor Note(s): Strong, penetrating, rancid, cheesy, butter-like. At low dilution, it becomes characteristically cheesy and buttery.
Compounds That Render Similar Flavor Note: Other short-chain fatty acids like propionic (less rancid, more pungent) and 2-methylbutyric acid (fruity-cheesy). Esters of butyric acid (e.g., ethyl butyrate) are fruity and not rancid.
Compounds Often Used Together With: An essential component in all cheese flavors (blue cheese, cheddar, parmesan), used with other fatty acids, methyl ketones, and lactones. It is also used in butter, butterscotch, caramel, and some fruit flavors (like apricot) to add depth and a fermented note.
All Potential Applications: Cheese flavors (all types), butter, butterscotch, caramel, rum, and some fruit and nut flavors.
General Usage Levels: Very potent. Usage levels in finished products are typically low, ranging from trace amounts to 10-50 ppm, depending on the desired cheesy intensity.
Important Considerations for Flavorists: Corrosive and has an extremely persistent and unpleasant odor in its concentrated form. It must be handled with extreme care to avoid contamination of work areas and clothing. Store in tightly sealed containers. FEMA GRAS.

2-Methyl Butyric Acid

FEMA Number: 2695
Flavor Note(s): Pungent, acidic, fruity, cheesy, with a distinct roasted nuance. Unlike butyric acid, it has a fruity character (reminiscent of apple or strawberry) combined with its cheesy-sweaty notes.
Compounds That Render Similar Flavor Note: 3-Methylbutyric acid (isovaleric acid) which is more sweaty, rancid, and cheese-like. The 2-methyl isomer is fruitier and less harsh.
Compounds Often Used Together With: Used in cheese flavors to add a complex, fruity-cheesy depth. It is also valuable in fruit flavors (apple, strawberry), nut flavors, and some brown flavors like cocoa and chocolate, often in combination with its esters and other short-chain acids.
All Potential Applications: Cheese flavors (especially aged/specialty cheeses), fruit flavors (apple, strawberry, tropical), cocoa, chocolate, coffee, nut flavors, and some fermented applications.
General Usage Levels: Used at low levels, typically from 1 to 20 ppm in the finished product, depending on the target profile.
Important Considerations for Flavorists: Corrosive and a skin, eye, and respiratory irritant. It has a strong, persistent odor. Handle with adequate ventilation and PPE. Store in tightly sealed containers away from heat and ignition sources. FEMA GRAS. d