Flavor Compounds: Functions, Applications, and Aroma Thresholds - Part 1

A list of compounds is presented in The Technology of Food Flavoring by Dr. Sun Baoguo, a renowned flavor chemist. The function and application cited reflect Dr. Sun’s expert opinions, and the aroma threshold is provided for each compound to give readers a sense of appropriate usage levels.

This is part of the list, with more to follow.

Acetophenone
Function: Top note
Application Flavor Types: Tobacco flavors
Aroma Threshold: ~10–100 ppb (Sweet, almond-like, floral; moderate threshold)

Allyl 2-methyl-2-butenoate
Function: Modifier
Application Flavor Types: Meat flavors
Aroma Threshold: ~0.1–5 ppb (Sharp, pungent, alliaceous; very low threshold)

Amyl Propionate
Function: Modifier
Application Flavor Types: Apricot, blackcurrant, gooseberry flavors
Aroma Threshold: ~5–100 ppb (Sweet, fruity, apricot-like; moderate threshold)

Angelica Root Oil
Function: Top note, Body, Blending agent
Application Flavor Types: Seasoning, medicinal, beverage flavors
Aroma Threshold: ~10–150 ppb (Herbal, earthy, woody; moderate threshold)

Benzaldehyde
Function: Top note, Fixative
Application Flavor Types: Cherry, fruit, nut flavors
Aroma Threshold: ~0.5–10 ppb (Intense almond, cherry; very low threshold)

Benzoic Acid
Function: Modifier, Body, Modifier
Application Flavor Types: Berry, fruit, seasoning flavors
Aroma Threshold: ~50–500 ppb (Faint, balsamic, slightly sweet; moderate to high threshold)

Benzoin Ester
Function: Top note, Modifier, Fixative
Application Flavor Types: Candy, confectionery flavors
Aroma Threshold: ~10–200 ppb (Sweet, balsamic, vanilla-like; moderate to high threshold)

Benzoin Resin
Function: Top note, Body, Blending agent
Application Flavor Types: Medicinal flavors
Aroma Threshold: ~10–150 ppb (Balsamic, vanilla, warm; moderate threshold)

Benzyl Alcohol
Function: Body, Modifier
Application Flavor Types: Fruit, alcoholic beverage flavors
Aroma Threshold: ~50–500 ppb (Faint, sweet, floral; moderate to high threshold)

Benzyl Phenylacetate
Function: Modifier
Application Flavor Types: Honey flavors
Aroma Threshold: ~10–100 ppb (Sweet, honey, floral; moderate threshold)

Butyl Phenylacetate
Function: Top note, Body
Application Flavor Types: Honey flavors
Aroma Threshold: ~5–100 ppb (Sweet, fruity, honey-like; moderate threshold)

Butyl Propionate
Function: Modifier
Application Flavor Types: Raspberry, cherry, licorice flavors
Aroma Threshold: ~5–100 ppb (Sweet, fruity, rum-like; moderate threshold)

Cedarwood Oil
Function: Top note, Body, Blending agent, Modifier
Application Flavor Types: Medicinal flavors, beverage flavors
Aroma Threshold: ~10–150 ppb (Woody, balsamic, sweet; moderate threshold)

Cedrol
Function: Top note, Blending agent, Modifier
Application Flavor Types: Seasoning flavors
Aroma Threshold: ~5–100 ppb (Woody, cedar, balsamic; low to moderate threshold)

Cedrone
Function: Fixative
Application Flavor Types: Carbonated beverage flavors
Aroma Threshold: ~1–50 ppb (Woody, musk-like, persistent; low threshold)

d-Carvone
Function: Top note
Application Flavor Types: Lime, fruit, seasoning flavors
Aroma Threshold: ~1–50 ppb (Spearmint, caraway; low to moderate threshold)

d-Limonene
Function: Body
Application Flavor Types: Apple, honey, meat flavors
Aroma Threshold: ~10–200 ppb (Citrus, orange; moderate to high threshold)

d-Pinene
Function: Top note, Body
Application Flavor Types: Liqueur, seasoning flavors
Aroma Threshold: ~5–50 ppb (Pine, turpentine, fresh; low to moderate threshold)

Decyl Propionate
Function: Modifier
Application Flavor Types: Peach flavors
Aroma Threshold: ~10–200 ppb (Fruity, waxy, peach-like; moderate to high threshold)

Dodecyl Propionate
Function: Top note, Modifier
Application Flavor Types: Banana, melon, apple flavors
Aroma Threshold: ~10–200 ppb (Fruity, waxy, creamy; moderate threshold)

Ethyl 2,3-dimethylhexanoate
Function: Modifier
Application Flavor Types: Fruit, seasoning flavors
Aroma Threshold: ~1–50 ppb (Fruity, waxy; moderate threshold)

Ethyl 2-nonynoate
Function: Top note
Application Flavor Types: Apricot, peach, violet flavors
Aroma Threshold: ~0.01–1 ppb (Powerful green, fruity, waxy; very low threshold)

Ethyl 3-methyl-3-phenylglycidate
Function: Top note, Body, Modifier
Application Flavor Types: Strawberry, cherry, raspberry flavors
Aroma Threshold: ~0.1–5 ppb (Intense strawberry, fruity; very low threshold)

Ethyl Benzoate
Function: Blending agent, Top note, Body
Application Flavor Types: Fruit, honey, strawberry flavors
Aroma Threshold: ~1–50 ppb (Sweet, fruity, floral; low to moderate threshold)

Ethyl Phenylacetate
Function: Top note, Fixative
Application Flavor Types: Fruit, honey, citrus flavors
Aroma Threshold: ~1–20 ppb (Sweet, honey, floral; low threshold)

Ethyl Phenylacetoacetate
Function: Modifier
Application Flavor Types: Chocolate, honey, seasoning flavors
Aroma Threshold: ~10–150 ppb (Sweet, honey, balsamic; moderate threshold)

Ethyl Propionate
Function: Top note
Application Flavor Types: Butter, fruit flavors
Aroma Threshold: ~1–50 ppb (Sweet, fruity, rum-like; low to moderate threshold)

Ethylene Glycol Diacetate
Function: Blending agent
Application Flavor Types: Meat, seasoning flavors
Aroma Threshold: ~50–500 ppb (Faint, sweet, fruity; moderate to high threshold)

Eucalyptus Oil
Function: Body, Blending agent
Application Flavor Types: Medicinal flavors
Aroma Threshold: ~10–200 ppb (Camphoraceous, fresh, medicinal; moderate threshold)

γ-Dodecalactone
Function: Body
Application Flavor Types: Coconut, fruit flavors
Aroma Threshold: ~0.1–10 ppb (Peach, coconut, fatty; very low to low threshold)

γ-Tridecalactone
Function: Top note, Body, Blending agent
Application Flavor Types: Stone fruit, fruit flavors
Aroma Threshold: ~0.5–20 ppb (Coconut, peach, buttery; low threshold)

γ-Undecalactone
Function: Body
Application Flavor Types: Peach, fruit flavors
Aroma Threshold: ~0.1–5 ppb (Intense peach, apricot, fruity; very low threshold)

Heptyl Propionate
Function: Modifier
Application Flavor Types: Fruit flavors
Aroma Threshold: ~5–100 ppb (Fruity, woody, berry-like; moderate threshold)

Hexyl Propionate
Function: Top note, Body
Application Flavor Types: Fruit flavors
Aroma Threshold: ~1–50 ppb (Sweet, fruity, green; low to moderate threshold)

Isoamyl Phenylacetate
Function: Top note, Body
Application Flavor Types: Butter, condensed milk, fruit, honey flavors
Aroma Threshold: ~5–50 ppb (Sweet, cocoa, honey-like; low to moderate threshold)

l-Geraniol
Function: Body
Application Flavor Types: Seasoning flavors
Aroma Threshold: ~1–20 ppb (Sweet, floral, rose-like; low threshold)

Lime Oil
Function: Modifier
Application Flavor Types: Traditional food, seasoning flavors
Aroma Threshold: ~10–300 ppb (Fresh, citrus, green; moderate threshold)

Linalyl Benzoate
Function: Blending agent
Application Flavor Types: Berry, citrus, fruit, peach flavors
Aroma Threshold: ~10–100 ppb (Sweet, floral, balsamic; moderate threshold)

Menthol
Function: Top note, Body
Application Flavor Types: Candy, cooling product flavors
Aroma Threshold: ~10–100 ppb (Cooling, minty, fresh; moderate threshold)

Menthone
Function: Top note, Body
Application Flavor Types: Candy, cooling product flavors
Aroma Threshold: ~5–50 ppb (Minty, cooling, peppermint-like; low to moderate threshold)

Methyl 2-nonynoate
Function: Top note, Modifier
Application Flavor Types: Citrus flavors
Aroma Threshold: ~0.01–1 ppb (Strong violet, green, citrus; very low threshold)

Methyl 2-octenoate
Function: Blending agent, Fixative
Application Flavor Types: Citrus flavors
Aroma Threshold: ~1–20 ppb (Green, fruity, violet-like; low threshold)

Methyl Benzoate
Function: Modifier, Body
Application Flavor Types: Raspberry, pineapple, strawberry, banana, cherry, berry, coffee flavors
Aroma Threshold: ~1–50 ppb (Fruity, phenolic, wintergreen-like; low to moderate threshold)

Methyl N-methylanthranilate
Function: Top note
Application Flavor Types: Mint flavors
Aroma Threshold: ~0.5–10 ppb (Grape, floral, minty; low threshold)

Naphthaldehyde
Function: Modifier
Application Flavor Types: Fruit, seasoning flavors
Aroma Threshold: ~1–30 ppb (Sweet, almond-like, cherry; low threshold)

Nonyl Propionate
Function: Top note
Application Flavor Types: Peach flavors
Aroma Threshold: ~5–150 ppb (Fruity, fatty, peach-like; moderate threshold)

Octyl Propionate
Function: Top note, Body
Application Flavor Types: Fruit flavors
Aroma Threshold: ~5–100 ppb (Sweet, fruity, waxy; moderate threshold)

Phenylacetaldehyde
Function: Modifier
Application Flavor Types: Pineapple, honey flavors
Aroma Threshold: ~0.5–10 ppb (Intense green, honey, rose; very low threshold)

Phenylacetic Acid
Function: Top note
Application Flavor Types: Honey flavors
Aroma Threshold: ~10–200 ppb (Sweet, honey-like, animalic; moderate threshold)

Phenylethanol
Function: Body, Blending agent
Application Flavor Types: Fruit flavors
Aroma Threshold: ~10–100 ppb (Rose, floral, honey-like; moderate threshold)

Pinene
Function: Body, Blending agent
Application Flavor Types: Beverage flavors
Aroma Threshold: ~5–50 ppb (Pine, woody, fresh; low to moderate threshold)

Propionic Acid
Function: Top note
Application Flavor Types: Fruit flavors
Aroma Threshold: ~20–200 ppb (Sharp, sour, cheesy; moderate to high threshold)

Propyl Benzoate
Function: Blending agent, Modifier
Application Flavor Types: Fruit flavors
Aroma Threshold: ~5–100 ppb (Sweet, fruity, balsamic; moderate threshold)

Propyl Propionate
Function: Modifier
Application Flavor Types: Plum, cherry flavors
Aroma Threshold: ~5–100 ppb (Sweet, fruity, apple-like; moderate threshold)

Thyme Oil
Function: Top note, Body, Modifier
Application Flavor Types: Herbal, bitter flavors
Aroma Threshold: ~5–100 ppb (Herbal, medicinal, spicy; low to moderate threshold)

Thymol
Function: Modifier
Application Flavor Types: Medicinal flavors
Aroma Threshold: ~10–100 ppb (Herbal, medicinal, thyme-like; moderate threshold)

Thymoquinone
Function: Top note, Body, Modifier
Application Flavor Types: Medicinal flavors
Aroma Threshold: ~1–50 ppb (Pungent, spicy, medicinal; low to moderate threshold)

Undecyl Propionate
Function: Top note, Modifier
Application Flavor Types: Pineapple, melon, banana flavors
Aroma Threshold: ~5–100 ppb (Sweet, fruity, waxy; moderate threshold)

White Pepper Oil
Function: Top note, Body, Blending agent
Application Flavor Types: Citrus, cola, candy flavors
Aroma Threshold: ~5–100 ppb (Spicy, piney, fresh; low to moderate threshold)

α-Amylcinnamaldehyde
Function: Body, Modifier
Application Flavor Types: Fruit, nut, honey flavors
Aroma Threshold: ~1–20 ppb (Jasmine, floral, fatty; low to moderate threshold)

α-Amylcinnamic acid
Function: Body
Application Flavor Types: Apricot, peach, sweet flavors
Aroma Threshold: ~10–100 ppb (Sweet, honey-like, fruity; moderate threshold)

α-Ethylcinnamaldehyde
Function: Modifier
Application Flavor Types: Chocolate, fruit, sweet flavors
Aroma Threshold: ~0.5–10 ppb (Sweet, floral, cinnamon-like; low threshold)

α-Geraniol
Function: Body, Modifier
Application Flavor Types: Orange, lemon, seasoning, floral flavors
Aroma Threshold: ~1–20 ppb (Sweet, rose, floral; low threshold)

α-Heptylcinnamaldehyde
Function: Modifier
Application Flavor Types: Berry flavors
Aroma Threshold: ~1–30 ppb (Fatty, floral, green; low to moderate threshold)

α-Hexylcinnamaldehyde
Function: Body
Application Flavor Types: Fruit flavors
Aroma Threshold: ~1–20 ppb (Jasmine, floral, citrus; low threshold)

α-Muskene
Function: Fixative, Modifier
Application Flavor Types: Floral, musk flavors
Aroma Threshold: ~0.1–10 ppb (Musk, warm, sweet; very low threshold, highly persistent)

α-Octylcinnamaldehyde
Function: Top note, Body
Application Flavor Types: Citrus, sweet orange, orange, fruit flavors
Aroma Threshold: ~1–25 ppb (Citrus, fatty, waxy; low threshold)

α-Pinene
Function: Modifier
Application Flavor Types: Berry, lime, seasoning flavors
Aroma Threshold: ~5–50 ppb (Fresh, pine, woody; low to moderate threshold)

α-Terpineol
Function: Top note, Top note, Body
Application Flavor Types: Citrus, fruit, seasoning flavors
Aroma Threshold: ~10–100 ppb (Floral, lilac, citrus; moderate threshold)

β-Ionol
Function: Body
Application Flavor Types: Citrus, sweet orange, orange, fruit flavors
Aroma Threshold: ~0.1–5 ppb (Woody, floral, violet-like; very low threshold)

β-Ionone
Function: Modifier
Application Flavor Types: Nut flavors
Aroma Threshold: ~0.01–1 ppb (Extremely potent violet, woody, berry; one of the lowest thresholds)

β-Phenylethanol
Function: Top note, Modifier
Application Flavor Types: Citrus flavors
Aroma Threshold: ~10–100 ppb (Rose, floral, honey-like; moderate threshold)

β-Pinanol
Function: Top note
Application Flavor Types: Woody flavors
Aroma Threshold: ~5–50 ppb (Pine, woody, fresh; low to moderate threshold)

β-Pinene
Function: Top note, Body, Modifier
Application Flavor Types: Nut flavors
Aroma Threshold: ~5–50 ppb (Pine, woody, fresh; low to moderate threshold)

δ-Decalactone
Function: Body
Application Flavor Types: Butter, fruit, dairy flavors
Aroma Threshold: ~0.5–20 ppb (Creamy, coconut, peach; low threshold)

δ-Dodecalactone
Function: Body, Modifier
Application Flavor Types: Alcoholic beverages, beverages, cream flavors
Aroma Threshold: ~0.5–30 ppb (Buttery, fatty, coconut; low threshold)

2,3-Butanedione
Function: Top note, Body
Application Flavor Types: Butter flavor
Aroma Threshold: ~0.2–10 ppb (Intense buttery, creamy; one of the lowest thresholds in dairy flavors)

2,3-Dimethoxybenzene
Function: Top note, Body, Modifier
Application Flavor Types: Fruit, berry, butter, cheese flavors
Aroma Threshold: ~0.5–20 ppb (Sweet, earthy, nutty; low threshold)

2,3-Dimethylbenzene
Function: Modifier
Application Flavor Types: Tobacco, honey flavors
Aroma Threshold: ~50–500 ppb (Sweet, smoky; relatively higher threshold)

2-Heptanone
Function: Modifier
Application Flavor Types: Fruit flavors
Aroma Threshold: ~50–300 ppb (Fruity, spicy, cinnamon-like; moderate threshold)

2-Methyl-3-furanthiol
Function: Top note, Body
Application Flavor Types: Roasted, citrus flavors
Aroma Threshold: ~0.01–0.5 ppb (Extremely potent meaty, roasted; one of the lowest known thresholds)

2-Methylundecanal
Function: Modifier
Application Flavor Types: Berry, fruit, melon flavors
Aroma Threshold: ~1–30 ppb (Fatty, citrus, melon; low to moderate threshold)

2-Undecanol
Function: Blending agent
Application Flavor Types: Fruit, berry flavors
Aroma Threshold: ~10–100 ppb (Fatty, citrus, waxy; moderate threshold)

3,7-Dimethyloctanal
Function: Top note, Modifier
Application Flavor Types: Lemon, citrus flavors
Aroma Threshold: ~0.5–10 ppb (Fresh, citrus, green; low threshold)

3-Hydroxypropionaldehyde
Function: Body, Modifier
Application Flavor Types: Apricot, bitter almond, cherry flavors
Aroma Threshold: ~5–50 ppb (Sweet, caramel-like, nutty; moderate threshold)

3-Methylbutanal
Function: Top note
Application Flavor Types: Citrus flavors
Aroma Threshold: ~0.5–5 ppb (Sharp, malty, green; very low threshold)

3-Methylbutanol
Function: Modifier
Application Flavor Types: Berry, grape, cheese flavors
Aroma Threshold: ~50–300 ppb (Fusel, alcoholic, fermented; moderate threshold)

4-Carvomenthenol
Function: Top note, Body
Application Flavor Types: Dairy flavors
Aroma Threshold: ~10–100 ppb (Minty, spicy, herbal; moderate threshold)

5-Methylpyrazine
Function: Modifier
Application Flavor Types: Citrus, seasoning flavors
Aroma Threshold: ~0.5–20 ppb (Nutty, roasted, earthy; low threshold)

10-Undecenal
Function: Modifier
Application Flavor Types: Honey flavor
Aroma Threshold: ~0.5–10 ppb (Powerful, waxy, citrus-like; detectable at very low levels)

Note: Aroma thresholds are approximate and can vary depending on the matrix (water, oil, air) and individual sensitivity. Values are provided as general reference ranges based on common flavor industry data.

Definitions and explanations of terms used to describe the function of a compound

Here are definitions for each function term used in the flavor industry, along with explanations to help understand their roles in flavor composition.

Flavor Function Definitions

Top Note

Definition: The initial, most volatile impression of a flavor that is perceived immediately upon smelling or tasting. Top notes are typically sharp, fresh, light, and fleeting.

Explanation: Top notes are the "first impact" of a flavor. They create the initial aroma that reaches the nose the moment a product is opened or consumed. Because they are composed of highly volatile molecules (low molecular weight), they evaporate quickly and are short-lived. Top notes are crucial for capturing attention and creating a positive first impression. Common top notes include citrus, green, fresh fruity, and sharp aldehydic characters.

Example: In a strawberry flavor, the bright, fresh, green note perceived immediately upon smelling is the top note.

Body (or Middle Note / Heart Note)

Definition: The core, substantive character of a flavor that emerges after the top note fades. Body notes provide the main identifiable character, fullness, and roundness of the flavor profile.

Explanation: Body notes form the "heart" of the flavor. They are less volatile than top notes, appearing after the initial impact and lasting longer. These notes define what the flavor actually is—whether it's strawberry, butter, chocolate, or citrus. Body notes provide weight, complexity, and authenticity. Without a well-developed body, a flavor would feel thin, hollow, or one-dimensional. Body notes often include fruity, creamy, nutty, floral, or spicy characteristics that anchor the overall profile.

Example: In a butter flavor, the rich, creamy, diacetyl-forward character that defines it as "butter" is the body.

Modifier

Definition: A component used to adjust, enhance, or alter specific aspects of a flavor profile, often adding nuance, realism, or uniqueness without becoming the dominant character.

Explanation: Modifiers are the "fine-tuning" ingredients. They may not be recognizable on their own but contribute essential subtleties that make a flavor more realistic, natural, or interesting. Modifiers can add green notes to a fruit flavor, enhance the toasted character of a nut flavor, or introduce a fermented nuance to a dairy flavor. They are typically used at low levels and work behind the scenes to elevate the overall quality. A modifier can also correct undesirable traits or balance the interaction between top notes and body.

Example: In a peach flavor, a small amount of green, waxy aldehyde can act as a modifier to make the peach taste fresher and more realistic, mimicking the natural skin note of a fresh peach.

Blending Agent (or Coordinator / Harmonizer)

Definition: A component that smooths out rough edges, unifies disparate notes, and creates a cohesive, harmonious flavor profile where all elements blend seamlessly.

Explanation: Blending agents act as "bridges" between different flavor components. They help merge top notes with the body, soften harsh or sharp notes, and create a smooth transition from the initial impact to the lingering aftertaste. These ingredients often have neutral, sweet, creamy, or balsamic characteristics that do not compete with the main flavor but instead enhance its roundness and polish. A well-chosen blending agent can transform a disjointed collection of notes into a unified, professional flavor.

Example: Vanillin or ethyl vanillin is often used as a blending agent in fruit flavors to soften acidity and create a smooth, sweet harmony between the bright top notes and the fruity body.

Fixative (or Fixative Agent)

Definition: A component that slows the evaporation of more volatile molecules, extending the longevity and persistence of a flavor, particularly the top and middle notes.

Explanation: Fixatives are the "anchors" of a flavor. They have low volatility (high molecular weight) and work by physically or chemically interacting with more volatile molecules, reducing their evaporation rate. This ensures that the flavor remains consistent over time and that the desirable top notes do not dissipate too quickly. Fixatives are especially important in products with long shelf lives, such as baked goods, candles, or perfumery, where flavor longevity is critical. Common fixatives include certain resins, musks, lactones, and high-molecular-weight esters.

Example: In a citrus flavor, a small amount of a high-boiling-point compound like a long-chain ester or a musk can act as a fixative, helping the bright lemon or orange top notes last longer instead of evaporating immediately upon application.

Summary Table

Practical Analogy: A Musical Ensemble

To better understand how these functions work together, imagine a flavor as a piece of music:

• Top Notes are the opening notes of a melody—bright, attention-grabbing, and immediate.
• Body is the main theme or the lead instrument—the recognizable core that defines the piece.
• Modifiers are the subtle ornamentations and embellishments—trills, vibrato, or background harmonies that add depth and realism.
• Blending Agents are the conductor or the rhythm section—they ensure all instruments play together smoothly, creating cohesion.
• Fixatives are the sustain pedal or the reverb—they allow the music to linger, preventing it from ending too abruptly.

Additional Notes

In practice, a single compound can serve multiple functions depending on its concentration, the specific flavor system, and the intended application. For example, a compound listed as a modifier in one flavor might act as part of the body in another. The classification reflects its typical role within the context of the flavor compositions listed.

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