Important Synthetic Flavor Compounds - Part 12 (difurfuryl sulfide, maltol, ethyl maltol, indole, 2,3-dimethyl pyrazine, trimethyl pyrazine, tetramethyl pyrazine, 2-acetyl pyrazine, 2-methoxy-3-methyl pyrazine, 2-methoxy 3-ethyl pyrazine)

Editor

22 Mar 2026 • 14 min read

Part 12 (difurfuryl sulfide maltol ethyl maltol indole 2,3-dimethyl pyrazine trimethyl pyrazine tetramethyl pyrazine 2-acetyl pyrazine 2-methoxy-3-methyl pyrazine 2-methoxy 3-ethyl pyrazine)

These are among the 128 synthetic flavor compounds that John Wright, in his book Flavor Creation, suggests every flavorist should know and work with.

Here's the revised content with CAS numbers, standardized formatting, regulatory clarity, safety details, and expanded technical information for each compound:

Important Synthetic Flavor Compounds - Part 12 (Enhanced Edition)

Difurfuryl Sulfide

CAS Number: 13678-67-6
FEMA Number: 3238
Regulatory Status: FEMA GRAS
Flavor Note(s): Powerful, earthy, mushroom, coffee, meaty, sulfury. The taste is earthy, mushroom, metallic, with bloody savory notes.
Odor Threshold: Extremely low; estimated in the low ppb range (1–10 ppb) in water
Compounds That Render Similar Flavor Note: Furfuryl mercaptan (coffee, meaty), 2-methyl-3-furanthiol (meaty), and other sulfur-containing furans.
Compounds Often Used Together With: Used with other sulfur compounds, furanones, and pyrazines in coffee, meat, and savory flavor complexes to build roasted and meaty profiles.
All Potential Applications: Coffee, meat (beef, chicken), savory flavors, and roasted notes for beverages, soups, sauces, and seasonings.
General Usage Levels: Extremely potent. In finished products: 0.05–2 ppb. In flavor concentrates: 0.0001–0.001% (1–10 ppm). Always handle as a highly diluted solution (0.01–0.1%) due to potency.
Safety & Handling: Yellow-brown to brown solid. Melting point: 29–32°C (84–90°F). Flash point: >230°F (>110°C). LogP (o/w): 2.51. Store in a cool, dry place in tightly sealed containers, protected from light. As a potent sulfur compound, may cause olfactory fatigue; use adequate ventilation. Shelf life: 12–24 months when stored properly.

Maltol

CAS Number: 118-71-8
FEMA Number: 2656
Regulatory Status: FEMA GRAS. International Note: In China, it is regulated as a synthetic food flavor with specific applicable food categories and maximum content limits.
Flavor Note(s): Sweet, caramelic, cotton candy-like, fruity, with a jammy nuance. It enhances sweetness and provides a creamy mouthfeel.
Odor Threshold: Approximately 10–50 ppb in water
Compounds That Render Similar Flavor Note: Ethyl maltol (more intense, sweeter), furaneol (strawberry, caramel), and other caramelic furanones.
Compounds Often Used Together With: Used extensively with ethyl maltol and vanillin in vanilla, chocolate, caramel, and fruit flavors. It synergizes with many sweet and fruity notes.
All Potential Applications: Vanilla, chocolate, caramel, butterscotch, strawberry, pineapple, and other fruit flavors for beverages, baked goods, confectionery, and dairy products.
General Usage Levels: Used at moderate levels. In finished products: 5–100 ppm, depending on application. In flavor concentrates: 0.05–1.0%. For dairy applications, use 10–30 ppm; for confectionery, 20–100 ppm.
Safety & Handling: White crystalline powder. Melting point: 160–164°C (320–327°F). Flash point: >200°F (>93°C). Soluble in propylene glycol and ethanol; sparingly soluble in water. Store in a cool, dry place in tightly sealed containers, protected from light and moisture. Stable under normal storage conditions. Shelf life: 24 months.

Ethyl Maltol

CAS Number: 4940-11-8
FEMA Number: 3487
Regulatory Status: FEMA GRAS. Not restricted by IFRA (as of 51st Amendment). Approved in EU under Regulation (EC) No 1334/2008.
Flavor Note(s): Sweet, sugary, caramelised, jammy, strawberry-like odour reminiscent of candyfloss (cotton candy). The flavor is sweet, burnt cotton sugar candy-like, with jammy, strawberry notes.
Odor Threshold: Approximately 1–10 ppb in water (more potent than maltol)
Compounds That Render Similar Flavor Note: Maltol (softer, less intense), furaneol (strawberry, caramel), and other caramelic compounds.
Compounds Often Used Together With: Used with vanillin (reinforces creamy sweetness), methyl anthranilate (adds grape-candy freshness), gamma-undecalactone (evokes peach or milky fruit), and delta-decalactone (deepens creamy and coconut-like effects).
All Potential Applications: Vanilla, caramel, strawberry, pineapple, and other fruit flavors. Used extensively in confectionery, baked goods, soft drinks, tobacco, and dairy products.
General Usage Levels: Highly diffusive and bloom-enhancing at low concentrations. In finished products: 2–50 ppm (often used at 5–20 ppm for fruit flavors, 10–50 ppm for vanilla/caramel). In flavor concentrates: 0.02–0.5%. Acts as a rounder and smoother in fruity-lactonic blends.
Safety & Handling: White to slightly yellow crystalline powder. Melting point: 89–93°C (192–199°F). Flash point: >200°F (>93°C). Stable in alcohol and oil bases with good thermal resistance. Store in a cool, dry place in tightly sealed containers, protected from light and moisture. Shelf life: 24 months.

Indole

CAS Number: 120-72-9
FEMA Number: 2593
Regulatory Status: FEMA GRAS. Note: Subject to concentration restrictions in some applications due to its potent odor profile.
Flavor Note(s): Animal, fecal, mothball-like at high concentrations. At low dilutions (0.1% or less), it becomes floral, jasmine-like, and sweet.
Odor Threshold: Approximately 10–100 ppb in water (fecal/animal at higher concentrations)
Compounds That Render Similar Flavor Note: Skatole (3-methylindole; more fecal-intense), anthranilates (floral-grape), and other nitrogen-containing heterocycles.
Compounds Often Used Together With: Used with jasmine, neroli, orange blossom, and other white floral notes in floral flavors. Also used in cheese (particularly Swiss) and animalic savory nuances.
All Potential Applications: Jasmine, neroli, orange blossom, and other floral flavors for beverages, confectionery, and dairy. Used in cheese flavors (Swiss, provolone) and small amounts in fruit flavors to add naturalness.
General Usage Levels: Very potent. In finished products: 0.05–2 ppb for floral applications (higher levels become objectionable). In flavor concentrates: 0.0001–0.01% (1–100 ppm). For jasmine and orange blossom, use at 0.1–0.5 ppb; for cheese notes, 0.5–2 ppb.
Safety & Handling: White to off-white crystalline flakes or powder. Melting point: 52–54°C (126–129°F). Flash point: >200°F (>93°C). Can cause skin sensitization; use appropriate gloves (nitrile) and avoid inhalation. Store in a cool, dark place in tightly sealed containers, protected from light and air. Sublimes at room temperature; ensure tight closure. Shelf life: 24 months when stored properly.

2,3-Dimethyl Pyrazine

CAS Number: 5910-89-4
FEMA Number: 3271
Regulatory Status: FEMA GRAS. Food Chemicals Codex listed.
Flavor Note(s): Nutty, nut skin, cocoa, peanut butter, coffee, walnut, caramellic, roasted, musty, powdery, potato.
Odor Threshold: Approximately 100–500 ppb in water
Compounds That Render Similar Flavor Note: 2,5-Dimethylpyrazine (nutty, earthy), 2,6-Dimethylpyrazine (nutty, cocoa), and trimethylpyrazine (nutty, potato).
Compounds Often Used Together With: Used with other pyrazines, thiazoles, and furanones in nut, cocoa, coffee, and savory flavor complexes. Pairs well with 2,5-dimethylpyrazine for peanut and cocoa profiles.
All Potential Applications: Nut flavors (peanut, walnut, filbert), cocoa, coffee, potato, corn chip, and baked good flavors.
General Usage Levels: High odor strength; recommended smelling in a 0.10% solution or less. In finished products: 0.5–10 ppm. In flavor concentrates: 0.005–0.1% (50–1000 ppm). For peanut and cocoa applications: 2–5 ppm.
Safety & Handling: Colorless to pale yellow clear liquid. Flash point: 128°F (53°C). Store in a cool, dry place in tightly sealed containers, protected from light. Flammable; keep away from ignition sources. Use with adequate ventilation. Shelf life: 24 months.

Trimethyl Pyrazine (2,3,5-Trimethyl Pyrazine)

CAS Number: 14667-55-1
FEMA Number: 3244
Regulatory Status: FEMA GRAS
Flavor Note(s): Nutty, musty, powdery cocoa, potato and musty odor. Taste is raw, musty, nutty, potato.
Odor Threshold: Approximately 50–200 ppb in water
Compounds That Render Similar Flavor Note: Tetramethylpyrazine (nutty, cocoa, vanilla-like), 2,3-dimethylpyrazine (nutty, cocoa), and other alkylpyrazines.
Compounds Often Used Together With: Used with other pyrazines in cocoa, coffee, potato, and nut flavor complexes. Commonly paired with 2,3-diethylpyrazine for more complex roasted notes.
All Potential Applications: Cocoa, coffee, potato, peanut, and other nut and savory flavors for beverages, baked goods, and seasonings.
General Usage Levels: Used at low to moderate levels. In finished products: 1–15 ppm. In flavor concentrates: 0.01–0.15% (100–1500 ppm). For cocoa and coffee applications: 3–10 ppm.
Safety & Handling: Colorless to pale yellow clear liquid. Flash point: 130°F (54°C). Store in a cool, dry place in tightly sealed containers, protected from light. Flammable; use proper grounding when transferring. Shelf life: 24 months.

Tetramethyl Pyrazine (2,3,5,6-Tetramethyl Pyrazine)

CAS Number: 1124-11-4
FEMA Number: 3237
Regulatory Status: FEMA GRAS
Flavor Note(s): Nutty, musty and vanilla with dry, brown cocoa nuances. Taste is nutty, musty, cocoa, drying, peanut-like and raw coffee notes.
Odor Threshold: Approximately 100–500 ppb in water (less volatile than lower alkylpyrazines)
Compounds That Render Similar Flavor Note: Trimethylpyrazine (nutty, potato), 2,3-dimethylpyrazine (nutty, cocoa), and other alkylpyrazines with roasted notes.
Compounds Often Used Together With: Used with other pyrazines and furanones in cocoa, coffee, nut, and vanilla flavor complexes. Adds dry, roasted depth to sweet brown flavors.
All Potential Applications: Cocoa, coffee, peanut, and other nut and brown flavors where a dry, roasted cocoa note is desired. Also used in vanilla and caramel blends for added complexity.
General Usage Levels: Used at low to moderate levels. In finished products: 0.5–10 ppm. In flavor concentrates: 0.005–0.1% (50–1000 ppm). For cocoa and chocolate applications: 2–8 ppm.
Safety & Handling: White to off-white crystalline powder. Melting point: 85–90°C (185–194°F). Flash point: >200°F (>93°C). Store in a cool, dry place in tightly sealed containers, protected from light and moisture. Soluble in alcohol and propylene glycol; sparingly soluble in water. Shelf life: 24 months.

2-Acetyl Pyrazine

CAS Number: 22047-25-2
FEMA Number: 3126
Regulatory Status: FEMA GRAS. Food Chemicals Codex listed.
Flavor Note(s): Popcorn, nutty, corn chip, bread crust, chocolate, hazelnut, coffee, musty, roasted, potato odor. Flavor is roasted, nutty, bready, yeasty, popcorn, corn chip.
Odor Threshold: Approximately 0.5–5 ppb in water
Compounds That Render Similar Flavor Note: 2-Acetyl-1-pyrroline (popcorn, but more intense), 2-acetylpyridine (popcorn, nutty), and other acetyl heterocycles.
Compounds Often Used Together With: Used with pyrazines, thiazoles, and furanones in popcorn, corn chip, bread, nut, and coffee flavor complexes. Commonly paired with 2,3-dimethylpyrazine for roasted nut profiles.
All Potential Applications: Popcorn, corn chip, bread, roasted nut, coffee, and cocoa flavors for savory and baked goods applications. Also used in tobacco flavors.
General Usage Levels: Very high odor strength; recommend smelling in a 0.10% solution or less. Substantivity: 400 hours at 10.00% in dipropylene glycol. In finished products: 0.1–5 ppm. In flavor concentrates: 0.001–0.05% (10–500 ppm). For popcorn applications: 1–3 ppm.
Safety & Handling: White to pale yellow crystalline powder. Melting point: 76–78°C (169–172°F). Flash point: >212°F (>100°C). Store in a cool, dry place in tightly sealed containers, protected from light and moisture. Soluble in alcohol and propylene glycol. Shelf life: 24 months.

2-Methoxy-3-Methyl Pyrazine

CAS Number: 2847-30-5
FEMA Number: 3249
Regulatory Status: FEMA GRAS. Approved in the EU under Regulation (EC) No 1334/2008 with FL No. 07.211.
Flavor Note(s): Potent earthy, nutty, and green bell pepper-like aroma. It has a strong, diffusive character with a low odor threshold, making it an impactful note even at low concentrations.
Odor Threshold: Extremely low; 2–10 ppt (parts per trillion) in water
Compounds That Render Similar Flavor Note: 2-Methoxy-3-ethylpyrazine (earthy, potato), 2-isopropyl-3-methoxypyrazine (green pepper, earthy), and 2-isobutyl-3-methoxypyrazine (green pepper, bell pepper).
Compounds Often Used Together With: Used with other pyrazines and green notes in vegetable, nut, and earthy flavor complexes. It synergizes well with other pyrazines and green notes, enhancing complexity.
All Potential Applications: Vegetable flavors (bell pepper, pea, asparagus), nut flavors, earthy profiles, and wine/green grape nuances.
General Usage Levels: Extremely potent. Typical use levels in finished food products: 0.01–0.1 ppm (10–100 ppb). In flavor concentrates: 0.0001–0.001% (1–10 ppm). Always handle as a highly diluted solution (0.01–0.1%). Formulators should be cautious of its potent aroma, as overuse can lead to an overpowering effect.
Safety & Handling: Colorless to pale yellow liquid. Flash point: approximately 150–160°F (65–70°C). The compound is stable under typical food processing conditions but may degrade under extreme heat or acidic environments. Store in a cool, dry place in tightly sealed containers, protected from light. Use adequate ventilation. Shelf life: 24 months.

2-Methoxy-3-Ethyl Pyrazine

CAS Number: 25680-58-4
FEMA Number: (Note: FEMA number not confirmed in available literature; flavorists should consult current FEMA GRAS lists before use)
Regulatory Status: Verify current FEMA GRAS status before use. Occurs naturally in grape, potato, and wine.
Flavor Note(s): Earthy, raw potato, earthy, green pepper, bell pepper, nutty.
Odor Threshold: Extremely low; estimated 1–20 ppt (parts per trillion) in water
Compounds That Render Similar Flavor Note: 2-Methoxy-3-methylpyrazine (earthy, bell pepper), 2-isopropyl-3-methoxypyrazine (green pepper), and 2-isobutyl-3-methoxypyrazine (bell pepper).
Compounds Often Used Together With: Used with other methoxypyrazines and green notes in potato, vegetable, and wine flavor complexes. Pairs with cis-3-hexenol for fresh green profiles.
All Potential Applications: Potato, vegetable (green pepper), and wine flavor nuances where an earthy, vegetative note is desired. Used in savory and culinary flavors.
General Usage Levels: Extremely potent. In finished products: 0.01–0.1 ppm (10–100 ppb). In flavor concentrates: 0.0001–0.001% (1–10 ppm). Always use as a highly diluted solution.
Safety & Handling: Colorless clear liquid. Flash point: 156°F (69°C). LogP (o/w): 1.8. Store in a cool, dry place in tightly sealed containers, protected from light. Use adequate ventilation due to potent aroma. Natural occurrence in grape, potato, and wine makes it valuable for authentic wine and vegetable profiles. Shelf life: 24 months when stored properly.

Below is the old version