Important Synthetic Flavor Compounds - Part 13 (2-methoxy 3-isobutyl pyrazine, 2-isopropyl 4-methyl thiazole, 2-isobutyl thiazole, pyridine 2-acetyl pyridine, 2,4,5-trimethyl oxazole, trithioacetone)

Editor

22 Mar 2026 • 4 min read

Part 13 (2-methoxy 3-isobutyl pyrazine 2-isopropyl 4-methyl thiazole 2-isobutyl thiazole pyridine 2-acetyl pyridine 2,4,5-trimethyl oxazole trithioacetone.)

These are among the 128 synthetic flavor compounds that John Wright, in his book Flavor Creation, suggests every flavorist should know and work with. Part 13 is the last part of the 128 flavor compounds.

2-Methoxy-3-Isobutyl Pyrazine

FEMA Number: 3132
Flavor Note(s): Powerful green, characteristic of green bell pepper and green peas . It is a key component of the harsh green odor of galbanum . The odor is strong, diffusive, and green.
Compounds That Render Similar Flavor Note: 2-Methoxy-3-methylpyrazine (earthy, nutty, less green), 2-Methoxy-3-ethylpyrazine (earthy, potato), 2-Isopropyl-3-methoxypyrazine (green pepper, earthy).
Compounds Often Used Together With: Used with other green notes such as undecatriene isomers to build complex galbanum and vegetable profiles . Also used in coffee and green-floral compounds such as petitgrain .
All Potential Applications: Vegetable flavors (green bell pepper, green peas), coffee flavors, and green-floral compounds . It also occurs naturally in grapes and red wine, contributing to the green bell pepper character in certain varieties .
General Usage Levels: Extremely potent. The threshold value in red wine is estimated to be 15 ng/L (parts per trillion) . In finished products, usage levels are typically in the low ppb range.
Important Considerations for Flavorists: Appears as a colorless clear liquid with a flash point of 176°F (80°C) . In China, it is regulated as a synthetic food flavor and can only be used for that functional purpose in specific food categories with maximum content limits . FEMA GRAS.

2-Isopropyl-4-Methyl Thiazole

FEMA Number: 3555
Flavor Note(s): A fruit flavor intensifier with a peach flavor and distinct vegetable and tropical notes . Used in peach, apricot, nectarine, durian, mango, pear, and blackcurrant flavors . The odor is described as a green, vegetable note .
Compounds That Render Similar Flavor Note: 2-Isobutylthiazole (green, tomato leaf), other thiazole derivatives with fruity-green profiles.
Compounds Often Used Together With: Used with other fruity esters and tropical notes in peach, mango, and other tropical fruit flavor complexes.
All Potential Applications: Peach, apricot, nectarine, durian, mango, pear, and blackcurrant flavors . Present naturally in Indonesian durian fruit, red tomatoes, yeast extract, coriander seed oil, and roast meats .
General Usage Levels: Used at low levels due to its potency as a flavor intensifier . Typical usage in finished products is in the low ppm range.
Important Considerations for Flavorists: Appears with a flash point of 48°C (cc) . Soluble in alcohol and propylene glycol, insoluble in water . FEMA GRAS.

2-Isobutyl Thiazole

FEMA Number: 3134
Flavor Note(s): Green, wasabi, privet, tomato leaf, earthy, vegetable, metallic, musty, waxy . The flavor is green, vegetable, tomato, raw, musty . It adds the characteristics of ripe tomatoes .
Compounds That Render Similar Flavor Note: 2-Isopropyl-4-methyl thiazole (peach-tropical, less green), other thiazoles with green-vegetable character.
Compounds Often Used Together With: Used with other green and vegetable notes in tomato, vegetable, and savory flavor complexes. It enhances the flavor of fresh lime and is used in blackcurrant, papaya, melon, raspberry, and roast beef flavors .
All Potential Applications: Tomato, blackcurrant, papaya, melon, raspberry, roast beef, and fresh lime flavors . Also used in vegetable and savory applications where a green, tomato leaf note is desired.
General Usage Levels: High odor strength; recommended smelling in a 0.10% solution or less . In finished products, typical usage is in the low ppm range.
Important Considerations for Flavorists: Appears as a colorless to pale yellow clear liquid with a flash point of 135.00 °F (57.22 °C) . LogP (o/w) is approximately 1.715 . Soluble in alcohol and stable in most media . FEMA GRAS.

Pyridine

FEMA Number: 2966
Flavor Note(s): Information not present in search results. Pyridine has a sharp, pungent, fishy, and unpleasant odor at high concentrations.
Compounds That Render Similar Flavor Note: Picolines (methylpyridines), other nitrogen-containing heterocycles with pungent, fishy notes.
Compounds Often Used Together With: Information not present in search results.
All Potential Applications: Synthetic food flavor, limited to this functional purpose .
General Usage Levels: Information not present in search results. Used at extremely low levels due to its potent and unpleasant odor.
Important Considerations for Flavorists: In China, it is regulated as a synthetic food flavor and can only be used for that functional purpose in specific food categories with maximum content limits . Pyridine is highly flammable and toxic; handle with extreme care using appropriate PPE and ventilation. FEMA GRAS.

2-Acetyl Pyridine

FEMA Number: 3251
Flavor Note(s): Popcorn, corn chip, fatty, tobacco, musty, nutty . The flavor is cornmeal, nutty, bready . It is often referred to as "popcorn pyridine" .
Compounds That Render Similar Flavor Note: 2-Acetyl-1-pyrroline (popcorn, but more intense and roasty), 2-acetylthiazole (popcorn, nutty), other acetyl-substituted heterocycles.
Compounds Often Used Together With: Used with other pyrazines, thiazoles, and furanones in popcorn, corn chip, bread, nut, and coffee flavor complexes.
All Potential Applications: Popcorn, corn chip, bread, roasted nut, coffee, cocoa, and tobacco flavors . Occurs naturally in bread wheat, cocoa, coffee, filbert, lamb, peanut, potato chip, and tea leaf .
General Usage Levels: High odor strength; recommended smelling in a 1.00% solution or less . Substantivity is 9 hours at 100.00% . In finished products, typical usage ranges from 0.1 to 5 ppm.
Important Considerations for Flavorists: Appears as a pale yellow to brown clear liquid with a flash point of 164.00 °F (73.33 °C) . LogP (o/w) is 0.85 . Soluble in alcohol, dipropylene glycol, and ethyl ether . FEMA GRAS.

2,4,5-Trimethyl Oxazole

FEMA Number: 4394
Flavor Note(s): Information not present in search results. Oxazoles generally contribute nutty, green, and roasted notes.
Compounds That Render Similar Flavor Note: Other alkyl-substituted oxazoles, pyrazines (nutty, roasted), thiazoles (nutty, green).
Compounds Often Used Together With: Information not present in search results.
All Potential Applications: Flavoring agent or adjuvant .
General Usage Levels: Information not present in search results. Due to its FEMA GRAS status and typical potency of oxazoles, usage levels are likely in the low ppm range.
Important Considerations for Flavorists: Listed in the FDA's Substances Added to Food (EAFUS) database . FEMA GRAS Publication No. 23; JECFA Flavor Number 1553 . FEMA GRAS.

Trithioacetone (2,2,4,4,6,6-Hexamethyl-1,3,5-trithiane)

FEMA Number: 3475 (Note: FEMA number from general knowledge; not confirmed in search results)
Flavor Note(s): Powerful, tropical, passionfruit, guava, durian, with a sulfurous, juicy, and slightly catty nuance.
Compounds That Render Similar Flavor Note: 4-Mentha-8-thiol-3-one (black currant, catty), other sulfur-containing heterocycles with tropical character.
Compounds Often Used Together With: Used with other sulfur compounds and fruity esters in passionfruit, guava, and durian flavor complexes.
All Potential Applications: Passionfruit, guava, durian, and other tropical fruit flavors for beverages, candies, and dairy products.
General Usage Levels: Extremely potent. Used at very low levels, typically in the parts per billion (ppb) range in finished products.
Important Considerations for Flavorists: Appears as a crystalline solid with a melting point around 24°C. It exists in isomeric forms. As a potent sulfur compound, it requires careful handling and storage in tightly sealed containers under inert gas to prevent oxidation. FEMA GRAS.

###