Pyrazines have been in common use in flavors for the past 50 years, and all flavorists tend to gravitate towards their favorite members of this interesting family of chemicals. 2-Acetyl pyrazine (FEMA# 3126; CAS# 22047-25-2) is one of my overall favorite raw materials because of its unique character, power and flexibility, and the fact that it is found widely in nature.
Pyrazines, together with related chemicals such as pyridines, can be characterized by odor as predominantly roasted, peanut or popcorn. The best example of a chemical with a roasted note is trimethyl pyrazine (FEMA# 3244). 2,3-Dimethyl pyrazine (FEMA# 3271) is the best example of a chemical with a peanut character, and 2-acetyl pyridine (FEMA# 3251) is the best representative of the popcorn note. Most finished flavor categories require a combination of these three profile characters, in differing proportions. Roasted notes dominate chocolate flavors, peanut notes dominate nut flavors and, unsurprisingly, popcorn notes are dominant in popcorn flavors.
2-Acetyl pyrazine has a very attractive combination of all three notes, most notably roasted and popcorn, and for this reason it is very effective in a wide range of heated flavor profiles. Several similar chemicals are used in flavors, notably 2-acetyl-3-ethyl pyrazine (FEMA# 3250), 2-acetyl-3-methyl pyrazine (FEMA# 3964) and 2-acetyl- 3,5-dimethyl pyrazine (FEMA# 3327), 2-acetyl-6-methyl pyrazine, 2-acetyl- 6-ethyl pyrazine, 2-acetyl-5-methyl pyrazine and 2-acetyl-3,5,6-trimethyl pyrazine. Of these alternatives none are as ubiquitous in nature as 2-acetyl pyrazine, but several are interesting. 2-Acetyl-3-methyl pyrazine is the next most useful member of the family and can be used in a way similar to 2-acetyl pyrazine, providing a little more heat stability at the price of reduced impact. 2-Acetyl-3-ethyl pyrazine has noticeably less impact, but it has an interesting earthy note that works well in peanut flavors.