Chocarom pyrazine

Chocarom Pyrazine A Remarkable Pyrazine for Flavors and Fragrances... 

Chocarom Pyrazine is a colorless transparent liquid consisting of a 1 1 isomeric mixture of 3,5-dimethyl-2-isobutylpyrazine and 3,6-dimethyl-2-isobutylpyrazine, as shown in Figure 1. Relevant CAS numbers are [38888-81-2] for dimethyl-isobutylpyrazine (positions not defined), and [70303-42-3] for 3,5-dimethyl-2-isobutyl-pyrazine. 

Chocarom Pyrazine isomers were isolated from the skin and flesh of potato Solanum tuberosum L.) cultivars after baking 4). 3,5-Dimethyl-2-isobutylpyrazine [2,5-dimethyl-3-(2-methylpropyl)-pyrazine] was isolated by Oruna-Concha, Craig, Duckham and Ames from the following potato cultivars - Cara, Nadine, Flanna and Marfona. 3,6-Dimethyl-2-isobutyl-pyrazine [3,5-dimethyl-2-(2-methylpropyl)pyrazine], was found by the same team in Cara and Marfona potato cultivars. 2,5-Dimethyl-3-isobutylpyrazine was also detected by Welty, Marshall and Grun in chocolate ice cream prepared from cocoa flavor (5). Both pyrazines were also found as key odorant compounds in dark chocolate by Counet, Callemien, Ouwerx and Collin (6). The role of amino acids in alkyl-substituted pyrazines formation in model systems containing pyruvaldehyde was examined by Mea (7). 2,5-Dimethyl-3-isobutylpyrazine was formed in the model system with valine. Both isomers were prepared synthetically by Chen (S) by reacting acetol, isobutyraldehyde and ammonium acetate, with low yield of 22.3%. Subsequent proprietary work by the author has improved the yield to 65%. 

The odor and flavor of Chocarom Pyrazine is reminiscent of the warmth of cocoa and hazelnut. It is slightly musky animalic, with patchouli and vetiver tones and a mentholic note. The odor character is displayed graphically in Figure 2. 

Figure 2. Radar organoleptic description of Chocarom Pyrazine...

The main uses of Chocarom Pyrazine for food are for chocolate, cocoa, baked goods, breakfast cereals, milk products, roasted and processed vegetables, soups, baked potatoes, sweet sauces and mint flavors. 

Table I. Acceptable Daily Intake for Chocarom Pyrazine 10)...

Chocarom Pyrazine is a rich chocolate building-block for bakery, dairy products confectionery and ice-cream flavors. The recommended dosage is 500-3000 ppm in the final product, as described in Table I. 

One of the most impressive perfumery creations using Chocarom Pyrazine is Tonkinarom, a fragrance base which has the following... 

As seen in the table, both Chocarom Pyrazine isomers, i.e. 3,6-diniethyl-2-isobutylpyrazine and 3,5-dimethyl-2-isobutyl-pyrazine, have cp values of ca. 82,000, thus belonging to the low cp value pyrazines group. This characteristic shows more clearly the pyi azines odor impact, as shown in the following graphs of low, medium and... 

Chocarom Pyrazine is a colorless transparent liquid, insoluble in water. In ethyl alcohol 50% it is soluble from 1 1 to 1 10. 

Chocarom Pyrazine was kept at 15 C for 55 days in order to measure changes in its physical parameters and odor profile. The color changed to 70 APHA (40 APHA start point) no change was seen in other physical parameters and odor profile. In another experiment Chocarom Pyrazine was kept at 40 C for 22 days. The color changed to 70 APHA (40 APHA start point) no change in other physical parameters and odor profile. 

The structure and composition of Chocarome pyrazine was elucidated by a combination of GC, MS and NMR analyses (Figures 7 and 8 and tables III - VI). The substitution pattern of 3,5-dimethyl-2-isobutylpyrazine and 3,6-dimethyl-2-isobutyl-pyrazine was elucidated by a combination of NMR methods, especially in mixtures by gradient selected H, N HMBC experiments at natural abundance level (I /). Since the N-NMR spectrum of pyrazines was proven to be a powerful tool for their structural elucidation 12, IS) it is used to study these type of molecules. Tables V and VI details the N-NMR chemical shift of both nitrogen atoms of each isomer ... 

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