Use of gas chromatography-olfactometry to identify key odorant compounds in dark chocolate. Comparison of samples before and after conching.
After vacuum distillation and liquid-liquid extraction, the volatile fractions of dark chocolates were analyzed by gas chromatography-olfactometry and gas chromatography-mass spectrometry. Aroma extract dilution analysis revealed the presence of 33 potent odorants in the neutral/basic fraction. Three of these had a strong chocolate flavor: 2-methylpropanal, 2-methylbutanal, and 3-methylbutanal. Many others were characterized by cocoa/praline-flavored/nutty/coffee notes: 2,3-dimethylpyrazine, trimethylpyrazine, tetramethylpyrazine, 3(or 2),5-dimethyl-2(or 3)-ethylpyrazine, 3,5(or 6)-diethyl-2-methylpyrazine, and furfurylpyrrole. Comparisons carried out before and after conching indicate that although no new key odorant is synthesized during the heating process, levels of 2-phenyl-5-methyl-2-hexenal, Furaneol, and branched pyrazines are significantly increased while most Strecker aldehydes are lost by evaporation.
Counet
Christine
C
Unité de Brasserie et des Industries Alimentaires, Université catholique de Louvain, Croix du Sud, 2/Bte7, B-1348 Louvain-la-Neuve, Belgium.
Callemien
Delphine
D
Ouwerx
Caroline
C
Collin
Sonia
S
D000447:Aldehydes / Q000032:analysis; D002099:Cacao / Q000737:chemistry*; D002849:Chromatography, Gas; D005663:Furans / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D006591:Hexobarbital; D006358:Hot Temperature; D009812:Odorants; D011719:Pyrazines / Q000032:analysis; D012903:Smell; D013649:Taste
D000447:Aldehydes; D005663:Furans; D011719:Pyrazines; C058427:furaneol; D006591:Hexobarbital; C017439:isobutyraldehyde