TABLE 4.
Volatiles identified using GC-MS in conched chocolate made from spontaneous and inoculated cocoa pulp fermentationsa
| Volatile by stage | Sensorial descriptor(s) (references) | Concn (μg/kg) |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Robust parents |
Aromatic parents |
Hybrids |
P. kluyveri Y274 | Cyb. fabianii Y689 | S | |||||||
| Y115 | Y927 | H28 | Y184 | Y397 | H40 | H42 | H57 | |||||
| Fermentation | ||||||||||||
| Aldehydes | ||||||||||||
| 2-Methylbutanal | Chocolate (61), malty (62) | 37.8 | 38.3 | 19.2 | 14.6 | 3.9 | 19.4 | 15.0 | 11.3 | 12.3 | 13.1 | 8.4 |
| 2-Phenyl-2-butenal | Roasted (61), rum (61), cocoa (61), sweet (61) | 22.9 | 11.2 | 10.0 | 6.1 | 8.2 | 5.1 | 6.5 | 4.1 | 5.9 | 7.3 | 2.1 |
| 3-Methylbutanal | Chocolate (61), malty (57, 62) | 127.8 | 132.1 | 58.9 | 54.3 | 15.9 | 63.8 | 58.0 | 45.0 | 45.9 | 49.9 | 28.9 |
| 5-Methyl-2-phenyl-2-hexenal | Roasted cocoa (63), sweet (63) | 12.6 | 4.1 | 4.2 | 1.7 | 2.1 | 2.3 | 3.3 | 1.0 | 3.0 | 2.2 | 1.3 |
| Benzaldehyde | Almond (64) | 37.0 | 41.7 | 30.1 | 31.5 | 12.1 | 38.7 | 30.4 | 27.0 | 22.1 | 17.0 | 11.7 |
| Phenylacetaldehyde | Floral (61), honey (57, 61, 62) | 53.5 | 36.6 | 17.5 | 11.4 | 8.6 | 19.4 | 20.2 | 11.7 | 15.3 | 18.4 | 4.9 |
| Alcohols | ||||||||||||
| 2-Methyl-1-butanol | 0.1 | 3.7 | 0.8 | 3.7 | 1.2 | 2.3 | 2.0 | 2.3 | 1.2 | 0.8 | 0.2 | |
| 2-Phenylethanol | Floral (61, 62) | 142.0 | 122.9 | 67.6 | 73.2 | 62.8 | 78.1 | 70.7 | 76.4 | 60.3 | 40.2 | 30.6 |
| Isoamyl alcohol | Malty (25), bitter (25), chocolate (25) | 0.1 | 27.1 | 7.0 | 16.3 | 2.7 | 17.4 | 5.4 | 11.6 | 10.9 | 4.6 | 1.2 |
| Esters | ||||||||||||
| 2-Heptyl acetate | 1.7 | 3.2 | 1.3 | 1.4 | 1.8 | 7.6 | 5.0 | 8.7 | 2.3 | 1.9 | 1.5 | |
| Ethyl acetate | Solvent (64), fruity (17) | 2.0 | 3.7 | 3.4 | 28.9 | 1.4 | 9.1 | 5.3 | 7.7 | 11.5 | 3.3 | 1.8 |
| Ethyl decanoate | Pear (58), grape (58), brandy (58), floral (65) | 3.4 | 3.7 | 1.4 | 0.9 | 0.6 | 2.2 | 1.8 | 3.6 | 1.4 | 0.9 | 0.6 |
| Ethyl dodecanoate | Fruity (58), floral (58) | 7.1 | 3.1 | 3.1 | 1.5 | 1.4 | 2.2 | 3.2 | 2.7 | 4.0 | 1.4 | 1.6 |
| Ethyl hexanoate | Apple (64), fruity (57), banana (57) | 0.1 | 0.1 | 0.1 | 2.4 | 0.1 | 2.5 | 0.1 | 2.4 | 0.1 | 0.1 | 1.5 |
| Ethyl octanoate | Apple (64), fruity (57), pineapple (57) | 7.5 | 19.1 | 5.0 | 15.8 | 7.3 | 9.2 | 14.7 | 8.8 | 4.5 | 4.4 | 2.5 |
| Ethyl phenylacetate | Sweet (57), waxy (57) | 3.0 | 1.9 | 1.6 | 2.0 | 0.9 | 1.2 | 2.2 | 1.8 | 1.1 | 1.0 | 1.0 |
| Isoamyl acetate | Banana (64), fruity (17), pear (17) | 2.4 | 5.5 | 11.9 | 6.8 | 2.4 | 12.4 | 5.1 | 6.6 | 5.5 | 2.7 | 7.2 |
| Methyl acetate | 17.7 | 13.7 | 33.0 | 35.7 | 16.6 | 30.0 | 25.7 | 42.6 | 20.3 | 20.1 | 14.1 | |
| Phenylethyl acetate | Floral (62), fruity (57), sweet (57) | 30.3 | 29.5 | 16.7 | 37.1 | 27.2 | 15.6 | 21.1 | 22.9 | 16.8 | 13.2 | 12.3 |
| Ketones | ||||||||||||
| 1-Hydroxy-2-propanone | 26.7 | 23.0 | 8.3 | 6.3 | 5.4 | 8.1 | 13.2 | 8.4 | 6.1 | 9.6 | 2.2 | |
| 2-Butanone | 5.1 | 5.3 | 4.3 | 3.3 | 1.1 | 3.2 | 3.0 | 2.0 | 1.9 | 2.0 | 1.8 | |
| 2-Heptanone | 1.5 | 1.9 | 2.5 | 2.4 | 1.1 | 5.2 | 2.3 | 4.0 | 4.3 | 1.4 | 2.9 | |
| 2-Nonanone | Floral (66), fatty (66) | 9.5 | 15.6 | 6.3 | 6.3 | 5.1 | 22.4 | 13.1 | 33.5 | 15.6 | 7.6 | 4.2 |
| Acetoin | Buttery (67), cream (67) | 278.7 | 276.5 | 106.0 | 147.5 | 52.3 | 252.8 | 238.9 | 258.3 | 505.2 | 260.7 | 55.5 |
| Diacetyl | Buttery (57, 61) | 78.1 | 70.4 | 64.7 | 58.6 | 25.3 | 75.9 | 78.0 | 61.4 | 124.4 | 50.5 | 48.7 |
| Sulfides | ||||||||||||
| Dimethyl disulfide | Cabbage (66) | 1.0 | 0.9 | 0.9 | 0.9 | 0.4 | 0.6 | 1.0 | 0.6 | 0.6 | 0.4 | 0.6 |
| Volatile acids | ||||||||||||
| 2-Methylbutanoic acid | Sweaty (57, 62) | 0.1 | 48.1 | 35.0 | 19.7 | 0.1 | 16.7 | 22.1 | 18.7 | 11.0 | 17.4 | 5.8 |
| Acetic acid | Sour (57, 62) | 2,555.7 | 2,489.6 | 1,087.5 | 1,984.2 | 734.0 | 1,711.0 | 2,907.2 | 2,303.5 | 1,818.9 | 1,983.9 | 279.7 |
| Butanoic acid | Sweat (62), buttery (57), rancid (57) | 2,555.7 | 10.0 | 3.4 | 4.8 | 1.3 | 4.4 | 10.1 | 7.7 | 6.1 | 6.1 | 0.3 |
| Isobutyric acid | Sweaty (57, 62) | 26.9 | 48.8 | 20.1 | 36.6 | 7.7 | 25.7 | 47.4 | 44.3 | 45.4 | 41.6 | 3.8 |
| Isovaleric acid | Sweaty (57, 62) | 0.1 | 173.1 | 44.7 | 62.5 | 0.1 | 51.4 | 102.2 | 64.5 | 48.4 | 74.5 | 15.8 |
| Propanoic acid | Rancid (25) | 24.0 | 24.8 | 12.9 | 18.8 | 8.8 | 17.7 | 28.3 | 25.8 | 15.6 | 19.3 | 8.2 |
| Roasting | ||||||||||||
| 1-(2-Furanyl)ethanone | Sweet (57), balsamic (57), cocoa (57) | 1.3 | 2.1 | 1.6 | 0.8 | 1.0 | 1.2 | 1.3 | 0.9 | 1.4 | 0.9 | 1.5 |
| 2,3,5-Trimethyl-6-ethylpyrazine | Candy (67), sweet (67) | 16.1 | 13.8 | 8.2 | 4.5 | 6.7 | 10.4 | 13.8 | 20.2 | 7.9 | 10.1 | 6.0 |
| 2,3-Dimethylpyrazine | Caramel (58), cocoa (58), hazelnut (61) | 6.5 | 6.5 | 2.9 | 3.0 | 1.3 | 3.9 | 4.6 | 3.1 | 2.6 | 3.1 | 1.2 |
| 2,5-Dimethylpyrazine | Cocoa (58), roasted nuts (58) | 2.6 | 2.4 | 1.7 | 1.9 | 1.3 | 1.6 | 1.4 | 0.9 | 1.1 | 1.3 | 1.0 |
| 2,6-Dimethylpyrazine | Nutty (58), coffee (58), green (58) | 5.4 | 4.7 | 1.8 | 0.9 | 0.6 | 1.7 | 2.3 | 0.9 | 0.8 | 1.6 | 0.8 |
| 2-Acetylpyrrole | Bread (58), walnut (58), licorice (58) | 91.6 | 42.4 | 23.8 | 8.0 | 24.9 | 17.4 | 43.2 | 11.6 | 13.8 | 25.9 | 10.2 |
| 2-Ethyl-3,5-dimethylpyrazine | Earthy (62), potato-chip (57, 62) | 17.5 | 10.7 | 4.9 | 1.9 | 4.9 | 3.6 | 7.8 | 3.8 | 2.5 | 5.5 | 3.6 |
| 2-Methyltetrahydro-3-furanone | 8.6 | 4.9 | 3.3 | 1.3 | 0.8 | 1.3 | 3.1 | 1.1 | 0.9 | 1.8 | 1.5 | |
| Methylpyrazine | Green (61), hazelnut (61), cocoa (58), roasted nuts (58) | 5.4 | 3.8 | 2.2 | 1.4 | 0.8 | 2.8 | 2.8 | 1.3 | 1.3 | 0.8 | 0.4 |
| Tetramethylpyrazine | Cocoa (58, 61), mocha (61), milk coffee (58, 61) | 212.9 | 247.7 | 123.1 | 86.1 | 86.7 | 198.5 | 336.1 | 288.4 | 198.2 | 316.7 | 396.9 |
| Trimethylpyrazine | Earthy (57, 62), cocoa (58, 61), roasted (61), green (61) | 30.1 | 29.2 | 13.0 | 7.2 | 8.1 | 15.5 | 26.8 | 14.0 | 9.3 | 19.5 | 15.2 |
a
Two spontaneous (S) and 20 inoculated fermentations were performed, with 10 yeast strains tested in duplicate. The cocoa liquors of the fermentation duplicates were pooled prior to being processed into chocolate (see Materials and Methods for details). 2-Pentyl acetate, ethyl 2-methylbutanoate, ethyl isobutyrate, ethyl isovalerate, ethyl lactate, ethyl propanoate, isobutyl acetate, methyl lactate, and propyl acetate were detected in the cocoa liquors but not in the chocolates.