TABLE 2.
Volatile compounds identified in CDM after 24 h of fermentation at 30°C with the six LAB strains in mono- and cocultures and in unfermented CDM used as controls (CDM TRYP and CDM PROT)a
| Compound (trivial name) | m/z | Ab | Identification | Associated odor/flavorb | CAS no. | LRI | Max fold changec | Culture associated with the maximal culture/control ratio | Origin |
|---|---|---|---|---|---|---|---|---|---|
| 3-Methylbutanal | 58 | MBT | S, LRI, DB | Fruity | 590-86-3 | 918 | 905 ± 15 | Lla244 × Lla450 | cata, Leu |
| 2,3-Butanedione (diacetyl) | 42 | D | LRI, DB | Buttery | 431-03-8 | 975 | 39 ± 3 | Lla244 × Lla450 | metab, C |
| 2,3-Pentanedione | 100 | PD | LRI, DB | Buttery | 600-14-6 | 1,062 | 150 ± 23.4 | Efa2412 × Lla450 | metab, C |
| Hexanal | 44 | H | LRI, DB | Grassy | 66-25-1 | 1,080 | 0.06 ± 0.02 | Lla2125 | CDM |
| 1-Propanol, 2-methyl | 74 | MPP | LRI, DB | Fusel | 78-83-1 | 1,114 | 3,890 ± 240 | Lla244 × Lpl465 | cata, Val |
| Heptanal | 44 | HP | LRI, DB | Green | 111-71-7 | 1,183 | 0.12 ± 0.06 | Lla2125 × Lla450 | CDM |
| 2-Hydroxy-3-butanone (acetoin) | 88 | AC | LRI, DB | Buttery | 513-86-0 | 1,277 | 22,211 ± 3,014 | Lla2125 × Lpl1524 | metab, C |
| 2-Nonanone | 58 | NN | S, LRI, DB | Cheesy | 821-55-6 | 1,383 | 6.8 ± 0.4 | Lla244 × Lla450 | cata, FFA |
| Acetic acid | 60 | A | S, LRI, DB | Sour | 64-19-7 | 1,476 | 558 ± 82 | Efa2412 × Lla450 | metab, C |
| Benzaldehyde | 106 | BZH | S, LRI, DB | Nutty | 100-52-7 | 1,535 | 3.3 ± 0.1 | Efa2412 × Lla450 | cata, Phe |
| 2-Methylthiolan-3-one | 60 | MTL | LRI, DB | Sulfurous fruity berry | 13679-85-1 | 1,539 | 20.6 ± 2.6 | Lla244 | cata, Met |
| Benzeneacetaldehyde | 91 | BZAH | LRI, DB | Honey | 122-78-1 | 1,635 | 223 ± 7 | Lla244 | cata, Phe |
Receiver strains Lla450, Lpl465, and Lpl1524 were grown on CDM TRYP, which corresponds to CDM PROT supplemented with 0.5 g/liter of casein tryptone. The selection criterion for the volatile compounds was a culture/control ratio of >5 or < 0.1. Compound name is according to IUPAC (International Union of Pure and Applied Chemistry) nomenclature. CAS, Chemical Abstract Service registry; S, retention time and mass spectrum from standard; LRI, linear retention index; DB, mass spectral data library of the National Institute of Standards and Technology (NIST); Ab, abbreviation, cata, catabolism; metab, metabolism; C, carbohydrate; FFA, free fatty acid. For strain codes, see Table 4.
Flavor description according to The Good Scents Company Information System.
Culture/control ratio. Max, maximum.