2009_Book_FoodChemistry

5.2 Aroma Analysis 355
Fig. 5.12. Gas chromatogram of the diastereomers of 3a,4,5,7a-tetrahydro-3,6-dimethyl-2(3H)-benzofuranone
(wine lactone) on a chiral phase (according to Guth, 1997)
Table 5.12. Odor threshold values of diastereomeric
3a,4,5,7a-tetrahydro-3,6-dimethyl-2(3H)-benzofuranone
No. a Stereoisomer- Odor threshold
conformation (ng/l air)
1 (3S,3aS,7aS) 0.007–0.014
2 (3R,3aR,7aR) 14–28
3 (3R,3aR,7aS) >1000
4 (3R,3aS,7aS) 8–16
5 (3S,3aR,7aR) 0.05–0.2
6 (3S,3aS,7aR) 0.00001–0.00004
7 (3S,3aR,7aS) 80–160
8 (3R,3aS,7aR) >1000
a Numbering as in Fig. 5.12.
stance of this type can be determined by enantioselective
analysis if safe data on the enantiomeric
excess of the compound in the particular food
are available. It should also be taken into account
that the ee value can change during food processing,
e. g., that of filbertone decreases during the
roasting of hazelnuts (cf. Table 5.13).
Table 5.13. Enantiomeric excess (ee) of chiral aroma
substances in some foods
Aroma substance Food ee (%)
R(+)-γ-Decalactone Peach, apricot,
mango, strawberry >80
pineapple, maracuya
R(+)-δ-Decalactone Milk fat 60
R(+)-trans-α-Ionone Raspberry 92.4
Carrot 90.0
Vanilla bean 94.2
R(-)-1-Octen-3-ol Mushroom, >90
chanterelle
S(+)-E-5-Methy1-2- Hazelnut, raw 60–68
hepten-4-one Hazelnut, roasted 40–45
(filbertone)
R-3-Hydroxy-4,5- Sherry ca. 30
dimethyl-2(5H)-
furanone (sotolon)