Food Chemistry

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 toGuth, 1997)

Table 5.12.Odor threshold values of diastereomeric
3a,4,5,7a-tetrahydro-3,6-dimethyl-2(3H)-benzo-
furanone

No.a Stereoisomer- Odor threshold
conformation (ng/lair)

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

aNumbering as in Fig. 5.12.

stance of this type can be determined by enantio-
selective 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 process-

ing, 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)