2009_Book_FoodChemistry

15.4 Baked Products 735
Table 15.55. Chemical composition of some types of bread
Bread Water Protein Available Dietary Lipid Minerals
(N × 5.8) carbohydrates fiber
(%) (%) (%) (%) (%) (%)
White bread 38.3 7.6 49.7 3.2 1.2 1.6
White mix bread 37.6 6.2 47.7 4.6 1.1 1.5
Rye mix bread 39.1 6.4 43.7 6.1 1.1 1.8
Rye bread 38.1 6.2 45.8 6.5 1.0 1.6
Rye whole grain bread 42.0 6.8 38.7 8.1 1.2 1.5
Crisp bread 7.0 9.4 66.1 14.6 1.4 2.3
Table 15.56. Aroma profile of baguette after 1 h and
4h a
Aroma quality
Intensity b after
1h
4h
Roasty 1.8 1.9
Malty 1.9 0.4
Sweet 1.2 0
Fatty 1.0 2.3
a After leaving the oven the baguettes were cooled for
1 h at room temperature, then wrapped in aluminium
foil and stored at room temperature for another 3 h.
b The intensity of each aroma quality was evaluated
from 0–3 (strong). Average values of five testers.
aroma profile are greatly reduced and the fatty
note predominates (Table 15.56). These changes
are caused by the differences in the evaporation
rates of the aroma substances. To determine these
rates, the amounts of odorants which evaporate
from a baguette in 15 min are collected at the
times given in Table 15.58 and measured. The
results in Table 15.58 show the evaporation rates
of the malty smelling aldehydes methylpropanal,
2- and 3-methylbutanal decrease continuously in
accordance with the changes in the aroma profile.
This also results in the fact that odorants like the
fatty smelling (E)-2-nonenal are more detectable
with time. However, the intensity of the fatty
note also increases because the evaporation
rate of (E)-2-nonenal increases (Table 15.58),
possibly due to the decomposition of the linoleic
acid hydroperoxides formed during baking.
Table 15.57. Odorants of the baguette crust a
Compound Concen- Aromatration
value b
(µg/kg)
Methylpropanal 1750 31
2-Methylbutanal 962 18
3-Methylbutanal 335 26
Methional 29 107
Dimethyl trisulfide 5.1 59
2,3-Butandione 1320 203
2-Acetyl-1-pyrroline 16 2191
2-Ethyl-3,5-dimethylpyrazine 3.2 19
Hexanal 214 7
1-Octen-3-one 6.6 150
(E)-2-Nonenal 87 164
(E,E)-2,4-Decadienal 56 21
a After leaving the oven the baguettes were cooled for
1 h at room temperature, then the crust was separated,
frozen with liquid nitrogen and analyzed.
b On the basis of the odor threshold of the compound
on starch.
2-Acetyl-1-pyrroline evaporates uniformly (Table
15.58); the intensity of the roasty note is
correspondingly stable during storage for 4 hours
(Table 15.56). The losses of this odorant in the
white bread crust on longer storage is shown
in Table 15.59.
The aroma is influenced by the recipe but also by
the fermentation, e. g., the Strecker aldehydes increase
and those from lipid peroxidation decrease
if the dough matures at lower temperatures (Table
15.60). An extension of the kneading process