2009_Book_FoodChemistry

4.2 Monosaccharides 283
(4.88)
(4.89)
Strecker aldehydes which are important for
their aroma are methional, phenylacetaldehyde,
3- and 2-methylbutanal and methylpropanal
(cf. 5.3.1.1). Other compounds which are formed
via the Strecker degradation and influence
the aroma of food are H 2 S, NH 3 , 1-pyrroline
(cf. 5.3.1.6) and cysteamine (cf. 5.3.1.4). Recently,
the corresponding Strecker acids have
also been found, especially in the presence of
oxygen. They can be formed via the oxidation of
the intermediate eneaminol (Formula 4.88). All
the α-dicarbonyl compounds obtained on carbohydrate
degradation as well as the reductones
can undergo Strecker reactions. The product
spectrum is significantly increased due to the
redox reactions of the resulting intermediates.
The complex course of a Strecker reaction is
represented in Formula 4.89 with the formation
of 2-hydroxy-3-methyl-cyclopent-3-enone. Apart
from the pathway shown in Formula 4.46, this
reaction is also of importance. When amino
acids with functional groups in the side chain
are involved, even more complex reactions are
possible (cf. 5.3.1.4–5.3.1.8).