2009_Book_FoodChemistry

280 4 Carbohydrates
(4.79)
(4.80)
instable compounds which undergo reactions
with other amino components. In the presence
of mainly primary amines (amino acids),
aminoreductones are formed (pyrrolinones,
Formula 4.79) and in the presence of secondary
amino acids, relatively stable carbocyclic
compounds (Formula 4.80).
The following compounds were detected in reaction
mixtures containing proline and hydroxyproline.
Their formation must proceed via the
1-deoxyosones as well:
(4.81)
The pyrrolidino- and dipyrrolidinohexose reductones
were characterized as bitter substances
obtained from heated proline/saccharose mixtures
(190 ◦ C, 30 min, molar ratio 3:1; c sbi :0.8
and 0.03 mmol/l).
4.2.4.4.5 Secondary Products of 4-Deoxyosones
As shown in Formula 4.38, 2-hydroxyacetylfuran
is one the reaction products of 4-deoxyosone.
However, this compound is preferentially
formed in carbohydrate degradation in the absence
of amine components. If it is formed from
the Amadori product in accordance with Formula
4.57, the amino acid remains in the reaction
product, producing furosine (Formula 4.82). In
the presence of higher concentrations of primary
amines, the formation of 2-hydroxyacetylfuran
(and also furosine) is significantly suppressed
in favor of the corresponding pyrrole and pyridiniumbetaine
(Formula 4.84). The reason for
this is that the triketo structures formed from
4,5-dideoxyosone by enolization react with
primary amines, amino acids or ammonia to give
pyrrole and pyridine derivatives (Formula 4.83).
(4.82)