2009_Book_FoodChemistry

4.2 Monosaccharides 273
formation of l-deoxy-2,3-diulose, also called
1-deoxyosone. In addition, 4-deoxy-2,3-diulose,
also called 4-deoxyosone, can be formed by
water elimination at C-4 of 2,3-eneaminol
(Formula 4.57). In contrast to the previously
mentioned pathways, the amino acid residue remains
bound to the carbohydrate in this reaction
path. As shown in the reaction scheme, all three
deoxyosones occur in different cyclic hemiacetal
forms.
As in the case of the deoxyosones, the concentrations
of Amadori and Heyns compounds vary,
depending on the reaction conditions (pH value,
temperature, time, type and concentration of
the educts). As a result, there is a change in the
product spectrum and, consequently, in the color,
taste, odor, and other properties of the food in
each case.
Like all α-dicarbonyl compounds, deoxyosones
can be stabilized as quinoxalines by a trapping reaction
with o-phenylenediamine (Formula 4.58)
and subsequently quantitatively determined using
liquid chromatographic techniques. In this way,
deoxyosones were detected for the first time as
intermediates in carbohydrate degradation.
The stable secondary products of the Maillard reaction,
that are isolated from many different reaction
mixtures and have known structures, can
be generally assigned to a definite deoxyosone by
a series of plausible reaction steps (enolization,
elimination of water, retroaldol cleavage, substitution
of an amino function for a hydroxy function
etc.).
Of the large number of secondary products known
today, a few typical examples will be dealt with
here for each deoxyosone.
(4.54)
(4.55)
(4.56)