2009_Book_FoodChemistry

4.2 Monosaccharides 287
(4.97)
(4.98)
tatively determined in different foods. The data
(Table 4.15) show that especially in alkali-baked
products, about 60–70% of the arginine present in
the flour reacts to imidazolinone.
(4.99)
Apart from the modification of amino acid side
chains in individual protein strands, cross-linkage
of two protein chains can also occur. Some of
the structures are shown in Formula 4.100.
Pentosidine was first found in physiological
protein. It strongly fluoresces and is formed by
bridging an arginine residue with a lysine residue
via a pentose. The concentrations of pentosidine
in food are comparatively low (Table 4.16).
The formation of pentosidine is assumed to
be as shown in Formula 4.101. Formation of
the Amadori product with the ε-amino group
of lysine is followed by water elimination at
C-2 and C-3 of pentose with the formation
of the 4,5-diulose, which condenses with the