Page 44 - Academic Press Encyclopedia of Physical Science and Technology 3rd BioChemistry

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Encyclopedia of Physical Science and Technology EN006C-254 June 28, 2001 19:52

116 Food Colors

FIGURE 14 Simplified scheme of melanoidin formation by the sugar–amine reaction (± means presence or
absence).

rearrangement for aldoses. The Amadori and Heyns com- intermediate products are collectively called reductones,
pounds are subsequently subjected to a variety of trans- because they are strongly reducing compounds that ac-
formations, which may include deamination, dehydration, count for the reducing properties of systems undergoing
enolization, cyclization, and degradation. The products Maillard browning.
of those reactions finally condense or polymerize with It should be mentioned here that a side reaction of the
or without the participation of an additional amino com- Maillard browning results in the formation of flavorful
pound to form dark pigments of a colloidal nature and compounds, such as those associated with the roasting
ill-defined composition—the melanoidins. Some of the of meat, coffee, or nuts and the baking of bread. This