Deoxyosone secondary product

Amadori products are only intermediates formed in the course of the Maillard reaction. In spite of their limited stability, these products can be used under certain conditions as an analytical indicator of the extent of the heat treatment of food. Unlike the acidic (pH <3) and alkaline (pH >8) sugar degradation reactions, the Amadori compounds are degraded to 1-, 3-, and 4-deoxydicarbonyl compounds (deoxyosones) in the pH range 4-7. As reactive a-dicarbonyl compounds, they yield many secondary products. Formulas 4.54. 57 summarize the degradation reactions starting with the Amadori compound. 

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. 

If pyrrole formation occurs with an amino acid, this product can react further (Formula 4.63) to yield a bicychc lactone (V in Formula 4.59). Other secondary products of 3-deoxyosone are compounds with a pyranone structure. In fact, P-pyranone (VI in Formula 4.59) is under discussion as the most important intermediate. It can be formed from the pyranose hemiacetal form of 3-deoxyosone (Formula 4.64). This compound has been identified only in the full acetal form (e. g., with carbohydrates on drying) because only this structure makes a relatively stable end product possible. The compounds mentioned have acidic hydrogen atoms in position 4, easily allowing condensation reactions with aldehydes and polymerization or the formation of brown dyes. 

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