Color formation due to non enzimatic browning in amorphous, glassy, anhydrous model systems

CAROLINA SCHEBOR; MARÍA DEL PILAR BUERA; JORGE CHIRIFE

FOOD CHEMISTRY

Elsevier

Año: 1999 vol. 65 p. 427 - 432

0308-8146

Polymeric matrix model systems (gelatinized starch, maltodextrin and polyvinylpyrrolidone (PVP) MW 40 000) containing a low concentration of added Maillard's reactants (glucose and l-lysine) were freeze dried, further desiccated (P2O5) to `zero' % moisture, and heated for 48 h at 90C. Under these conditions, all model systems were well below their measured glass transition temperature (Tg). Skim-milk powder samples (1.7 and 3.9% (dry basis) moisture) were also stored at 45 or 60C, and browning was recorded. Browning was observed in the glassy polymericmatrices kept well below Tg and in the virtual absence of water. Browning developed in the milk powder samples stored at 60C at a higher rate than at 45C, even when both systems were in glassy conditions. This suggests that the Tg parameter should not be considered as an absolute threshold of stability with regard to non-enzymatic browning reactions.