The fluorescence of advanced Maillard products is a good indicator of lysine damage during the Maillard reaction

The objective of this study was to determine whether in heat-treated milk-r esembling models or milk there is a lag phase, before lactulosyllysine (LL) is converted into advanced Maillard products (AMP), and if there is a step during the heat treatment where LL is actively degraded into AMP. For that purpose, a low temperature (60-85 degreesC) and a long heat treatment (15- 90 h) were chosen. We observe that the heat treatment first induces a paral lel increase in furosine and AMP fluorescence, confirming that AMP are prod uced very early during the heat treatment. At this step, both indicators ar e correlated with each other and precisely reflect the lysine damage. After a time, however, furosine reaches a steady-state concentration, whereas AM P fluorescence still increases, remaining correlated with the lysine blocka ge. Nevertheless, heat treatment applied to milk does not reach this step s o that AMP fluorescence appears as a rapid alternative to furosine quantifi cation.