The purpose of this work was to investigate the physicochemical changes occurring during
the thermal-based production of água-mel, a traditional Portuguese honey-related food product. The
refractive index, color parameters (hue angle, H◦
; chroma, C*), and the content of total reducing
sugars, glucose, fructose, total brown pigments, and 5-hydroxymethylfurfural were monitored along
the entire production process, and their evolution was kinetically modelled. Thermal processing
caused a gradual decrease in sugars, which was accompanied by the formation of brown pigments and
5-hydroxymethylfurfural, increased concentration of soluble solids as evaluated through refractive
index measurements, as well as the appearance of darker colors. In particular, a zero-order kinetic
model could explain the changes in H◦ and reducing sugars, while the evolution of refractive
index, brown pigments, 5-hydroxymethylfurfural, C*, fructose, and glucose were best fitted using a
first-order kinetics model