Evolution of Physicochemical Parameters during the Thermal-Based Production of Água-mel , a Traditional Portuguese Honey-Related Food Product

The purpose of this work was to investigate the physicochemical changes occurring during the thermal-based production of , a traditional Portuguese honey-related food product. The refractive index, color parameters (hue angle, H°; chroma, ), 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, , fructose, and glucose were best fitted using a first-order kinetics model.