in a linear increase (r N 0.97) in absorbance of curcumin, taking the dilution factor into account (Fig. 3). Only a slight increase in absorbance
(adjusted for the dilution) was observed in curcumin-GS up to 10–20%
(v/v) ethanol followed firstly by a more pronounced linear increase
(r N 0.99 between 20–50% (v/v) ethanol) and then stabilization above
50% (v/v) ethanol (Fig. 3). The absorption maximum of curcumin was
red-shifted to 540 nm in 50% (v/v) sulfuric acid (Fig. 4, Table 4).