Enhanced solubility of quercetin by forming composite particles with transglycosylated materials

• The solubilizing effect was ranked as follows: Rutin-G > Hsp-G > Stevia-G.
• The spray-dried powder containing Rutin-G is highly soluble.
• The structural similarity of quercetin/Rutin-G enhanced the solubility of quercetin.
• The antioxidant activity of quercetin powder could be improved by Rutin-G.

To enhance the apparent solubility of quercetin for the formulation of highly absorbable functional foods, we developed a novel approach with three types of transglycosylated materials by making composite particles via spray-drying. Alpha-glycosyl hesperidin (Hsp-G), alpha-glycosyl stevia (Stevia-G) and alpha-glycosyl rutin (Rutin-G) were used as candidate materials. The incubation of quercetin together with transglycosylated materials dramatically increased the dissolved amount of quercetin. The solubilizing effect was ranked as follows: Rutin-G > Hsp-G > Stevia-G. The apparent solubility of quercetin from the spray-dried sample with Rutin-G was determined to be 43-fold higher than that of the quercetin crystal. This increased solubility was likely due to the formation of molecular-level quercetin/Rutin-G composites via spray-drying. We reported that different types of aggregated-nanostructures may form from transglycosylated materials in aqueous media. The difference in the affinity among quercetin and aggregated nanostructures may relate to the solubility enhancement, indicating that the structural similarity of quercetin and Rutin-G helped the solubilizing effect.