Increasing solubility of red bell pepper carotenoids by complexation with 2-hydroxypropyl-β-cyclodextrin

• We extracted carotenoids from red bell peppers cultivated in Brazil.
• Inclusion complexes of carotenoids with hydroxypropyl-β-cyclodextrins were prepared.
• Characterization of inclusion complexes was carried out.
• Molecular inclusion increased the solubility of red bell pepper pigments.

Red bell pepper carotenoids were complexed with 2-hydroxypropyl-β-cyclodextrin (2-HPβCD) in different mass ratios (1:4, 1:6, 1:8 and 1:10) through ultrasonic homogenization in order to increase carotenoid solubility and their use as natural pigment in food. Inclusion complexes, red bell pepper extract and physical mixtures were analyzed by DSC, FT-IR, 1H NMR and DLS. Solubility assay was performed to identify the effect of complexation on the solubility of carotenoids. From characterization assays, results showed that inclusion process occurred for all tested ratios. Results for water solubility assays demonstrated clear differences between solubility index of inclusion complexes (8.06 ± 2.59–16.55 ± 4.40 mg/mL) and physical mixtures (3.53 ± 1.44–7.3 ± 1.88 mg/mL), while carotenoid extract was no water soluble, as expected. These results indicated that molecular inclusion of carotenoids in 2-HPβCD was efficient to enhance their solubility in water, enabling application of red bell pepper carotenoid as natural pigment and/or bioactive substances in food.