Capsicum annuum extracts/β-cyclodextrin complexes

Abstract

In this study, thermal analyses and Karl Fischer titration correlations on the new varieties of Capsicum annuum L. extracts/β-cyclodextrin complexes were performed. Two of seven studied Capsicum varieties containing the highest concentration of capsaicin (0.7 and 1.1 mg g−1 of dry sample) were used for obtaining Capsicum extracts/β-cyclodextrin complexes by co-crystallization method. Thermogravimetric analysis (TG) indicates mass losses with 5–5.7 % lower for the complexes in comparison with β-cyclodextrin, while differential scanning calorimetry analysis (DSC) shows a temperature peak shift to lower values, from 378.2 K (105 °C) for β-cyclodextrin to 355.2–361.2 K (82–88 °C) for complexes. On the other hand, Karl Fischer water titration (KFT) indicates a water concentration of 10.9–11.8 %, with 3.1–4.1 % lower than for β-cyclodextrin (14.9 %). The antioxidant activity of Capsicum extracts/β-cyclodextrin complexes has values comparable with standard antioxidant compound solutions, being significant longer time than the starting extracts. Statistically significant correlations between TG, DSC, and KFT main parameters [TG mass loss up to 423.2 K (150 °C), DSC peak temperature corresponding to water dissociation and KFT water content, and water reaction rate for “strongly-retained” water molecules partially replaced from the cyclodextrin cavity in the complexation process] were obtained, proving the formation of guest/host (Capsicum bioactive compounds/β-cyclodextrin) supramolecular systems.