Thermal characterization of Arrabidaea chica (Humb. & Bonpl.) B. Verl. dry extracts obtained by spray dryer

This work aimed at characterizing, by thermogravimetry (TG/DTG) and DTA, dry extracts of Arrabidaea chica (Humb. & Bompl.) B. Verl. ( A. chica ) leaves obtained by spray drying using maltodextrin and gum arabic as adjuvants. Dry extracts structure and morphology were also evaluated through FT-IR spectroscopy and scanning electron microscopy (SEM). TG/DTG and DTA analyses were used to determine samples thermal profiles. Thermal analysis demonstrated that the blend containing 25 % hydroalcoholic A. chica extract, 25 % gum arabic and 50 % maltodextrin had the strongest interaction between adjuvants and hydroalcoholic extract, thus proving the best blending proportion. FT-IR spectroscopy profile, which was used to infer the chemical composition of powdered A. chica leaves and dry extract (F4), showed typical absorption bands deriving from links of functional groups remained over the powdered A. chica leaves. SEM revealed a heterogeneous morphology with smooth surface and rough surface of different dry extracts obtained. Thermoanalytical and spectrometric techniques proved valuable tools to investigate physicochemical characteristics of dry extracts obtained from A. chica leaves.