Optimization of spray-drying microencapsulation of curcumin as a strategy for enhancing water solubility and evaluation of antioxidant activities

Curcumin is a natural pigment obtained from turmeric (Curcuma longa L.) rhizome, which has shown different health benefits and potential uses in food and pharmaceutical products, but its application is limited by its insolubility and instability. The present work focuses on microencapsulation of curcumin by spray dryer, in order to improve its solubility and bioactivity. The process includes the use of different biopolymers such as pectin, whey protein and mannitol as wall materials. Thus, a series of curcumin microcapsules were prepared, and the whey protein presented the highest encapsulation capacity (15.77 mg of curcumin). Subsequently, the Taguchi experimental design was used to optimize the operating conditions of the spray dryer, considering the orthogonal array L9 exploring three factors with three levels: feed flow rate (3, 4.5, 6 mL/min), inlet air temperature (130, 150, 170°C), and drying air flow (30, 35, 40 m3/h). As a result, the optimal operating conditions were a 3 mL/min of feed flow rate, 150°C of inlet air temperature, and 40 m3/h of drying air flow and in these conditions, the encapsulation efficiency was 20.71 ± 2.83 μg/mL and the solubility 18.92 ± 2.47 μg/mL. Finally, it was evaluated the antioxidant activity of the microcapsules prepared with four different concentrations of curcumin by DPPH• radical scavenging activity and peroxidation inhibition assay. The result of the DPPH method showed a 98% ± 0.015 value which has a similar profile in all treatments, whereas a lower (20.75% ± 1.15) value was obtained of the lipoperoxidation test. This study provides practical information on the selection of wall materials and encapsulation methods for microencapsulating curcumin for various applications, particularly it would be helpful to the industrial food application.