Azadirachta indica A. Juss (Meliaceae) microencapsulated bioinsecticide: Spray drying technique optimization, characterization, in vitro release, and degradation kinetics

Insecticides based on Azadirachta indica have been demonstrated as useful in pest control and bioinsecticides that are microencapsulated can reduce the amount of product utilized, and minimize impacts on the environment and human health. The objective of this study was to optimize drying, and evaluate the release and degradation kinetics of microencapsulated extracts from A. indica seeds. The Box-Behnken model (33) and surface response methodologies were used to find the best spray drying conditions for the chosen variables. They were: in-let temperature of 160 °C, feed flow of 3.3 mL/min, and nozzle diameter of 0.7 mm. The drying efficiency and EE under these conditions were respectively 71.15% ± 2.18 and 56.88% ± 0.28. In the release kinetics study, the release time for Azadirachtin (100%) was 20h. The 50% photo-degradation time for Azadirachtin was 21.07 days. Our results support industrial scale-up studies, and can help application measures in the field. [Display omitted] •Microencapsulated bioinsecticides are a strategy for integrated pest management.•Drying optimization can improve physical-chemical properties of powder.•Microencapsulated powder showed a distinct release profile of azadirachtin.•The powder showed appropriate release and degradation kinetics for agriculture use.