Stability studies of neem seed oil-in-water emulsion formulation

Neem seed oil (NSO) is a natural oil extracted from the seeds of the neem tree ( Azadirachta indica ). It is widely used in agriculture, due to its antifungal and insecticidal properties. This study aims to investigate neem seed oil extract and the stability of its emulsion formulation. The effects of surfactant type (Tween 80 or lignosulfonate) and surfactant-to-oil ratio on emulsion stability were evaluated. The results demonstrated that NSO emulsions could be successfully stabilized using both Tween 80 and lignosulfonate. The optimal surfactant-to-oil ratio for Tween 80 was found to be 1:2, while for lignosulfonate, a ratio of 1:4 was most effective. The stability of the emulsions was influenced by both surfactant type and storage temperature. NSO emulsions stored at refrigeration temperature exhibited higher stability compared to those stored at room temperature. Droplet size analysis revealed that the average droplet size of the most stable emulsion (ET2b) was 1.068 μm, which is within the desired range for emulsions. The microscopic profiles of the emulsions indicated that droplet agglomeration and coalescence were the primary factors affecting emulsion stability. Overall, this study provides valuable insights into the formulation and optimization of NSO emulsions for agricultural applications. The findings suggest that NSO emulsions have the potential to serve as effective and environmentally friendly alternatives to synthetic pesticides. • Neem seed oil has been successfully extracted using cold press methods. • Varying the composition of emulsion formulations resulted in different droplet sizes and distributions. • Surfactants with different structures influenced droplet size and stability. • The optimal neem seed oil emulsion formulations were ET2b (with Tween 80) and EL4b (with lignosulfonate).