Production of more sustainable emulsions formulated with eco-friendly materials

Abstract Sustainable development involves the search for new products with a low environmental impact. Hence, the aim of this work is to obtain stable and concentrated aqueous emulsions containing bitter fennel oil and a biomass-derived emulsifier by studying different processing variables and techniques. Firstly, the effects of the application of a premix step previous to homogenization and of the geometry of the high-energy rotor-stator device used (Silverson L5M or Ultraturrax T50) on the droplet size distribution (DSD) and physical stability (PS) of emulsions were investigated. The use of a premix worsens both the physical stability and the average droplet diameters of the emulsions, the most stable emulsion being that obtained with the Silverson L5M alone. Secondly, the stability of this emulsion was improved. To achieve this goal, this coarse emulsion was microfluidized at different pressures (from 5000 to 25000 psi), reaching submicron sizes and monomodal distributions, except for that subjected to 25000 psi which resulted in clear overprocessing. Creaming and oiling off were the main destabilization processes. The emulsion exhibiting the lowest droplet sizes and the best physical stability was prepared at 20000 psi. This work contributes to the development of sustainable agrochemical prototypes.