The effect of different process variables, such as solid/liquid ratio (1: 1, 1: 3, or 1: 5 g/ml) and stirring speeds (0, 200, or 400 rpm), was studied on the extraction mechanisms of eucalyptus essential oil obtained by hydrodistillation (HD). Different performance parameters such as obtained yield, energy requirements, and environmental impact were compared to those obtained by steam distillation (SD). Two different mathematical models were used to describe the process behavior. The obtained results indicate that the system with a solid/liquid ratio of 1:5 g/ml using a stirring speed of 400 rpm yielded maximum for HD (1.19% ± 0.01%). The environmental impact expressed as Ecopoints (EI99) ranged between 50.87 ± 13.18 and 78.17 ± 13.82 mPT/g essential oil (EO) for systems with steam injection, whereas for HD took values between 16.9 ± 0.3 and 19.24 ± 1.4 mPT/g EO at optimal operating conditions. The model parameters allowed us to identify that large amounts of steam at lower heating velocities induce a high accumulation of EO in the aqueous layer (vapor-liquid equilibrium at the interface), favoring the extraction process.

Droplet size has significant scientific and industrial relevance in the effectiveness of atomization for several applications in the chemical, pharmaceutical, and food industries. This technology is widely employed in the food industry for processes such as spray drying, microencapsulation, edible coatings, and food disinfection, among others. This work comprehensively reviews the effect of liquid properties and equipment operating factors influencing droplet size in pneumatic and ultrasonic atomization. The discussion on the atomization theories includes the different models for estimating droplet size as a function of selected variables for both processes. The different model approaches are reviewed, focusing on their advantages, disadvantages, applications, and limitations. Furthermore, selected models were employed to carry out different sensitivity analyses showing the effect of variables related to the liquid properties, the type and characteristics of the atomizers, and the operating conditions, allowing the reader to appreciate the most critical factors in both atomization systems.