## 4 Conclusions  
In this study, oil-in-water nanoemulsions formulated with lemon essential oil were developed using various mixtures of surfactants (Tween 80 and Span 20) as an emulsifying agent. These different mixtures resulted in different HLB numbers.  
The emulsion with an HLB number of 11 exhibited a monomodal droplet distribution and an Ostwald ripening phenomenon with aging time. Contrarily, emulsions with an HLB number of 13 or above exhibited a bimodal droplet distribution and coalescence with aging time. The emulsion with an HLB number of 12 exhibited a monomodal distribution and remained stable during the period studied. These findings indicated that DSDs (monomodal or bimodal) and destabilization mechanisms (coalescence or Ostwald ripening) were both influenced by the HLB number. It appears that an HLB number lower than 12 promotes Ostwald ripening, while an HLB number higher than 12 promotes coalescence.  
All of the nanoemulsions developed exhibited Newtonian behavior, with viscosity values lower than 16 mPa-s. Hence, these systems revealed a lack of a microstructure. These findings indicated that a creaming process could take place because the droplets could freely move. By using the MLS technique, the occurrence of not only coalescence/OR but also of creaming was highlighted in these systems. However, a study of the physical stability of the emulsions suggested that the creaming process was least evident in the emulsion with an HLB number of 12. This may be due to the monomodal distribution presented by this system and the stable droplet size distribution with aging time observed.  
In conclusion, we may say that, using the formulation described above, emulsions with an HLB number of 12 not only exhibit the best droplet size distribution but also the greatest physical stability, with no growth in droplet size and low creaming, which is extremely important for food emulsions. Such lemon essential oil nanoemulsions--with their antibacterial properties--might therefore be used as matrices for food products such as sauces, dressings and beverages. In this study, we sought to gain new knowledge about nanoemulsions formulated with lemon essential oil. Our findings highlight how different HLB numbers may influence the physical stability of food nanoemulsions.  
Conceptualization, M.-C.A.-R. and J.M.; methodology, M.-C.A.-R. and J.M.; software, L.V. and M.-C.A.-R.; validation, M.-C.A.-R. and J.S.; formal analysis, M.-C.A.-R. and J.S.; investigation, L.V.; resources, J.M.; data curation, M.-C.A.-R. and J.M.; writing--original draft preparation, J.S.; writing--review and editing, J.S. and M.-C.A.-R.; visualization, J.S. and M.-C.A.-R.; supervision, M.-C.A.-R. and J.S.; project administration, M.-C.A.-R.; funding acquisition, J.M. and M.-C.A.-R. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the FEDER/Consejeria de Transformacion Economica, Industria, Conocimiento, y Universidades de la Junta de Andalucia (Programa Operativo FEDER 2014-2020, project reference: US-1380760); and the Ramon y Cajal contracts (Reference: RYC2021-033481-1).  
Not applicable.  
The data will be provided on request.  
The authors declare no conflict of interest. The funders had no role in the design of this study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.