## 1 Introduction  
The sensory characteristics of extra virgin olive oil (EVOO) are very relevant to the choice that the customer makes at the moment of purchasing the product. Thus, consumers have been gaining knowledge of the different desirable sensory notes found in virgin olive oil in the last few years, and producers are consequently adapting production to a higher quality [1, 2, 3, 4, 5, 6, 7]. In order to improve quality, producers are collecting in the right ripening period to prioritize quality in addition to yield [8, 9, 10, 11, 12]. Furthermore, the contribution of the different cultivars is carefully handled in addition to other agromomical factors [7, 13, 14] and commercialization variables [1, 3]. Thus, all these factors affect the volatile composition [4, 13, 15, 16] and, therefore, the aroma of the product. In addition to the sensory attributes, consumers are also aware of the health benefits associated with virgin olive oil consumption, and they attribute these benefits to the presence of phenols, among other compounds. The phenols are also relevant in EVOO because of their sensory impact, contributing to bittermess and pungency. Thus, it is important to develop and improve the sensory properties of EVOO while maintaining its health characteristics, in order to have a pleasant product that is at the same time also healthy. That means that all the processes during production and distribution involving lipid oxidation may affect volatile and phenol concentrations, and therefore they need to be carefully addressed and optimized. In the optimization of virgin olive oil quality, the different variables associated with the mechanical methods used for oil extraction have to be considered since they affect virgin olive oil quality and the content of phenols and volatiles [17]. In particular, a lot of interest has been put into the first phases of EVOO production. In addition, several studies have been addressed with the aim of improving quality, especially in the last few years, using new technologies or optimizing the variables that affect EVOO composition [18; 19; 20; 21; 22]. Further, the interest of the research activities was focused on the initial part of the process, starting from the malaxation phase, in which temperature, time, and oxygen play a significant role in the development of chemical and biochemical reactions influencing the quality of the final product [18; 22; 23; 24]. Notably, the thermal conditioning of the olive paste by means of a heat exchanger prior to malaxation has proven to be of paramount importance for managing the enzyme activities responsible for the production of volatile compounds and the oxidation of phenols [18; 22; 25]. Recently, other technologies were imported into the olive oil sector, coming from other food industries. This is the case for ultrasound, pulsed electric field, and high vacuum malaxation. These technologies, when applied to the production of virgin olive oil, are able to increase the quality and the extraction yield in different ways. All these technologies have the purpose of freeing the oil from the vacuoles and improving the separation of phases during malaxation in order to have the best condition before extraction [20; 21; 26; 27; 28]. However, not only the yield extraction is the main interest of applying these technologies, but also the quality improvement, for example, due to the rise in phenol concentration and the production of oils with healthier properties and an extended shelf life [19; 28; 29; 30]. The increase in phenol concentration is due to the fine cellular breaking and the freeing of the cytoplasmatic liquid, thus promoting the contact between oil droplets and all the other minor compounds [31; 32; 33]. In addition to the work focused on improving the malaxation step, research has recently been focused on the crushing step.