Acoustic cavitation by means ultrasounds in the extra virgin olive oil extraction process

Abstract The virgin olive oil extraction process has changed very little over the past 20 years when the mechanical crushers, malaxers, horizontal and vertical centrifuges, took place in the olive mills. However, malaxation process remains the main critical step due to the discontinuity of this process. In previous activities, the same authors demonstrated how application of new emerging technologies could offer an interesting number of advantages to remove this bottleneck and, among the others, the ultrasound (US) technology is the most promising one, due to its mechanical and thermal effects due to the acoustic cavitation phenomenon. Acoustic cavitation, provided by means of low frequency high power ultrasounds, increases the quality, the work capacity and efficiency of the extraction plant, guaranteeing the sustainability. The paper shows how the authors have designed, realized and tested the first in the world continuous ultrasonic full-scale device for the extra virgin olive oil industry, with the aim to obtain the best product quality at the highest efficiency. Considering the heterogeneity of the olive paste, which is composed of different tissues, and considering the large number of parameters able to influence the process, a 3D multiphase CFD analysis was used as auxiliary tool in the design a so-called Sono-Heat-Exchanger (SHE). This innovative device, to be placed between the crusher and the decanter, is a combination of a heat-exchanger with plate-shape ultrasonic transducers. Finally, experimental results about yields and phenols contents demonstrated the relevance of this innovation

Effects of Ultrasound and Green Synthesis ZnO Nanoparticles on Biogas Production from Olive Pomace

Abstract Agro-biomass residues can play a crucial role in promoting the fossil-fuel replacement in agro-food farms. Apulia, a region in Southern Italy, concentrates 22% of farms and 57% of total national olive and olive oil production, resulting the leader producer of the Country. So that, a high quantity of biomass (olive pomace) can be recovered from the milling process. This study investigates the biogas production that occurs during the anaerobic digestion of olive pomace by means of an ultrasound pre-treatment or by means of green synthesis of ZnO Nanoparticles mixed with olive pomace, in order to facilitate its digestion or co-digestion. Measurement of dry matter and biogas produced volume during the anaerobic process were investigated starting from 3-phase and 2-phase olive pomace by means of high specific energy and low frequency ultrasound values. The results highlight a promising influence of ultrasound pre-treatment useful at increasing the biogas yield of olive pomace

La qualità degli oli vergini in funzione delle macchine utilizzate per la preparazione della pasta di olive

Quality of virgin olive oil as function of the machines utilised for olive paste preparation. The mechanical extraction of the oil from the olives involves, as initial fundamental operation, with the preparation of the olive paste by means of various machines - different one from the other both in the processing principle and in the building characteristics - influencing the quality of the extracted oil. On the basis of such possible mechanical and technological variables experimental trials on olives milling has been carried on in different processing conditions using four different kinds of machines in order to verify their efficiency:a stone mill, a hammer crusher, a disk crusher and a depicking machine. On all the extracted oils the traditional analyses have been performed provided by the EC Regulation n. 2568/91, those relative to the content of total phenols and to the resistance to forced oxidation. The achieved results suggest suitable rules of selection of the machines in relation to the characteristics of the olives too, and improvements in the building techniques of the olive oil extraction machines. These techniques on one hand tend to increase the dispersion of the thermal energy developed in the crushing or roller milling cases, on the other to reduce the absolute amount of energy produced with the removal of the whole pit. The whole with the main aim of producing high quality and highly preservable virgin oils