Plant innovation in the olive oil extraction process: A comparison of efficiency and energy consumption between microwave treatment and traditional malaxation of olive pastes

• Microwave technology was compared to malaxation in olive paste conditioning.
• A comparison of yield, thermal and electrical energy consumption was carried out.
• The extraction yield of two systems do not shown significant differences.
• Microwave implementation in olive oil extraction plants could be feasible.

In this study, we discuss the introduction of microwave radiation replacing the malaxation of olive paste and associated experimentation. A major limitation of olive oil extraction plants is the discontinuity in the extraction process due to the current technology used during the conditioning of the olive paste. In this work, a microwave-assisted system was developed and applied in an industrial-scale olive oil extraction plant to preliminarily analyse the installation and determine any advantages to improving the process continuity. The apparatus, which is specifically designed to be industrially implemented, was evaluated in terms of electrical and thermal energy consumption and the extraction yield of the olive oil. Special attention was given to a microstructural investigation of the olive paste using SEM analyses. The microwave treatment does not significantly influence the extraction yield compared with conventional malaxation, but the SEM results demonstrated that the microwave technique efficiently breaks down cell walls and membranes, thus increasing the release of oil. In addition, some benefits are observed that result from making the olive oil extraction process continuous. The results acquired from this study are promising for microwave implementation in olive oil extraction plants in the future.