Some Technological Pretreatments Applied During Olive Oil Extraction: Impacts on Quality Parameters and Minor Constituents

Abstract

The mechanically extraction of olive oil has three main steps: preparation of the paste (crushing with a mechanical metal crusher and kneading with malaxer), solid-liquid and liquid-liquid separation (horizontal-axis centrifugal separator (decanter)). For every extraction process (solid-liquid separation type), the factors such as temperature, time, adjuvants, amount of processing water oxygen and processing type can be changed. Moreover, the need to production of high-quality virgin olive oil at the highest yield and minimum cost, as well as using an environmentally friendly olive oil production encourages the processing of olive oil in different forms and research of new technologies. The main goal for this purpose is to reduce the process time and increase the extraction yield along with transform the discontinuous malaxing step in a continuous phase and improve the working capacity. Another important aspect to consider is the reduction of energy requirements of the process, thereby reducing both environmental and financial costs. This trend triggered the rapid progress in the application of emerging technologies in olive processing. Ultrasounds (US), microwaves (MW), and pulsed electric fields (PEF), flash thermal conditioning (FTC) are emerging technologies that have already found application in the virgin olive oil extraction process on pilot scale plants. This paper aims to describe the basic principles of these technologies as well as the results concerning their impact on virgin olive oil yields. In this review, different technological processes being implemented in recent years to prevent the loss caused by the conventional methods in the production of olive oil and effects of these technological treatments on quality and chemical characteristics of the olive oil is gathered.