Microwave-assisted treatment for continuous olive paste conditioning: Impact on olive oil quality and yield

• An industrial microwave apparatus was implemented in an olive oil extraction plant.
• It was shown to be flexible for application in olive oil plant.
• It produced a great reduction in the kneading time.
• It could be a useful tool for controlling the amounts of phenols in the olive oil.

Olive paste conditioning using microwave technology was integrated into an olive oil extraction plant using industrial-scale microwave-assisted apparatus. This first effort at integrating microwave technology contributed significantly to the continuous conditioning of the olive paste. The components of the equipment were designed and sized for optimal efficiency in an earlier preliminary study. With the aim of improving the operation of the extraction plants towards providing a continuous management of the process, an investigation of effects of optimal scheduling on olive oil quality was conducted. The objective was to evaluate the impact of the microwave treatment used to condition the olive paste on olive oil quality and yield and comparing it with the conventional industrial malaxation. The short process time of the rapid microwave treatment resulted in a low oxidation of the olive oil and consequently a reduction in the peroxide value compared with the conventional method. Using the microwave treatment, a higher concentration of volatile compounds in the oil was obtained with a lower content of phenolic compounds that are associated with spicy and bitter notes. No significant differences were found with extraction yield. Microwave processing was therefore confirmed as an attractive alternative to the conventional malaxation, with the main advantages being the rapid processing time and the high olive oil quality.