Controlling the atmosphere in the malaxation machine headspace in order to improve the quality of Sicilian extra virgin olive oils

Abstract

During the mechanical extraction process of Virgin Olive Oil (VOO) some important physical phenomena and enzymatic transformations occur influencing the final product quality. The control of process parameters is crucial to ensure the quality of VOO, therefore process monitoring and control is a fundamental requirement in the modern VOO processing industry. The present work proposes a research performed in order to develop a system for the oxygen continuous monitoring inside the malaxation machine to enhance the Sicilian extra virgin olive oil typicality and to establish a correlation with the quality of the final product. The results showed that the use of oxygen during malaxation, allowed to improve some qualitative parameters of the oils’ volatile composition. The volatile components showing a marked improvement are hexanal and 2-hexenal (E) among the aldehydes and1-hexanol and 3-hexen-1-ol (Z) among the alcohols. The presence of oxygen during malaxation in addition to the charge that olive paste absorbs in the process of kneading, on the one hand improves the volatile composition, on the other hand it worsens the phenolic component, even if slightly. This is not negative for Nocellara del Belice variety that is well equipped with phenolic composition. The research confirms the importance of continuously monitoring and control the oxygen concentration inside the malaxation machine for improving the virgin olive oil quality.