Partial De-Stoning of Olive Paste to Increase Olive Oil Quality, Yield, and Sustainability of the Olive Oil Extraction Process.

Stone recovery in the olive oil extraction process can be an opportunity to increase both incomes and environmental sustainability. To this aim a new partial de-stoning machine (called Moliden) is installed at the first stage of an olive oil extraction plant to investigate its influence on the quality and sustainability of the extraction process. Quantitative and qualitative results are compared with those achieved using a conventional extraction process. Despite the 60% of stone recovered, no significant differences are registered for oil yield and extractability. A high-quality biomass is recovered by the partial de-stoner machine, belonging to A1 class quality when compared to the standard of the wood pellet, with the only exception of the moisture content. The partial de-stoning also improves the extra virgin olive oil (EVOO) quality in terms of hydrophilic phenols resulting in an enhancement of bitter and pungent sensory notes and most of all provides a beneficial effect for human health. Practical Applications: The new concept of partial de-stoner machine proposed in this work allows reducing the equipment employed in the extraction process of olive oil, since it consists of two sections: crushing and de-stoning. When compared with a standard unit, which recover pits from pomace, it provides a higher quality stone to be used as a biomass fuel. This leads to economic benefits for the millers and has a significant impact on the environmental sustainability of the process.