Quality losses in virgin olive oil due to washing and short-term storage before olive milling

Abstract

To identify critical points during olive mill pre-processing operations, the effect of the closed circuit washing stage on the olives microbiological contamination and the influence of the successive short-term storage on olives and VOO quality were evaluated. Microbiological, physical and chemical parameters were assessed in olives and oils at three mill pre-processing stages: reception, washing and short-term storage. Olive washing in closed loop systems was shown to be a critical control point at the olive mill due to microbiological cross-contamination and fruit physical damage. Moreover, when the olives were short-term stored before oil extraction positive VOO sensory attributes decreased by as much as one point of intensity, as justified by the changes observed in phenolic and lipoxygenase derived compounds. These results confirm the high risk of fruit cross-contamination due to the poor hygiene of the water used in olive mills to wash olive, and point o ut t he e ffect of on VOO quality of a common practice such as short term silo storage of olives.