Towards an index of damage of olive paste during virgin olive oil extraction: The role of β-OH-acteoside diastereomers for risk assessment of the fusty/muddy sediment sensory defect

The aim of this study was to propose an index/marker of thermal/oxidative damage of olive paste during virgin olive oil extraction to assess the risk of sensory defects in the obtained oil. Several olive oil extraction trials were carried out over two production years applying different time, temperature, and oxygen exposure conditions during malaxation. The phenolic composition of the olive pastes was analyzed by High Performance Liquid Chromatography-Diode Array Detector-Mass Spectrometry (HPLC-DAD-MS). The chemical (legal quality indexes, phenolic compounds by HPLC-DAD-MS, volatile compounds by Head Space-Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS)) and sensory characteristics of the obtained oils were analyzed. The content of the β-OH-acteoside diastereomers in olive paste increased linearly with malaxation time as a function of malaxation temperature and oxidative conditions, following a pseudo-zero order kinetic. At the same time, two volatile compounds linked to sensory defects (2- and 3-methylbutanal) increased in the obtained oils when increasing malaxation time and temperature, and a relationship between them and the fusty/muddy sediment defect in olive oil samples was observed. A further direct relationship between the β-OH-acteoside content in the olive pastes and the 2+3-methylbutanal content in the oils was observed. Therefore, the β-OH-acteoside diastereomers content in olive pastes has been suggested as an index/marker to indicate the risk of sensory defects in virgin olive oil as a function of the thermal and oxidative conditions during malaxation. A threshold value of 100 mg/kg of the content of β-OH-acteoside diastereomers was proposed, above which the fusty/muddy sediment defect is perceptible.