Real-time monitoring of aroma-related VOC dynamics during olive malaxation using PTR-ToF-MS

Extra virgin olive oil (EVOO) sensory quality is strongly influenced by volatile organic compounds (VOCs) formed during processing, mainly through the lipoxygenase (LOX) pathway during crushing and malaxation. However, the dynamic evolution of aroma compounds during extraction has never been investigated in real time. Here, PTR-ToF-MS was applied for the first time to continuously monitor VOC emissions during industrial olive oil extraction. Two cultivars, Leccino and Olivastra Seggianese, were processed at three malaxation times (20, 25, and 40 min); selected C6 aroma compounds were monitored second-by-second. Real-time monitoring revealed a unimodal emission pattern for all VOCs, with a rapid increase followed by progressive decline. Peak emissions occurred at approximate to 15 min (Leccino) and approximate to 18 min (Olivastra Seggianese). Prolonged malaxation (40 min) caused 60-75% losses of total C6 volatiles relative to peak concentrations. Olivastra Seggianese consistently showed higher VOC emissions than Leccino, likely reflecting differences in ripening stage and metabolic activity. Off-line PTR-ToF-MS confirmed these trends: shorter malaxation times preserved higher concentrations of LOXderived compounds, particularly at m/z 81.069 and 99.080, associated with green and fruity notes. PCA discriminated oils by cultivar and malaxation time. Sensory evaluation agreed: oils from 20 to 25 min were classified as extra virgin with higher fruity intensity, whereas prolonged malaxation reduced sensory quality and produced fusty defects. Overall, PTR-ToF-MS provides a real-time tool to monitor aroma evolution and identify optimal malaxation conditions. Its implementation in olive mills could support dynamic process control, preserve cultivar-specific aroma, and improve quality and commercial value of premium EVOO.