High Power Ultrasound: Impact on Olive Paste Temperature, Malaxation Time, Extraction Efficiency, and Characteristics of Extra Virgin Olive Oil

Abstract

High power ultrasound (HPU) provides rapid heating of olive paste and disrupts cell walls, helping small oil droplets exit tissue and coalesce. This has been shown to improve oil yield and reduce malaxation time without affecting oil quality. Indirect and direct HPU at different treatment times were examined on Arbequina and Frantoio olive pastes. Olive pastes were mixed at four different malaxation times to evaluate extraction efficiency. Additionally, oil yield and different quality parameters were observed. HPU increased olive paste temperature from 20 ± 0.5 to 25.5 °C, achieving the optimum kneading temperature of 29 ± 1 °C in less mixing time. HPU significantly (P 0.05) in oil yield between 35 and 45 min malaxation time, suggesting the possibility to reduce malaxation by 10 min with HPU. No significant differences (P > 0.05) were observed in any quality parameters observed, except peroxide value, which increased slightly. Significant increases (P < 0.05) in total tocopherol and pigments with increasing HPU treatment time occurred, while a decrease in total polyphenol and oxidative stability index resulted after 8 min treatment. HPU influenced L, a, and b values causing the oil to become darker. Sensory results showed no differences between commercially available and HPU-treated samples. These results suggest the possibility of using HPU treatment to increase oil extraction capacity and yield without loss of product quality.