Continuous conditioning of olive paste by high power ultrasounds: Response surface methodology to predict temperature and its effect on oil yield and virgin olive oil characteristics

• The high power ultrasound allows an instantaneous heating.
• RSM predicted accurately the paste temperature rising.
• Higher oil extraction yield was obtained.
• The treatment reduced the malaxation step duration.
• No alteration or change observed on the virgin olive oil quality.

The purpose of this work is the study of the continuous conditioning of olive paste using High Power Ultrasounds (HPU) previous to malaxation, and its effect on extraction yield and Virgin Olive Oil (VOO) characteristics. For this purpose a laboratory scale device for HPU treatment experiments was developed.The HPU induced an instantaneous heating of olive paste until 28 °C whereas it took 20–30 min in the traditional malaxation condition. The temperature increase depended on olive characteristics, olive paste flow rate and HPU intensity. A response surface model was carried out to predict the olive paste temperature for the variables identified previously. The sonication treatment improved the oil yield and gave higher extractability than conventional malaxation. The HPU treatment did not cause alteration on VOO quality indexes and composition. Olive oil volatile compounds related with oxidation mechanisms showed lower concentration for VOOs from HPU treated olive paste.