Continuous high power ultrasound treatment before malaxation, a laboratory scale approach: Effect on virgin olive oil quality criteria and yield

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Continuous application of high power ultrasound (HPU) on olive paste previous to malaxation at laboratory scale for virgin olive oil (VOO) extraction and its effect on process yield and the VOO quality have been studied. For the VOO samples, we determined the quality indices (free acidity value, peroxide value, K232, K270), bitterness, volatile composition, phenolic content (total and biophenols), tocopherol content, and pigments.The application of ultrasound induced a quick heating of the paste from 20 to 28°C. The sonication treatment improved the industrial oil yield by 1% and the oil extractability by 5.74%. Moreover the HPU treatment did not cause changes in the quality indices, fatty acid composition and volatile aromatic compounds of the VOO. Furthermore the fat autoxidation process was not accelerated by this treatment. Meanwhile oil obtained from olive pastes treated with HPU showed higher content of tocopherol, chlorophylls and carotenoids whereas a reduction in phenolic content and bitterness index was observed.Practical applications: The high power ultrasound (HPU) treatment of olive paste, before malaxation during the virgin olive oil (VOO) elaboration process, can improve the oil extraction yield without alteration of its quality parameters. The olive paste instantaneous heating observed with the HPU can allow the reduction of the malaxation step duration. The results obtained nowadays at laboratory scale are promising for the possibility of the continuous HPU treatment introduction in the olive oil elaboration process as aid or alternative to the malaxation. For this purpose further experiment at pilot and industrial scale are needed.Continuous application of high power ultrasound before malaxation and its effect on the oil extractability and virgin olive oil characteristics.