title: Cavitation and non-cavitation regime for large-scale ultrasonic standing wave particle separation systems--In situ gentle cavitation threshold determination and free radical related oxidation.
abstract: We here suggest a novel and straightforward approach for liter-scale ultrasound particle manipulation standing wave systems to guide system design in terms of frequency and acoustic power for operating in either cavitation or non-cavitation regimes for ultrasound standing wave systems, using the sonochemiluminescent chemical luminol. We show that this method offers a simple way of in situ determination of the cavitation threshold for selected separation vessel geometry. Since the pressure field is system specific the cavitation threshold is system specific (for the threshold parameter range). In this study we discuss cavitation effects and also measure one implication of cavitation for the application of milk fat separation, the degree of milk fat lipid oxidation by headspace volatile measurements. For the evaluated vessel, 2 MHz as opposed to 1 MHz operation enabled operation in non-cavitation or low cavitation conditions as measured by the luminol intensity threshold method. In all cases the lipid oxidation derived volatiles were below the human sensory detection level. Ultrasound treatment did not significantly influence the oxidative changes in milk for either 1 MHz (dose of 46 kJ/L and 464 kJ/L) or 2 MHz (dose of 37 kJ/L and 373 kJ/L) operation.
authors.affiliation: Mechanical Engineering and Biotactical Engineering, IRIS, Faculty of Science, Engineering & Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia; CSIRO Food and Nutrition, Werribee 3030, Melbourne, Victoria, Australia. Electronic address: l.johansson@swin.edu.au.
authors.forename: Linda
authors.initials: L
authors.lastname: Johansson
authors.affiliation: CSIRO Food and Nutrition, Werribee 3030, Melbourne, Victoria, Australia.
authors.forename: Tanoj
authors.initials: T
authors.lastname: Singh
authors.affiliation: Mechanical Engineering and Biotactical Engineering, IRIS, Faculty of Science, Engineering & Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia; CSIRO Food and Nutrition, Werribee 3030, Melbourne, Victoria, Australia.
authors.forename: Thomas
authors.initials: T
authors.lastname: Leong
authors.affiliation: CSIRO Food and Nutrition, Werribee 3030, Melbourne, Victoria, Australia.
authors.forename: Raymond
authors.initials: R
authors.lastname: Mawson
authors.affiliation: Mechanical Engineering and Biotactical Engineering, IRIS, Faculty of Science, Engineering & Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia.
authors.forename: Sally
authors.initials: S
authors.lastname: McArthur
authors.affiliation: Mechanical Engineering and Biotactical Engineering, IRIS, Faculty of Science, Engineering & Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia.
authors.forename: Richard
authors.initials: R
authors.lastname: Manasseh
authors.affiliation: CSIRO Food and Nutrition, Werribee 3030, Melbourne, Victoria, Australia.
authors.forename: Pablo
authors.initials: P
authors.lastname: Juliano
keywords: Cavitation threshold; Lipid oxidation; Luminol; Milk separation; Sonochemiluminescence; Ultrasonic large-scale particle separation