title: Temperature effects on the ultrasonic separation of fat from natural whole milk.
abstract: This study showed that temperature influences the rate of separation of fat from natural whole milk during application of ultrasonic standing waves. In this study, natural whole milk was sonicated at 600kHz (583W/L) or 1MHz (311W/L) with a starting bulk temperature of 5, 25, or 40°C. Comparisons on separation efficiency were performed with and without sonication. Sonication using 1MHz for 5min at 25°C was shown to be more effective for fat separation than the other conditions tested with and without ultrasound, resulting in a relative change from 3.5±0.06% (w/v) fat initially, of -52.3±2.3% (reduction to 1.6±0.07% (w/v) fat) in the skimmed milk layer and 184.8±33.2% (increase to 9.9±1.0% (w/v) fat) in the top layer, at an average skimming rate of ∼5g fat/min. A shift in the volume weighted mean diameter (D[4,3]) of the milk samples obtained from the top and bottom of between 8% and 10% relative to an initial sample D[4,3] value of 4.5±0.06μm was also achieved under these conditions. In general, faster fat separation was seen in natural milk when natural creaming occurred at room temperature and this separation trend was enhanced after the application of high frequency ultrasound.
authors.affiliation: Mechanical and Product Design Engineering, Faculty of Science, Engineering and Technology, Swinburne University of Technology, VIC 3122, Australia. Electronic address: tleong@swin.edu.au.
authors.forename: Thomas
authors.initials: T
authors.lastname: Leong
authors.affiliation: CSIRO Animal Food and Health Sciences, 671 Sneydes Rd, Werribee, VIC 3030, Australia.
authors.forename: Pablo
authors.initials: P
authors.lastname: Juliano
authors.affiliation: Mechanical and Product Design Engineering, Faculty of Science, Engineering and Technology, Swinburne University of Technology, VIC 3122, Australia.
authors.forename: Linda
authors.initials: L
authors.lastname: Johansson
authors.affiliation: CSIRO Animal Food and Health Sciences, 671 Sneydes Rd, Werribee, VIC 3030, Australia.
authors.forename: Raymond
authors.initials: R
authors.lastname: Mawson
authors.affiliation: Biotactical Engineering, IRIS, Faculty of Science, Engineering and Technology, Swinburne University of Technology, VIC 3122, Australia.
authors.forename: Sally L
authors.initials: SL
authors.lastname: McArthur
authors.affiliation: Mechanical and Product Design Engineering, Faculty of Science, Engineering and Technology, Swinburne University of Technology, VIC 3122, Australia.
authors.forename: Richard
authors.initials: R
authors.lastname: Manasseh
mesh_terms: D000818:Animals; D004041:Dietary Fats / Q000302:isolation & purification*; D008892:Milk / Q000737:chemistry*; D010316:Particle Size; D013010:Sonication / Q000295:instrumentation / Q000379:methods*; D013696:Temperature
chemical_list: D004041:Dietary Fats
keywords: Milk; Milk fat globules; Separation; Ultrasound