title: Influence of high power ultrasound on selected moulds, yeasts and Alicyclobacillus acidoterrestris in apple, cranberry and blueberry juice and nectar.
abstract: The purpose of this study was to investigate the effect of non-thermal technology, high power ultrasound (HPU) on inactivation of Aspergillus ochraceus 318, Penicillium expansum 565, Rhodotorula sp. 74, Saccharomyces cerevisiae 5 and Alicyclobacillus acidoterrestris DSM 3922 in clear juices and nectars from apple, blueberry and cranberry juice concentrate. Inoculated juice and nectars were treated by high power ultrasound (20kHz) according to procedure set by central composite design (CCD). Three operational parameters, amplitude (60, 90 and 120μm), temperature (20, 40 and 60°C), and treatment time (3, 6 or 9min) were varied in order to observe the influence of ultrasound and combination of ultrasound and slight heating (thermosonication) on growth and inactivation of selected microorganisms. Number of vegetative cells of A. acidoterrestris DSM 3922 were not significantly reduced by high power ultrasound (p>0.05), except in apple juice, where statistical significant (p<0.05) influence of quadratic interaction of amplitude on bacteria reduction were observed. In all samples of fruit juices and nectars in terms of ultrasonic treatment at 60°C and times of 3, 6 and 9min, regardless of the value of the amplitude, complete inactivation of the growth of yeasts and moulds were achieved, while at 20 and 40°C it is not observed. The value of reduction of cells of selected yeasts and moulds for ultrasound treatments at 60°C and the duration of the 3, 6 and 9min ranged from 3.556 to 5.934 log units, depending on the initial number of selected yeasts and moulds before treatment.
authors.affiliation: Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia. Electronic address: arezek@pbf.hr.
authors.forename: Anet
authors.initials: A
authors.lastname: Režek Jambrak
authors.affiliation: Vindija d.d, Međimurska 6, 42000 Varaždin, Croatia.
authors.forename: Marina
authors.initials: M
authors.lastname: Šimunek
authors.affiliation: Vindija d.d, Međimurska 6, 42000 Varaždin, Croatia.
authors.forename: Silva
authors.initials: S
authors.lastname: Evačić
authors.affiliation: Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia.
authors.forename: Ksenija
authors.initials: K
authors.lastname: Markov
authors.affiliation: Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, 10000 Zagreb, Croatia.
authors.forename: Goran
authors.initials: G
authors.lastname: Smoljanić
authors.affiliation: Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia.
authors.forename: Jadranka
authors.initials: J
authors.lastname: Frece
mesh_terms: D001419:Bacteria / Q000166:cytology / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005506:Food Contamination / Q000517:prevention & control*; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D000067030:Fruit and Vegetable Juices / Q000382:microbiology* / Q000528:radiation effects*; D005658:Fungi / Q000166:cytology / Q000528:radiation effects*; D019220:High-Energy Shock Waves; D011829:Radiation Dosage; D013242:Sterilization / Q000379:methods*
keywords: Alicyclobacillus acidoterrestris; Fruit juice and nectar; High power ultrasound; Moulds; Yeasts