title: Study of the inactivation of spoilage microorganisms in apple juice by pulsed light and ultrasound.
abstract: The aim of this study was to evaluate the effect of ultrasound (US) (600 W, 20 kHz and 95.2 μm wave amplitude; 10 or 30 min at 20, 30 or 44 ± 1 °C) and pulsed light (PL) (Xenon lamp; 3 pulses/s; 0.1 m distance; 2.4 J/cm(2)-71.6 J/cm(2); initial temperature 2, 30, 44 ± 1 °C) on the inactivation of Alicyclobacillus acidoterrestris ATCC 49025 spores and Saccharomyces cerevisiae KE162 inoculated in commercial (pH: 3.5; 12.5 °Brix) and natural squeezed (pH: 3.4; 11.8 °Brix) apple juices. Inactivation depended on treatment time, temperature, microorganism and matrix. Combination of these technologies led up to 3.0 log cycles of spore reduction in commercial apple juice and 2.0 log cycles in natural juice; while for S. cerevisiae, 6.4 and 5.8 log cycles of reduction were achieved in commercial and natural apple juices, respectively. In natural apple juice, the combination of US + 60 s PL at the highest temperature build-up (56 ± 1 °C) was the most effective treatment for both strains. In commercial apple juice, US did not contribute to further inactivation of spores, but significantly reduced yeast population. Certain combinations of US + PL kept on good microbial stability under refrigerated conditions for 15 days.
authors.affiliation: Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires Ciudad Universitaria (1428) C.A.B.A., Argentina; Agencia Nacional de Promoción Científica y Tecnológica de la República Argentina, Argentina.
authors.forename: Mariana
authors.initials: M
authors.lastname: Ferrario
authors.affiliation: Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires Ciudad Universitaria (1428) C.A.B.A., Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina, Argentina.
authors.forename: Stella Maris
authors.initials: SM
authors.lastname: Alzamora
authors.affiliation: Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires Ciudad Universitaria (1428) C.A.B.A., Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina, Argentina. Electronic address: sguerrero@di.fcen.uba.ar.
authors.forename: Sandra
authors.initials: S
authors.lastname: Guerrero
mesh_terms: D001419:Bacteria / Q000254:growth & development / Q000528:radiation effects; D001628:Beverages / Q000382:microbiology*; D005519:Food Preservation / Q000295:instrumentation / Q000379:methods*; D008027:Light; D027845:Malus / Q000382:microbiology*; D014465:Ultrasonics; D015003:Yeasts / Q000254:growth & development / Q000528:radiation effects
keywords: Fruit juices; Hurdle technology; Microbiological stability; Pulsed light; Ultrasound