D'Amico Dennis J, Silk Todd M, Wu Junru, Guo Mingruo
Department of Nutrition and Food Sciences, University of Vermont, Burlington, Vermont 05405, USA.
J Food Prot. 2006 Mar;69(3):556-63. doi: 10.4315/0362-028x-69.3.556.
Nonthermal technologies are emerging as promising alternatives to heat treatment for food processing. Ultrasound, defined as sound waves with a frequency greater than 20 kHz, has proven bactericidal effects, especially when combined with other microbial-reduction strategies such as mild heating. In this study, ultrasound treatment (sonifier probe at 20 kHz, 100% power level, 150 W acoustic power, 118 W/cm2 acoustic intensity) with or without the effect of mild heat (57 degrees C) was effective at reducing microbial levels in raw milk, Listeria monocytogenes levels inoculated in ultrahigh-temperature milk, and Escherichia coli O157:H7 in apple cider. Continuous flow ultrasound treatment combined with mild heat (57 degrees C) for 18 min resulted in a 5-log reduction of L. monocytogenes in ultrahigh-temperature milk, a 5-log reduction in total aerobic bacteria in raw milk, and a 6-log reduction in E. coli O157:H7 in pasteurized apple cider. Inactivation regressions were second-order polynomials, showing an initial period of rapid inactivation, eventually tailing off. Results indicate that ultrasound technology is a promising processing alternative for the reduction of microorganisms in liquid foods.
非热技术正在成为食品加工热处理的有前景的替代方法。超声波被定义为频率大于20 kHz的声波，已证明具有杀菌作用，特别是与其他微生物减少策略（如温和加热）结合使用时。在本研究中，有或没有温和加热（57摄氏度）作用的超声处理（20 kHz的超声探头，100%功率水平，150 W声功率，118 W/cm2声强）在降低原料奶中的微生物水平、超高温奶中接种的单核细胞增生李斯特菌水平以及苹果酒中的大肠杆菌O157:H7方面是有效的。连续流动超声处理与温和加热（57摄氏度）结合18分钟，导致超高温奶中单核细胞增生李斯特菌减少5个对数级，原料奶中总需氧菌减少5个对数级，巴氏杀菌苹果酒中大肠杆菌O157:H7减少6个对数级。失活回归是二阶多项式，显示出最初快速失活的时期，最终逐渐减弱。结果表明，超声技术是减少液态食品中微生物的一种有前景的加工替代方法。
