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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Healthy Processed Foods Research » Research » Publications at this Location » Publication #190018
Title: ULTRASOUND PASTEURIZATION: THE EFFECTS OF TEMPERATURE, SOLUBLE SOLIDS, ORGANIC ACIDS AND PH ON THE INACTIVATION OF ESCHERICHIA COLI ATCC 25922

Author
item SALLEH-MACK, SITI - CORNELL UNIV., NEW YORK
item Roberts, John

Submitted to: Ultrasound Sonochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2006
Publication Date: 9/11/2006
Citation: Salleh-Mack, S.Z., Roberts, J.S. 2006. Ultrasound pasteurization: The effects of temperature, soluble solids, organic acids and pH on the inactivation of Escherichia coli ATCC 25922. Ultrasound Sonochemistry. doi:10.106/j.ultsonch. 2006.07.004. 14:323-329 (2007). .

Interpretive Summary: The use of ultrasound was investigated as a method to pasteurize fruit juices at lower temperatures than conventional thermal pasteurization systems. Important physical parameters of fruit juices that have shown to have some effects on thermal inactivation of microorganisms are sugar concentration, organic acids and pH. The objectives of this research are to investigate the effects of these physical parameters and temperature on ultrasound inactivation of Escherichia coli (E. coli), which is the target microorganism in fruit juice pasteurization.

Technical Abstract: The objectives of this research were to study the effects of temperature, sugar concentration (8, 12, and 16 g/100 ml), organic acids (citric and malic acids) and pH (2.5 and 4.0) on ultrasound pasteurization. The model organism used for the research was Escherichia coli ATCC 25922, and ultrasound treatment times were conducted to achieve a 5 log (base 10) reduction. Ultrasound generates heat, therefore the study involved removing the heat using a jacketed beaker with refrigerant (-30 degrees C) to maintain processing temperature at or below 30 degrees C and eliminate the thermal inactivation effects. Overall, ultrasound increased the sensitivity of E. coli to thermal inactivation. The presence of soluble solids had a protective effect where the sonication time requirement increased. Similar to heat sensitivity, the lower pH environment resulted in E. coli having less resistance to sonication. The type of organic acid had the least significant effect on ultrasound inactivation of E. coli.