studied the effect of pH on the inactivation of Escherichia coli and
observed a significant effect on the ultrasound inactivation (24 kHz/
9 min), where a lower pH caused a major reduction in the count of
microorganisms. The same authors evaluated the presence of soluble
solids at higher concentrations and observed that longer ultrasound
treatments were necessary to obtain the same reduction
as observed in the treatment control. Then, the concentration of
soluble solids in the medium had a protective effect.