Innovative Ultrasonics specializes in process development, engineering design, installation and equipment in the area of high-powered ultrasonics for new and existing industrial applications.
Enzyme Reactions
Ultrasound can increase enzyme activity if applied appropriately, but can result in de-naturation if the power intensity is too high. The activation effect was observed by Ishimori et al. (1981) for the action of α-chymotrypsin on casein, where a two-fold increase in activity was observed after ultrasonic treatment at a frequency of 20kHz. The enhanced enzyme activity was due to the increased penetration of the casein micelle, induced by cavitational effects close to the enzyme's surface.
Inactivation has been reported (Mason 1998) for enzymes such as:
> pepsin
> invertase (involved in sucrose inversion)
> peroxidase (greater than 90% reduction in peroxidase activity was observed during ultrasonic treatment at 20 kHz for 3 hrs).
Stimulation of β-galactosidase activity (and subsequent lactose hydrolysis) in Lactobacillus delbrueckii and L. helveticus was reported by Toba et al. (1990), following high power sonication of skim milk for 20 mins. Lactose concentrations were reduced by 71-74% compared to 39-51% without sonication, producing a sweeter product due to increased concentrations of galactose (and glucose).
Mason (1998) makes the generalisation that oxidases are generally inactivated by sonication, catalases are only affected at low concentrations, reductases and amylases appear highly resistant. Conditions such as temperature, enzyme concentration, the presence of oxygen in the matrix, need to be closely controlled.