Power ultrasound technology in food processing

Power ultrasound has many potential applications in the food industry. Our work so far has shown that ultrasound technology can potentially improve heat and mass transfer in downstream processes. It could, for example, allow users to increase soluble solids content in feed–stocks for spray driers, thereby significantly increasing spray drier capacity. However, there are many other possible applications, and we are keen to hear from industrial clients who have a specific objective in mind that they would like to explore.

Potential to modify viscosity

It has been reported that ultrasound also has the potential to modify the viscosity of food products in order to enhance the efficiency of downstream processing. The viscosity of a food product can have significant effects on process efficiency and product quality. Temporarily thinning products prior to any process that is rate limited by viscosity could greatly improve efficiency, which could in turn lead to improvements in energy efficiency, and product sensory and nutritional quality.

We have already carried out work on the effect that treatment with power ultrasound has on the viscosity of food thickeners, such as when modified starch, xanthan gum and guar gum are pumped through a test system. A flow cell was used to pump the sample past a sonotrode, with flow rates of 2.5–5 l/min. All treated samples were sonicated for up to 30 seconds, at a frequency of 20KHz, and viscosity measurements were taken directly after treatment, and after 4 and 24 hours to establish viscosity reduction and possible recovery. In these trials there were significant viscosity reductions and the effect was dependent on residence time and power input – i.e. the strength of the ultrasound and the length of time the thickeners were subjected to it. However, in our research, the effect was not reversible – i.e. the thickeners remained 'thinned'. Work is ongoing at Campden BRI to find the conditions that permit reversible viscosity modification.

Contact: Edyta Margas
+44(0)1386 842257
edyta.margas@campdenbri.co.uk