Ultrasound tracks fermentation

An acoustic system developed at Pacific Northwest National Laboratory eliminates the need for laborious and costly sampling of slurries in large containers.

Fermentation-based industries, such as beer and pharmaceuticals, could benefit from the system’s non-invasive, continuous and objective ‘listening’ technique in tracking microbial growth through different process phases.

In an experimental or production fermentation process, it is frequently necessary to monitor the growth of organisms within a fermentor. The typical method for doing this is a time-consuming and invasive process of collecting, diluting and counting a sample at periodic intervals.

But the researchers at PNNL have automated the process by deploying ultrasonic technology.

The system works by analysing how ultrasonic signals are scattered and absorbed within the fermentor media as a function of time. Conceptually, the acoustic system is relatively simple. It consists of either a single transducer or paired transducers placed on opposite sides of a container.

Because both the backscattered acoustic signals and the acoustic signals that transit the vessel contain useful information about the slurry, the signals from the transducers are digitised and analysed so that an operator can immediately detect changes in the fermentation process.

The system can be automated, runs continuously unattended and can be configured to trigger process controls such as valves and switches.

 ‘The beauty of acoustics is that it can tell you what’s going on within a mixture without having to disrupt the process by physically drawing a sample and analysing it,’ said Dick Pappas, a senior research scientist at the research organisation..

 ‘And because we can measure how fast sound travels across a vat, for instance, and the change in the signal’s frequency and strength, we can also tell when a mixture has changed from what it should be, possibly heading off a negative situation. Similarly, we can tell when a mixture is brewed to perfection.’

More about the technology is available here.