A new technology helps scientists know what's happening inside fermentation processes, like those that produce beer, but also pharmaceuticals, without sticking their fingers inside the product. This new acoustic method can improve the quality of the finished product.

Beer is produced in large tanks, where large amounts of slurries made of sugars derived from starch-based material, like malted barley, are fermenting for a few weeks. Sampling the murky slurries to analyze microbial growth is a painstaking process, which is about to be eliminated by the new, non-invasive technique.

A group of researchers at Pacific Northwest National Laboratory developed a new method of analyzing the fermentation and the growth of the microorganisms required by the process by literally listening to the beer.

The acoustic applications use ultrasounds to perform acoustic backscatter and transit measurement with the help of sensors attached to the exterior of the holding tank. Vast amounts of vital information can thus be collected to ensure the highest quality of the finished product, like velocity, amplitude and frequency.

A relatively simple concept, this technology uses one or more transducers to transform electric signals coming from the holding tanks into sounds, which are then digitized and analyzed by operators to detect even the slightest changes in the fermentation process.

"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 analyzing it," said Dick Pappas, senior research scientist. "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."