Application of Acoustic Devices In the Brewing Industry

Hough,J. S., Wadeson, A. and Welsby, V. C.

Abstract
Many potential applications arise for acoustics in brewing but have not been extensively used except for ultrasonic disintegration of hops and ultrasonic fobbing prior to capping of beer bottles. Recently a pulse echo device has been developed to measure liquid height and has been applied commercially, particularly for fermentation vessels and beer ageing tanks. With a laboratory version of this sonar equipment in a 2 metre tube, a linear relationship was shown between iquid depth and recorded time for sound to pass through that depth of liquid. Beer, wort, sugar and saline solutions, but not pure alcohol. showed greater sound velocities than water. However as alcohol was diluted to 30% vlv, the velocity progressively increased to values greater than that of water; with further watering, the speed approached that of water. For worts and beers specific gravity and sound velocity were roughly proportional. Increase in temperature gave a non-linear rise in sound speed. Suspended solids had little effect on sound velocity. During fermentation, sound speed fell because carbohydrate was consumed but this fall was largely compensated by alcohol production.
Keywords: