Turbidity measurement in beer
If a beam of light strikes a particle in a liquid, the light is scattered. This phenomenon is referred to as turbidity. In measuring turbidity during the lautering process, it has been shown that only light scattered in a forward direction should be measured to achieve a meaningful correlation between the concentration of solids and the measurement value. Measurements performed at a 90° angle do not correlate with the amount of solids in wort due to particle size and dependence on color. In addition to the amount of scattered light, the absorption (light transmission) is also measured. The utilization of dual beams eliminates disruptive parameters such as color, lamp age and window fouling.
For monitoring filter efficacy, measurements employing forward scattered light are advantageous (measured at an angle ranging from 11 to 25°).
With a suitable turbidity measuring device, the visual impression of turbidity is quantified.
This method is suitable for filtered top-fermented and bottom-fermented beer.
The degree of turbidity present in a beer sample can be compared to a clear beer of the same brand and style to which EBC formazin standard solution has been added to produce haze in the beer. The degree of turbidity can be determined through visual comparison of the two beers.