This method describes how to determine the clarity or turbidity of water using a turbidimeter.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
A water sample containing undissolved substances diminishes the incident light radiation and scatters it unevenly in all directions. The intensity of the scattered radiation depends on the wavelength of the incident light, on the measurement angle and on the form and size of the suspended particles. The results of the turbidimetric analysis are related to a “standard formazin turbidity”.
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.
Valid for all non-turbid beers
By incrementally adding increasing amounts of a saturated ammonium sulfate solution to beer, haze appears as a result of protein precipitation. The amount of the ammonium sulfate solution necessary to produce haze is directly proportional to the stability of the beer. The ammonium sulfate precipitation value expresses the ml of saturated ammonium sulfate solution that must be added to 100 ml of beer in order to produce a barely perceptible opalescence.
The Esbach reaction test provides an indication of the physical and chemical stability of beer, particularly for those which have been treated with bentonite [1, 2].
Suitable for all non-turbid beers
Higher molecular weight proteins are precipitated with the Esbach reagent (solution of picric acid and citric acid). The haze that is formed is determined spectrophotometrically.
This method describes how to determine the true color of water by means of spectrophotometry.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
The color of water is determined by measuring the absorbance at a minimum of three wavelengths at various points across the visual spectrum:
λ1 = 436 nm (obligatory), λ2 = 525 nm, λ3 = 620 nm (for λ2, λ3 minor deviations are permitted). If necessary, measurements at additional wavelengths must be carried out.
This method describes how to determine the clarity or turbidity of water using a transparent cylinder.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods