Hach-Lange DR 5000 brewerie analysis, supplementary software LZV570 - Manual (Page 20)

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Working procedures
2.5 Beer colour (spectrophotometric EBC method)
Principle
This method is designed to eliminate subjective effects attributable
to the human eye as well as differences in the colour impression
when the beer samples are compared with the colour card. This
method is an official reference method.
The absorbance is measured in a 10 mm rectangular cuvette at a
wavelength of exactly 430 nm. The colour in EBC units is obtained
by converting with a suitable factor.
Fields of application
Plant wort, beer, liquid malt substitutes of all kinds.
Measuring range
0–60 units
Accessories
• Spectrophotometer (430 nm ± 0.5 nm)
• 10 mm rectangular cuvettes (OS grade)
Sample preparation
1. Dilute the sample so that the absorbance is within the linearity
range of the spectrophotometer.
2. Filter the sample through a membrane filter. Filtration is not
necessary if the turbidity of the diluted sample is less than 1
EBC turbidity unit.
3. If necessary, clarify the sample by adding 0.1% kieselguhr and
filtering before the membrane filtration is carried out.
4. Measure the absorbance (A) at 430 nm against dist. water
(blank value).
Results
The results are expressed in EBC units to 2 significant decimal
places.
Interferences
A spectrometric absorbance curve does not reflect the colour
impression of the human eye, because light of the same intensity
does not have a uniform effect on the eye in different parts of the
spectrum. In addition the absorbance curves at 430 nm are very
steep, so slight measurement errors may occur. Moreover, there
are differences when light beers are compared with diluted dark
beers.
Literature
MEBAK Brautechnische Analysenmethoden
4th Edition 2002 Volume II, pp 88ff