Standard Reference Method - EBC

The EBC system of color measurement is similar to the SRM. Measurements are taken at 430 nm in a 1 cm cell but the unit of color is 25 times the dilution factor times A₄₃₀ as opposed to 12.7 times the dilution factor times A₄₃₀ so that

Thus EBC is approximately twice SRM and this applies at any color depth. The agreement between SRM and Lovibond is fair for pale beers (10 °L ~ 12.7 SRM) but worsens for darker beers or worts (40 °L ~ 53.4 SRM).

Both systems demand that the beer be free of turbidity prior to the measurement at 430 nm. In the SRM a second measurement is taken at 700 nm. If the absorption at this wavelength is less than 0.039 (this number comes from ) times the absorption at 430 nm the beer is considered turbidity free. If not, it is to be filtered or centrifuged and the reading repeated. If the ratio test is not passed after clarification then the beer does not have "average spectral characteristics" and, technically, is not qualified to be characterized by the SRM method. The augmented SRM method described below removes this difficulty.

In the EBC system the beer is required to be filtered if its turbidity is more than 1 EBC turbidity unit (equivalent to 1 FTU). No absorption measurement is made other than at 430 nm. (the turbidimeter measures scattering at 650 nm).

Note that an earlier version of EBC color was based on absorption at 530 nanometers, which permitted no direct conversion between the two systems. However, if one assumes a linear log absorption spectrum (the Linner hypothesis from the realm of caramel color), and knows the Linner Hue Index, the absorptions are related by:

A formula for converting between the old EBC color value and SRM sometimes continues to appear in literature. It should not be used, as it is flawed and based on measurements which are no longer taken.

Part of the problem with this formula is that beer spectra are not log linear. The absorption of 1 cm of a beer with "average spectral characteristics" (average here means the average of the absorption spectra of the ensemble of 99 beers as described in) at wavelength is well described by

While it is clear that one could use this formula to compute A₅₃₀ from the SRM measured at 430 nm and thus interconvert between SRM and old EBC this is not where its value lies. Because it represents, at least approximately, the full absorption spectrum of the beer it can be used to calculate the tristimulus color (three color coordinates in a chosen color space which describes the color an observer actually sees) of a beer of known SRM by following the prescription of ASTM E-308.