Beer color is an important sensory attribute, the first one that the consumer observes. There are two standard methods accepted for determining the color of these products, one related to the European Brewery Convention (EBC) and the other is the Standard Reference Method (SRM). Both methods are based on absorbance, but in case of the more and more popular fruit beers these methods give false result since these products appear in varied colors and have different spectra than regular beers. In this study 39 different types of beers were investigated, including fruit beers and beer based mixed drinks to compare their color in CIE 1976 L*a*b* color space, absorption-based colors and transmission spectra. DE* ab values of products with less than 5% EBC difference ranged from 4.5 to 17.4. There were magnitude differences in the transmission spectra of these products, fruit beers showed different tendencies due to the added fruit or fruit juice. The highest DE* ab value belonged to two traditional Weissbiers. Absorption-based methods are not able in many cases to differentiate between products which have nearly the same EBC or SRM color but visually are different. A multi-wavelength method would be reasonable to be developed for more objective and accurate beer color determination.

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In this paper, Just Noticeable Differences (JNDs) of color-normal subjects measured towards the Protan, Deutan, and Tritan confusion points are presented as a function of the chromaticity of the reference points. Measurements were executed with the Cambridge Colour Test Trivector test in equidistant reference points towards eight directions equally spaced and centered on the neutral reference point in the CIE 1976 UCS diagram.Results were evaluated as the function of the distance between the reference points and the neutral point. The reference points were the chromaticities of the backgrounds of the pseudoisochromatic plates in the test, and the neutral point was defined as equal energy white. The evaluation was performed considering ∆Eu'v' differences and L/(L + M) and S/(L + M) ratios of the cone-excitations.Chromatic discrimination thresholds exceeded the normative upper limit of color normal subjects in ∆Eu'v' units at extreme reference points. Shifting the reference points from the neutral point towards the confusion points indicated an increase of Just Noticeable Differences measured towards the confusion points following second-order polynomials. Based on our results a model estimating the JNDs expressed in ∆Eu'v' units towards the confusion points was recommended.Even though CIE 1976 UCS diagram is not a perceptually uniform color space, the Just Noticeable Differences measured with the CCT correlate with the corresponding L' and S' cone excitations. This confirms the basic applicability of the CIE 1976 UCS diagram for characterizing Just Noticeable Differences. For complete perceptual analysis, the use of cone-excitation-based metrics is still essential and recommended.