Tube tests for photometric analysis
NANOCOLOR Vicinal Diketones
Measuring range 0.015–0.600 mg/kg Diacetyl
PK of 20 Tests
Vicinal diketones are part of yeast metabolism and accumulate as an intermediate product in the green beer during primary fermentation. In the course of fermentation, the intermediate product is metabolized again. In modern fermentation processes, falling below an internally defined threshold marks the end of maturation and the start of cold storage. The best-known repre-sentative of the vicinal diketones is diacetyl, which is often also described as butter flavor. Classically, diacetyl is considered to be an off-flavor, although isolated beer styles also allow a perceptible note.
Diacetyl can be determined quickly and easily with the NANOCOLOR Vicinal diketones round cell test. The diketones react with a phenylenediamine derivative to form a quinoxaline derivative. This can be evaluated photometrically at 335 nm.
NANOCOLOR Bitter Units
Measuring range 2.0–80.0 BU
PK of 20 Tests
In brewery analysis, the bitter units are a measure of the bitter substances obtained from the hops during wort boiling. The alpha acids contained in the hops are isomerized during the boiling or hot holding process and thus made water soluble. These iso-alpha acids influence the taste as well as the foam stability and give the product bacteriostatic properties.
With the test kit NANOCOLOR® Bitter Units, the bitter substances in beer or wort are extracted using isooctane. They are then measured in a 10 mm quartz cuvette in the UV range at 275 nm.
