Applicable for malt (or the wort produced from it) and all (laboratory) worts
The analysis sample (e.g., Congress wort or wort from above the grain bed during lautering) undergoes a chemical reaction with an acetic acid/thiobarbituric acid solution; the resulting product is yellow in color and is measured spectrophotometrically.
Hydroxymethylfurfural (HMF) is a reaction product of the Maillard reaction and is an indicator for thermal stress in foods.
This method is suitable for the determination of HMF in beer and wort.
HMF is determined by means of polymer resin cation exchanger with a UV detector measured at 283 nm. A minimal amount of sample preparation is required.
The method is suitable for the determination of steam-volatile aging indicators in beer.
Volatile aging indicator substances are driven out of the sample through steam distillation. The ethanol distillate is adjusted to be alkaline and saturated with NaCl. The extraction of the aroma compounds is performed by shaking out with dichloromethane and the phases separated by centrifuging. The organic phase is further concentrated in a stream of nitrogen gas. Ammonia solution is added to remove the acids, as the acids would coelute, thus preventing the quantification of important substances.
Determination of hydroxymethylfurfural using HPLC
Fruit juice, NAB, beverages
5-Hydroxymethylfurfural (HMF) is separated using HPLC and reversed phases. This substance is measured with a UV detector.
HPLC analysis specifically detects 5-hydroxymethylfurfural.
A photometric method, B-590.59.111 Hydroxymethylfurfural - photometrisch, using barbituric acid and o-toluidine detects all aldehydes present in the sample. This method serves as an alternative for laboratories without HPLC.
Determination of hydroxymethylfurfural by photometric means
5-Hydroxymethylfurfural (HMF) is detected in a color reaction with barbituric acid and o-toluidine. However, this detects all of the aldehydes present in the sample. The determination by HPLC specifically detects the HMF. As with other aldehydes, HMF reacts with barbituric acid and p-toluidine to create a reddish compound. HMF reacts with any sulfurous acid that is present, as do other aldehydes; in this case, it is, therefore, undetectable without prior treatment. If more than 10 mg/l of free sulfurous acid are present, this will bind to acetaldehyde. Subsequently, the determination can be performed. The presence of excess acetaldehyde does not interfere with the analysis.