Simultaneous determination of iso-a-acids and reduced iso-a-acids (rho, tetra, hexa) in beer and beer-based beverages using HPLC
This method is not suitable for beer and beer-based beverages containing a mix of hexa- and iso-products (co-elution).
This method separates iso-α-acids and reduced iso-α-acids (rho, tetra, hexa) chromatographically [2].
The separated compounds are detected spectrophotometrically at 270 nm. Quantification is performed using International Calibration Standards (ICS).
These standards do not contain all of the isomers of a certain type of iso-α-acids. Currently, ICS-I (DCHA-Iso) contains only the trans-isomeric complexes with dicyclohexylamine (DCHA). ICS-R (DCHA-rho) only has the cis-isomers in a complex with DCHA. ICS-T (tetra) comprises both cis- and trans-isomer complexes with DCHA, and ICS-H (DCHA-hexa) includes only cis-isomers with DCHA.
Commercially available hop products contain a greater number of isomers than the standards.
Thus, there are more peaks in the chromatogram than in the corresponding international calibration standards, in particular, with the cis-iso-cohumulone as well as the cis-iso-n-humulone and cis-iso-ad-humulone. The application of this method to these kinds of beers should be conducted with this in mind, since it is not entirely known whether these additional peaks are actually isomers of iso-α-acids.
The method describes how to determine the content of tetrachloroethene and trichloroethene in drinking water through extraction and gas chromatography.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
This method describes the rapid method for determining the germinative capacity of an individual lot of barley.
Barley intended for the production of malt is evaluated on the basis of its germinative capacity.
In living kernels, in the presence of oxidoreductases and their corresponding coenzymes, the colorless compound triphenyltetrazolium chloride is reduced to formazan, which is red in color [1].
This method describes the complexometric determination of calcium in water.
Calcium ions are bound by the disodium salt of ethylenediaminetetraacetic acid (EDTA) as water-soluble chelates (undissociated complexes). Calconcarboxylic acid serves as an indicator due to its specificity for calcium ions.
