The β-glucan content of barley intended for use in beer production should be known.
Malt intended for use in beer brewing or elsewhere in the food industry
This method describes how to determine the β-glucan in laboratory wort by means of a fluorimetric method using microtiter plates (MTP).
Applicable for all (laboratory) worts
This method describes the general requirements for boiler feed water:
Boiler feed water for use in the production of beer and other foods
The requirements for boiler feed water are detailed in the analysis methods listed below.
Determination of formic acid by enzymatic means
This analysis is suitable for wort, beer, beer-based beverages and NAB.
Formic acid can be found in beer in small quantities, and it is also formed by contaminating bacteria, for example, by lactic acid bacteria (rods).
In the presence of the enzyme formate dehydrogenase (FDH), the formic acid created in this reaction is quantitatively oxidized to bicarbonate by nicotinamide adenine dinucleotide (NAD):
HCOO- + NAD+ + H2O \(^{\underrightarrow{FDH}}\) HCO3- + NADH + H+
The amount of NADH formed during the reaction is equivalent to the amount of formic acid and can be determined photometrically based on its absorbance at 334, 340 or 365 nm.
Oxalic acid (oxalate) is transformed into formic acid and CO2 in this reaction catalyzed by the enzyme oxalate decarboxylase (Ox-DC):
Oxalic acid \(^{\underrightarrow{Ox-DC}}\) formic acid + CO2
The quantity of NADH produced during the reaction is equivalent to the amount of formic acid and is determined photometrically owing to its absorption at 334, 340 or 365 nm. In preparation for this test, the free formic acid present in the solution is determined along with the oxalic acid. Each are accounted for in the blank.