The method is suitable for beer brewed to any original gravity or to any alcohol content.
Volatile compounds in beer are concentrated through distillation and extracted with dichloromethane. The solvent phase is analyzed with a gas chromatograph. The linearity of the detector and the determination of the concentrations of analytes in the sample are achieved by using multiple concentration levels within the relevant range and through evaluation of the relative area under the peaks.
Determination of the aromatic alcohols guaiacol, tryptophol, 4-ethyl guaiacol, 4-vinyl guaiacol, eugenol, tyrosol, 4-ethylphenol, 2-phenylethanol in beer
The method is suitable for beer brewed to any original gravity or to any alcohol content.
The aromatic alcohols in beer are isolated using solid-phase extraction and are detected using gas chromatography-mass spectrometry.
Determination of the total acidity through titration
This method is used to determine the total titratable acids in beverages and concentrates.
Titratable acidity represents the sum of the free acids present in a beverage, with the exception of the dissolved carbon dioxide (carbonic acid). In fruit juices and the beverages prepared from them, they usually consist of malic acid, citric acid and tartaric acid.
The titration of the degassed beverage sample (freed from carbonic acid) is carried out potentiometrically using 0.25 mol/l sodium hydroxide solution either to a pH of 7.0 calculated as tartaric acid or to a pH of 8.1 calculated as citric acid.
Acidulated malt intended for use in beer brewing or elsewhere in the food industry
L-lactic acid (L-lactate) is oxidized by nicotinamide adenine dinucleotide (NAD) in the presence of L-lactate dehydrogenase (L-LDH) to pyruvic acid. For oxidation of D-lactic acid, the enzyme D-lactate dehydrogenase (D-LDH) is required.
|
L-lactate + NAD+ |
L-LDH
|
pyruvate + NADH + H+ |
|
D-lactate + NAD+ |
D-LDH
|
pyruvate + NADH + H+ |
The equilibrium of these reactions is much closer to lactate. The equilibrium can be shifted towards the pyruvate and NADH side of the equation by removing the pyruvate with the help of the following reaction involving the enzyme glutamate-pyruvate transaminase (GPT) in the presence of L-glutamate.
|
pyruvate + L-glutamate |
GPT
|
L-alanine + α-ketoglutarate |
The amount of NADH formed during the reactions is equivalent to the amount of lactic acid or D-lactic acid; the absorbance is determined photometrically at 334, 340 or 365 nm.
This method describes how to evaluate the sensory impact of lactic acid or food-grade lactic acid.
Lactic acid or food-grade lactic acid which are used in the brewing and food production industries
Food-grade lactic acid may be used to adjust the pH during mashing and wort production for products not subject to the regulations of the Reinheitsgebot or the German purity law concerning beer.
This method describes how to determine the acid consumption or acid capacity of water.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods