This method describes how to determine the extract content of malt used to produce laboratory wort.
Malt intended for use in beer brewing or elsewhere in the food industry
The extract content of malt refers to the compounds from finely ground malt (fine grind), which are brought into solution during a standardized mashing process.
The extract content is determined by the weight ratio sL 20/20 of the wort on the basis of the official sugar tables (Plato tables) at 20 °C. sL 20/20 stands for the weight ratio of a volume of wort at 20 °C to the same volume of water at the same temperature.
This method describes how to determine the fermentable sugars in the (Congress) wort using high performance liquid chromatography.
Applicable for all (laboratory) worts
The separation is based upon a combination of reversed phase, normal phase, ion exclusion and ion exchange chromatography. The detection is carried out using an RI detector.
Determination of sorbitol by ion chromatography and pulsed amperometric detection
This method is suitable for fruit juices and other non-alcoholic beverages.
The sugar alcohols are separated using a strongly alkaline eluent and ion exchange column and detected and quantified electrochemically using a pulsed amperometric detector (PAD).
By applying a potential, the ions are oxidized at a gold electrode and induce a measurable charge. To prevent the electrode from being occupied in a very short time, the potential is then reversed to reduce and release the ions from the electrode.
Determination of sucrose by enzymatic means
Suitable for wort, beer, malt beverages, nutrient beer, mixed beer beverages, NAB, juices and beverages
Sucrose is important as a fermentable sugar for the technology of wort and beer production. Sucrose also plays a role in the evaluation and assessment of malt beverages and nutritional beers.
D-glucose content is determined before and after enzymatic hydrolysis of sucrose.
Sucrose is hydrolyzed by the enzyme β-fructosidase (invertase) at pH 4.6 to glucose and fructose:
\(\text{Sucrose + } H_2O \space {\xrightarrow{β-fructosidase}} \space \text{D-glucose + D-fructose}\)
Glucose is phosphorylated by the enzyme hexokinase (HK) and adenosine 5'-triphosphate (ATP) to glucose 6-phosphate (G-6-P):
\(\text{Glucose}+\text{ATP} \space \xrightarrow{HK} \space \text{G-6-P + ADP}\)
In the presence of the enzyme glucose-6-phosphate dehydrogenase (G6P-DH), G-6-P is oxidized from nicotinamide adenine dinucleotide phosphate (NADP) to gluconate-6-phosphate. Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is formed:
\(\text{G-6-P + NADP} \hspace{0.8em} \xrightarrow{G6P-DH} \hspace{0.8em} \text{gluconate-6-phosphate + NADP + H}^+\)
The amount of NADPH formed during the reaction is equivalent to the amount of glucose. NADPH is a measurand and is determined on the basis of its absorbance at 334, 340 or 365 nm.
The sucrose content is calculated from the difference between the glucose concentration before and after enzymatic inversion.
This method describes how to determine the fermentable carbohydrates in wort or in the Congress wort using high performance liquid chromatography.
Applicable for all (laboratory) worts
Fructose, glucose as well as disaccharides and trisaccharides (maltose and maltotriose) are determined using high performance liquid chromatography (HPLC).
Wort or beer is deionized using an ion exchanger. The sample is filtered and concentrated using a solid-phase column and analyzed chromatographically. The concentration of the sugars present in the sample is calculated from the chromatograms obtained by analysis of the calibration solutions.
Acidulated malt intended for use in beer brewing or elsewhere in the food industry