Search: carbohydrates

Carbohydrates are split by acid hydrolysis in the boiling heat under reflux with acid. After neutralization and filtration of the hydrolysis mixture, the glucose content is determined enzymatically after dilution. In this process, glucose is phosphorylated by the enzyme hexokinase (HK) and adenosine 5'-triphosphate (ATP) to glucose 6-phosphate (G-6-P):

\(\text{Glucose + ATP} \space ^{\underrightarrow{\text{HK}}} \space \text{G-6-P + ADP}\)

In the presence of the enzyme glucose-6-phosphate dehydrogenase (G6P-DH), G-6-P is oxidized by nicotinamide adenine dinucleotide phosphate (NADP) to gluconate-6-phosphate. Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is formed:

\(\text{G-6-P + NADP}^+ \space ^{\underrightarrow{\text{G6P-DH}}} \space \text{NADPH + H}^+\)

The amount of NADPH formed during the reaction is equivalent to the amount of glucose. NADPH is determined based upon its absorbance at 334, 340 or 365 nm.

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.

The carbohydrates are calculated as a sum of the fermentable extract as determined through an analytical method and through the calculated value for dextrins according to B-420.43.999 Berechnung der Dextrine.

Aside from carbohydrates composed solely of glucose molecules (with, for example, 0.69 g/100 ml of utilizable carbohydrates remaining in the beer), in highly attenuated beer there are small amounts of pentose molecules (approx. 300 mg/l) and also various glycosides (approx. 100–200 mg/l).

According to their degree of digestibility, additional utilizable carbohydrates amount to 500 mg/l at the most (equal to 0.05 g/100 ml). As a rule, 0.05 g/100 ml is also added to the total value for carbohydrates. 

Fructose, glucose as well as disaccharides and trisaccharides (maltose and maltotriose, DP 2 and DP 3) are determined using high-pressure 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.

Separation by HPLC is based on a combination of reversed-phase, normal-phase, ion-exclusion and ion-exchange chromatography