This is a mathematical method for calculating the dextrin content as a difference between the total glucose content and the fermentable extract as determined through analytical methods.
Suitable for beer
The dextrin content is calculated through multiplication of the difference between the total glucose content and the fermentable extract by a factor of 0.915.
Determination of maltose and maltotriose by enzymatic means
Suitable for malt, beer, NAB, sports drinks, energy drinks.
Starch, the main carbohydrate in malt, is hydrolyzed during the mashing process partly to fermentable sugars and partly to (iodine-normal) dextrins. The determination of starch is therefore of interest for brewing technology.
In the beverage industry, maltodextrins are used in sports and energy drinks
Starch is cleaved to glucose by the enzyme amyloglucosidase at pH 4.6:
Starch + (n–1) H2O \(\xrightarrow{amyloglucosidase}\) n D-glucose
The D-glucose formed is phosphorylated by the enzyme hexokinase (HK) and adenosine 5'-triphosphate (ATP) to glucose 6-phosphate (G-6-P):
Glucose + ATP \(\xrightarrow{HK}\) D-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:
G-6-P + NADP+ \(\xrightarrow{G6P-DH}\) D-gluconate-6-phosphate + NADPH + 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 absorption at 334, 340 or 365 nm.
It is not possible to distinguish enzymatically between high-polymer and low-molecular starch.