Search: higher alcohols

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.

Higher alcohols and esters in beer are determined by gas chromatography using the headspace method, e.g., the volatile compounds are transferred from the gas space in the sample vial to the GC system for analysis. The method is suitable for beer brewed to any original gravity or to any alcohol content.

High molecular weight dextrins and starch present in the wort extracted from brewery spent grain are precipitated through the addition of ethanol, centrifuged and dissolved in phosphate buffer, followed by the addition of an iodine solution. Depending on the molecular weight and degree of branching, a red to blue color forms, the intensity of which is measured spectrophotometrically at 578 nm.

D-Sorbit is present in pomaceous fruit and stone fruit.

D-Sorbitol is oxidized to D-fructose by nicotinamide adenine dinucleotide (NAD) in the presence of the enzyme sorbitol dehydrogenase (SDH), forming reduced nicotinamide adenine dinucleotide (NADH).

D-Sorbitol + NAD^{+ \(\xrightarrow{SDH}\)}D-G-6-P fructose + NADH + H⁺

The reaction equilibrium heavily favors the reactants NAD+ and D-sorbitol. It shifts toward D-fructose, when the NADH formed in this reaction reacts with iodine nitrotetrazolium chloride (INT) in a subsequent reaction. Formazan is created in the presence of diaphorase, which is an irreversible reaction.

NADH + INT + H⁺ \(\xrightarrow{diaphorase}\) NAD⁺ + Formazan

The maximum absorbance of the formazan is measured at 492 nm.