Suitable for beer-based mixed drinks, non-alcoholic soft drinks, soft drinks, fruit juice, soft drinks, juices, drinks.

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

\(\text{(1) D-Sorbitol + NAD}^+ \space ^{\underrightarrow{\text{SDH}}} \space \text{D-Fructose + NADH + H}^+\)

\(\text{(2) Xylitol + NAD}^+ \space ^{\underrightarrow{\text{SDH}}} \space \text{D-Xylulose + NADH + H}^+\)

(1) In the case of sorbitol, the equilibrium heavily favors the reactants NAD⁺ and D-sorbitol side.
It is shifted towards D-fructose by the NADH + H⁺ formed reacting with iodonitrotetrazolium chloride (INT) in a subsequent reaction. Formazan is created in the presence of diaphorase, which is an irreversible reaction.

(2) In the case of xylitol, the equilibrium heavily favors the reactants NAD^⁺ and D-xylitol side.
It is shifted towards the D-xylose side by reacting the NADH + H^⁺ formed with iodonitrotetrazolium chloride (INT) in a subsequent reaction. Formazan is created in the presence of diaphorase, which is an irreversible reaction.

\(\text{NADH + H}^+ \space +\space\text{ INT }\space^{\underrightarrow{\text{Diaphorase}}} \space \text{ NAD}^+\space \text{+ INT-Formazan}\)

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

The determination is only specific if the sample contains only D-sorbitol or only xylitol.