Residual Sugar

This method is used for determination of residual sugars (glucose+fructose) concentration in a variety of matrices. The standard range of this method is 0.25 to 10 g/L, however, this method is also applicable to other ranges.


Samples are mixed with Tris buffer at pH 7.6 and dialyzed to eliminate color interferences. They are then combined with an enzyme mixture that converts the sugar to glucose-6-phosphate. In the presence of NADP+ and G6PD, the glucose-6-phosphate is oxidized to gluconate-6-phosphate and NADPH. A tetrazolium salt is then reduced by the NADPH producing a formazan that is measured at 590nm. The absorbance is directly proportional to the glucose+fructose concentration.


Strongly reducing compounds can negatively interfere.


Instrument Method Number Range
Astoria 300 305-A044-B00 0.25 - 10 g/l
Astoria 2 200-A044-B00 0.25 - 10 g/l
rAPID-T see Glucose + Fructose