Inaccuracy of AOAC method 2009.01 with amyloglucosidase for measuring non-digestible oligosaccharides and proposal for an improvement of the method

• AOAC method 2009.01 could not accurately measure non-digestible oligosaccharides.
• Method using porcine intestinal enzymes is more suitable than determination for non-digestible oligosaccharides by AOAC method 2009.01.
• Porcine small intestinal enzymes should replace amyloglucosidase in AOAC method to quantify non-digestible oligosaccharide in foods.

We wished to clarify the inaccuracy of AOAC method 2009.01 for the measurement of non-digestible oligosaccharides and to propose an improved method using porcine intestinal enzymes. Amyloglucosidase used in AOAC method 2009.01 scarcely hydrolyses sucrose, palatinose and panose (which are readily digested by intestinal enzymes). Hence, oligosaccharides could not be measured accurately by AOAC method 2009.01. To confirm the inaccuracy of the method, we used porcine intestinal enzymes instead of amyloglucosidase. Using the improved method, fructooligosaccharide and galactooligosaccharide were measured accurately as non-digestible oligosaccharides, but sucrose, palatinose, panose and isomaltooligosaccharide were not. The improved method hydrolysed digestible oligosaccharides into monosaccharides. These results demonstrate that the inaccuracy of AOAC method 2009.01 for oligosaccharide measurement is due to incomplete hydrolysis by amyloglucosidase. We propose that amyloglucosidase should be replaced with porcine intestinal enzymes for such measurements.