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AACC International Approved Methods - AACC Method 32-32.01. Measurement of Total Fructan in Foods by an Enzymatic/Spectrophotometric Method

AACC International Approved Methods


AACCI Method 32-32.01
Measurement of Total Fructan in Foods by an Enzymatic/Spectrophotometric Method


Fructan and fructooligosaccharides occur in a wide range of plant materials. Interest in measurement of fructans such as inulin and oligofructose has been stimulated by applications made to regulatory authorities that fructans be incorporated into dietary fiber for food-labeling purposes. In this method, samples are extracted with hot water to dissolve the fructan. Aliquots of extract are treated with a specific sucrase to hydrolyze sucrose to glucose and fructose and with a mixture of pure starch-degrading enzymes to hydrolyze starch to glucose. All reducing-sugars are then reduced to the sugar alcohols by treatment with alkaline borohydride. The solution is neutralized and excess borohydride is removed by treatment with dilute acetic acid. The fructan is then hydrolyzed to fructose and glucose with purified fructanase (exoinulinase plus endoinulinase), and these sugars are measured with the p-hydroxybenzoic acid hydrazide (PAHBAH) method for reducing sugars. With this method, color response is the same for fructose and glucose. The procedure can be used to measure fructan in a wide range of plant materials and food materials to which fructan has been added.

A spreadsheet calculator accompanies this method.