title: Measurement of total fructan in foods by enzymatic/spectrophotometric method: collaborative study.
abstract: An AOAC collaborative study was conducted to evaluate the accuracy and reliability of an enzyme assay kit procedure for measuring oligofructans and fructan polysaccharide (inulins) in mixed materials and food products. The sample is extracted with hot water, and an aliquot is treated with a mixture of sucrase (a specific sucrose-degrading enzyme), alpha-amylase, pullulanase, and maltase to hydrolyze sucrose to glucose and fructose, and starch to glucose. These reducing sugars are then reduced to sugar alcohols by treatment with alkaline borohydride solution. The solution is neutralized, and excess borohydride is removed with dilute acetic acid. The fructan is hydrolyzed to fructose and glucose using a mixture of purified exo- and endo-inulinanases (fructanase mixture). The reducing sugars produced (fructose and glucose) are measured with a spectrophotometer after reaction with para-hydroxybenzoic acid hydrazide. The samples analyzed included pure fructan, chocolate, low-fat spread, milk powder, vitamin tablets, onion powder, Jerusalem artichoke flour, wheat stalks, and a sucrose/cellulose control flour. Repeatability relative standard deviations ranged from 2.3 to 7.3%; reproducibility relative standard deviations ranged from 5.0 to 10.8%.
authors.affiliation: Megazyme International Ireland Ltd., Bray Business Park, County Wicklow, Ireland.
authors.forename: B V
authors.initials: BV
authors.lastname: McCleary
authors.forename: A
authors.initials: A
authors.lastname: Murphy
authors.forename: D C
authors.initials: DC
authors.lastname: Mugford
mesh_terms: D001894:Borohydrides; D004798:Enzymes; D005504:Food Analysis / Q000379:methods*; D005630:Fructans / Q000032:analysis*; D006026:Glycoside Hydrolases / Q000378:metabolism; D006868:Hydrolysis; D007202:Indicators and Reagents; D007444:Inulin / Q000032:analysis; D011786:Quality Control; D012996:Solutions; D013053:Spectrophotometry / Q000379:methods*; D013393:Sucrase / Q000378:metabolism; D000516:alpha-Amylases / Q000378:metabolism; D000520:alpha-Glucosidases / Q000378:metabolism
chemical_list: D001894:Borohydrides; D004798:Enzymes; D005630:Fructans; D007202:Indicators and Reagents; D012996:Solutions; C025364:sodium borohydride; D007444:Inulin; D006026:Glycoside Hydrolases; D000516:alpha-Amylases; D000520:alpha-Glucosidases; C100181:pullulanase; D013393:Sucrase