2.8. AMS determination by enzymatic method
AMS content of all samples was determined by enzymatic AMS/AMP assay procedure utilising commercial K-Amyl (Megazyme International, Ltd., Wicklow, Ireland) kit. Starch was completely dispersed in dimethylsulphoxide in a boiling water bath. Concanavalin A addition caused precipitation of AMP and the precipitate was removed by centrifugation. AMS was hydrolysed by enzyme mixture (amyloglucosidase and α-amylase). The resulting glucose was determined with enzyme reagent containing glucosidase and peroxidase. The absorbance of the resulting red complex was measured at λ = 510 nm on the Varian Cary-100 UV–Visible spectrophotometer (Agilent Technologies, Santa Clara, CA, USA). AMS content (in %) was calculated as the ratio of absorbance of the supernatant to total absorbance of starch: