Total starch content of the samples was analysed using a method derived from Megazyme (Megazyme International Ireland Ltd., Ireland). About 50mg of sample was wetted with ethanol, heated (boiling water bath) in dimethyl sulphoxide (DMSO) and digested with thermostable -amylase (Megazyme E-BLAAM) in MOPS (Sigma M-9381) buffer before sodium acetate buffer and amyloglucosidase (Megazyme E-AMGDF) were added and incubated as described before (Mahasukhonthachat et al., 2010; Sopade & Gidley, 2009). The glucose content was determined using an enzymatic glucose reagent (TR15104 Enzymatic glucose oxidase reagent; Microgenics Diagnostic Pvt Ltd., Australia), and the absorbance of the colouration was measured (Pharmacia LKB-Ultrospec III) at 505 nm. Each sample was analysed in duplicate