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The term starch damage refers to a number of changes to the starch granule structure, which are detectable by different analytical techniques. Damaged starch is the substrate for amylases, which in turn provides carbohydrates that are used in the production of certain foods and food ingredients; as a result, therefore, determination of levels in flours is a procedure carried out routinely by many manufacturers of starch based products. Enzymatic assay methods emulate the susceptibility of damaged starch granules to enzymatic attack. The first aim of this study was to evaluate enzymatic methods(1,2) to determine damaged starch in wheat flours and non-wheat flours. The most reliable and simplest method tested was the AACC 76-31 method(2) (used in the form of a kit); this could be replaced with other enzymes and reagents, which was just as effective and less costly. The effect of different types of enzymes (fungal alpha amylase and pancreatic alpha amylase) and the effect of their incubation times on a variety of flour samples was also examined. The products of enzymatic digestion of damaged starch were identified and quantified using two HPLC systems(3). It was found that the two enzymes tested produced different combinations of reducing sugars (mainly glucose, maltose and maltotriose) in the different flours tested and that the rate of breakdown of these flours over a 60 minute time period also varied. “Percent maltose values” correlated well with percentage damaged starch results obtained by an enzymatic colorimetric method (r2= 0.98). These effects on the starch granule were observed using a Scanning Electron Microscope. No difference was observed in the breakdown patterns of the two enzymes but differences in the way in which the A and B type crystalline structures digest was seen. The general progress of breakdown of the starch granules could be seen but it was not clearly distinguishable at ten minute intervals. Finally, starch granules were examined with regard to starch crystallinity using x-ray powder diffraction. No reduction in crystallinity of the starch in the flours tested was found following digestion for up to a period of sixty minutes.
Bailey, K. (1998). Studies on the amylolytic breakdown of damaged starch in cereal and non-cereal flours. Masters dissertation. Technological University Dublin. doi:10.21427/D70K7Q