| Susceptibility of waxy starch granules to mechanical damage. Cereal Chemistry 77:750-753 |
Bettge,A.D., Giroux,M.J. and Morris,C.F.
USDA-ARS Western Wheat Quality Lab and Montana State University Dept of Plant Sciences |
| Starch samples isolated from wheat flour that represented four possible waxy states (0, 1, 2 and 3-gene waxy) were subjected to crushing loads under both dry and wet conditions. Calibrated loads
of 0.5 to 20 kg were applied to the starch samples and the percentage of damaged
granules was visually determined. Under dry crushing conditions, starches containing
amylose (0, 1 and 2-gene waxy) had between 1% (5 kg load) to 3% (15 and 20 kg
load) damaged granules, whereas waxy starch (3-gene waxy; less than 1% amylose)
began rupturing at 0.5 kg load (3.5% damaged granules) and had 13% damaged granules
when 10 kg or more load was applied. Under wet crushing conditions, normal and
partial waxy starch (0, 1 and 2-gene waxy) showed little difference in percentage
of damaged granules when compared to the results of dry crushing. Waxy starch
(3-gene waxy) however, showed substantially increased numbers of damaged granules:
12% damaged granules at 0.5 kg load, rising to 55% damaged granules at 15 kg
load. The results indicate that waxy starch granules are less resistant to mechanical
damage than normal starch granules. Further, blends of normal and waxy wheats
or wheat flours intended to have a particular amylose/amylopectin ratio will
be a complex system with unique processing and formulation considerations and
opportunities.
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