Millet Starch

Starch is the major component of millet grains and has significant effects on the properties of millet-based food products. Millet starches were isolated after pretreatments with acid, alkaline, and salt solutions to separate nonstarch components (protein in particular). The sizes of millet starch granules vary between submicrometer to ~20 μm. Millet starch granules have A-type crystalline structure, and their shapes are mostly polygonal while some small ones may be spherical. The thickness of crystalline lamellae of millet starch is relatively small compared to starches from other sources. Nonwaxy millet starches have amylose contents of 10–35% depending on the species and genotypes. The chain length of millet amylopectin is at a low level in the starch community, which might explain the lower iodine-binding capacity of millet amylopectins. Low glycemic index (GI) of millet grains is of great interest for food applications. However, the starch in its isolated form did not show excellent resistance to enzymatic hydrolysis. Interactions between millet starch and other components might be the reason for the low GI of millet grains. A great diversity was found in the properties (including gelatinization, swelling power, gel texture, retrogradation, and pasting properties) of millet starches as a result of a large gene pool of millet. Modifications amplified the versatility of millet starches in applications.