Starch properties of Amaranthus pumilus (seabeach amaranth): a threatened plant species with potential benefits for the breeding/amelioration of present Amaranthus cultivars

This study reports on the physicochemical properties of starch isolated from the seeds of Amaranthus pumilus (a threatened plant species) and compares it to that of the commonly cultivated/commercially produced Amaranthus hypochondriacus K343 (Plainsman). Seeds of both investigated species were found to possess comparable quantities/levels of total starch. Although no significant differences (P⩾0.05) were found between the composition of the two starches with regard to their moisture, ash, protein and fat contents, the starch of A. pumilus was found to contain significantly higher (P⩾0.05) amounts of amylose than that of A. hypochondriacus. The higher levels of amylose found in A. pumilus starch were believed to be responsible for the higher differential scanning calorimetric To, Tp and Te starch temperatures than those of A. hypochondriacus starch which would indicate higher levels of ordered crystalline structure in the former. Scanning electron microscopy and integrated light scattering techniques both revealed a uniform average starch granule diameter of approximately 1 μm for both investigated species. This study further supports and compliments a previous study which showed that much genetic diversity exists between A. pumilus and A. hypochondriacus, indicating that potential breeding possibilities for the improvement of commonly cultivated amaranth lines do exist, if A. pumilus is not first driven to extinction.