*3.1. Physical Characteristics of Te*ff *Seeds*

All six teff seed samples were ground and used for three different protein fractionation methods, during which color changes in residues and supernatants were monitored. The pictorial data from Mekel-W and Mekel-B during Method 3 extraction procedures were selected as representatives because the same results were observed for all samples (See below). The two seed types have indubitably different colors with linen white and brown colors, respectively (Figure 1a,b). However, the difference in color became less pure when finely ground (Figure 1c,d).

**Figure 1.** Physical appearances of Mekel-W and Mekel-B during sample preparation. (**a**) Seeds (left to right; Mekel-W, Mekel-B), (**b**) Teff seed flour (left to right; Mekel-W, Mekel-B), (**c**) Residue before ethanol extraction (left to right; Mekel-W, Mekel-B), (**d**) Residue after ethanol extraction (left to right; Mekel-W, Mekel-B), (**e**) tert-butanol extract supernatants (left to right; Mekel-W, Mekel-B), (**f**) NaOH extract supernatants (left to right; Mekel-W, Mekel-B).

No change in color of residue was observed after albumins (water extraction) or globulins (NaCl extraction) were removed while white teff residue became more elastic and viscous than brown. After alcohol extraction for prolamin fraction, however, the color of the residue of brown teff flour changed from reddish brown to a dark umber color while the white type remained same color (Figure 1e,f). The supernatants of water and salt extractions of both seed types were colorless, while the alcohol extract supernatants of white and brown teff flours were of light and yellowish color, respectively (Figure 1g). After alkaline (0.075M NaOH) extraction, the color of the supernatant was a dark brown or amber color (Figure 1h).
