Icp260

Adjustment of the moisture contents (MC) of the tef flour was conducted by adding distilled water to reach 15, 20, and 25% from an initial value of 12% on a wet basis. The flours were continuously mixed while adding the water and then stored for 24 h at 4  ±  2 °C with polyethylene bags for moisture equilibration. A total of 75 g of tef flour of each MC level was weighted and placed in a 1000 mL hermetically sealed cylindrical Teflon^® container and treated (900 W, 2450 MHz) in a MW oven (SHARP R-342 Osaka, Japan) for 1, 2, 4, 6, and 8 min in cycles of 10 s of radiation and 50 s of rest. During the treatment, the Teflon^® containers were continuously rotated (60–70 rpm) to distribute radiation evenly. The temperature in the containers was controlled using Testoterm^® temperature strips (TESTO, Madrid, Spain). The treated flours were dried at 35 °C in an incubation chamber (Memmert ICP260, Schwabach, Germany) until their MC reached 12%, and then sieved to <500 µm.

XRD assay was performed using a Bruker-D8-Discover-A25 diffractometer (Bruker AXS, Rheinfelden, Germany) equipped with a CuKα radiation (λ = 0.154 nm) operating at 40 kV and 30 mA. Prior to measurement, all samples were equilibrated to 15% humidity using an incubation chamber (Memmert ICP260, Schwabach, Germany) at saturated humidity and 15 °C. Diffractograms and crystallinity were obtained as described by Villanueva et al. [11 (link)], in the range of 5–40° (2θ) at a rate of 1.2°/min, a scan step size of 0.02°, a divergence slit width of 1°, and a scatter slit width of 2.92°.