2.3.2. Water Retention Capacity

To determine the water retention capacity (WRC), accurately weighed BF milling fractions (2.0 g) were loaded into a weighed centrifuged tube with 20 mL of water and stirred continuously on a water bath at 25 ◦C (Memmert Waterbath, Germany) for 1 h. After centrifugation at 1600 rpm for 25 min, the supernatant was filtrated off on a paper towel and the sample was dried at 105 ◦C for 2 h to obtain residue dry weight [37]. The weights obtained were specified as a % water per gram of flour.

#### 2.3.3. Swelling Capacity

Swelling capacity (SC), also known as the swelling index (SI) was determined according to the method previously applied by Olapade et al. (2003) [38] with minor changes. This property indicates the volume in milliliter taken up by the swelling of flour (1 g) under specific conditions. One gram for each BF fractions was mixed in a centrifuge tube with 10 mL of water and then a weighed tube was heated in a water bath at 80 ◦C for 15 min. After centrifugation at 2000 rpm for 30 min, the supernatant was decanted and the pellet was estimated. The final volume attained by the sample was measured as a percent of swelled per gram of sample, which gave SC.

#### 2.3.4. Volumetric Density

Volumetric density (VD), known also as bulk density, was measured following the procedure described by Ikegwu (2009) [39]. Buckwheat flour milling fractions (50 g) were placed into a dry graduated cylinder (50 mL) and it was shaken slightly until no volume differences were observed. Volumetric density was determined as a sample weight (g) per sample volume (mL).
