Starch Isolation and Characterization of Rice Cultivars

Starch isolation. The starch was isolated from the flour of 4 representative rice cultivars via alkaline extraction as previously described [2 (link)]. The isolated starch samples were thoroughly ground, sifted through a 35 mesh (i.e., 0.50 mm) sieve (Brass Frame Stainless Mesh, Humboldt Mfg., Co., Raleigh, NC, USA), and kept at 4 °C until further analyses [2 (link)]. Nitrogen (N) and protein content. The N content of purified starch was estimated by using the Kjeldahl method according to the AOAC method 920.87 [28 ]. N values were then converted to protein content by N × 5.95. Moisture content. The moisture content was measured according to AACC Air Oven Method 44-19 [29 ] using a hot air oven (Binder Inc., Tuttlingen, Germany) at 135 °C for 2 h. Amylose content. Approximately 20 mg of the isolated starch was used to determine amylose content by using Amylose/Amylopectin Assay Kit (Megazyme International Ireland Ltd., Wicklow, Ireland) following the manufacturer’s recommendations.