Molecular and thermal characterization of starches isolated from African rice (Oryza glaberrima)

Abstract

Starch is the principal component of rice that affects its cooking and nutritional quality. This study investigated molecular and thermal properties of starches isolated from seven Africa rice accessions (ARAs) in comparison with two commonly produced Asian rice varieties (ARVs) and a developed cross (sativa  glaberrima) variety (NERICA 4). All starch granules were polyhedral and tightly packed with size distribution ranging from 2-22 mm and displayed type-A X-ray diffraction pattern. ARAs starch granules had higher ratio of absorbance to scattering when exposed to iodine vapor exhibiting greater flexibility and availability of glucan chains to form complexes with iodine as compared to ARVs. The enthalpies of starch gelatinization (15.1-15.8 J/g) and retrograded gel melting (9.2-10.8 J/g) were higher in ARAs than in NERICA 4 (14.5 and 9.2 J/g, respectively) and ARVs, (13.3-14.3 and 6.4-7.3 J/g, respectively) possibly due to their higher amylose content and longer chains. Significant (p < 0.05) differences in peak, trough, final, breakdown, and setback viscosities were also observed among the starches with Koshihikari Asian rice having the highest peak viscosity (310 RVU). These differences in molecular structure and thermal properties between the ARAs and ARVs are likely to influence the cooking and eating quality of the ARAs.

Thermal and Functional Properties of Hairless Canary Seed (Phalaris canariensis L.) Starch in Comparison with Wheat Starch

“…Particle size distribution of starch samples was determined with the Mastersizer 2000 particle analyzer (Malvern Instruments, Malvern, U.K.), as described by Gayin et al (2016). Digital images of starch samples were acquired with a Hitachi S-570 scanning electron microscope (Hitachi Scientific Instruments, Rexdale, ON, Canada).…”

“…Digital images of starch samples were acquired with a Hitachi S-570 scanning electron microscope (Hitachi Scientific Instruments, Rexdale, ON, Canada). X-ray diffraction measurements were obtained with a Rigaku X-ray diffractometer (Rigaku-Denki, Tokyo, Japan), according to the method of Gayin et al (2016). A working distance of 15 mm and an accelerating voltage of 10 kV were used.…”

“…A working distance of 15 mm and an accelerating voltage of 10 kV were used. Particle size distribution of starch samples was determined with the Mastersizer 2000 particle analyzer (Malvern Instruments, Malvern, U.K.), as described by Gayin et al (2016). To prevent lump formation, starch samples were added in sufficient quantity to generate a laser obscuration range of 12-14%.…”

“…A 300 reverse Fourier (convergent beam) lens was used for the analyses. Digital images of starch samples were acquired with a Hitachi S-570 scanning electron microscope, according to the method of Gayin et al (2016). X-ray diffraction measurements were obtained with a Rigaku X-ray diffractometer (Rigaku-Denki, Tokyo, Japan), according to the method of Gayin et al (2016).…”

Genomic characterization of African cultivated and wild Oryza species

“…Interest in studying starch related traits in African rice is however growing (Gayin et al 2016a;Gayin et al 2016b;. This study investigated the genetic basis of AC in African rice by genetic mapping of the progenies of an interspecific cross between O. glaberrima and O.…”