title: Impact of molecular and crystalline structures on in vitro digestibility of waxy rice starches.
abstract: The in vitro digestibility, molecular structure and crystalline structure of waxy rice starches isolated from six Korean cultivars (Shinsun, Dongjin, Baekok, Whasun, Chungbaek, and Bosuk) were investigated. The molecular weight (M(w)) of waxy rice starches ranged from 1.1 × 10(8)g/mol to 2.2 × 10(8)g/mol. Chungbaek waxy rice starch had the highest average chain length (24.3) and proportion (20.7%) of long branch chains (DP ≥ 37), and the lowest proportion (19.0%) of short branch chains (DP 6-12) among the tested six waxy rice starches. The relative crystallinity and intensity ratio of 1047/1022 ranged from 38.9% to 41.1% and from 0.691 to 0.707, respectively. Chungbaek had the highest gelatinization temperature and enthalpy. Chungbaek had the highest pasting temperature (70.7 °C), setback (324 cP) and final viscosity (943 cP), whereas Baekok showed the highest peak viscosity (1576 cP) and breakdown (1031 cP). Chungbaek had lower rapidly digestible starch (RDS) content and expected glycemic index (eGI), and higher resistant starch (RS) content, whereas Whasun exhibited higher RDS content and eGI. The slowly digestible starch (SDS) content of Shinsun (38.3%) and Bokok (32.0%) was significantly higher than that of other cultivars (11.3-22.0%).
authors.affiliation: Division of Food and Nutrition, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 500-757, South Korea.
authors.forename: Su-Yeon
authors.initials: SY
authors.lastname: You
authors.affiliation: Graduate School of Life Sciences and Biotechnology, Korea University, 5-1 Anam-dong, Sungbuk-gu, Seoul 136-701, South Korea.
authors.forename: Seung-Taik
authors.initials: ST
authors.lastname: Lim
authors.affiliation: Graduate School of Life Sciences and Biotechnology, Korea University, 5-1 Anam-dong, Sungbuk-gu, Seoul 136-701, South Korea.
authors.forename: Ju Hun
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Division of Food and Nutrition, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 500-757, South Korea. Electronic address: hchung@jnu.ac.kr.
authors.forename: Hyun-Jung
authors.initials: HJ
authors.lastname: Chung
mesh_terms: D000687:Amylopectin / Q000737:chemistry; D003459:Crystallins / Q000737:chemistry; D038321:Glycemic Index; D066298:In Vitro Techniques; D015394:Molecular Structure; D012275:Oryza / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013213:Starch / Q000737:chemistry* / Q000378:metabolism; D014783:Viscosity; D014961:X-Ray Diffraction
chemical_list: D003459:Crystallins; D013213:Starch; D000687:Amylopectin
keywords: Crystalline structure; In vitro digestibility; Molecular structure; Waxy rice starch