title: Influence of molecular structure on physicochemical properties and digestibility of normal rice starches.
abstract: Normal rice starches were isolated from six different rice varieties grown in Korea and their molecular structure, crystalline structure, and in vitro digestibility were investigated. Apparent amylose content was the highest in starch from Junam cultivar (25.5%) and lowest in Hopum (22.4%). Starch from Hiami cultivar had the lowest molecular weights of amylose and amylopectin, average amylopectin chain length, proportion of short chains (DP 6-12), and proportion of long chains (DP≥37) among the tested rice starches. The relative crystallinity and ratio of 1047/1022 ranged from 30.2 to 36.7% and from 0.638 to 0.652, respectively. Hiami had the lowest gelatinization temperatures and the highest gelatinization enthalpy. Hiami had the highest pasting temperature (92.1°C), the lowest setback (515cP) and final viscosity (876cP), whereas Hanareum had the lowest pasting temperature (82.7°C), the highest setback (1002cP), and final viscosity (1580cP). The rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) content ranged from 43.9-53.5%, 35.5-52.6%, and 0.5-15.6%, respectively. The Junam cultivar had the lowest RDS content, whereas Hiami had the highest RDS content. The RS content of Hanareum (16.2%) and Boramchan (14.5%) was significantly higher than that of other normal rice cultivars (3.0-6.5%).
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: National Institute of Crop Science, Rural Development Administration, 54 Seoho-ro, Gwonseon-gu, Suwon-si, Gyeonggi-do 441-853, South Korea.
authors.forename: Sea-Kwan
authors.initials: SK
authors.lastname: Oh
authors.affiliation: Department of Food Science and Biotechnology, Andong National University, 1375 Gyeongdong-ro, Andong-si, Gyeongsangbuk-do 760-749, South Korea.
authors.forename: Hyun-Seok
authors.initials: HS
authors.lastname: Kim
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; D000688:Amylose / Q000032:analysis; D055598:Chemical Phenomena; D004063:Digestion; D008970:Molecular Weight; D012275:Oryza / Q000737:chemistry*; D013045:Species Specificity; D013213:Starch / Q000737:chemistry* / Q000378:metabolism; D013696:Temperature
chemical_list: D013213:Starch; D000688:Amylose; D000687:Amylopectin
keywords: In vitro digestibility; Molecular structure; Rice starch