title: Toward underlying reasons for rice starches having low viscosity and high amylose: physiochemical and structural characteristics.
abstract: BACKGROUND
  To understand the reasons for low starch viscosity in rice variety Q11 (Qing-lu-zhan 11), the physiochemical and structural characteristics of flours and starches were investigated and compared with another rice cultivar with similar high amylose but normal viscosity.
  
  
  RESULTS
  Our results showed that residual α-amylase activity and proteins were not the major causes of low starch viscosity in Q11 rice. Homogeneous small granule size and lower swelling power of high-amylose Q11 rice starches was one reason for the low swelling volume and thus the low pasting property. Q11 starch paste contained some partially swollen granules, which could increase the fluidity and thus cause the low paste viscosity. The small gelatinization enthalpy might be due to the lower crystallinity in Q11 starches. Moreover, Q11 starches consisted of more amylose with short chains, but also amylopectin with fewer short chains (DP 11-21) and more long chains (DP 22-54), which might be other important factors contributing to the low viscosity of Q11 starches.
  
  
  CONCLUSIONS
  These data can add to our understanding of the relationships between low viscosity and physiochemical properties, and will be helpful in elucidating the underlying mechanism of formation of low starch viscosity, as well as applications for low-viscosity rice starches.
authors.affiliation: Jiangsu Key Laboratory of Crop Genetics and Physiology, Key Laboratory of Plant Functional Genomics of the Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou, 225009, People's Republic of China.
authors.forename: Changquan
authors.initials: C
authors.lastname: Zhang
authors.forename: Lijia
authors.initials: L
authors.lastname: Zhu
authors.forename: Ke
authors.initials: K
authors.lastname: Shao
authors.forename: Minghong
authors.initials: M
authors.lastname: Gu
authors.forename: Qiaoquan
authors.initials: Q
authors.lastname: Liu
mesh_terms: D000687:Amylopectin / Q000737:chemistry*; D000688:Amylose / Q000737:chemistry*; D003460:Crystallization; D005782:Gels; D006801:Humans; D012275:Oryza / Q000737:chemistry* / Q000145:classification; D010316:Particle Size; D012639:Seeds / Q000737:chemistry*; D013045:Species Specificity; D013213:Starch / Q000737:chemistry*; D013816:Thermodynamics; D014783:Viscosity; D000516:alpha-Amylases / Q000378:metabolism
chemical_list: D005782:Gels; D013213:Starch; D000688:Amylose; D000687:Amylopectin; D000516:alpha-Amylases