TY - JOUR
T1 - Amorphous packing of amylose and elongated branches linked to the enzymatic resistance of high-amylose wheat starch granules
AU - Li, Haiteng
AU - Dhital, Sushil
AU - Flanagan, Bernadine M.
AU - Mata, Jitendra
AU - Gilbert, Elliot P.
AU - Gilbert, Robert G.
AU - Gidley, Michael J.
N1 - Funding Information:
This work was supported by an Australian Research Council Linkage grant LP160100310 . RGG gratefully acknowledges the support of a National Science Foundation of China grant C1304013151101138 and of the 2017 Jiangsu Innovation and Entrepreneurship Talents Program . Haiteng Li acknowledges the support of Start-up Foundation of Jiangsu University ( 4111360012 ) and Natural Science Foundation of Jiangsu Province ( BK20210749 ). The authors thank ANSTO for the Bruker SAXS beam time.
Publisher Copyright:
© 2022 Elsevier Ltd
PY - 2022/11/1
Y1 - 2022/11/1
N2 - To elucidate starch structural features underlying resistant starch formation, wheat starch granules with three (A-, B- and C- type) crystalline polymorphisms and a range of amylose contents were digested in vitro. The changes in multi-level structure of digestion residues were compared. In the residues of A- and C-type starches, the molecular fine structure (distributions of chain length and whole molecular size), as analyzed by size exclusion chromatography (SEC), remained similar during digestion. In contrast, B-type high amylose wheat starch (HAWS) showed distinct changes in multi-level structures of digestion-resistant fractions: (1) the peak of longer amylopectin branches shifted to a lower degree of polymerization (40 DP); (2) production of α-limit dextrin (~2 nm hydrodynamic radius) in the residues; (3) a small increase of double helix content during digestion, in contrast to 6 % reduction for the A-type starch; (4) a decrease (6 °C lower) in the melting temperature of amylose-lipid complexes. The comparison suggests that elongated branches in B-type starch contribute to the formation of resistant fraction (including α-limit dextrin) against α-amylase. The amorphous packing of starch polymers with elongated branches together with the absence of surface pores and channels is proposed to be the basis for the enzymatic resistance of granular HAWS.
AB - To elucidate starch structural features underlying resistant starch formation, wheat starch granules with three (A-, B- and C- type) crystalline polymorphisms and a range of amylose contents were digested in vitro. The changes in multi-level structure of digestion residues were compared. In the residues of A- and C-type starches, the molecular fine structure (distributions of chain length and whole molecular size), as analyzed by size exclusion chromatography (SEC), remained similar during digestion. In contrast, B-type high amylose wheat starch (HAWS) showed distinct changes in multi-level structures of digestion-resistant fractions: (1) the peak of longer amylopectin branches shifted to a lower degree of polymerization (40 DP); (2) production of α-limit dextrin (~2 nm hydrodynamic radius) in the residues; (3) a small increase of double helix content during digestion, in contrast to 6 % reduction for the A-type starch; (4) a decrease (6 °C lower) in the melting temperature of amylose-lipid complexes. The comparison suggests that elongated branches in B-type starch contribute to the formation of resistant fraction (including α-limit dextrin) against α-amylase. The amorphous packing of starch polymers with elongated branches together with the absence of surface pores and channels is proposed to be the basis for the enzymatic resistance of granular HAWS.
KW - Amorphous packing
KW - Crystalline polymorphism
KW - Digestion
KW - High-amylose starch
KW - Structural evolution
UR - http://www.scopus.com/inward/record.url?scp=85134879249&partnerID=8YFLogxK
U2 - 10.1016/j.carbpol.2022.119871
DO - 10.1016/j.carbpol.2022.119871
M3 - Article
C2 - 35989013
AN - SCOPUS:85134879249
VL - 295
JO - Carbohydrate Polymers
JF - Carbohydrate Polymers
SN - 0144-8617
M1 - 119871
ER -