Eric Bertoft - Academia.edu (original) (raw)

Papers by Eric Bertoft

Research paper thumbnail of Segmental mobility of polymers in hydrothermally treated maize starches varying in amylose content

Research paper thumbnail of Structural and thermodynamic properties of rice starches with different genetic background: Part 1. Differentiation of amylopectin and amylose defects

Research paper thumbnail of Branching patterns in leaf starches from Arabidopsis mutants deficient in diverse starch synthases

Carbohydrate Research, 2015

Research paper thumbnail of Evolution of amylopectin structure in developing wheat endosperm starch

Carbohydrate Polymers, 2014

Research paper thumbnail of Structure of clusters and building blocks in amylopectin from developing wheat endosperm

Carbohydrate Polymers, 2014

Changes in internal structure of amylopectin (AP) during wheat endosperm development were studied... more Changes in internal structure of amylopectin (AP) during wheat endosperm development were studied by isolating clusters and building blocks of AP from both large A-type and small B-type starch granules at different maturity stages up to harvest time at 49 days after anthesis (DAA). Clusters isolated from B-type granules had a degree of branching (DB) of 16.5-16.8% and were more tightly branched than those isolated from A-type granules (DB 15.7-16.2%). The degree of polymerization (DP) of the clusters increased in both types of granules during the pre-physiological maturity stage up to 28 DAA. Clusters at maturity were smaller with less branches and building blocks than at the end of the pre-maturity stage. It is suggested that this was due to a continuous trimming of the cluster structure after the active period of starch synthesis. Differences were evident between A- and B-type granules with regards to glucan trimming and the type of new chains produced.

Research paper thumbnail of Structure of Arabidopsis leaf starch is markedly altered following nocturnal degradation

Carbohydrate polymers, Jan 6, 2015

Little is known about the thermal properties and internal molecular structure of transitory starc... more Little is known about the thermal properties and internal molecular structure of transitory starch. In this study, granule morphology, thermal properties, and the cluster structure of Arabidopsis leaf starch at beginning and end of the light period were explored. The structural properties of building blocks and clusters were evaluated by using diverse chromatographic techniques. On the granular level, starch from end of day had larger granule size, thinner crystalline lamellae thickness, lower free surface energy of crystals, and lower tendency to retrograde than that from end of night. On the molecular level, the starch had lower amylose content, larger cluster size, and higher number of blocks per cluster at the end of day than at end of night. It is concluded that the core of the granules contains a more permanent molecular and less-ordered physical structure different from the transitory layers laid down around the core at daytime.

Research paper thumbnail of Structure-function relationships of starch components

Research paper thumbnail of The molecular structures of starch components and their contribution to the architecture of starch granules: A comprehensive review

Research paper thumbnail of Structure of starches extracted from near-isogenic wheat lines

Journal of Thermal Analysis and Calorimetry, 2007

Research paper thumbnail of Molecular structure of amylopectin from amaranth starch and its effect on physicochemical properties

International Journal of Biological Macromolecules, 2008

Research paper thumbnail of The building block structure of barley amylopectin

International Journal of Biological Macromolecules, 2011

Research paper thumbnail of On the interconnection of clusters and building blocks in barley amylopectin

International Journal of Biological Macromolecules, 2013

Research paper thumbnail of The cluster structure of barley amylopectins of different genetic backgrounds

International Journal of Biological Macromolecules, 2011

Research paper thumbnail of Unit and Internal Chain Profile of Millet Amylopectin

Cereal Chemistry, 2014

ABSTRACT The unit chain compositions of debranched foxtail, proso, pearl, and finger millet amylo... more ABSTRACT The unit chain compositions of debranched foxtail, proso, pearl, and finger millet amylopectins and their phi,beta-limit dextrins were analyzed by high-performance anion-exchange chromatography. The phi,beta-limit dextrins reflected amylopectin internal chain profiles. The amylopectins had average chain lengths ranging from 17.94 to 18.12. The ranges of external chain length, internal chain length, and total internal chain length of the millet amylopectins were 11.85-12.33, 4.75-5.09, and 11.64-12.28, respectively. The relative molar concentration of B-chains in the amylopectins was close to 50% in all samples. Significant differences were, however, observed in the proportions of very short "fingerprint" B-chains (B-fp, degree of polymerization 3-7) and the major group of short B-chains (BSmajor): foxtail and proso millets possessed high amounts of B-fp-chains, whereas finger and pearl millets had higher amounts of BSmajor-chains, suggesting possible differences in the fine structure of the clusters and building blocks of the amylopectins. Millet amylopectin can be classified structurally as type 2.

Research paper thumbnail of Relationship between branching density and crystalline structure of A- and B-type maize mutant starches

Carbohydrate Research, 2000

Research paper thumbnail of The molecular structure of waxy maize starch nanocrystals

Carbohydrate Research, 2009

Research paper thumbnail of Fine structure characterization of amylopectins from grain amaranth starch

Carbohydrate Research, 2009

Research paper thumbnail of Iodine binding to explore the conformational state of internal chains of amylopectin

Carbohydrate Polymers, 2013

Previous studies have found that the proportion of long chains of amylopectin correlates to its f... more Previous studies have found that the proportion of long chains of amylopectin correlates to its functional and nutritional properties. As a possible explanation of this correlation, the iodine binding property of amylopectin internal chains was investigated as an indirect evidence of their ability to form helices for intra- or inter-molecular interactions. Waxy and amylose-extender waxy corn starches were hydrolyzed by β-amylase for varying periods of time to incrementally remove the external chains, and the absorbance and the wavelength of maximum absorbance of iodine binding were examined. Experimental results suggest that iodine can bind with both external and internal chains; a significant amount of absorption comes from the latter, as stepwise removal of external chains only somewhat reduced absorption. Internal amylopectin chains, thus, were concluded to likely pre-exist in helical form, as opposed to a conformational change into helices facilitating iodine binding in the absence of external chains. Such internal chain helical structures possibly drive intermolecular interactions that would explain why amylopectin with high proportion of internal chains form harder gels, create pastes less prone to shear breakdown, and are more slowly digesting.

Research paper thumbnail of Impact on molecular organization of amylopectin in starch granules upon annealing

Carbohydrate Polymers, 2013

Research paper thumbnail of Structural and physical properties of granule stabilized starch obtained by branching enzyme treatment

Carbohydrate Polymers, 2013

Research paper thumbnail of Segmental mobility of polymers in hydrothermally treated maize starches varying in amylose content

Research paper thumbnail of Structural and thermodynamic properties of rice starches with different genetic background: Part 1. Differentiation of amylopectin and amylose defects

Research paper thumbnail of Branching patterns in leaf starches from Arabidopsis mutants deficient in diverse starch synthases

Carbohydrate Research, 2015

Research paper thumbnail of Evolution of amylopectin structure in developing wheat endosperm starch

Carbohydrate Polymers, 2014

Research paper thumbnail of Structure of clusters and building blocks in amylopectin from developing wheat endosperm

Carbohydrate Polymers, 2014

Changes in internal structure of amylopectin (AP) during wheat endosperm development were studied... more Changes in internal structure of amylopectin (AP) during wheat endosperm development were studied by isolating clusters and building blocks of AP from both large A-type and small B-type starch granules at different maturity stages up to harvest time at 49 days after anthesis (DAA). Clusters isolated from B-type granules had a degree of branching (DB) of 16.5-16.8% and were more tightly branched than those isolated from A-type granules (DB 15.7-16.2%). The degree of polymerization (DP) of the clusters increased in both types of granules during the pre-physiological maturity stage up to 28 DAA. Clusters at maturity were smaller with less branches and building blocks than at the end of the pre-maturity stage. It is suggested that this was due to a continuous trimming of the cluster structure after the active period of starch synthesis. Differences were evident between A- and B-type granules with regards to glucan trimming and the type of new chains produced.

Research paper thumbnail of Structure of Arabidopsis leaf starch is markedly altered following nocturnal degradation

Carbohydrate polymers, Jan 6, 2015

Little is known about the thermal properties and internal molecular structure of transitory starc... more Little is known about the thermal properties and internal molecular structure of transitory starch. In this study, granule morphology, thermal properties, and the cluster structure of Arabidopsis leaf starch at beginning and end of the light period were explored. The structural properties of building blocks and clusters were evaluated by using diverse chromatographic techniques. On the granular level, starch from end of day had larger granule size, thinner crystalline lamellae thickness, lower free surface energy of crystals, and lower tendency to retrograde than that from end of night. On the molecular level, the starch had lower amylose content, larger cluster size, and higher number of blocks per cluster at the end of day than at end of night. It is concluded that the core of the granules contains a more permanent molecular and less-ordered physical structure different from the transitory layers laid down around the core at daytime.

Research paper thumbnail of Structure-function relationships of starch components

Research paper thumbnail of The molecular structures of starch components and their contribution to the architecture of starch granules: A comprehensive review

Research paper thumbnail of Structure of starches extracted from near-isogenic wheat lines

Journal of Thermal Analysis and Calorimetry, 2007

Research paper thumbnail of Molecular structure of amylopectin from amaranth starch and its effect on physicochemical properties

International Journal of Biological Macromolecules, 2008

Research paper thumbnail of The building block structure of barley amylopectin

International Journal of Biological Macromolecules, 2011

Research paper thumbnail of On the interconnection of clusters and building blocks in barley amylopectin

International Journal of Biological Macromolecules, 2013

Research paper thumbnail of The cluster structure of barley amylopectins of different genetic backgrounds

International Journal of Biological Macromolecules, 2011

Research paper thumbnail of Unit and Internal Chain Profile of Millet Amylopectin

Cereal Chemistry, 2014

ABSTRACT The unit chain compositions of debranched foxtail, proso, pearl, and finger millet amylo... more ABSTRACT The unit chain compositions of debranched foxtail, proso, pearl, and finger millet amylopectins and their phi,beta-limit dextrins were analyzed by high-performance anion-exchange chromatography. The phi,beta-limit dextrins reflected amylopectin internal chain profiles. The amylopectins had average chain lengths ranging from 17.94 to 18.12. The ranges of external chain length, internal chain length, and total internal chain length of the millet amylopectins were 11.85-12.33, 4.75-5.09, and 11.64-12.28, respectively. The relative molar concentration of B-chains in the amylopectins was close to 50% in all samples. Significant differences were, however, observed in the proportions of very short "fingerprint" B-chains (B-fp, degree of polymerization 3-7) and the major group of short B-chains (BSmajor): foxtail and proso millets possessed high amounts of B-fp-chains, whereas finger and pearl millets had higher amounts of BSmajor-chains, suggesting possible differences in the fine structure of the clusters and building blocks of the amylopectins. Millet amylopectin can be classified structurally as type 2.

Research paper thumbnail of Relationship between branching density and crystalline structure of A- and B-type maize mutant starches

Carbohydrate Research, 2000

Research paper thumbnail of The molecular structure of waxy maize starch nanocrystals

Carbohydrate Research, 2009

Research paper thumbnail of Fine structure characterization of amylopectins from grain amaranth starch

Carbohydrate Research, 2009

Research paper thumbnail of Iodine binding to explore the conformational state of internal chains of amylopectin

Carbohydrate Polymers, 2013

Previous studies have found that the proportion of long chains of amylopectin correlates to its f... more Previous studies have found that the proportion of long chains of amylopectin correlates to its functional and nutritional properties. As a possible explanation of this correlation, the iodine binding property of amylopectin internal chains was investigated as an indirect evidence of their ability to form helices for intra- or inter-molecular interactions. Waxy and amylose-extender waxy corn starches were hydrolyzed by β-amylase for varying periods of time to incrementally remove the external chains, and the absorbance and the wavelength of maximum absorbance of iodine binding were examined. Experimental results suggest that iodine can bind with both external and internal chains; a significant amount of absorption comes from the latter, as stepwise removal of external chains only somewhat reduced absorption. Internal amylopectin chains, thus, were concluded to likely pre-exist in helical form, as opposed to a conformational change into helices facilitating iodine binding in the absence of external chains. Such internal chain helical structures possibly drive intermolecular interactions that would explain why amylopectin with high proportion of internal chains form harder gels, create pastes less prone to shear breakdown, and are more slowly digesting.

Research paper thumbnail of Impact on molecular organization of amylopectin in starch granules upon annealing

Carbohydrate Polymers, 2013

Research paper thumbnail of Structural and physical properties of granule stabilized starch obtained by branching enzyme treatment

Carbohydrate Polymers, 2013