Size separations of starch of different botanical origin studied by asymmetrical-flow field-flow fractionation and multiangle light scattering

Perspectives on Starch Structure, Function, and Synthesis in Relation to the Backbone Model of Amylopectin

Understanding functionality of polysaccharides such as starch requires molecular representations that account for their functional characteristics, such as those related to gelatinization, gelation, and crystallization. Starch macromolecules are inherently very complex, and precise structures can only be deduced from large data sets to generate relational models. For amylopectin, the major, well-organized, branched part of starch, two main molecular representations describe its structure: the classical cluster model and the more recent backbone model. Continuously emerging data call for inspection of these models, necessary revisions, and adoption of the preferred representation. The accumulated molecular and functional data support the backbone model and it well accommodates our present knowledge related to the biosynthesis of starch. This Perspective focuses on our current knowledge of starch structure and functionality directly in relation to the backbone model of amylopectin.

Flow field-flow fractionation coupled with multidetector: A robust approach for the separation and characterization of resistant starch

The unique properties of resistant starch (RS) have made it applicable in the formulation of a broad range of functional foods. The physicochemical properties of RS play a crucial role in its applications. Recently, flow field-flow fractionation (FlFFF) has attracted increasing interest in the separation and characterization of different categories of RS. In this review, an overview of the theory behind FlFFF is introduced, and the controllable factors, including FlFFF channel design, sample separation conditions, and the choice of detector, are discussed in detail. Furthermore, the applications of FlFFF for the separation and characterization of RS at both the granule and molecule levels are critically reviewed. The aim of this review is to equip readers with a fundamental understanding of the theoretical principle of FlFFF and to highlight the potential for expanding the application of RS through the valuable insights gained from FlFFF coupled with multidetector analysis.

Optimization for size separation of graphene oxide sheets by flow/hyperlayer field-flow fractionation

Graphene oxide (GO)-a chemical derivative of graphene with numerous oxygen functional groups on its surface-has attracted considerable interest because of its intriguing properties in relation to those of pristine graphene. In addition to the inherent wide lateral size distribution of GO sheets arising from the typical oxidative exfoliation of graphite, control of the lateral size of GO is critical for desired GO-based applications. Herein, flow/hyperlayer field-flow fractionation (flow/hyperlayer FFF) is optimized to separate GO sheets by lateral dimensions. Optimized fractionation is achieved by investigating the influences of carrier solvent, channel thickness, and flow rate conditions on the steric/hyperlayer separation of GO sheets by flow FFF. Due to the strong hydrodynamic lift forces of extremely thin GO sheets, a thick flow FFF channel (w = 350 μm) and a very low field strength are required to retain the GO sheets within the channel. GO sheets with narrow size fractions are successfully collected from two different graphite sources during flow/hyperlayer FFF runs and are examined to verify the size evolution. Considering the average lateral diameter of the GO fraction calculated on the basis of the assumption of a circular disk shape, the retention of the GO sheets is 2.2-5.0 times faster than that of spherical particles of the same diameter. This study demonstrates that through flow/hyperlayer FFF, the size distribution of GO sheets can be determined and narrow size fractions can be collected (which is desirable for GO-based applications), which are commonly influenced by the GO lateral dimension.

A review of wheat starch analyses: Methods, techniques, structure and function

Wheat starch has received much attention as an important source of dietary energy for humans, an interesting carbohydrate and a polymeric material. The understanding of the structure and function of wheat starch has always been accompanied by newer technological tools. On the one hand, the general knowledge of wheat starch is constantly being enriched. On the other hand, an increasing number of studies are trying to add new insights to what is already known from two frontier perspectives, namely, wheat starch supramolecular structures and wheat starch fine structures (CLDs). This review describes the structure and function of wheat starch from the perspective of wheat starch analysis techniques (instruments).

Applications of asymmetrical flow field-flow fractionation for separation and characterization of polysaccharides: A review

Polysaccharides are the most abundant natural biopolymers on the earth and are widely used in food, medicine, materials, cosmetics, and other fields. The physicochemical properties of polysaccharides such as particle size and molecular weight often affect their practical applications. In recent years, asymmetrical flow field-flow fractionation (AF4) has been widely used in the separation and characterization of polysaccharides because it has no stationary phases or packing materials, which reduces the risk of shear degradation of polysaccharides. In this review, the principle of AF4 was introduced briefly. The operation conditions of AF4 for the analysis of polysaccharides were discussed. The applications of AF4 for the separation and characterization of polysaccharides from different sources (plants, animals, and microorganisms) over the last decade were critically reviewed.