Influence of temperature on the apparent molar masses and sizes of pregelatinized wx corn in aqueous media determined using asymmetrical flow field-flow fractionation

Abstract

Pre‐gelatinized wx corn starch dispersions in aqueous media were heated at various temperatures ranging from 100 to 200°C (in 20°C increment) employing a dedicated microwave reactor. The influence of varying temperature upon the apparent molar masses and sizes of pre‐gelatinized wx corn heated in aqueous media (water and 1 M KSCN) were determined using asymmetrical flow field‐flow fractionation coupled with a multi‐angle light scattering and a RI detector (AF4/MALS/RI). The microwave reactor allowed the accurate monitoring and regulation of temperature, microwave energy, and pressure during the dispersion/dissolution process. The ultra‐high apparent molar masses, apparent radii of gyration and hydrodynamic sizes determined for wx corn starch heated for 60 s in water indicate the presence of large aggregates. However, the lower apparent molar masses and radii of gyration values obtained for wx corn starch heated in 1 M KSCN suggest that KSCN reduced the aggregation of starch macromolecules. Significant structural changes were observed for wx corn starch heated in the presence of KSCN at 200°C.

Nanoprecipitation of native pea starches treated in alkaline media at various temperatures employing a dedicated microwave reactor

“…Native pea starch in 1 M NaOH undergoes significant structural change at 100°C as indicated by their lower M w,app , R g,app , and R h values compared to native pea starch treated at lower temperatures. These finding are similar to our previous studies on the influence of temperature upon the apparent molecular characteristics of wx corn starch in 1 M KSCN .…”

“…The drop‐wise addition of starch/alkali solution into ethanol results in the precipitation of the starch nano‐precipitates . Asymmetrical flow field‐flow fractionation coupled with a multi‐angle light scattering and a RI detector (AF4/MALS/RI) is a well‐established technique for the analysis of starch materials as it allows the elution of starch macromolecules, aggregates and particles . Dynamic light scattering measurements are undertaken for the determination of particle size distributions of nanomaterials, colloids, and polymers in solutions/dispersions .…”

“…Dynamic light scattering measurements are undertaken for the determination of particle size distributions of nanomaterials, colloids, and polymers in solutions/dispersions . However, filtration of solutions and dispersions is required which may lead to unrealistic results and only mean average particle sizes are reported . The advantages of employing AF4/MALS/RI for the characterization of highly heterogeneous material such as starch in aqueous media include the opportunity to analyze unfiltered solutions , the determination of molar mass and size (radius of gyration and sphere‐equivalent hydrodynamic radius) distributions and the investigation of aggregation behavior of starch related the self‐assembly of starch macromolecules .…”

“…However, filtration of solutions and dispersions is required which may lead to unrealistic results and only mean average particle sizes are reported . The advantages of employing AF4/MALS/RI for the characterization of highly heterogeneous material such as starch in aqueous media include the opportunity to analyze unfiltered solutions , the determination of molar mass and size (radius of gyration and sphere‐equivalent hydrodynamic radius) distributions and the investigation of aggregation behavior of starch related the self‐assembly of starch macromolecules . The nature and of treatment of starch granules in the aqueous media is known to influence the aggregation behavior of starch macromolecules and the information regarding their molecular and supramolecular characteristics may lead to better understanding regarding the self‐assembly of starch which eventually leads to formation of nanostructures, microstructures, gels and films .…”