Molecular Dispersion of Starch as a Crucial Parameter during Size-Exclusion Chromatography

Abstract

Starch, α-polyglucan consisting of a large number of anhydroglucose units joined by α-1,4- and α-1,6-glycosidic bonds, seems to be characterized by a simple structure when compared to other natural polymers. Nevertheless, starches of various botanical origins have different physicochemical properties that are related to the differences in molecular and supramolecular structure of this polymer. In terms of the functional value of starch, the behavior of its macromolecules in solution is the most important result of its structural features. Extremely high molecular mass is the fundamental structural property of starch. Water, considered simply as a solvent for solubilization, does not provide molecular dispersion of starch without its degradation. The objectives of this study are to characterize the suitability of a new aqueous media (urea/NaOH) for enhancing the dispersion of native corn and potato starches and its effect on the consequent size-exclusion chromatography (SEC) analysis. The results were referred to other aqueous base solvents used for dispersing starch (NaOH and KOH). The samples were separated using SEC with triple detection and phosphate buffer (pH 8.0) with urea as the eluent. The characteristics of tested normal and waxy starches were compared. The results revealed that urea/NaOH did not degrade starch during the dispersion process. The recovery of starches, however, was not higher than 42%. These results prove that while the urea/NaOH solvent allows to obtain cold-water-soluble starch, the degree of disintegration of the intramolecular interactions of amylopectin chains is still insufficient.

Insight into the Molecular Weight of Hydrophobic Starch Laurate-Based Adhesives for Paper

“…Table 1 contains the details of the molecular weight (M w ) of all samples, while the reaction times of 4 h and above are sufficient to achieve starch laurates (GPC signal at a retention time of 9 min in water). Furthermore, the results from the DMSO system present that there is an extra new peak in starch laurate samples (29 min) in Table 1 that indicated the hydrolysis product, while the starch laurate peaks were not detected because of its incomplete solubility in DMSO [ 19 , 20 ]. Nevertheless, DMSO may be unsuitable for the detection of esterified starch likely due to the low solubility of starch laurate in DMSO.…”

Synthesis, characterization, and antibacterial activities of novel starch derivatives against E. coli and S. aureus

“…The molar mass of QA‐ST was determined in aqueous SEC using a buffer solution (pH = 7.0) of 0.1 M NaNO 3 with 100 ppm NaN 3 as the eluent. Results are M n = 2270 g mol –1 , M w = 5000 g mol –1 , and Đ = 2.20, which are low molar masses values as compared with unmodified starches from different sources, [ 40 ] but in this case, these low values do not affect the applications to which the developed materials are directed. The chromatogram shown in Figure for QA‐ST seems almost unimodal, but a slight shoulder in the low molar mass region can be appreciated.…”

Polymer-Solvent Interactions in Modified Starches Pastes–Electrokinetic, Dynamic Light Scattering, Rheological and Low Field Nuclear Magnetic Resonance Approach

“…Moreover, some of the parameters derived from both analyses, such as radius of gyration R g and hydrodynamic radius R h , seem to be the same [ 14 , 45 , 46 , 47 ]. However, the appropriate measurement of molecular mass distribution by SEC analysis followed by static light scattering requires molecular distribution of polymer in solution, while the DLS method was designed for studies of dispersion of solid particles [ 14 , 45 , 46 , 47 , 77 , 78 ]. Relevant data on the molecular mass distribution obtained with SEC for, among others, three food grade starches of the same degree of substitution was recently published [ 76 ] and was used in the analysis.…”