Determination of molar mass distribution of tapioca starch using asymmetrical flow field flow fractionation

Abstract

The apparent average molar masses (M w,app ) and apparent average radii of gyration (R g,app ) of native tapioca starch and fractions were determined using asymmetrical flow field flow fractionation (AF4) coupled with multi-angle light scattering and RI detectors (AF4/MALS/RI). AM-type (Fraction A) and AP-type (Fraction B) were chemically separated from native tapioca starch. Native tapioca starch and Fractions (A and B) were dissolved in 1 M KSCN using a high pressure microwave vessel. The effect of varying cross flow rates at a fixed channel flow rate upon the M w,app and R g,app distributions of native tapioca starch and Fractions (A and B) were investigated. The average M w,app values for native tapioca starch, Fraction (A) and Fraction (B) were 59 Â 10 6 , 2.1 Â 10 6 and 19 Â 10 6 g/mol, respectively, with average R g,app values of 165, 73 and 87 nm, respectively. Hydrodynamic radii (R h ) values for native tapioca starch and fractions were determined directly from AF4 experimental parameters.

Composition, structure, physicochemical properties, and modifications of cassava starch

“…The iodine affinity (%) and blue value of cassava amylopectin (4 genotypes) were 258 0.18-0.23% and 0.080-0.091, respectively (Charoenkul et al, 2006b). 259 The size/molecular weight of cassava amylopectin was 6,000-17,100 (4 genotypes) by (Juna & Huber, 2012) or 188 nm (Tetchi et al, 2007). This large discrepancy to a large extent 267 essentially can be attributed to the analytical method.…”

“…This may give rise to the possible discrepancy in the amylose size as measured by 244 these two different techniques. The average radius of gyration of amylose determined by 245 AF4/MALS/RI was 73 nm (Juna & Huber, 2012). 246 The branches of amylose can be detected by treated it with exo-acting amylases such as β-247 amylase to obtain the β-limit dextrins.…”

Treatment of wx corn starch dispersions in a microwave reactor and their hydrodynamic properties determined using asymmetrical flow field‐flow fractionation

“…The reliable determination of the de‐facto molecular characteristics requires complete dissolution of starch–glucan materials 1–7. A detailed literature survey on the influence of various dissolution protocols and analytical techniques upon molar masses, radii of gyration and hydrodynamic radii ( R h ) values for wx corn starch (99% AMP) has been previously published 7.…”

“…Aggregation of the starch–glucan molecules in aqueous media is a dynamic process and is highly influenced by the inherent nature of the sample and the dissolution procedures employed 1–7. Furthermore, it is difficult to ascertain the degree of aggregation of starch solutions and dispersions.…”

“…Dissolution procedures employing a high pressure microwave vessel treatment (HPMV) 3–9 are rapid in comparison to other dissolution procedures such as autoclaving 10, 11 alkali/acid treatments 12 or use of organic solvents (particularly, DMSO) 12, 13 (Table 1). Some dissolution processes, such as HPMV, require a pre‐gelatinisation step to aid the disruption of the starch granules and improves the dispersion of the starch materials in aqueous media 3–9, 14 as shown in Table 1. However, domestic microwave instruments lack the ability to control and monitor the processing temperature inside the vessel.…”