Sweet potato amylose and amylopectin with narrower distribution of molar mass and chain length obtained by a repeated retrogradation–hydrolysis procedure

Abstract

The wide molar mass distribution of native starch creates obstacles in investigating the physicochemical characteristics of starch, such as retrogradation, because samples thought to be the same are actually compounds containing many chains with different molar masses. In this paper, the sweet potato amylose and amylopectin isolated from retrograded starch were treated with the retrogradation–hydrolysis method three times, and their physicochemical changes in this process were determined by absorbance of the starch–iodine complex, light microscopy, and molar mass and chain length distributions. The results showed that repeated retrogradation and hydrolysis caused the molar mass distribution of sweet potato amylose and amylopectin to reduce from 4.2 × 107–205 and 7971–223 to 6.0 × 104–730 and 4533–211 g mol−1, respectively. This retrogradation–hydrolysis cut the chain length distribution of sweet potato amylose from DP 9–35 to DP 3–13, but that of amylopectin remained unchanged. The double helix in sweet potato amylopectin will not form if the percentage of chain length with DP ≥ 4 is less than 25%. Repeated retrogradation and hydrolysis was an appropriate method to obtain amylose or amylopectin with a narrower molar mass distribution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43849.

Retrogradation of sweet potato amylose and amylopectin with narrow molecular weight distribution

“…Molar mass distribution was determined according to the reference (Philpot, et al ., 2006; Lian et al ., 2016). Sweet potato amylose or amylopectin (100 mg) was blended with 80 mL distilled water and heated in boiling water by continuous stirring for 20 min to dissolve the samples.…”

A New Method to Purify Hydroxyl Monascus Red Pigment by Retrogradation of Both Pigments and Maize Amylopectin

“…The maize amylopectin with narrow molecular weight was prepared according to refs. . Maize starch at weight of 10 g was blended with 100 mL distilled water and gelatinized for 20 min at 95 °C by continuous stirring.…”

“…Then the retrograded amylopectin could be resolved in 4.0 M KOH and the hydrogen bonds in it opened. Lastly, the amylopectin in solutions precipitated by ethanol after the pH of solutions was adjusted to neutral by 6.0 M HCl, hydroxyl MRP/citrinin and the newly formed KCl remained in solution . Optimum conditions such as ratio of pigment to amylopectin, autoclaving, and aging time for the method were investigated, and the isolation mechanism was deduced by analysis of visible absorption, ESI‐MS, X‐diffraction, IR and 13 C solid NMR.…”

Multiple Ethanolic‐Precipitation: An Approach to the Separation of Dextrin Fractions with Narrow Molecular Weight Distributions from Acid‐Hydrolyzed Waxy Corn Starch

“…[2] However, dextrin obtained by starch hydrolysis usually shows a wide molecular weight distribution, which influences its property and further restricts its application. [3][4][5] DOI: 10.1002/star.202000038…”

“…[ 2 ] However, dextrin obtained by starch hydrolysis usually shows a wide molecular weight distribution, which influences its property and further restricts its application. [ 3–5 ] For example, dextrin can increase the viscosity of the beverage solution but some high‐molecular‐weight fractions may reduce its stability. [ 6,7 ] Therefore, it is indispensable to fractionate dextrin obtained by starch hydrolysis into different molecular weight fractions with narrow molecular weight distributions in the fields of basic research and for further application.…”