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

Abstract

Dextrin is widely used in the food, biomedical, and cosmetic industries. In this work, a new ethanolic fractionation method, the multiple ethanolicprecipitation (MEP), is established to fractionate the acid-hydrolyzed waxy corn starch (AHWCS) that consists of a high concentration of low-molecularweight dextrin. Through these multiple precipitation processes, the effect of the dextrin concentration on fractionation is weakened, which makes the fractionation only dependant on the molecular weight of dextrin. Five dextrin fractions (P 1 , P 2 , P 3 , P 4 , and P 5) with narrow molecular weight distributions are obtained. The weight-average molar mass (M w) and the molecular weight dispersity (D) of five fractions are 7.3 × 10 4 g mol −1 (2.0), 2.3 × 10 4 g mol −1 (2.1), 1.6 × 10 4 g mol −1 (2.2), 8.9 × 10 3 g mol −1 (2.1), and 4.5 × 10 3 g mol −1 (3.3), respectively. Additionally, the increase of molecular weight tends to decrease the moisture-absorption but increase the viscosity and thermal stability, which can provide a basis for the application of different molecular weight dextrin fractions in different fields. These results suggest that the MEP method is a low cost and efficient approach for directly separating dextrin fractions with narrow molecular weight distributions from the AHWCS.

Characterization of Nano- and Microstructures of Native Potato Starch as Affected by Physical, Chemical, and Biological Treatments

“…The final viscosity curve was observed to be close to the viscosity curves of native starches, indicating that ethanolic precipitation gelatinized the granules. Normally, starch granules are insoluble in cold water and only form suspensions; however, hydrolysis due to ethanolic precipitation treatment breaks the starch granule structure, producing low-molecular-weight dextrin [42] of nanometer size. Therefore, the modified starch solution obtained by ethanolic precipitation showed a reduction in the paste property parameters Pv, Bd, Sb, and Fv (Figure 5), resulting in higher stability, clarity, binding properties.…”