The Influence of Starch Modification with Amylosucrase Treatment on Morphological Features

Hyeyoung Lee,Inmyoung Park

doi:10.3390/pr8111409

Abstract

Amylosucrase (AS) is a starch-modifying enzyme from Neisseria polysaccharea used to produce low-glycemic starches such as slowly digestible starch (SDS) and resistant starch (RS). The morphology of native, control, and AS-modified waxy corn starches (230 and 460 U) was examined using a particle size analyzer and field-emission scanning electron microscopy (FE-SEM). AS modification of the starch elongated the glucose and resulted in higher SDS and RS contents. The mean particle sizes of the control, 230 U-AS-, and 460 U-AS-treated starches were 56.6 µm, 128.0 µm, and 176.5 μm, respectively. The surface of the 460 U-AS-treated starch was entirely porous and coral-like, while the 230 U-AS-treated starch had a partial dense and flat surface which did not react with AS. FE-SEM of the granule cross section confirmed that the center contained a dense and flat region without any evidence of AS reaction to either of the AS-treated starches. It was assumed that the particle size and porous and sponge-like particle features might be related to the SDS and RS fractions.

Highlights

Starch is the major dietary source of carbohydrates and plays an important role in energy supply in humans
We aimed to identify how the particle size and morphology of starch are related to its nutritional fractions (RDS, slowly digestible starch (SDS), and resistant starch (RS))
Using a particle size analyzer, we determined that the average particle size of waxy corn starch was 32.3 μm and that of control starch was 56.6 μm

Summary

Introduction

Starch is the major dietary source of carbohydrates and plays an important role in energy supply in humans. It is made up of a large number of glucose units, amylose and amylopectin, linked by α-d-(1→4) and/or α-d-(1→6) glycosidic bonds. SDS is completely digested in the small intestine through a slow digestive process and is the main determinant of the postprandial glucose level [2,3]. Both SDS and RS have a low glycemic index (GI) and thereby reduce the risk of developing diabetes, obesity, and cardiovascular diseases [3,4]

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