Production of an in Vitro Low-Digestible Starch via Hydrothermal Treatment of Amylosucrase-Modified Normal and Waxy Rice Starches and Its Structural Properties

Abstract

We investigated dual modification of normal and waxy rice starch, focusing on digestibility. Amylosucrase (AS) was applied to maximize the slowly digestible and resistant starch fractions. AS-modified starches were adjusted to 25-40% moisture levels and heated at 100 °C for 40 min. AS-modified starches exhibited a B-type crystalline structure, and hydrothermal treatment (HTT) significantly (p < 0.05) increased the relative crystallinity with moisture level. The thermal transition properties of modified starches were also affected by the moisture level. The contents of rapidly digestible starch fraction in AS-modified normal and waxy starches (43.3 ± 3.9 and 18.1 ± 0.6%) decreased to 13.0 ± 1.0 and 0.3 ± 0.3% after HTT, accordingly increasing the low digestible fractions. Although the strengthened crystalline structures of AS-modified starches by HTT were not stable enough to maintain their rigidity under cooking, application of AS and HTT was more effective in waxy rice starch than normal rice starch when lowering digestibility.

Versatile biotechnological applications of amylosucrase, a novel glucosyltransferase

“…The structure of the dually treated starches may be suitable for SDS formation, by treating glycogen branching enzymes with potato starch before AS treatments (Jo et al, 2016). Another approach to increase the SDS content in AStreated starches is to use physical treatments, such as hydrothermal treatments and temperature-cycled storage on AS-treated starches (Kim et al, 2016b;Nam et al, 2018). The high RS contents of the AS-treated starches are derived from their perfect and rigid crystalline structures, formed through the interchain interactions between the elongated branch chains of AS.…”

Structural factors governing starch digestion and glycemic responses and how they can be modified by enzymatic approaches: A review and a guide

“…The resultant modification of AP chains has a profound impact on starch physicochemical properties and digestibility. Enzymatic treatment of pregelatinized starches leads to a substantial increase in the portion of intermediately sized and long (DP ≥ 37) AP chains (Kim et al, 2014(Kim et al, , 2016(Kim et al, , 2017Nam et al, 2018;Shin et al, 2010;. These elongated AP chains retrograde to a considerable extent already during enzymatic incubation (typically at 30-35 • C for a few hours) (Kim et al, 2014(Kim et al, , 2016 or upon storage at low temperature.…”

Functional characteristics, dry heating and irradiation treatment of starch – A short review

“…Dry heating increased degree of substitution of succinylation in waxy corn starch and the starch was also found to be good fat substitute in muffins. Dry heating of starch with lysine resulted into cross linking between lysine and starch leading to reduction in relative crystallinity and increase in peak viscosity of the treated starch (Kim et al, 2016). Similarly, Zuo et al (2013) modified corn starch with maleic anhydride (4:1) under dry heating (50-90 °C) for 1-4h and demonstrated with the help of XPS formation of ester bonds.…”