Morphology and phase transition of waxy cornstarch in solvents of 1-allyl-3-methylimidazolium chloride/water

Effect of solution on starch structure: New separation approach of amylopectin fraction from gelatinized native corn starch

The complete dissolution of starch without degradation are necessary prerequisites for starch fractionation to obtain amylose or amylopectin (AP). With the recent, continuous progress in finding efficient and eco-friendly starch-dissolving solutions, applying new solvents for starch fractionation is important. In this study, the effects of dimethyl sulfoxide (DMSO), NaOH, and CaCl2 solutions on starch structure and AP product parameters during starch fractionation were compared with respect to the starch deconstruction effect. This study proved that the CaCl2 solution could effectively dissolve corn starch (50 °C, solubility of 98.96 %), and promote the regeneration of starch into uniform and fine particles. Furthermore, the three solvents (DMSO, NaOH, and CaCl2) changed the crystal structure of corn starch, but they were all non-derivatizing solvents. The effect of the CaCl2 solution on the molecular structure of corn starch was the least significant of the three solvents. Finally, the extraction rate of AP from the CaCl2 solution reached 69.45 %. In conclusion, this study presents a novel and effective method for AP extraction.

Preparation of chemical staple fibers by plasticizing bleached coniferous pulps with 1-allyl-3-methylimidazolium chloride

In this study, we prepared chemical staple fibers (CSFs) by plasticizing bleached coniferous pulps (BCPs) with 1-allyl-3-methylimidazolium chloride (AMIMCl) under high temperature and pressure.

Catalyst-free esterification of high amylose starch with maleic anhydride in 1-butyl-3-methylimidazolium chloride: The effect of amylose content on the degree of MA substitution

The limited reactivity of starch towards maleic anhydride (MA) affords maleate with a low degree of MA substitutions (CC and COOH groups). In this study, we investigated the relationship between the starch structure, controlled by its amylose (AM)/amylopectin (AP) ratio, and the DS of starch maleates using C₄[mim]Cl as the recyclable media, and catalyst. The results indicated that starches with varying AM/AP ratio produced maleates with comparable CC groups (DS_NMR = 0.06-0.07). Following dissolution, the high amylose (DS_titration = 1.17, yield = 69.2 %) and regular starches (DS_titration = 1.17; yield = 59.3 %) produced high DS_titration maleates (COOH groups) at MA/AGU ratio of 12:1 (80 °C, 10 min). Comparatively, DS_titration value of waxy starch maleates (DS_titration = 0.88, yield = 59.3 %) was lower than AM-based starches, possibly due to the crosslinking tendency of AP branches consisting of carboxylic end-groups. Interestingly, DS_titration value for EHCS (1.17) ranged between its bulk (DS_NMR: 0.06) and surface distribution of MA (DSS_XPS 1.7); therefore, we considered it reliable for future reference.

Dissolution Behavior of Maize Starch in Aqueous Ionic Liquids: Effect of Anionic Structure and Water/Ionic Liquid Ratio

The effect of the anionic structure of ionic liquids (ILs) and water/IL ratio on the dissolution behavior of maize starch at room temperature (22-23 °C) was investigated. The ILs used were 1-ethyl-3-methylimidazolium chloride ([C₂mim][Cl]), 1-ethyl-3-methylimidazolium formate ([C₂mim][HCOO]), and 1-ethyl-3-methylimidazolium acetate ([C₂mim][CH₃COO]). The structural analysis indicated that the long- and short-range molecular order in the starch after treatment with water/[C₂mim][Cl] and water/[C₂mim][HCOO] mixtures decreased with the decreasing water/IL ratio from 10:1 to 2:1 and was completely disrupted at the 2:1 ratio. However, the ordered structure of starch was disrupted completely in the water/[C₂mim][CH₃COO] ratio of 5:1. The disruption extent of starch structures followed the order: [C₂mim][CH₃COO] > [C₂mim][HCOO] > [C₂mim][Cl] at water/IL ratios of 10:1 and 5:1, but the opposite was observed at lower water/IL ratio (2:1). Our results clearly showed that both the nature of the anion and water/IL ratio affected the dissolution behavior of maize starch. The hydrogen bonding capacity of IL anions and viscosity of water/IL mixtures were proposed to play the key roles in the structural disruption of starch. These findings would be of great importance for rationally designing "green and sustainable" processes for the utilization of promising natural biopolymers.

Toward a Better Understanding of Different Dissolution Behavior of Starches in Aqueous Ionic Liquids at Room Temperature

The purpose of this study was to understand the dissolution behavior of maize and potato starches in 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]):water mixtures at room temperature. With an increasing ratio of ionic liquid (IL):water, the long- and short-range ordered structures and granule morphology of both starches were disrupted progressively. The multiscale structure of maize starch was disrupted completely after treatment with the [Emim][OAc]:water mixture of 6:4, indicating good dissolution performance of this mixture for maize starch. This mixture seemed to provide a balance between the viscosity of the solvent and availability of ions to disrupt starch H-bonds. The different dissolution behaviors of maize and potato starches in [Emim][OAc]:water mixtures were attributed to structural differences of the granule surfaces. Our results showed that the dissolution behavior of starches was affected by both starch sources and properties of [Emim][OAc]:water mixtures, which may provide guidance for the development of green technology for processing of biopolymers with low energy consumption.

A new characterization methodology for starch gelatinization

A gelatinization degree control system, with a combination of Artificial Neural Networks (ANNs) and computer vision, was successfully developed. An intelligent measurement framework was purposely designed to achieve a precise investigation on phase transition and morphology change of starch in real time, as well as a process control during gelatinization. Base on a variation of birefringence number, the degree of gelatinization (DG) control system provided a direct and fast methodology without subjective uncertainty in studying starch gelatinization. In the course, the whole system was a cascade structure with the hot-stage temperature chosen as the inner-loop parameter, thus the granule morphology and birefringence at different DG could be easily observed and compared in real time, and the relative transition temperature was simultaneously calculated.