Effects of acid hydrolysis on the evolution of starch fine molecular structures and gelatinization properties

Mechanistic investigation of impact of malic acid, ultrasound and dual treatment on starch digestibility of cooked whole rice grains

Physical, chemical, and dual modifications can all significantly affect the digestibility of isolated rice granules, while their effects on the starch digestibility of whole cooked rice grains remain elusive. Therefore, the impact of malic acid, ultrasound, and ultrasound + malic acid dual treatment on the starch digestibility of cooked rice grains with different starch molecular structures was investigated in this study. Ultrasound mainly caused cavitation on the surface of rice grains, promoting the leaching of materials (> 11 %) and amylose during cooking. This led to a faster retrogradation rate, smaller pores, and a lower maximum starch digestion extent. In contrast, malic acid caused a faster digestion rate due to the significant degradation of starch molecules, although its moderate esterification smoothed the cooked rice grain surface and slightly reduced the maximum starch digestion extent. Compared to malic acid treatment, the dual treatment showed a much higher degree of esterification, which may thus contribute to its significantly lower maximum starch digestion extent (up to 21 %). Collectively, these findings suggest that both ultrasound and dual treatment can be effective strategies for producing cooked rice grains with slower starch digestibility, with implications for improving the public health.

High-solids gel properties of acid-hydrolyzed waxy maize starch are determined by the molecular-weight distribution

This study aimed to understand the effect of molecular-weight distribution on the properties of acid-hydrolyzed waxy maize starches (AH-WMSs) prepared at different acid concentrations and hydrolysis times at 50 °C. A reduction in molecular weight of AH-WMS resulted in increased paste fluidity and light transmittance, as well as decreased sedimentation, amylose‑iodine complex, and pasting viscosity. Freshly prepared AH-WMS viscoelastic gels at 20 % solids showed thixotropy at 25 °C and 50 °C, and both the shear stress and the area of hysteresis loop decreased with decreasing molecular weights. After storage at 4 °C for 24 h, the AH-WMS viscoelastic gels exhibited anti-thixotropy at 25 °C. However, the anti-thixotropy behavior disappeared at 50 °C for those with lower molecular weights. Freshly prepared viscoelastic gels obtained from AH-WMSs with higher molecular weights showed higher values of liquidity, firmness, consistency, cohesiveness, and viscosity at 20 % and 30 % solids. After storage at 4 °C for 24 h, AH-WMS viscoelastic gels at 30 % solids transformed into solid gels, and the gel strength decreased with decreasing molecular weights. AH-WMSs with a similar molecular-weight distribution displayed similar pasting, rheological, and textural properties at high solids.

Influence of carboxyl content on the rheological properties and printability of oxidized starch for 3D printing applications

With the rapid development of 3D printing technology, the development of starch gels based on 3D printing with excellent printing properties has attracted great attention. This study successfully prepared four types of oxidized starch (OMS) with varying carboxyl group contents (0.203 %, 0.612 %, 1.043 %, and 1.278 %) by controlling the amount of sodium hypochlorite. Rheological analysis of these OMS gels revealed typical shear-thinning behavior and excellent structural recovery during heating shear across various concentrations. As the concentration of OMS increased, key parameters such as consistency index (K), storage modulus (G'), yield stress (τy), and flow stress (τf) also increased, signifying enhanced molecular chain entanglement and densification with reduced digestibility. Conversely, at a constant concentration, increasing carboxyl group content led to decreased K, G', τy, and τf values due to molecular chain degradation, resulting in diminished aggregation and increased network pore size. Notably, OMS gels demonstrated favorable printability within a specific range of G' (4314.0-6690.0 Pa), τy (1254.8-2697.5 Pa), and τf (822.3-2296.3 Pa). Meanwhile, oxidized starch (OMS2 and OMS3) gels exhibited exceptional printability, attributed to appropriate molecular chain length and carboxyl content, which promoted sufficient physical crosslinking. These findings provided theoretical insights and foundational data for developing 3D printable starch-based materials.

Effects of glutathione on the physicochemical properties of high hydrostatically pressure gelatinized maize starch

This research prepared gelatinized waxy maize starch (WMS), low-amylose maize starch (LAS), and high-amylose maize starch (HAS) with different glutathione (GSH) content (5, 10, and 15 %) using high hydrostatic pressure (HHP) at 600 MPa. Scanning electron microscopy (SEM) revealed damaged morphology of WMS and complete swelled granules of LAS and HAS with different degree of gelatinization (DG) values, 92.86, 59.36, and 17.45 %, respectively. Fourier transform infrared spectroscopy (IR spectra), laser confocal micro-Raman (LCM-Raman) spectroscopy, and X-ray diffraction (XRD) results suggested that the crystallinity content of gelatinized WMS and HAS with addition of GSH was higher than that of LAS, and the gelatinized LAS and HAS were mainly of C type and V type, respectively. The resistant starch of LAS (25.15 %) and HAS (34.76 %) increased with GSH addition. The crosslinking between GSH and amylose/amylopectin caused changes in physicochemical properties. This study will provided theoretical basis for GSH usage in food industry.

Silanization of Starch and Its Effect on Cross-Linking and Mechanical, Dynamic, Hydrophobic, and Aging Properties of Polymeric Compositions Containing Natural Rubber

In recent years, the search for more sustainable fillers for elastomeric composites than silica and carbon black has been underway. In this work, silanized starch was used as an innovative filler for elastomeric composites. Corn starch was chemically modified by silanization (with n-octadecyltrimethoxysilane) via a condensation reaction to produce a hydrophobic starch. Starch/natural rubber composites were prepared by mixing the modified starch with elastomer. The morphology, hydrophobicity, and chemical structure of starch after and before modification were studied. The results showed that starch after silanization becomes hydrophobic (θw = 117.3°) with a smaller particle size. In addition, FT-IR spectrum analysis confirmed the attachment of silane groups to the starch. The modified starch dispersed better in the natural rubber matrix and obtained a more homogeneous morphology. The composite achieved the best dynamic (ΔG' = 203.8 kPa) and mechanical properties (TSb = 11.4 MPa) for compositions with 15 phr of modified starch. In addition, the incorporation of silanized starch improved the hydrophobicity of the composite (θw = 117.8°). The higher starch content allowed the composites to achieve a higher degree of cross-linking, resulting in better resistance to swelling in organic solvents. This improvement is due to enhanced elastomer-filler interactions and reduced spaces that prevent solvent penetration into the material's depths. The improved mechanical properties and good dynamic properties, as well as improved hydrophobicity, were mainly due to improved interfacial interactions between rubber and starch. This study highlights the potential and new approach of silane-modified starch as a sustainable filler, demonstrating its ability to enhance the mechanical, dynamic, and hydrophobic properties of elastomeric composites while supporting greener material solutions for the rubber industry.

Increasing degree of substitution inhibits acetate while promotes butyrate production during in vitro fermentation of citric acid-modified rice starch

Citric acid-modified starch functions as a resistant starch, while the combined effects of its fine molecular structure and degree of substitution on gut microbiota are not well understood. To this end, citric acid-modified starches with varying degrees of substitution were synthesized from rice starches with distinct molecular structures and their impact on gut microbiota composition and short-chain fatty acid (SCFA) production was analyzed. Notably, rice starch with a higher degree of substitution significantly reduced acetate production, while promoted butyrate production. Correlation analysis further suggested that amylopectin chains with 12 < DP ≤ 36 and amylose chains with 100 < DP ≤ 500 alter the growth of Faecalibacterium_prausnitzii and Bacteroides_vulgatus, consequentially determining the production of SCFAs. Collectively, these findings indicate that citric acid-modified rice starch with different degrees of substitution can target specific gut bacteria and SCFA production, thus conferring beneficial impact on human health.

Acid Hydrolysis of Quinoa Starch to Stabilize High Internal Phase Emulsion Gels

Starch nanocrystals (SNCs) to stabilize high internal phase emulsions (HIPEs) always suffer low production efficiency from acid hydrolysis. Due to its small granule size, Quinoa starch (QS) was selected to produce SNCs as a function of acid hydrolysis time (0-4 days), and their structural changes and potential application as HIPEs' stabilizers were further explored. With increasing the acid hydrolysis time from 1 day to 4 days, the yield of QS nanocrystals decreased from 30.4% to 10.8%, with the corresponding degree of hydrolysis increasing from 51.2% to 87.8%. The occurrence of QS nanocrystals was evidenced from the Tyndall effect and scanning electron microscopy with particle size distribution. The relative crystallinity of QS subjected to different hydrolysis times (0-4 days) increased from 22.27% to 26.18%. When the acid hydrolysis time of QS was 3 and 4 days, their HIPEs showed self-standing after inversion, known as high internal phase emulsion gels (HIPE gels), closely related to their densely packed interfacial architecture around oil droplets, seen on an optical microscope, and relatively high apparent viscosity. This study could provide a theoretical guidance for the efficient production and novel emulsification of SNCs from QS to HIPE gels.

Value addition of mango kernel for development and characterization of starch with starch nanoparticles for packaging applications

The present research was conducted to explore the potential of mango kernel starch from the Chaunsa variety to develop starch and starch nanoparticles (SNPs) based films. The investigation included starch isolation from mango kernel followed by the preparation of SNPs by acid hydrolysis and a thorough examination of various physicochemical properties for film formation. The properties of SNPs were found to be distinctly different from those of native starch. SNPs exhibited an aggregated form with an irregular surface, whereas native starch had an oval and elongated shape with a smooth surface. X-ray diffraction (XRD) analysis confirmed that the starch type in SNPs was of the A-type. Additionally, the pasting properties of SNPs were minimal due to the acid hydrolysis process. SNP-based composite film was developed with (5 %) SNP concentration added. This successful incorporation of SNPs enhanced biodegradability, with complete degradation occurring within three weeks. Moreover, the composite films displayed increased burst strength, measuring 1303.51 ± 73.7 g, and lower water vapor transmission rates (WVTR) at (7.40 ± 0.50) × 10-3 g per square meter per second and reduced water solubility at 35.32 ± 3.0 %. This development represents a significant advancement in the field of eco-friendly packaging materials.

Extraction, purification and characterization of amylose from sago and corn: Morphological, structural and molecular comparison

In the present work, a comprehensive study was carried out to better understand the molecular characteristics of amylose extracted from sago starch, using butanol as the extraction solvent. The sago derived amylose was compared with amylose extracted from corn starch and both characterized through different techniques, i.e. size exclusion chromatography, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, Raman spectroscopy, Scanning electron microscopy, Atomic force microscopy and Zeta potential measurements. The purity of the amylose extracted from sago and corn was 99.20 % and 93.46 %, respectively. From XRD results, it was revealed that sago amylose had more crystallinity with high thermal stability compared to corn amylose. Based on Raman spectra, single and double helices formed in both extracted amyloses, but due to their intrinsic differences, the intensities associated with these helices varied for sago and corn amylose. Purified amyloses were shown to have two different forms of spherulite morphology: torus and spherical shapes with varying degrees of roughness. Our findings demonstrated that sago starch is a novel and low-cost source for supplying amylose, a promising polymer for different applications.

Spotlight on the Multiscale Structural and Physicochemical Properties of Red Adzuki Bean Starch through Partial Amylose Removal Combined with Hydrochloric Acid

To explore the effect of amylose within starch granules on the efficiency of starch hydrolysis by acid, we chose the warm water extraction method to treat red adzuki bean starch to obtain different degrees of amylose removal granule models and to prepare samples in combination with acid hydrolysis. The amylose content was reduced after acid hydrolysis, reducing the peak viscosity (2599-1049 cP), while the solubility was significantly increased. In contrast, the short-chain content of the deamylose-acid hydrolysis samples was reduced considerably, exacerbating the trend towards reduced starch orderliness and increased solubility. This work reveals the granular structure of starch from the point of view of deamylose and contributes to a thorough understanding of the mechanisms of acid hydrolysis. It might add to knowledge in starch science research and industrial applications for the acid processing of starch-based foods, particularly with regard to the most important factors controlling the structure and function of starch.

Thermoplastic starch/polyvinyl alcohol blends modification by citric acid-glycerol polyesters

Thermoplastic starch/polyvinyl alcohol (TPS/PVA) films have limitations for being used in long-term applications due to starch retrogradation. This leads to plasticizer migration, especially when low molecular weight plasticizers such as glycerol, are used. In this work, we employed mixtures of oligomers based on glycerol citrates with higher molecular weight than glycerol as plasticizers for potato-based TPS/PVA blends obtained by melt-mixing. This constitutes an alternative to reduce plasticizer migration while keeping high swelling degree, and to provide high mechanical performance. The novelty lies in the usage of these oligomers by melt-mixing technique, aspect not deeply explored previously and that represents the first step towards industrial scalability. Prior to the blending process, oligomers mixtures were prepared with different molar ratios of citric acid (0-40 mol%) and added them. This minimizes the undesirable hydrolysis effect of free carboxylic groups on starch chains. The results demonstrated that the migration of plasticizers in TPS/PVA blends decreased by up to 70 % when the citric acid content increased. This reduction was attributed to the higher molecular weight (the majority in the range 764-2060 Da) and the 3D structure of the oligomers compared to using raw glycerol. Furthermore, the films exhibited a 150 % increase in Young's modulus and tensile strength without a reduction in elongation at break, while maintaining a high gel content, due to a moderate crosslinking.

Molecular structure and characteristics of phytoglycogen, glycogen and amylopectin subjected to mild acid hydrolysis

The structure and properties of phytoglycogen and glycogen subjected to acid hydrolysis was investigated using amylopectin as a reference. The degradation took place in two stages and the degree of hydrolysis was in the following order: amylopectin > phytoglycogen > glycogen. Upon acid hydrolysis, the molar mass distribution of phytoglycogen or glycogen gradually shifted to the smaller and broadening distribution region, whereas the distribution of amyopectin changed from bimodal to monomodal shape. The kinetic rate constant for depolymerization of phytoglycogen, amylopectin, and glycogen were 3.45 × 10-5/s, 6.13 × 10-5/s, and 0.96 × 10-5/s, respectively. The acid-treated sample had the smaller particle radius, lower percentage of α-1,6 linkage as well as higher rapidly digestible starch fractions. The depolymerization models were built to interpret the structural differences of glucose polymer during acid treatment, which would provide guideline to improve the structure understanding and precise application of branched glucan with desired properties.

Enhanced Bioaccessibility of Microencapsulated Puerarin Delivered by Pickering Emulsions Stabilized with OSA-Modified Hydrolyzed Pueraria montana Starch: In Vitro Release, Storage Stability, and Physicochemical Properties

Puerarin is a bioactive flavonoid isolated from Kudzu roots that possesses numerous health benefits. However, its poor bioavailability and existing complex delivery systems with safety issues are challenging tasks for its incorporation into functional foods. Preparing modified-starch-stabilized Pickering emulsions containing microencapsulated puerarin with improved bioaccessibility was the key objective of the present research work. Acid-hydrolyzed high-amylose Pueraria montana starch (PMS) was modified with octenyl succinic anhydride (OSA) and evaluated as an emulsifier to prepare emulsions. The FTIR, SEM, and XRD results showed that PMS was successfully modified. Furthermore, the emulsification index (EI), mean droplet size, and ζ-potential values showed that modified starch with a higher degree of substitution (DS) enhanced the storage stability of emulsions. Similarly, the retention degree and encapsulation efficiency results of puerarin proved the assumption after storage of 16 d. The Pickering emulsions also helped in the controlled release of microencapsulated puerarin in vitro. The study outcomes proved that Pickering emulsions stabilized with OSA-modified PMS have promising applicability in functional foods as efficient food-grade delivery systems, enhancing oral supplementation and accessibility of puerarin.

Relations between starch fine molecular structures with gelatinization property under different moisture content

Although gelatinization property has been intensively investigated with its relation to starch structures, how a combination of starch molecular structures and moisture content affect the gelatinization remains unclear. The gelatinization of six rice starches with a wide range of amylose content was investigated under different moisture content in this study. Results showed that starch gelatinization temperatures increased and biphasic endothermic peaks appeared over the decreased moisture content. For the first time, amylose content was shown to have a parabolic relationship with gelatinization temperatures. Distinct linear relations among starch fine molecular structures with gelatinization parameters were observed under different moisture contents, which suggested that amylose short chains were involved in the first endothermic peak, while interactions among amylose intermediate chains and relatively shorter amylopectin trans-lamellar chains dominantly contributed to the second endothermic peak when gelatinized under limited moisture content. These results help in better understanding of starch structure-gelatinization relation.

Leached starch content and molecular size during sorghum steaming for baijiu production is not determined by starch fine molecular structures

Sorghum steaming properties are important for both flavor and brewing efficiency of baijiu (Chinese alcohol liquor). However, it is currently unclear with respects to structural factors that affect sorghum steaming properties during baijiu production. In this study, starch fine molecular structures were characterized by size-exclusion chromatography and fluorophore-assisted carbohydrate electrophoresis for 8 sorghum varieties used in baijiu production. Starch crystalline structures and ordering of double helices were characterized by the X-ray diffraction and differential scanning calorimetry. Results showed that only small differences were observed for starch molecular size distributions and chain-length distributions in the raw sorghum flour. Of significance, the leached starch content and molecular size during steaming was very different among these sorghum varieties. Furthermore, Spearman correlation analysis showed that there was no significant correlation between starch fine structural parameters with the leached starch content. On the other hand, the correlation analysis showed that leached starch molecular size was negatively correlated with starch crystallinity, while positively correlated with the onset and peak gelatinization temperatures. It is concluded that the sorghum steaming property is controlled by the starch crystalline structures instead of starch fine molecular structures. These results could help the baijiu industry to produce baijiu with more desirable properties.