Field Nuclear Magnetic Resonance Research Articles

Molecular origin of the plasticizing effect difference of glycerol with other polyols on plasticizing polyvinyl alcohol (PVA) as elucidated by solid-state NMR

Glycerol has been proved to be an effective plasticizer for polyvinyl alcohol (PVA), which can significantly increase PVA’s processability and ductility, whose molecular origin remains unclear. In current study, the physical structure and chain dynamics of polyol plasticized PVA were studied in detail, including ethylene glycol, glycerol, erythritol, xylitol, and sorbitol under the same addition level. The glycerol plasticized PVA exhibits the most significant reduction in Young’s modulus, enhanced superior toughness, and the lowest melting temperature (195 °C) as compared with other polyols. The molecular mechanism was elucidated through comprehensive analysis, with a particular focus on solid state NMR (SS NMR) results. The physical structure was first elucidated by the Small Angle X-ray Scattering (SAXS) and Wide Angle X-ray Scattering (WAXS). The crystallinity of the glycerol plasticized PVA was the lowest 29 % by WAXS and the thickness of the amorphous layer was the largest 7.76 nm by SAXS among different plasticized PVA films. This suggests the significant influence of glycerol on structure change of PVA. The molecular dynamics information was further accessed by Low Field Nuclear Magnetic Resonance (LF NMR), where two key features are obtained: i) Different dynamics dimensionality. The 1H spin diffusion NMR was used to check the dimensionality from the aspect of chain dynamics. Compared with other plasticizers, LF NMR result shows that glycerol plasticized PVA has a two-dimensional (2D) structure; ii) Chain dynamics heterogeneity in the interphase. With respect to the chain dynamics heterogeneity in the interphase, the glycerol plasticized PVA shows the most heterogeneous dynamics, with the lowest ratio of the rigid amorphous fraction (RAF) of 0.507 in the interphase. Current study provides a versatile analytical strategy to quantify the plasticizing effect.

Predicting the compressive strength of tight sandstone based on the low field NMR and pseudo-triaxial compression measurements

The compressive strength is very important for petroleum and other engineering studies. However, the effect of pore size and fluid distribution on the rock’s strength is not fully understood. We developed comprehensive research to study the controlling factors of the compressive strength based on low field nuclear magnetic resonance (NMR) measurements and pseudo-triaxial compression test for tight sandstones. The relationship between the compressive strength and the NMR obtained parameters are investigated completely, aiming for a better estimation of the compressive strength using the NMR data. The result shows that the rock’s strength is strongly controlled by the pore size distribution and the fluid existing state. Generally, the compressive strength is negatively correlated with the average transversal relaxation time, the movable water saturation, and the porosity, but positively correlated with the irreducible water saturation. The result reveals that the rock with larger pore radius and higher percentage of movable fluid is easier to reach the failure state. Further, the precision of the empirical model by multiple regression of the geometric mean of the relaxation time and the porosity is greatly improved compared with the model established by the brittle minerals, which is potentially to be use for geophysical prospecting when the NMR logging data is available.

Fractal evolution model of proton spatial distribution in low water/binder cement-based composites (LW/B-CC) during early-age hydration process

This study establishes the fractal evolution model of proton spatial distribution in low water/binder cement-based composites (LW/B-CC) based on fractal theory and low field nuclear magnetic resonance (LF NMR) technology. The results show that the fractal evolution process of gel water, capillary water and surface water distributions in LW/B-CC presents three stages: the first 4–6 h after the beginning of hydration, 4–6 h to 12 h, and 12 h to long-term stage. In the first and second stages, the fractal dimensions of gel and capillary water increase linearly with hydration time, while the fractal dimension of surface water decreases linearly. The boundary is a sudden change of fractal dimensions after about 4–6 h of hydration. The third stage starts after about 12 h of hydration, at which time the fractal dimensions begin to converge to fixed values. Besides, this study reveals the mathematical relationship between fractal dimension (Df) and particle size distribution modulus (q), which is conducive to achieve the full-cycle regulation of LW/B-CC.

Effect of guar gum, gelatin, and pectin on moisture changes in freeze-dried restructured strawberry blocks

This study aimed to investigate the effects of edible gum addition on moisture changes in freeze-dried restructured strawberry blocks (FRSB), which involved five groups: the control, 1.2% guar gum, 1.2% gelatin, 1.2% pectin, and the composite group with 0.5% guar gum, 0.5% gelatin, and 0.45% pectin. The results indicated that the drying rates of the five groups of FRSB presented similar early acceleration and later deceleration trends. Moisture content in FRSB was linearly predicted by peak area of low field nuclear magnetic resonance with R2 higher than 0.90 for all the five groups. The FRSB samples in the gelatin and composition groups formed a denser porous structure and had a lower hygroscopicity after four days of storage. This study provides a theoretical basis for controlling the processing of FRSB.

Investigating the effects of base oil type on microstructure and tribological properties of polyurea grease

The soaring prices and physiological toxicity of lithium-based grease make polyurea grease a promising alternative due to its balanced cost and performance. Employing preformed thickeners to avoid toxic raw materials has become a preferred method for eco-friendly preparation of polyurea grease. However, the underlying mechanism of base oil modulates the microstructure of polyurea greases prepared with preformed thickeners, subsequently influencing their macroscopic performance remains unclear. Herein, three polyurea greases were synthesized by regulating the base oil types ((poly(α-olefin) oil (PAO40), alkyl naphthalene oil (AN30), and polyether oil (OSP320)) with the same preformed thickener. The real-time polarizing microscope observation of the grease structure evolution process revealed that the preformed thickeners gradually expanded in the base oil and formed a fiber structure. An increased polarity disparity between thickener and base oil leads to a reduced swelling rate and increased fiber length. As a result, compared with high polarity OSP320 and low polarity AN30, non-polar PAO40 induces a more interconnected 3D network composed of long fiber in obtained grease (PG). Low field nuclear magnetic resonance characterization and molecular simulations reveal this network exhibits significant binding ability towards base oil, reducing the movement ability of the base oil, endowing PG with the highest structural strength, achieving effective lubrication and low noise performance. These in-depth understandings will help promote the research and development of polyurea greases.

Development of 3D printed k-carrageenan-based gummy candies modified by fenugreek gum: Correlating 3D printing performance with sol-gel transition

Temperature-responsive inks were formulated using k-carrageenan, fenugreek gum (FG), rose extracts, and sugar, of which the first two were used as the gelling agents. The interactions among components in these mixed ink formulations were investigated. Sol-gel transition and rheological properties of these inks were also correlated with extrusion, shape formation, and self (shape)-supporting aspects of 3D printing. Results indicated that incorporating FG increased inks' gelation temperature from 39.7 °C to 44.7–49.6 °C, affecting the selection of printing temperature (e.g., 0 % FG: 40 °C, 0.15 % FG: 45 °C, 0.3 % FG-0.6 % FG: 50 °C). Inks in solution states with lower viscosity (<5 Pa·s) were amenable to ensure their smooth extrusion through the tip of the printing nozzle. A shorter sol-gel transition time (approximately 100 s) during the shape formation stage facilitated the solidification of inks after extrusion. The addition of FG significantly (p<0.05) improved the mechanical properties (elastic modulus, hardness, etc.) of the printed models, which facilitated their self-supporting behavior. Low field nuclear magnetic resonance indicated that the inclusion of FG progressively restricted water mobility, consequently reducing the water syneresis rate of the mixed inks by 0.86 %–3.6 %. FG enhanced hydrogen bonding interactions among the components of these mixed inks, and helped to form a denser network.

Characterization of moisture migration and diffusion in two types of tobacco biomass during the dehydration process by the TG-NMR analysis.

The tobacco waste generated from the tobacco agriculture and industry, including the discarded stem and leaf, often needs dehydration pretreatment before thermal conversion utilization. In order to study the water activity and migration of tobacco waste during the pretreatment process, TG-NMR (Thermogravimetric Nuclear Magnetic Resonance) was used to obtain the drying curves and LF-NMR (Low Field Nuclear Magnetic Resonance) T2 inversion spectrum at each stage of tobacco drying. Meanwhile, the variation pattern of pore distribution during the dehydration process of two types of tobacco waste has been obtained. Combined with the pore distribution changes, a possible spatial migration mode of water was proposed. The change of adsorption energy of water during tobacco drying was calculated, and verified the above hypothesis. This study results provide reference for the optimization of dehydration pretreatment process for different tobacco waste in order to reduce energy consumption during recycling of tobacco biomass.

Adsorption–desorption characteristics of coal-bearing shale gas under three-dimensional stress state studied by low field nuclear magnetic resonance spectrum experiments

The micro-scale gas adsorption–desorption characteristics determine the macro-scale gas transport and production behavior. To reveal the three-dimensional stress state-induced gas adsorption–desorption characteristics in coal-bearing shale reservoirs from a micro-scale perspective, the coal-bearing shale samples from the Dongbaowei Coal Mine in the Shuangyashan Basin were chosen as the research subject. Isothermal adsorption–desorption experiments under three-dimensional stress state were conducted using the low field nuclear magnetic resonance (L-NMR) T2 spectrum method to simulate the in-situ coal-bearing shale gas adsorption–desorption process. The average effective stress was used as the equivalent stress indicator for coal-bearing shale, and the integral of nuclear magnetic resonance T2 spectrum amplitude was employed as the gas characterization indicator for coal-bearing shale. A quantitative analysis was performed to examine the relationship between gas adsorption in coal-bearing shale and the average effective stress. And a quantitative analysis was performed to examine the relationship between the macroscopic and microscopic gas quantities of coal-bearing shale. Experimental findings: (1) The adsorption–desorption process of coal-bearing shale gas follows the L-F function model and the D-A-d function model respectively with respect to the amount of gas and the average effective stress. (2) There is a logarithmic relationship between the macroscopic and microscopic gas quantities of coal-bearing shale during the adsorption–desorption process. This quantitatively characterizes the differences in the curves, which may be related to the elastic–plastic deformation, damage and fracture of the micropores in coal-bearing shale, as well as the hysteresis of gas desorption and the stress field of the gas occurrence state.

Correlation of low field nuclear magnetic resonance relaxation with composition and glass transition of hard candies

Hard candies produced from sucrose and doctoring agents such as glucose syrup (GS) and high fructose corn syrup (FS) have been investigated in terms of their final composition, glass transition temperature (Tg), degree of crystallinity, total soluble solids (TSS) content and water activity (aw). Time domain (TD) 1H NMR longitudinal relaxation time (T1) and second moment (M2) measurements have been used to understand the glassy state and crystallization characteristics for different hard candy formulations. The investigated candies include sucrose as the main sugar component. Different levels of doctoring agents have been mixed with sucrose to obtain products with different characteristics. It has been shown that addition of any doctoring agent to sucrose formulations decreases the Tg of the system significantly (p≤ 0.05). Furthermore, GS or FS addition also induce significant changes in TSS and aw. T1 and M2 results are almost parallel to each other, both reaching the highest values for the highest sucrose concentration (p≤ 0.05). The results demonstrate that the glass transition and crystallization characteristics of hard candy formulations can be monitored and analyzed by TD NMR relaxometry, alternative to other frequently used conventional methods including differential scanning calorimetry (DSC) and X-ray diffraction.

Petrophysical insights into pore structure in complex carbonate reservoirs using NMR data

The study delves into pore structure attributes within the complex Eocene carbonate of an Indian offshore field, encompassing pore throat, radius and their characteristics. Nuclear Magnetic Resonance (NMR) experimental data reveals crucial insights into pore structures and fluid states. This study compares the NMR T2 distribution curve with capillary pressure data from the Mercury Injection Capillary Pressure (MICP) technique, deriving linear and nonlinear conversion coefficients to transform NMR T2 spectra into equivalent pore radius distribution. Pore radius-dependent porosity partitioning, linked to permeability and the distribution of irreducible water, is conducted utilizing NMR-derived data. Following the T2 cut-off analysis, a two-segment fractal analysis of NMR T2 distribution is also carried out. This analysis unveils associations between fractal dimensions and various petrophysical parameters, including permeability, porosity, T2LM, irreducible water saturation and R50. The NMR-derived pore radius distribution is mostly unimodal, occasionally slightly bimodal. Six different pore size classes (less than 0.05 μm to more than 5 μm) are analysed in relation to permeability, porosity and irreducible water. Small pores (<1 μm) contribute more to irreducible water with low porosity and permeability. The fractal dimension of large pores correlates strongly with porosity, permeability, T2LM, irreducible water and R50 suggesting significant impact on reservoir seepage capacity. In addition to porosity partitioning, the current study demonstrates effectiveness in modelling modified permeability and correlating it with in situ permeability when applied to field NMR log data from the study area. While numerous studies focus on sandstone, our study marks the pioneering attempt at a comprehensive analysis on complex carbonate reservoirs.

Alkaline in-situ leaching of uranium in low-permeability sandstone: An experimental study using online low field nuclear magnetic resonance (LF-NMR) spectroscopy on multiphase response

Uranium leaching was influenced by multiphase flow and geological structure during in-situ recovery of uranium (ISRU). In this study, the characteristics of multiphase flow and pore structure responding to the alkaline ISRU was investigated, using a real-time triaxial coupling nuclear magnetic resonance experiment system. The component of leaching solute, flow regime and pore structure evolution was monitored online through the T2 spectrum and magnetic resonance imaging (MRI), and corresponding coupling correlation of uranium recovery and pore conductivity was analyzed. The result demonstrates that the uranium sandstone was composed of micropore (1–10 ms), mesopore (10–100 ms), and macropore (>100 ms) corresponding to different relaxation times (ms). The uranium migration was mainly dominated by mesopore, and mineral dissolution and precipitation were influenced by micropore and macropore. Uranium recovery based on colloidal tetravalent and hexavalent uranium particles was exponentially correlated with the volume of leaching solution passed through the solute (solid phase/pores) and slightly contributed by the seal pore and matrix-bearing uranium. The physical migration, mineral dissolution, carbonate precipitation, and alternation by reactive transport occurred and was influenced by the hydrodynamic pressure. The dissolution of U, Ca, and Si experienced a dynamic period (0–5 PV), buffer period (5–37 PV), transition period (37–200 PV), and stable period (200–319 PV); peak concentration of U occurred at 5 PV, and 73.4% of uranium was recovered in the scope of 0–37 PV. Here, 1 PV represents the sample pore volume of 3.95 cm3. The porosity and permeability were enlarged under the influence of the chemical dissolution and physical migration, but decreased with the precipitation of CaCO3 and SiO2 colloids. Permeability and porosity exhibited a positive correlation with the volume of solution passed through in the range of 0–100 PV, but a negative correlation was observed in the range of 100–319 PV. The findings provide significant insight into ISRU engineering practice.

Effect of structurally different pectin combined with polyphenol on water distribution, protein oxidation and heterocyclic amines formation in meat-based snacks

This research studied the effect of structurally different pectin combined with polyphenol (PP) on the physicochemical properties, inhibition of protein oxidation and heterocyclic amines (HAs) formation in fish meat snacks. The findings demonstrated that pectin with a high degree of esterification (DE) and average chain length (ACL) significantly reduced cooking loss, improved zeta potential values, and reduced particle size when combined with polyphenols, indicating an inhibition of protein aggregation and crosslinking. The addition of PP decreased the carbonyl formation as compared to individual polyphenol and control. Low Field Nuclear Magnetic Resonance (LF-NMR) analysis publicized that PP combination increased the water binding capacity, which resulted in less free water (T22 and T23) in those samples. Furthermore, LC/MS analysis revealed that PP combination, retained the water inside the macromolecules and prevented the relocation of water to the surface, which resulted in the less HAs formation as compared to control. The scanning electron microscopy (SEM) revealed that combination of PP samples formed a compact structure evidenced by less wide holes while control sample revealed loose structure. The findings suggest that 201 and 601 pectin combined with catechin have potential to improve the physicochemical properties and inhibition of hazardous compound formation.

Investigation of Nearest Neighbor Interactions in Nickel Substituted Cobalt Using 59Co IFNMR

Co100-x Nix (x = 10, 20, 30, 40) alloys were synthesized via the chemical method by reducing nitrates of cobalt and nickel using hydrazine as a reducing agent. The proportion of solvents, ethanol, and water was maintained constant for all the samples in the series. The structure and morphology of the samples were examined based on X-Ray diffraction (XRD) data and Scanning Electron Microscope (SEM) images. From XRD it was evident that the system had a mixture of hexagonal close packed (hcp) and face centered cubic (fcc) phases. The amount of hcp phase in the composition gradually reduced as the concentration of nickel increased. The effect of substitution of nickel on cobalt was studied using a home built 59Co internal field nuclear magnetic resonance (IFNMR) spectrometer. Further, the saturation magnetization and hence magnetic field anisotropy values, obtained from M vs H loops, are found to vary with nickel concentration. The NMR results show a broadening of the NMR signals in comparison with the pure phase of cobalt. The NMR spectra and the number of peaks were assigned to possible cobalt-nickel neighbors, and the percentage of such combinations is interpreted in terms of the frequency and intensity of the peaks. This percentage of different nickel-cobalt combinations was compared with the random distribution obtained using the binomial distribution function. This comparison shows a clear trend compared to that analysed by the IFNMR experiment.

Effect of pectin addition on the drying characteristics of freeze-dried restructured strawberry blocks

Pectin is a commonly used food additive, however, the freeze-drying characteristics of restructured strawberries with pectin addition are currently unclear. This study investigated the effects of 0, 3, 6, and 9 g/kg pectin addition on moisture content, drying date, moisture ratio, water state distribution during the freeze-drying process, as well as water uptake and volatile compounds of freeze-dried restructured strawberry blocks (FRSB). The drying rates at the four levels of pectin addition presented similar early acceleration and later deceleration trends. Moisture content in FRSB was linearly predicted by peak area of low field nuclear magnetic resonance with R2 higher than 0.90 for all the four groups. High pectin addition resulted in higher sulfides response values. Compared with the control group, the water uptake of FRSB samples in 0, 3, 6, and 9 g/kg group decreased by 12, 22, and 31%, respectively, which can be reasoned that pectin addition shielded hydrophilic functional groups from external water molecules. These results provide guidance for improving the drying characteristics, volatile compounds, and water uptake of FRSB by adding pectin.

Effect of targeted acetylation on wood–water interactions at high moisture states

Acetylation is a wood modification used to increase the durability. Although it is known that the wood moisture content is lowered, the exact mechanisms behind the increased durability are not known. However, since fungi need water in different locations for different purposes the location and state of water is most probably of importance in addition to the total moisture content. In a previous study, we used targeted acetylation to alter the wood–water interactions in different parts of the wood structure in water saturated and hygroscopic moisture states. The main range for fungal degradation is, however, between these moisture ranges. This study investigated the effect of targeted acetylation on location, state and amount of water at non-saturated, high moisture states using the pressure plate technique. Specimens were modified using acetic anhydride by two approaches: (1) uniform modification (2) interface modification acting on the cell wall-lumen interface. They were then conditioned to eight moisture states between 99.64 and 99.98% relative humidity in both absorption and desorption and the location and state of water was studied using Low Field Nuclear Magnetic Resonance, X-ray computed tomography and Differential Scanning Calorimetry. Capillary water was present at all the included moisture states for all specimen types, but the amounts of capillary water in absorption were small. Increasing degree of interface modification increased the amount of capillary water compared to untreated wood. In addition, the uniformly modified wood often had higher amounts of capillary water than the untreated wood. The amount of cell wall water was decreased by uniform modification, but slightly or not reduced by the interface modification. The combination of targeted modification and conditioning to high well-defined moisture states thus gave very different amounts of capillary water and cell wall water depending on the conditioning history (absorption or desorption) and choice of modification. This opens new possibilities for designing materials and moisture states for fungal degradation experiments of wood.

Reducing water activity and softening texture of Areca catechu L. by phosphates and Maillard peptides and their improvement on flavor

Many studies have focused on reducing Aw to prevent the growth of spoilage bacteria. The effects of complex phosphates (CP) and Maillard peptide complexes (MPCs) on water activity (Aw), water status, sensory attributes, flavor, and hardness of the areca nuts were studied to extend their shelf life and improve their eating quality. The results showed that the addition of 1.6% CP and 0.6% MPCs significantly reduced the Aw of areca nuts (Aw = 0.8116). Low field nuclear magnetic resonance indicated that it was due to that the CP and MPCs promoted the conversion of free water to bound water through hydrogen bonding or electrostatic interaction. In addition, CP combined with MPCs reduced the extrusion hardness and puncture hardness of areca nuts, accompanied with a significant increase in softness and pulpiness as assessed through sensory analysis, which might be due to the improved water binding capacity of areca nuts. Moreover, MPCs increased the content of N, S heterocyclic compounds of the areca nuts and contributed to an increased “kokumi” attribute compared with CP.

Neurometabolism and brain morphometry in an adolescent female with an extra-hepatic congenital portosystemic shunt.

Chronic hepatic encephalopathy (CHE) has been reported both in patients with congenital porto-systemic shunts (CPSS) and chronic liver disease. CHE is difficult to recognize in children as there is no clear definition and its manifestations are highly variable. CHE is associated with variations in brain volumes and metabolites that have already been demonstrated using 1.5-3T MRI systems. However, the in-depth study of brain metabolism requires the high spectral resolution of high magnetic fields. We analyzed the neurometabolic profile, brain volumes and T1 relaxation times of a child with a CPSS using high field proton magnetic resonance spectroscopy (1H MRS, 7T) combined with MRI and compared it to an age-matched control group. We also evaluated the impact of shunt closure on neurocognitive symptoms using adapted neuropsychological tests. 7T MRS revealed a significant increase in glutamine compared to controls, a decrease in brain osmolytes, and a slight elevation in NAA concentrations. 7T MRI scans showed morphological abnormalities but no changes in the signal intensity of the globus pallidus. Neurocognitive testing revealed attention deficit disorder, language difficulties, and mild intellectual disability. Most of these areas improved after shunt closure. In this paediatric case of type B HE with normal fasting ammonia, neurometabolic profile was compatible with what has been previously shown in chronic liver disease, while also demonstrating an isolated glutamine peak. In addition, neurocognitive function partially improved after shunt closure, arguing strongly for shunt closure in both presymptomatic and symptomatic patients.

Effect of ultrasound combined with psyllium husk powder on the structure and gel properties of goose myofibrillar protein

In this study, we aimed to investigate the effect of ultrasound (US) combined with different amounts of psyllium husk powder (PHP) (0 %, 0.5 %, 1 %, 2 %, 3 %) on the gelation and structure of goose myofibrillar protein (GMP). The analysis of circular dichroism, surface hydrophobicity and fluorescence spectroscopy showed that the combination of US and 2 % PHP could promote the development of myofibrillar protein (MP) secondary and tertiary structure, which could facilitate the exposure of active site and enhance the interaction between GMP and PHP. Meanwhile, the thermal stability was enhanced with US and PHP treatment. In addition, the analysis of rheology, Low field nuclear magnetic resonance (LF-NMR), Fourier transform infrared (FT-IR) spectroscopy and microstructure showed that US combined with 2 % PHP addition could make the gel network structure denser. Thus, these results suggested that the combination of US and 2 % PHP could promote the unfolding of GMP structure and improve its gel properties. This study provides new insights for the interaction of GMP and PHP under US treatment, improving the application of goose meat in practical production.

Alleviative effects of carboxymethyl chitosan on the quality deterioration of frozen rice dough during freeze thaw cycles

The objective of this study was to examine the impact of carboxymethyl chitosan (CMCh) on rice dough quality during freeze–thaw cycles (FTCs). We conducted a comprehensive analysis of frozen rice dough using various techniques, including scanning electron microscopy (SEM), low–field nuclear magnetic resonance (LF–NMR), confocal laser scanning microscopy (CLSM), Fourier transform infrared spectroscopy (FT–IR), size–exclusion high–performance liquid chromatography (SE–HPLC), small–angle X–ray scattering (SAXS), X–ray diffraction (X–RD), differential scanning calorimetry (DSC), and rapid visco–analysis (RVA). Our results revealed that adding carboxymethyl chitosan (CMCh) to frozen rice dough reduced damage to starch granules and gluten proteins during FTCs compared to dough without CMCh. This resulted in the deceleration of the modification of the ordered protein structure. Furthermore, the inclusion of CMCh resulted in increased cross–linking with the large protein polymer, impairing the capacity of bound water to transition into free water within the frozen rice dough. Consequently, this led to an elevation in the storage modulus (G′), effectively retarding the textural transformation of the frozen rice dough. Introducing CMCh to frozen rice dough subsequently decelerated the alterations in the short-range order and crystal structures of starch, consequently modifying the pasting and thermal properties of the frozen rice dough. Based on the results obtained from our experiments, CMCh has a decelerating effect on the impact of frozen rice dough on FTCs.

The anti-digestibility mechanism of soy protein isolate hydrolysate on natural starches with different crystal types

The effects of soy protein isolate hydrolysate (SPIH) on the physicochemical properties and digestive characteristics of three starch types (wheat, potato, and pea) were investigated. Fourier-transform infrared spectroscopy and molecular dynamics simulations showed that hydrogen bonds were the driving force of the interaction between SPIH and starch. Furthermore, the SPIH was predicted to preferentially bind to the terminal region of starch using molecular dynamics simulations. Compared to pure starch, adding 20 % SPIH to wheat starch, potato starch, and pea starch, the content of resistant starch increased by 39.71 %, 125.66 % and 37.83 %, respectively. Both the radial distribution function (RDF) and low field-nuclear magnetic resonance (LF-NMR) showed that SPIH reduced the flow of water molecules in starch, indicating that SPIH competed with starch for water molecules. Multiple characterization experiments and molecular dynamics simulations confirmed that the anti-digestibility mechanism of SPIH on natural starches with different crystal types could be attributed to the interaction between starch and SPIH, which decreased the catalytic efficiency of amylase. This study clarified the anti-digestibility mechanism of SPIH on natural starches, which provides new insights into the production of low-glycemic index foods for the diabetic population.