Exploring the influence mechanism of water grinding on the gel properties of corn starch based on changes in its structure and properties.

BACKGROUND: At present, most studies have focused on the preparation of modified starches by dry grinding. As an excellent starch plasticizer, water might enhance the action of grinding on the structure of starch granules, and water grinding might improve the gel properties of starch. Therefore, this article explored the influence mechanism of water grinding on the gel properties of corn starch based on the changes in its structure and properties. RESULTS: The results showed that water grinding could make water enter the starch granules and hydrate the starch molecules, and the starch gelatinized after water grinding for 20 min. Thus, water enhanced the action of grinding on the structure of the starch granules. Under the plasticization and grinding action of water grinding, the mechanochemical effect of the starch granules occurred. When the starch was in the aggregation stage (7.5-10 min), the crystallinity of the starch increased, and the starch molecules rearranged into a more stable structure, which increased apparent viscosity (η), elastic modulus (G') and viscous modulus (G″) of the starch gels. CONCLUSION: Therefore, appropriate water grinding (10 min) contributed to increasing the viscoelasticity of starch gels. This study provided a theoretical foundation for research on improving the properties of starch by mechanical modification in future. © 2023 Society of Chemical Industry.

Identification and Molecular Binding Mechanism of Novel α-Glucosidase Inhibitory Peptides from Hot-Pressed Peanut Meal Protein Hydrolysates.

Hot-pressed peanut meal protein hydrolysates are rich in Arg residue, but there is a lack of research on their α-glucosidase inhibitory activity. In this study, different proteases were used to produce hot-pressed peanut meal protein hydrolysates (PMHs) to evaluate the α-glucosidase inhibitory activity. All PMHs showed good α-glucosidase inhibitory activity with the best inhibition effect coming from the dual enzyme system of Alcalase and Neutrase with an IC50 of 5.63 ± 0.19 mg/mL. The fractions with the highest inhibition effect were separated and purified using ultrafiltration and cation exchange chromatography. Four novel α-glucosidase inhibitory peptides (FYNPAAGR, PGVLPVAS, FFVPPSQQ, and FSYNPQAG) were identified by nano-HPLC-MS/MS and molecular docking. Molecular docking showed that peptides could occupy the active pocket of α-glucosidase through hydrogen bonding, hydrophobic interaction, salt bridges, and π-stacking, thus preventing the formation of complexes between α-glucosidase and the substrate. In addition, the α-glucosidase inhibitory activity of PMHs was stable against hot, pH treatment and in vitro gastrointestinal digestion. The study demonstrated that PMHs might be used as a natural anti-diabetic material with the potential to inhibit α-glucosidase.

The effect of non-thermal physical modification on the structure, properties and chemical activity of starch: A review.

Non-thermal physical treatments has obvious advantages in regulating the structure and properties of starch compared with chemical treatment. Hance, this article summarized and compared the effects of three kinds of non-thermal physical treatments including grinding and ball milling, high hydrostatic pressure and ultrasonic on the structure, properties and chemical activity of starches from different plants. The potential applications of non-thermal physical modified starch were introduced. And strategies to solve the problems in the current research were put forward. It is found that although starch has a dense structure, the starch granules could be deformed under three kinds of non-thermal physical treatments, which could damage the granule morphology, microstructure, and crystal structure of starch, reduce particle size, increase solubility and swelling power, and promote starch gelatinization. Three kinds of non-thermal physical treated starch could be used as flocculant thickener, starch based edible films and fat substitutes. Non-thermal physical treatments caused the structure of starch to undergo three stages, which were similar to mechanochemical effects. When starch was in the stress stage and the transition stage from aggregation to agglomeration, its active sites significantly increase and move inward, ultimately leading to a significant increase in the chemical activity of starch.

Influences of high hydrostatic pressure on structures and properties of mung bean starch and quality of cationic starch.

It is difficult to improve the quality of chemical-modified starch by traditional technology. Hence, in this study, mung bean starch with poor chemical activity was used as raw material, the native starch was treated and the cationic starch was prepared under high hydrostatic pressure (HHP) at 500 MPa and 40 °C. By studying the changes in the structure and properties of native starch after HHP treatment, the influence mechanism of HHP on improving the quality of cationic starch was analyzed. Results showed high pressure could make water and etherifying agent enter the starch granules through pores, and HHP made the structure of starch undergone three stages similar to mechanochemical effect. After HHP treated for 5 and 20 min, the degree of substitution, reaction efficiency and other qualities of cationic starch increased remarkably. Hence, proper HHP treatment could help to improve the chemical activity of starch and quality of cationic starch.

Effect of improved extrusion cooking technology (IECT) on structure, physical properties and in vitro digestibility of starch.

Extrusion can modify the structure and physical properties of starch, while the extent of improved extrusion cooking technology (IECT) affects the starch with high moisture content and different crystal types remaining unclear. Therefore, the influence of IECT at different screw speeds on the structure, physical properties and in vitro digestibility of corn (A-type), potato (B-type) and pea (C-type) starches with high moisture content (42 %) was explored. Results indicated that IECT treatment caused similar variations on structure, physical properties, and in vitro digestibility of the 3 types of starches. The contents of slowly digestible starch (SDS) and resistant starch (RS) decreased by IECT treatment, accompanied by a reduction of crystallinity, enthalpy of gelatinization, gelatinization temperature and viscosity, while the content of rapidly digestible starch (RDS) and the ratio of bound water increased. And the changes in in vitro digestibility of starch were closely related to the damage to starch structure caused by IECT. Furthermore, most of starch granules were in the agglomeration stage by appropriate IECT treatment, which induced the exposure of a great quantity of enzyme binding sites to enhance the in vitro digestibility.

Exploring the mechanism of high hydrostatic pressure on the chemical activity of starch based on its structure and properties changes.

High hydrostatic pressure (HHP) could induce changes in the structure and properties of starch. Native corn starch was treated and octenyl succinic anhydride (OSA)-modified corn starch was prepared under different pressures (200, 350, 500 and 600 MPa) at 40℃ for 20 min. The mechanism of HHP on the chemical activity of starch was elucidated by analyzing the relationship between the changes of native starch structure and properties and the quality of OSA-modified starch. Results showed that HHP not only helped water and OSA to penetrate the starch granules but also made the structure of starch granules undergone three changes similar to mechanochemical effects. The starch granules treated by 200 MPa were in the stress stage, and the starch granules treated by 500 MPa were in the transition stage from aggregation to agglomeration. Proper pressure treatment could significantly improve chemical activity of starch and quality of OSA-modified starch.

Influence of enzymatic modification on the basis of improved extrusion cooking technology (IECT) on the structure and properties of corn starch.

Enzymatic modification can directly affect the structure and properties of starch, but generally causes high energy consumption in drying process. Improved extrusion cooking technology (IECT) itself is a starch modification technology. In this work, a co-extrusion method of starch with 42 % moisture and enzyme was adopted to reveal the effects of different enzyme dosages on the structure and properties of corn starch. After enzyme treatment on the basis of IECT, starch granules were broken into fragments without the occurrence of clear Maltese cross. R1047/1022 and R995/1022 values, peak intensity of Raman spectra and gelatinization temperature decreased, and the full width at half maximum at 480 cm-1 of Raman spectra raised. Moreover, the bound water proportion decreased from 87.44 % to 85.84 % âˆ¼ 78.67 %, and the maximum light transmittance and dextrose equivalent values increased to 34.13 % and 26.14, respectively. The solubility of starch granules was all above 60 %. Findings supported that the mechanochemical effect of IECT on starch was conducive to the enzymatic modification.

Ultrasonication effects on physicochemical properties of starch-lipid complex.

The starch-lipid complex between the pea starch (PSt) and glycerol monolaurate (GM) was prepared using ultrasound with different amplitudes, durations and application sequences. Fourier-transform infrared and nuclear magnetic resonance spectra showed the formation of amylose-lipid complex between PSt and GM in the ultrasonic field. Stronger diffraction intensities were observed in samples treated by ultrasonication, whereas the thermogravimetric analysis indicated that the thermal stability of starch was improved by the formation of the V-type inclusion complexes. An ultrasound pre-treatment prior to the addition of a guest molecule (UC) was more favorable to induce the formation of an amylose-lipid complexes than ultrasound treatment after PSt was incorporated with GM (CU). The UC-treated samples showed stronger diffraction intensities, higher melting enthalpy values and enzyme-resistant than that of CU-treated PSt-GM complexes.

Effects of soybean oil on rheological characteristics of dough under high hydrostatic pressure.

In order to improve the stability of dough with soybean oil, this article explored the effect of soybean oil addition on the rheological characteristics of dough under high hydrostatic pressure. The results showed that, compared with the dough without soybean oil, the ß-sheet, disulfide bonds content, and gauche-gauche-gauche in the dough increased by 4.23%, 0.85 µmol/g, and 4.16%, respectively when the dough was added with 6% soybean oil, which improved the degree of cross-linking polymerization of gluten protein and the stability of gluten network. Meanwhile, the dough had the highest elastic modulus and the lowest maximum creep compliance (6.85 × 10-4 Pa-1 ), indicating that 6% soybean oil significantly increased the elasticity and hardness of the dough. The results of short-range ordered structure and paste properties showed that with the addition of soybean oil, the ordered structure and paste viscosity decreased with the increase of soybean oil.

Effects of high starch content on the physicochemical properties of starch/PBAT nanocomposite films prepared by extrusion blowing.

Starch/PBAT nanocomposite films with high starch content were prepared using one-step compounding and subsequent extrusion blowing. The effects of the starch/PBAT weight proportions on the physicochemical properties of the films were investigated. The X-ray diffraction results demonstrated that the extent of intercalation of the starch/PBAT nanocomposite films increased with the increasing PBAT content. The dynamic mechanical analysis revealed that the compatibility of starch and PBAT improved with increasing PBAT content from 10 wt% to 50 wt%. The strength and flexibility of the films were greatly improved by blending with PBAT. The maximum tensile strength and elongation at break of the starch/PBAT nanocomposite films were 7.4 MPa and 614 %, respectively. The water-vapor barrier properties and hydrophobicity of the films were significantly improved with the increase in the PBAT content. The blown starch/PBAT nanocomposite films incurred low cost and demonstrated excellent mechanical and hydrophobic properties, which are suitable for the food-packaging field.

Ultrasound-assisted preparation of octenyl succinic anhydride modified starch and its influence mechanism on the quality.

The purpose of this study was to reveal the influence mechanism of preparing high quality modified starch by ultrasonic-assisted treatment. In this paper, ultrasonic modified starch and octenyl succinic anhydride (OSA) modified starch were prepared under ultrasonic conditions. The effect of ultrasound on the structure and properties of native starch were studied to see whether ultrasound could produce mechanochemical effect on starch granules. Then the mechanism of ultrasonic effect on the quality of OSA-modified starch was revealed by mechanochemical effect. The results showed that the morphology and crystalline regions of starch granules were destroyed after ultrasonic treatment, and the structure and properties of starch granules changed in different stages. These changes showed that ultrasonic treatment produced significant mechanochemical effect on starch granules. Thus the quality of OSA-modified starch prepared by ultrasonic-assisted treatment was improved significantly, and its influence mechanism was analyzed using the theory of mechanochemistry.

Effects of preparation conditions on the properties of agar/maltodextrin-beeswax pseudo-bilayer films.

The present study aims to develop an agar/maltodextrin-beeswax (A/M-BW) pseudo-bilayer film with high surface hydrophobicity by adjusting drying temperatures and homogenization conditions. Attenuated total reflectance-Fourier transform infrared determined the chemical components of the upper and lower surfaces of the films. X-ray diffraction characterized the crystalline behavior of film matrix. Scanning electron microscopy explored the distribution patterns of BW and phase separation phenomenon. Atomic force microscopy revealed the surface roughness of film. The pseudo-bilayer film prepared at 8000 rpm for 1 min (A/M-BW-8000-1) had the highest tensile strength (20.57 MPa), Young's modulus (640.60 MPa), contact angle (92.9°), and the lowest water vapor permeability (2.18 × 10-12 g m-1 s-1 Pa-1). The A/M-BW pseudo-bilayer film with excellent surface hydrophobicity and mechanical properties was obtained at higher drying temperature and lower homogenization intensity. The A/M-BW pseudo-bilayer film has promising potential for application in food packaging which requires higher water vapor resistance.

Mechanochemical effect of ultrasound on sweet potato starch and its influence mechanism on the quality of octenyl succinic anhydride modified starch.

The purpose of this study is to reveal the mechanism of preparing high quality modified starch by ultrasonic technology. In this paper, ultrasonic modified starch and octenyl succinic anhydride modified starch with low degree of substitution were prepared under ultrasonic conditions, using sweet potato starch as raw material. The effects of ultrasound on the structure and properties of native sweet potato starch were studied to see whether ultrasound could produce mechanochemical effect on starch. Then the mechanism of ultrasonic effect on quality of octenyl succinic anhydride modified starch was studied by mechanochemical effect. The results showed that after ultrasonic treatment for 1 min, the crystallinity decreased from 37.6 to 33.8% and reaction efficiency increased from 49.43 to 54.39%, while after ultrasonic treatments for 8 and 32-60 min had different changes. These changes showed that ultrasonic treatment produced significant mechanochemical effect on native sweet potato starch. Ultrasound significantly improved the quality of octenyl succinic anhydride modified starch, and its influence mechanism was revealed using the theory of mechanochemistry. This study provides a feasible method for the research of high quality modified starch and lays a theoretical foundation for expanding the application of ultrasound in various fields.

Effect of Alkali Treatment on Structure and Properties of High Amylose Corn Starch Film.

Alkali treatment is used for melt extrusion film formation with corn starch, but optimal conditions for this procedure are still unknown. In this study, the changes in properties and structure of high amylose corn starch (70%) films with different concentrations of sodium hydroxide (NaOH), prepared by melting extrusion, were investigated. With increasing sodium hydroxide concentrations, the tensile strength of the high-amylose starch film decreased gradually, while the elongation at break increased. The tensile strength of the high amylose starch (HAS) film with 2% NaOH-treatment was 10.03 MPa and its elongation at break was 40%. A 2% NaOH-treatment promoted the orderly rearrangement of starch molecules and formed an Eh-type crystal structure, which enlarged the spacing of the single helix structure, increased the molecular mobility of the starch, and slowed down the process of recrystallization; a 10% NaOH-treatment oxidized the hydroxyl groups of the high amylose corn starch during extrusion, formed a poly-carbonyl structure, and initiated the degradation and cross-linking of starch molecule chains.

Effects of Citric Acid on Structures and Properties of Thermoplastic Hydroxypropyl Amylomaize Starch Films.

Hydroxypropyl amylomaize starch (HPAS) films were prepared by hot press. The effects of initial pH of HPAS on the mechanical properties, molecular interaction, structure, and cross-linking degree of the resultant films were investigated. A weak acidic condition was suitable for cross-linking of citric acid and HPAS by reactive extrusion. The film of HPAS with an initial pH of 5.66 had the maximum tensile strength of 7.20 MPa and elongation-at-break of 94.53%, and the weight average molecular weight of HPAS increased to 4.17 × 105 g/mol. An appropriate initial pH facilitated the formation of diester bonds between HPAS and citric acid during extrusion, but too low initial pH levels resulted in hydrolysis of starch molecules and reduced the mechanical properties.

Influences of grinding on structures and properties of mung bean starch and quality of acetylated starch.

The aim of this study was to reveal the mechanism of preparing high quality modified starch by grinding. Modified starch and acetylated starch with low degree of substitution were prepared under grinding. The influences of grinding on structures and properties of mung bean starch and quality of acetylated starch were investigated. The influence mechanisms were analyzed using the theory of mechanochemistry and the models of starch granules and molecules. The results indicated that there were pores and umbilical points with loose structure in mung bean starch granules. During the grinding treatment, starch granules were constantly deformed like elastic balls, and starch molecules could keep moving and rearrange, resulting in changes in structures and properties of starch. It could be seen that grinding had a marked mechanochemical effect on starch granules. As a result, the reaction efficiency of the starch rose to 81.61% at 12 h of grinding, and other qualities (solubility and swelling power) were also improved.

Effects of Organic Modification of Montmorillonite on the Properties of Hydroxypropyl Di-Starch Phosphate Films Prepared by Extrusion Blowing.

The knowledge gained from starch-nanocomposite-film research has not been fully applied commercially because of the lack of appropriate industrial processing techniques for nanofillers and starch films. Three organically modified montmorillonites (OMMTs) were prepared using a semidry kneading method. The effects of the OMMTs on the structures and properties of starch nanocomposite films, prepared by extrusion blowing, were investigated. The X-ray diffraction (XRD) analysis results revealed that the OMMTs with various quaternary ammonium salts possessed differing layer structures and d-space values. The results of the XRD and Fourier-transform infrared spectroscopy (FT-IR) showed that the starch⁻OMMT interaction resulted in a structural change, namely the starch⁻OMMT films possessed a balanced exfoliated and intercalated nanostructure, while the starch⁻MMT film possessed an exfoliated nanostructure with non-intercalated montmorillonite (MMT). The results of the solid-state nuclear magnetic resonance (NMR) analysis suggested that the starch-OMMT nanocomposite possessed comparatively large quantities of single-helix structures and micro-ordered amorphous regions. The starch⁻OMMT films exhibited good tensile strength (TS) (maximum of 6.09 MPa) and water barrier properties (minimum of 3.48 × 10−10 g·m·m−2·s−1·Pa−1). This study indicates that the addition of OMMTs is a promising strategy to improve the properties of starch films.

Preparation of high quality starch acetate under grinding and its influence mechanism.

The goal of this study is to reveal mechanism of preparing high quality modified starch by advanced equipment in well-known modified starch enterprises. Corn starch was used as raw material to prepare starch acetate with low degree of substitution under grinding, and the effect of grinding on the quality of starch acetate was studied. The effects of grinding on structures and properties of native corn starch were investigated. The mechanochemical theory was used to analyze the influence mechanism of grinding on quality of starch acetate. The results showed that the reaction efficiency (RE) of starch acetate increased from 70.98% to 85.80% at 4 h of grinding, and other qualities (solubility and swelling power) also increased. However, RE and other qualities of starch acetate were very different at 12 and 20-60 h of grinding. The changes of structures and properties of native starch after grinding showed that grinding has a significant mechanochemical effect on corn starch granules. The models of starch molecules and granules were made to reveal the "secret" of these advanced equipment in well-known modified starch enterprises.