Relationship between internal structure and in vitro digestibility of A- and B-type wheat starch revealed by chemical surface gelatinization.

In this study, the properties of remaining starch granules obtained with different degrees of exfoliation were explored by removing the outer layers of A- and B-type wheat starch (AWS and BWS) granules with chemical surface gelatinization. SEM images revealed significant morphological variations with increasing exfoliation. CLSM and amylose content analysis indicated a predominance of lipid complexes in the outer granule layers, particularly in BWS. The structural characteristics of AWS and BWS were analyzed using PLM, XRD, FT-IR and DSC, verifying the conclusion of the alternation of starch crystalline and amorphous zone. And the amorphous regions are proportionally higher in the inner starch layer. Moreover, raw AWS and BWS granules were more easily digested from the outside in, with the RS content decreasing from 80.65 % to 66.92 % and 49.06 % to 45.01 %, respectively. The RS content of cooked WS were affected by the internally structures, particularly lipid content (11.46 % - 19.09 %) in BWS outer layers and amylose content (13.59 % - 19.43 %) in the inner layers. These results revealed the internal radial structural differences and digestibility patterns of AWS and BWS granules.

Effects of side-chain lengths on the structure and properties of anhydrides modified starch micelles: Experimental and DPD simulation studies.

Anhydride-modified starch micelles have great potential in the delivery of hydrophobic guest molecules. This study aimed to experimentally explore the effects of side-chain lengths on the structure and properties of anhydride-modified starch micelles, and to visualize the self-assembly and loading process of these micelles through Dissipative particle dynamics (DPD) simulations. Starch micelles could only form when the carbon chain length exceeded four. The highly hydrophobic C18 starch micelle exhibited the minimum particle size (65 nm) and maximum loading capability (59.10 µg/mg). For each addition carbon atom in the anhydride side chains, the critical micelle concentration (CMC) of starch micelles decreased average of 1.79 %. Thermodynamic results showed that the micellization was an entropy-dominated driven process, and longer carbon chains enhanced the stability of starch micelles. DPD results showed that the starch chains formed the small clusters then spherical aggregates and finally core-shell structure spherical micelle. Curcumin was loaded into micelles by adjoint aggregation-micellization-adsorption mechanism. Overall, this study provides microscopic insight into the micellization and drug-loading mechanisms for anhydrides modified starch micelles.

Preparation of Eudragit S100-pullulan/hydroxypropyl-ß-cyclodextrin complex-Eudragit S100 multilayer nanofiber film for resveratrol colon delivery.

Cyclodextrin-based electrospun nanofibers are promising for encapsulating and preserving unstable compounds, but quick dissolution of certain nanofibers hinders their delivery application. In this study, hydroxypropyl-ß-cyclodextrin (HPßCD) was used as an effective carrier of resveratrol (RSV) to obtain the RSV/HPßCD inclusion complex (HPIC), which was then incorporated into pullulan nanofibers. For enhancement of RSV release toward colon target, multilayer structure with a pullulan/HPIC film sandwiched between two layers of hydrophobic Eudragit S100 (ES100) nanofibers was employed. The relationship between the superiority of the ES100-pullulan/HPIC-ES100 film and its multilayer structure was verified. The intimate interactions of hydrogen bonds between two adjacent layers enhanced thermal stability, and the hydrophobic outer layers improved water contact resistance. According to release results, multilayer films also showed excellent colon-targeted delivery property and approximately 78.58 % of RSV was observed to release in colon stage. In terms of release mechanism, complex mechanism best described RSV colonic release. Additionally, ES100-pullulan/HPIC-ES100 multilayer films performed higher encapsulation efficiency when compared to the structures without HPIC, which further increased the antioxidant activity and total release amount of RSV. These results suggest a promising strategy for designing safe colonic delivery systems based on multilayer and HPIC structures with superior preservation for RSV.

Effects of heat-moisture treatment on structural characteristics and in vitro digestibility of A- and B-type wheat starch.

In this study, A- and B-type wheat starch granules (AWS and BWS) were separated and modified by heat-moisture treatment (HMT) with different moisture content (10 %-40 %). The effects of HMT on the structure characteristics and digestibility of raw/cooked AWS and BWS were investigated by SEM, FT-IR, XRD, DSC, TGA and NMR. SEM and FT-IR results showed that BWS was more sensitive to HMT than AWS. Interestingly, crystalline conformation of AWS and BWS changed from A type to A + V type after HMT, and the relative crystallinity (V-type) of starch increased to 2.7 % and 3.4 %, respectively. XRD and NMR results verified the formation of V-type crystalline structure. The resistant starch (RS) content of cooked starch was increased, especially for BWS (from 11.46 % to 28.29 %). Compared to the cooked starch, the RS content of raw AWS and BWS was affected by relative crystallinity and the size of starch granules. Furthermore, structure characteristics and digestion kinetics results indicated that the digestion rate of cooked AWS increased due to the deconstruction of starch chains, opposite to BWS (because of the more V-type crystals). The results enrich our understanding of the mechanism of digestion subjected to HMT by different grain sizes of the same wheat starch.

Preparation and Properties of Starch-Cellulose Composite Aerogel.

In this study, we conducted research on the preparation of aerogels using cellulose and starch as the primary materials, with the addition of N,N'-methylenebisacrylamide (MBA) as a cross-linking agent. The chemical, morphological and textural characteristics of the aerogels were found to be influenced by the proportions of cellulose, starch, and cross-linking agent that were utilized. An increase in the proportion of cellulose led to stronger adsorption forces within the aerogel structure. The aerogel showed a fine mesh internal structure, but the pores gradually increased with the further increase in cellulose. Notably, when the mass fractions of starch and cellulose were 5 wt% and 1 wt% respectively, the aerogels exhibited the smallest pore size and largest porosity. With an increase in the crosslinking agent, the internal structure of the aerogel first became dense and then loose, and the best internal structure was displayed at the addition of 3 wt%. Through texture analysis and the swelling test, the impact of the proportion of cellulose and MBA on the aerogel structure was significant. Dye adsorption experiments indicated that MBA affected the water absorption and expansion characteristics of the aerogel by improving the pore structure. Lastly, in tests involving the loading of vitamin E, the aerogels exhibited a higher capacity for incorporating vitamin E compared to native starch.

Development of Emulsion Gels Stabilized by Chitosan and Octenyl Succinic Anhydride-Modified ß-Cyclodextrin Complexes for ß-Carotene Digestion and 3D Printing.

ß-cyclodextrin (ß-CD)-based emulsion gels encapsulated with nutrition for three-dimensional (3D) printing are promising, while obstacles such as low bioaccessibility of bioactive compounds and the molding process in food manufacturing hinder their application. This study intended to develop stable composite emulsion gels using the complexes of chitosan (CS) and octenyl succinic anhydride (OSA)-modified ß-CD (OCD) to conquer these challenges. The esterification of OSA generated more negatively charged OCD and ester groups, which aided in the combination of OCD and CS through enhanced electrostatic and hydrogen bonding interactions. The addition of CS improved the emulsification properties of the complexes and acted as a bridge link in the aqueous phase, thereby increasing the gel strength of the composite emulsion gels. Moreover, the encapsulation of ß-carotene destabilized the strength of the emulsion gels by lowering the interfacial tension. The emulsion gel stabilized by OCD3/CS-0.75% at an initial pH not only successfully encapsulated ß-carotene and presented the highest bioaccessibility of 41.88 ± 0.87% in the in vitro digestion but also showed excellent 3D printability. These results provided a promising strategy to enhance the viscoelasticity of ß-CD-based emulsion gels and accelerate their application in bioactive compound delivery systems and 3D food printing.

Peptides as carriers of active ingredients: A review.

Bioactive compounds are highly valuable in the fields of food and medicine, but their application is limited due to easy deterioration after oral or skin administration. In recent years, the use of peptides as delivery systems for bioactive compounds has been intensively researched because of their special physicochemical characteristics. Peptides can be assembled using various preparation methods and can form several composite materials such as hydrogels, micelles, emulsions and particles. The composite material properties are determined by peptides, bioactive compounds and the construction methods employed. Herein, this paper provides a comprehensive review of the peptides used for active ingredients delivery, fabrication methods for creating delivery systems, structures, targeting characteristics, functional activities and mechanism of delivery systems, as well as their absorption and metabolism, which provided theoretical basis and reference for further research and development of functional composites.

Starch-based Janus particle: Fabrication, characterization and interfacial properties in stabilizing Pickering emulsion.

Janus particles (J-OSPs) based on the composite of chitosan nanoparticles (CSNPs) and octadecenyl succinic anhydride starch (OSPs) were tailor-made by Pickering emulsion method and electrostatic interaction. With different positions of OSPs embedded in the oil phase of Pickering emulsion template and the diversified shapes of starch particles, J-OSPs exhibited various asymmetric structures, which was verified by scanning electron microscope (SEM) and confocal laser microscope (CLSM). By characterizing the interfacial characteristics of J-OSPs, directional distribution of CSNPs was found to enhance the hydrophobicity of J-OSPs and changed its surface charges from positive to negative as pH increased. When J-OSPs were taken as stabilizers, the formed Pickering emulsion had the highest emulsion index and viscosity compared with OSPs and OSPs fully covered by CSNPs (F-OSPs), which was attributed to the self-assembly property of Janus particles that enabled them to form larger aggregates to hinder the collapse of droplets. This study provides a new idea for the construction of plant-derived Janus particles, and its superiority in stabilizing the Pickering emulsion will broaden the application of Janus particles in the field of storage and delivery of active substances.

Novel self-assembly nano OSA starch micelles controlled by protonation in aqueous media.

A new micellization method was applied to produce the nano octenyl succinic anhydride (OSA) modified starch micelles with controllable size. The underlying mechanism was explored by using Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), dynamic light scattering (DLS), zeta-potential, surface tension, fluorescence spectra and transmission electron microscope (TEM). Due to the new starch modification method, the electrostatic repulsion between the deprotonation carboxyl groups prevented the aggregation of starch chains. With the progress of protonation, the weaken electrostatic repulsion and enhanced hydrophobic interaction driven the self-assembly of micelles. The size of micelles increased gradually with the increase of the protonation degree (PD) and concentration of OSA starch. However, a V-shaped trends were observed in the size as the increase of substitution of degree (DS). Curcuma loading test indicated that micelles had good encapsulated capability and the maximum value was 52.2 µg/mg. The understanding of the self-assembly behavior of OSA starch micelles can facilitate and improve the starch-based carrier designs used to synthesis complex and smart micelle delivery system with good biocompatibility.

Facile synthesis of lipase-loaded starch nanoparticles as recyclable biocatalyst in Pickering interfacial systems.

To develop recyclable biocatalyst used in Pickering interfacial systems, the pH-responsive monomer [2-(dimethylamine)ethyl methacrylate] (DMAEMA) was grafted onto the maize starch molecule via free radical polymerization. Subsequently, combined with the gelatinization-ethanol precipitation and lipase (Candida rugosa) absorption process, an enzyme-loaded starch nanoparticle with DMAEMA grafting (D-SNP@CRL) was tailor-made, showing a nanometer size and regular sphere. X-ray photoelectron spectroscopy and confocal laser scanning microscopy confirmed a concentration-induced enzyme distribution within D-SNP@CRL, thereof the outside-to-inside enzyme distribution was proved to be optimum in achieving the highest catalytic efficiency. Benefited from the tunable wettability and size of D-SNP@CRL under pH variation, the generated Pickering emulsion could be readily applied as the recyclable microreactors for the n-butanol/vinyl acetate transesterification. This catalysis exhibited both highly catalytic activity and good recyclability, making the enzyme-loaded starch particle a promising green and sustainable biocatalyst in the Pickering interfacial system.

Molecular Targets and Mechanisms of 6,7-Dihydroxy-2,4-dimethoxyphenanthrene from Chinese Yam Modulating NF-κB/COX-2 Signaling Pathway: The Application of Molecular Docking and Gene Silencing.

Chinese yam (Dioscorea opposita) tuber has a significant effect of invigorating the intestine and improving the symptoms of long-term diarrhea according to the records of the Chinese Pharmacopoeia. Phenanthrene polyphenols from Chinese yam, with higher inhibition of cyclooxygenase-2 (COX-2) than anti-inflammatory drugs, are an important material basis in alleviating ulcerative colitis via nuclear factor kappa-B (NF-κB)/COX-2 pathway, based on our previous research. The present study further explored the target and molecular mechanisms of phenanthrenes' modulation of the NF-κB/COX-2 signaling pathway by means of molecular docking and gene silencing. Firstly, interleukin-8 (IL-8) and tumor necrosis factor-α (TNF-α) expression of 6-hydroxy-2,4,7-trimethoxyphenanthrene (PC2)/6,7-dihydroxy-2,4-dimethoxyphe-nanthrene (PC4) were compared on TNF-α induced human colon adenocarcinoma (Caco-2) cells. Secondly, molecular docking and dynamics simulation were implemented for PC2/PC4 and COX-2. Finally, COX-2 silencing was performed on TNF-α induced Caco-2 cells to confirm the target of PC4 on NF-κB/COX-2 pathway. Lower expression of IL-8 and TNF-α in PC4 treated Caco-2 cells indicated that PC4 had stronger anti-inflammatory activity than PC2. The binding of PC4 and COX-2 was stronger due to the hydrogen bond between hydroxyl group and Tyr385. No significant differences were found in phosphorylation nuclear factor kappa-B inhibitor alpha (pIkBα), phosphorylation NF-κB (pNF-κB) and phosphorylation extracellular signal-regulated kinase 1/2 (pERK1/2) expression between control and PC4 group after silencing, while these protein expressions significantly decreased in PC4 group without silencing, which confirmed that COX-2 was the important target for PC4 in alleviating ulcerative colitis. These findings indicate that PC4 was supposed to have inhibited NF-κB pathway mediated inflammation via suppression of positive feedback targeting COX-2.

Rapid preparation of starch nanocrystals by the mixed acid of sulfuric acid and hydrochloric acid.

In this work, waxy maize starch nanocrystals were prepared by mixed acid of sulfuric acid and hydrochloric acid for the first time. Physicochemical properties, crystalline structure, and particle size of starch nanocrystals prepared by mixed acid (HSNC) were measured. The results showed that there was no difference in particle morphology, group structure, and surface elements of HSNC and starch nanocrystals prepared by sulfuric acid (SNC), which was a conventional preparation method. The yield of HSNC was lower than that of SNC. However, the preparation time of HSNC was greatly shortened to 1 h which is only 0.83 % of the time (5 d) to prepare SNC by the sulfuric acid, and HSNC showed higher relative crystallinity and smaller size than those of SNC. In addition, when the ratio of sulfuric acid and hydrochloric acid to provide H ion concentration was 1:1 to hydrolyze starch for >1 h, the crystal pattern of HSNC would be changed to V-typed, while the crystal pattern of SNC was still A-typed. Thus, this work provided efficient method for preparing starch nanocrystals is provided, which can replace sulfuric acid hydrolysis to prepare SNC.

Co-Pigmentation Mechanism and Thermal Reaction Kinetics of Mulberry Anthocyanins with Different Phenolic Acids.

Applying the intermolecular co-pigmentation to improve the stability of mulberry anthocyanins is an important co-pigment method. Seven co-pigments, ferulic acid (FA), caffeic acid (CA), p-hydroxybenzoic acid (HBA), protocatechuic acid (PA), gallic acid (GA), vanillic acid (VA) and vanillin (VN) were selected to investigate mulberry anthocyanin co-pigmentation thermal reaction kinetics. The strongest co-pigment reactions were observed for FA at a molar ratio of 1:20, pH 3.5 and 20 °C, with the highest hyperchromic effects (52.94%), equilibrium constant (K) values (3.51) and negative values of Gibbs free energy (ΔG°) (-3.06 KJ/mol). Co-pigments that contained more free hydroxyl groups facilitated the co-pigmentation, and methyl contributed more to color enhancement, with respect to the hydrogen group. Ultra Performance Liquid Chromatography-Quadrupole-Time Of Flight-Mass/Mass Spectrometry (UPLC-Q-TOF-MS/MS) results indicated that FA and CA formed different anthocyanin derivatives with mulberry anthocyanin. The Fourier Transform Infrared Spectroscopy (FTIR) and molecular docking confirmed that hydrogen bonding, π-π stacking and hydrophobic interaction were formed between anthocyanins and three prevalent co-pigments (FA, CA and VA). CA and C3G could form four hydrogen bonds and two π-π stackings; this was the most stable system among three phenolic acid-C3G complexes. Due to the functional effect of phenolic acids, the addition of FA and CA not only enhanced the stability and color intensity of mulberry anthocyanins but also the functionality of the processing product.

Preparation of hydroxypropyl starch/polyvinyl alcohol composite nanofibers films and improvement of hydrophobic properties.

Starch-derived edible films have great potential as biodegradable food packaging and biomedical materials, in this study, we adopted a green method to prepare starch-based composite electrospun nanofibers films. The hydroxypropyl starches (HPS) were prepared to improve native starch solubility and properties, and a series of blend solutions were prepared with different HPS/polyvinyl alcohol (PVA) weight ratios. The comparison of the properties of HPS/PVA (HPA) nanofibers with different amylose contents were evaluated, and the fibers fabricated from hydroxypropyl high amylose starch (HP-HAS) had more continuous and homogeneous morphologies compared to the other starch fibers, it was also found that the addition of HP-HAS in the film has better mechanical properties than pure PVA film. Thus, to improve the hydrophobicity of the film, the HP-HAS/PVA (HPA(H)) nanofiber was selected for the hydrophobic study by the citric acid (CA) treatment. The hydrophobic surface was formed on the HPA(H) film by CA self-assembled coating with a water contact angle changed from 30.95° up to 100.74°. This study successfully prepared the modified starch/PVA composite nanofibers and established a simple method of self-assembled hydrophobic modification to improve water stability. Therefore, this green strategy is an alternative candidate in further study for food packaging and relative areas.

Preparation of graphene-starch composite film and its application in sensor materials.

In this work, a composite film was prepared by combining reduced graphene oxide (RGO) and starch nanocrystals (SNC). The results show that SNC can be well dispersed on graphene after mixed with the graphene oxide solutions. SNC had a greater impact on the morphology and microstructure of the composite film. Moreover, the introduction of SNC and the efficient reduction process of graphene oxide (GO) render these composite films good mechanical properties as well as high electrical conductivity. The tensile strength of the composite film was improved after being combined with graphene. However, as the addition rate of SNC increased, the strain-to-failure of the composite film decreased. Therefore, 10% reduced graphene-starch nanocrystals (10%RGO-SNC) was used as multifunctional sensor materials. And it had strong responses to different external stimuli, such as, temperature, humidity, bending/stretching, and solutions.

Effects of Heat-Moisture Treatment on the Digestibility and Physicochemical Properties of Waxy and Normal Potato Starches.

Heat-moisture treatment (HMT) is a safe, environmentally friendly starch modification method that reduces the digestibility of starch and changes its physicochemical properties while maintaining its granular state. Normal potato starch (NPS) and waxy potato starch (WPS) were subjected to HMT at different temperatures. Due to erosion by high-temperature water vapor, both starches developed indentations and cracks after HMT. Changes were not evident in the amylose content since the interaction between the starch molecules affected the complexation of amylose and iodine. HMT increased pasting temperature of NPS from 64.37 °C to 91.25 °C and WPS from 68.06 °C to 74.44 °C. The peak viscosity of NPS decreased from 504 BU to 105 BU and WPS decreased from 384 BU to 334 BU. The crystallinity of NPS decreased from 33.0% to 24.6% and WPS decreased from 35.4% to 29.5%. While the enthalpy values of the NPS declined from 15.74 (J/g) to 6.75 (J/g) and WPS declined from 14.68 (J/g) to 8.31 (J/g) at 120 °C. The solubility and swelling power of NPS decreased while that of WPS increased at 95 °C. Due to the lack of amylose in WPS, at the same HMT processing temperature, the reduction in peak viscosity of treated WPS compared to that of native starch was smaller than that of NPS. The resistant starch (RS) content of NPS after HMT at 120 °C was 73.0%. The slowly digestible starch (SDS) content of WPS after HMT at 110 °C was 37.6%.

Linear Dextrin as Potential Insulin Delivery System: Effect of Degree of Polymerization on the Physicochemical Properties of Linear Dextrin-Insulin Inclusion Complexes.

In the current study, linear dextrin (LD) was prepared using waxy potato starch debranched with pullulanase, which has attracted immense interest in the food, pharmaceutical, and cosmetic industries as a versatile ingredient. Various LDs were separated on the basis of their differential solubility in aqueous/ethanol solutions of different volumetric ratios. Three LD products-LD Fabrications with 40% ethanol (F-40); LD Fabrications with 50% ethanol (F-50); and LD Fabrications with 60%, 70%, and 80% ethanol (F-M)-were obtained with an average degree of polymerization (DP) values of 31.44, 21.84, and 16.10, respectively. The results of Fourier transform infrared spectroscopy (FT-IR) analysis revealed that the reaction mainly involved hydrogen bonding and a hydrophobic interaction between LD and insulin in the process of inclusion complex formation. X-ray diffraction (XRD) results indicated that insulin was encapsulated in LD. The results of circular dichroism (CD) showed that the changes in the secondary structure of insulin were negligible during the release from the inclusion complexes. The order of encapsulation capacity is as follows: the complex composed of F-M and insulin (F-M-INS) > the complex composed of LD and insulin (LD-INS) > the complex composed of F-50 and insulin (F-50-INS) > and the complex composed of F-40 and insulin (F-40-INS). F-M-INS inclusion complexes showed a better effect on reducing the release of insulin in gastric juice and promoting the release of insulin in intestinal juice and blood plasma than LD-INS.

Preparation of carboxymethyl starch/polyvinyl-alcohol electrospun composite nanofibers from a green approach.

A green approach for the preparation of starch-based composite nanofibers using electrospinning was developed. The water-soluble sodium carboxymethyl starch (CMS) with DS 0.31 was prepared. The addition of co-blending polymer polyvinyl-alcohol (PVA) was attempted to improve the CMS solution spinnability, which blends from aqueous solution were prepared at different CMS/PVA weight ratios. The solution parameters including viscosity, surface tension and conductivity were measured and the morphologies of nanofibers were observed by SEM. Smooth, continuous, and defect-free nanofibers were successfully obtained range from the blend of CMS/PVA weight ratios of 10:90 to 80:20. Diameter distribution diagrams suggested that the diameter of the nanofibers reduced with the concentration of CMS increasing. This is the first report that the thin nanofiber (135.29 nm) with bead-free was obtained at the maximal CMS content of 50.0 wt% in the CMS/PVA blend. This study provided a green approach to produce starch-based nano-scale fibers.

Preparation of hydroxybutyl starch with a high degree of substitution and its application in temperature-sensitive hydrogels.

In this work, hydroxybutyl starch prepared by acid, alkali, and acid-base synergistic pretreatments from waxy corn starch exhibited great potential for preparing temperature-sensitive hydrogels. The degree of substitution, morphology, and group structure of hydroxybutyl starch were determined. The hydroxybutyl starch prepared by acid-base synergistic pretreatment had the highest degree of substitution. Relative to the native starch, the surface of hydroxybutyl starch particles was smoother and rounder. The formation, microstructure, and properties of temperature-sensitive hydrogels were also determined in this work. The results indicated that the temperature-sensitive hydrogels containing hydroxybutyl starch had irregular pore structures and higher water absorption rates. As the starch content increased, the pore size of these hydrogels increased and then decreased, the water absorption rate increased and the deswelling rate decreased. The equilibrium swelling ratio of the hydrogel prepared by hydroxybutyl starch was greater than that of native starch.

Effect of dual modification with ultrasonic and electric field on potato starch.

Applying high voltage electric fields to starch is a novel method. Very limited studies were done on high ultrasonic power. Native potato starch (NPS) was modified by ultrasonic (US), electric field (ES) and a combination of the two treatments: ultrasonic prior to the electric field (UES), electric field prior to the ultrasonic (EUS) and ultrasonic and electric field at the same time (UAES). Physicochemical properties, texture profile property and in vitro digestibility of potato starch were characterized. Compared to the NPS single and dual-modified potato starch granules displayed deep pitting on the surface and their shape was deformed. X-ray diffraction results suggested that the characteristic peaks were not changed, whereas the relative crystallinity increased for all treatments except for the ES treatment. The ES granule also showed a relatively high average size distribution. The UES showed a lower level of conclusion temperature and resistant starch content (10.56%). The EUS exhibited the most desirable properties such as high light transmission, high water absorption capacity, solubility (77.50%), swelling power (50.48%) and resistant starch content (79.98%).