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A series of soy protein isolate (SPI)-based film-forming solutions were prepared by a co-drying process or by direct addition of alginate (ALG), with different degrees of phase separation and morphologies. For a non-phase separation system, a single Tg of the data was well fit by the calculation results of the Couchman–Karasz quotation; moreover, the initial state of SPI/ALG (20:1) and SPI/ALG (10:1) after homogenization and the state of SPI/ALG (20:1) after deposition for 30 min exhibited good uniformity; thus, a single Tg value was also measured in these cases (96.28 °C, 85.37 °C and 112.03 °C respectively). Two Tg values of 74.11 °C and 108.24 °C for SPI/ALG (20:1), 72.86 °C and 110.11 °C for SPI/ALG (10:1) were determined in the 100% of phase separation systems. The mixed interface, SPI-rich phase, and ALG-rich phase of SPI/ALG (10:1) co-blending system after deposition for 30 min were formed, resulting in three different Tg values of 74.32 °C, 90.15 °C and 125.17 °C. The SPI/ALG-CO (20:1) and SPI/ALG-CO (10:1) systems with co-drying process could significantly improve the interface properties and the surface activity of each component. The understanding of Tg led to new insights of defining the limit between the rubbery and glassy states in the film-forming co-blending systems. [ABSTRACT FROM AUTHOR]

Abstract: Differential thermal analysis (DTA) as a novel approach to monitor retrogradation degree of rice starch was investigated in this study. Our results found that the onset temperature (To), the peak temperature (Tp), and the conclusion temperature (Tc) were slightly reduced for the retrograded starch, while the differential temperature (ΔT) was significantly increased with the increasing of storage time (P ≤0.05). Based on the measurement of the ΔT, retrogradation degree (DR) of rice starch was evaluated, and it was compared with the data collected from the DSC. The result indicated that there was no significant difference in DR obtained from the two analytical methods, although the DR determined from the DTA was slightly higher than that from the DSC. These findings suggest that the DTA as well as the DSC is suitable for the measurement of starch retrogradation. [Copyright &y& Elsevier]

The impact of adding zein on the gluten network during extruded noodle processing and the quality of the noodles by extrusion-cooking were investigated. These changes were studied by size exclusion-high performance liquid chromatography (SE-HPLC), free sulfhydryl (SH) measurement, non-covalent interactions, Fourier-transform infrared spectroscopy (FTIR), particle size analysis, confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM). Zein reduced the protein aggregation, resulting in a higher free sulfhydryl content and increased hydrogen bonds and hydrophobic interactions during noodle processing. Moreover, Zein reduced the relative content of β-sheets by 4.54% and 7.48% at the extrusion and cooking stages, respectively. Zein decreased the particle size during extrusion but increased it during cooking. Zein improved the compactness and strength of noodle microstructure during cooking, exhibited higher hardness and impeded water mobility compared to extruded noodles made only with wheat flour (WF). The extruded noodles containing zein showed a significant increase of 26.10% and 61.11% in tensile strength and distance, respectively. Zein did not cause significant changes in the cooking loss and water absorption in the extruded noodles. Research on the impact of zein on protein during the processing of extruded noodles could provide a dependable approach and valuable mechanistic insights for improving the quality of extruded noodles. [Display omitted] • The inclusion of zein in the extruded noodle processing resulted in reduced protein aggregation. • Zein increased hydrogen bonds and hydrophobic interactions during extruded noodle processing. • Zein reduced the relative content of β-sheets in extruded noodles. • Zein improved the quality of extruded noodles to have higher hardness, and tensile force and distance. [ABSTRACT FROM AUTHOR]

Scalable mycelium biomaterials with excellent biodegradable and mechanical properties are attracting widespread attention. However, the inherent brittleness of biomass materials greatly limits their applications in reality, such as packaging and flexibility. In this work, three mycelium films were produced by the capacity of mycelium to spontaneously form three-dimensional biopolymer networks with a toughness of 127.32 kJ/m3 (Ganoderma lucidum), 71.95 kJ/m3 (Auricularia polytricha), and 87.52 kJ/m3 (Pleurotus ostreatus), respectively. After glycerol treatment, the toughness of the films increased by more than 440%, and these films' surfaces were made smooth and hydrophilic. It has been shown that the hydrogen bonding interactions between glycerol and polysaccharides as well as proteins in mycelium enhance the mechanical and hydration properties of mycelial films. The new strategy of using glycerol to improve the properties of mycelium films will advance on mycelium materials research. [Display omitted] • Edible mycelium bioplastic films were prepared by self-growth method. • Glycerol and hot-pressing improved bioplastic films properties. • There are hydrogen bonds between glycerol, mannoproteins and chitin. [ABSTRACT FROM AUTHOR]

Effect of pigskin-originated gelatin on dough properties and bread characteristics, especially on bread staling was investigated in terms of starch retrogradation and water migration in the present study. Results showed that gelatin significantly improved bread qualities during storage. Compared with the control, 7-day staling rate of bread containing 0.5% and 1.0% gelatin decreased by 6.56% and 20.83% respectively, indicating gelatin retarded the staling process of bread. This retardation effect was related to starch retrogradation and water migration. The relative crystallinity decreased from 15.12%, 11.60% to 10.75%, which demonstrated the alleviation effect of amylopectin crystallization. Bread samples containing 1.0% gelatin had the lowest retrogradation enthalpy of 2.93 ± 0.24 J/g followed by 0.5% gelatin bread and the control group, further indicating that gelatin may induce less water available to form crystal lattice and restrict the migration of starch molecules. The 5-day moisture loss rate for the control group was highest with the values of 12.39%, which was 1.43% and 1.83% higher than that of bread with 0.5% gelatin and 1.0% gelatin, respectively. Water activity and T 2 relaxation results provided the information that gelatin inhibited water migration upon storage and gelatin interacted with bread components. However, the effect of gelatin on improving bread quality and retarding staling could not be reflected by the dough properties measured through farinograph, extensograph and rheometer. This study suggested gelatin from pigskin had great potential to be served as an effective bread improver. Image 1 • Gelatin enhanced the bread qualities significantly, especially retarding the staling process. • Gelatin hindered the chain reassociation of starch molecules during storage. • Gelatin interacted with bread components and restricted water transfer. • Dough properties showed gelatin might to some extent weaken the gluten network. [ABSTRACT FROM AUTHOR]

Surfactin could improve the quality of fresh noodles (FNs) during storage. The impacts of different levels of surfactin (0.0%, 0.2%, 0.3%, and 0.4%) on the quality and gluten network structure of FNs after storage (0d, 1d, 2d, and 3d) at 25 °C were investigated. The results showed that the addition of surfactin inhibited the tendency of hardness and tensile strength to decrease in FNs and improved their cooking properties. Size exclusion (SE-HPLC) and electrophoresis were employed to evaluate the strength of the gluten network, which indicated that surfactin increased the cross-linking of the gluten network during storage by promoting more disulfide bonds (SS). Surfactin increased the total contents of SDS-soluble polymers (SDS-P) and SDS-insoluble polymers (SDS-I) from 24.66% (control samples) to 33.32% (FNs with 0.4% surfactin) after 3 days of storage. The secondary structure of gluten network was determined using Fourier transform infrared (FTIR) spectroscopy, suggesting that surfactin increased α-helices and decreased random coil during storage. Moreover, confocal laser scanning microscopy (CLSM) showed that surfactin additions delayed the depolymerization of the gluten network in FNs during storage. This research could provide a theoretical basis for using surfactin as improver for FNs. [Display omitted] • The gluten network of fresh noodles (FNs) collapsed during storage. • Surfactin addition improved cooking properties, textural, and water transfer. • Surfactin improved the gluten network and inhibited its depolymerization. • CLSM analysis showed a compact gluten network in FNs with added surfactin. [ABSTRACT FROM AUTHOR]

Protein oxidation results in structural modification which affects its functionalities. In this study, 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH) was selected as a representative of lipid peroxidation products to investigate the effect of oxidative modification on structural and foaming properties of egg white protein. Incubation of egg white protein with AAPH resulted in structural changes, regarding by sulfhydryl-disulfide interchange reaction and increase in dityrosine formation. Moderate oxidation led to exposure of hydrophobic groups of egg white protein, whereas, excessive oxidation induced a decrease in surface hydrophobicity. Molecular weight distribution and scanning electron microscopy showed that egg white protein underwent an aggregation after excessive oxidation. Furthermore, after treating with AAPH at 0.2 mM, the foaming ability of egg white protein increased from 85.6% to 91.4%, and the foaming stability increased from 80.6% to 85.3%. The excessive oxidation treatment (5 and 25 mmol/L AAPH) resulted in an enhanced foaming ability, while reduced its foaming stability. This study suggested that oxidation treatment has a potential to be implemented to modify foaming properties of egg white protein. [ABSTRACT FROM AUTHOR]

Compared to traditional heating methods by static immersion or stirring, induced electric field (IEF) treatment can significantly increase hydrolysis rate of potato starch. The aim of this study was to examine the characterization of acid hydrolysis of granular potato starch under IEF. Potato starch was hydrolyzed using 0.15 mol/L HCl combined with IEF (IEF-HCl) at an excitation voltage of 75 V from 4 h to 120 h. The changes in granular, crystal, and molecular structure of starch granules during IEF-HCl hydrolysis were investigated. Scanning electron microscope analysis showed the outer surface of potato starch was firstly attacked by free ions and then the inner structures was completely disrupted and broken into pieces. X-ray diffraction studies indicated that the crystallinity decreased from 38.92% to 34.9% after 4-h hydrolysis, and then gradually increased to 41.88% as hydrolysis time increased to 96 h, but decreased thereafter. The weight-average molecular weight dramatically decreased from 104.7 × 10 6 Da to 9.291 × 10 6 Da in the first 24 h and then decreased gradually. These results suggested that there were three steps in the catalytic process of IEF-HCl hydrolysis. Initially, hydrogen ions destroyed the external crystalline shell of granules. Next, hydrogen ions attacked the loose amorphous region and dense crystalline part within starch granules simultaneously. Finally, the remaining crystalline region was hydrolyzed slowly. [ABSTRACT FROM AUTHOR]

The rise of 3D printing technology has made the personalization of food possible. In this study, peanut protein-polysaccharide semi-interpenetrating networks were constructed to improve the gelling and printing properties of composite hydrogels. The rheological and mechanical test results showed that the storage modulus and fracture stress of peanut protein composite hydrogels increased with increasing carrageenan and gellan gum concentrations. The storage modulus (G′) and hardness of the composite hydrogels with 1.5% polysaccharide addition reached above 104 Pa and 700 g, respectively. The thermal reversibility of both carrageenan and gellan gum gels meant that composite hydrogels could be created as recyclable printable edible inks for 3D food printing. In addition, the composite hydrogels were designed to change color in response to alterations in pH, which meant they could be used in 4D food printing applications, i.e., in situations where the ink changes its attributes sometime after printing. The results of this study should facilitate the rational design and fabrication of plant-based edible inks that can be used for the development of personalized foods with unique properties. [Display omitted] • Peanut protein-polysaccharide semi-interpenetrating network hydrogels were built. • A recyclable food ink for 3D printing based on peanut protein hydrogels was prepared. • Color response of the printed object to pH was realized by adding natural pigment. • This study will contribute to the development of plant protein-based 3D printed food. [ABSTRACT FROM AUTHOR]

In this study, we explored the hydrolytic mechanism of glucan 1,4-α-maltotiohydrolase (AMTS). Kinetic parameters analysis of AMTS were performed using the amylopectin with different external chain lengths (ECL). Then, the waxy maize starch was gelatinized and hydrolyzed by AMTS to various degrees; retrogradation of starch hydrolysates were determined. Michaelis constant ( K m ) of the β -dextrin-3 (ECL 2.3) was eight folds than the amylopectin (ECL 17.8), but its catalytic efficiency ( k cat / K m ) was only 6.5% of amylopectin. AMTS preferred the external chains to the internal chains for hydrolysis, and amylopectin was hydrolyzed by AMTS through combined exo- and endo-action. In the initial hydrolysis stage, the exo-action of AMTS was predominant with slow reduction in M w and little changes in the internal chains of amylopection. The percentage of maltotriose in the soluble oligosaccharides (PM) was 90.5% at 2.1% degree of hydrolysis (DH), and gradually decreased from 90.5% to 71.2% at 35.4% DH. The PM decreased could be partially attributed to the increased transglycosylation reactions of AMTS. Complete inhibition of amylopectin retrogradation was observed with >15.9% hydrolysis for the increased shorter outer chains and low molecular weight dextrins. These results indicate that AMTS may be effective in retarding starch retrogradation in baked products. [ABSTRACT FROM AUTHOR]

In this study, the aqueous re-dispersibility of starch nanocrystal (SNC) powder was significantly improved by sodium hypochlorite (NaClO) oxidation, with more than 2% (w/w) active chlorine. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses verified the oxidation process of SNC. The oxidation degree (carboxyl groups content) increased from 0.41% to 0.581% (w/w) while the applied active chlorine increased from 1% to 4% (w/w). X-ray diffraction showed that NaClO oxidation induced minor destruction to SNC when the applied active chlorine exceeded 2%, and the relative crystallinity decreased from 45.6% to 42.8%. Due to the introduction of carboxyl groups, the zeta potential of oxidized SNC (OSNC, under 2% active chlorine level) suspension (re-dispersed from oven-dried OSNC powder) reached to −23 mV. Consequently, a high degree of individualized SNC with the particle size of 20 nm was obtained and the suspension maintained the stability for at least 20 days. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine 1-buatnol–hydrochloric acid (1-butanol–HCl) hydrolysis process of starch. Normal rice starch was hydrolyzed by 0.36% HCl in anhydrous 1-butanol at 40 °C from 4 h to 7 days. The changes in starch granule, crystalline, and molecular weight during the 1-butanol–HCl hydrolysis were determined using SEM, particle size analyzer, XRD, HPSEC–MALLS–RI, and iodine staining. SEM and particle size analyzer analysis showed that the granule morphology significantly changed and the granule size decreased from 5.47 μm to 5.07 μm after the hydrolysis by 1-butanol–HCl for 7 days. XRD results indicated that amorphous areas of normal rice starch were firstly hydrolyzed followed by the ordered areas during 1-butanol–HCl hydrolysis. The peak (2θ) of V-type crystallinity was detected at around 20° in the XRD curves of 1-butanol–HCl-hydrolyzed starches. This peak confirmed the formation of amylose–1-butanol complex. HPSEC–MALLS–RI and iodine staining analysis demonstrated that the weight-average molecular weight of normal rice starch sharply decreased from 2.4 × 107 Da to 4.9 × 105 Da after 1-butanol–HCl hydrolysis for 4 h, then gradually decreased, and finally stabilized at about 2.6 × 104 Da after hydrolysis for 4 days. These results suggest that the attack of 1-butanol–HCl on normal rice starch preferentially occurred in the amylopectin molecules of amorphous areas. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the effect of frozen storage on chemical and physical properties of wheat gluten-, glutenin- and gliadin-rich fractions was evaluated. Chemical changes were studied by size-exclusion (SE) and reversed-phase (RP) high-performance liquid chromatography (HPLC), thiol (SH) measurement, sodium dodecyl sulphate poly-acrylamide gel electrophoresis (SDS-PAGE), circular dichroism (CD) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Physical properties were determined by dynamic rheological measurements. During the frozen storage, depolymerization of glutenin macropolymer (GMP) was observed by SE-HPLC in gluten- and glutenin-rich fractions with a higher depolymerization rate of GMP in gluten-rich fraction, this further suggested that gliadin might have the potential to disaggregate the GMP. The depolymerization effects led to the major variation of thiol content. The results of SE-HPLC were also in accordance with that of the SDS-PAGE profiles of gluten and glutenin-rich fractions. No aggregation behavior was observed for α-gliadin and γ-gliadin containing cysteine in gluten- and gliadin-rich fractions, leading to the constant content of thiol content of gliadin during the frozen storage. The results of combined CD spectroscopy and FTIR spectroscopy indicated non-covalent interactions were also affected. Significant loss of elastic modulus (G′) and viscous modulus (G″) to gluten- and glutenin-rich fractions were detected with the increasing storage except that no apparent changes occurred in gliadin-rich fractions, suggesting that variation of glutenin functionality was quite important for that of gluten. Moreover, highly significant negative correlations between the content of SDS-soluble glutenin and data of G′ were found in gluten- and glutenin-rich fractions suggested depolymerization of GMP was the main indicator of deterioration of gluten and glutenin during the frozen storage. [Copyright &y& Elsevier]

Abstract: The effect of branched limited dextrin (BLD) on starch retrogradation was investigated to explain the anti-firming mechanism of α-amylase. The influence of BLD on the gelatinized wheat and waxy rice starch retrogradation was characterized by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WXRD). DSC and WXRD results showed that retrogradation of wheat and waxy rice starch gels were reduced with the addition of branched limit dextrins (F75 and F88). Avrami equation was used to analyze the enthalpies of retrograde wheat starch gels, and the value of k indicated that F75 and F88 reduced the kinetics of starch retrogradation. In addition, molecular dynamic (MD) simulation was adapted to predict the interaction of BLD and starch fraction, and the results showed that the BLD reduced starch retrogradation by the interplay between starch and BLD. [Copyright &y& Elsevier]

Abstract: Phosvitin (Pv) from hen egg yolk was conjugated to dextran (Dex) through the initial stage of Maillard reaction in an aqueous system (Pv:Dex, 1:4 (w/w); Mw of Dex, 40 kDa) at 100 °C for 6 h. The red shift of λ ma x occurred to Pv after the conjugation reaction from 355 to 362 nm and from 510 to 520 nm of intrinsic and extrinsic fluorescence emission spectra respectively. Circular dichroism spectra demonstrated that partial unordered secondary structure of Pv transformed into α-helix and β-turn after conjugating with Dex. The solubility of Pv–Dex conjugates represented an increase from 53.0% to 79.3% at pH 4.0. The zeta-potential of all tested emulsions decreased with lowering pH from 7.0 to 4.0. The interfacial thickness of Pv (1.0 mg/ml) absorbed onto latex particles at pH 4.0 was prominently increased by conjugation with Dex. Both the highest ESI and the slight fluctuation of D[4,3] of Pv–Dex conjugates illustrated that conjugation of Pv with Dex would be an effective method to improve its emulsion stability against more acidic pH environment. [Copyright &y& Elsevier]

Abstract: The effect of different dispersion pHs on zeta potentials, size distribution, and aggregation behavior of starch nanocrystals (SNC) prepared by sulfuric acid hydrolysis was examined in this study. The results showed that zeta potential of starch nanocrystals decreased from −6.7 mV to −34.5 mV as the dispersion pH increased from 2.07 to 11.96. Smaller starch nanocrystals and wider distribution peaks were observed with the increase of dispersion pH. The data obtained from field emission scanning electron microscopy (FE-SEM) also indicated that the aggregated parallelepiped nanoplatelets (1.5 μm) changed to monodispersed spherical-like nanoparticles (50 nm) with increasing of dispersion pH from 2.07 to 11.96. Considering these findings, the stable SNC suspension could be obtained by adjusting the dispersion pH to the range of 7.44–9.45. [Copyright &y& Elsevier]

Abstract: The effect of frozen storage on the water sorption capability, water mobility, secondary structure, thermal and microscopic properties of gluten-, glutenin- and gliadin-rich fractions were investigated. Lower water sorption capability was observed for samples after frozen storage, suggesting that more hydrophobic moieties were exposed. Conversions of α-helix structure to β-turn structures and specific β-sheet structures were observed in the secondary structure analysis of gluten- and gliadin-rich fractions. Frozen storage induced higher water mobility in hydrated gluten proteins. Similar changes were observed in gluten-water and gliadin-water systems, implying that the changes were primarily attributed to subdued gliadin-water interactions and gliadin can stabilize glutenin network to confine the water mobility. Meanwhile, thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed that thermal degradation temperature decreased while thermal denaturation stability increased in gluten- and glutenin-rich fractions with the increasing time of frozen storage. However, the enthalpies of all the gluten proteins decreased, indicating more disordered structures in the aged gluten proteins. The micrographs of scanning electron microscopy (SEM) also confirmed more disordered and weak structures in gluten- and glutenin-rich fractions induced by frozen storage. Furthermore, consistent changes in gluten-, glutenin- and gliadin-rich fractions indicated that the variations in conformational, thermal and microscopic properties of gluten might originate from glutenin and gliadin upon frozen storage. [Copyright &y& Elsevier]

Abstract: The influence of spring dextrin (SD) on the gelatinized starch retrogradation was investigated by wide X-ray diffraction (WXRD), differential scanning calorimetry (DSC) and molecular dynamic (MD) simulation. Different wheat and corn starch gels were prepared with the addition of SD3, SD5, SD7 or SD9. WXRD results showed that recrystallinity of wheat and corn starch gels was reduced with the addition of SD7 or SD9. Alternatively, SD3 or SD5 accelerated recrystallinity. Enthalpies of retrograde wheat and corn starch gels were analyzed using the Avrami equation and confirmed the WXRD results. Finally, MD simulation was adapted to predict the interaction of SD and starch fraction in water, and the results showed that the SD disturbed starch retrogradation by altering starch fraction–starch fraction interaction. Based on the obtained results of WXRD, DSC and MD, it was concluded that the addition of SDs significantly influences starch long-term retrogradation. [Copyright &y& Elsevier]

Superheated steam treatment (SST) can improve cereal-based foodstuff quality. Starch is the major component of cereal-based foodstuffs, playing a key role in food quality. For understanding the effect of SST on the moisture distribution, lamellar structure and molecular weight of wheat starch, the low-field nuclear magnetic resonance (LF-NMR), small angle X-ray scattering (SAXS) and size exclusion chromatography were employed. Compared with native starch, SST reduced the average thickness of crystalline layer and induced the depolymerization of starch molecules, which were attributed to the limited moisture transfer resulting in the partial gelatinization of starch granules. The structural variations had a synergistic effect on the rheological properties of starch samples. Upon SST, treated samples exhibited a weaker pseudoplasticity behavior and increased the deformability and mobility of gels systems. Furthermore, the lower tanδ values of treated starch samples were observed, indicating that the gels systems tended to the solid-like behaviors. [Display omitted] • Superheated steam treatment (SST) changed the water distribution of wheat starch. • SST transmuted the crystalline lamellae into the amorphous lamellae of wheat starch. • SST depolymerized starch molecular structure and decreased its molecular weight. • SST weakened the gels systems but increased its deformability and mobility. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a dual-retrogradation treatment (gelatinization–retrogradation–gelatinization–retrogradation) was designed for preparing slowly digestible starch (SDS) products from rice starch. The results showed that a maximum SDS yield in the tested samples increased from 39.3% to 56.7% by the dual retrogradation with the time interval of 36 h. The dual retrogradation also seemed to increase with the melting temperature range (T c–T o) of the SDS products. This increase indicated that more imperfect crystallites were formed during the dual-retrogradation treatment. Furthermore, compared to the single retrogradation, the dual retrogradation generated larger cavities and more solid connection parts in the SDS products. This internal microstructure could result in the increase of slow digestibility. These findings suggest that the dual retrogradation can be used in starchy products to increase the yield of SDS. [Copyright &y& Elsevier]

Abstract: Effect of pectin (34–40% esterification), glycerol and trehalose at two concentrations (0.1% and 0.5%, wt./wt%) on physicochemical and emulsifying properties of phosvitin (Pv) was investigated under the mild conditions (oil volume fraction, 0.25; protein concentration, 5 mg/mL; 10 mM sodium phosphate buffer, pH 7.0). Pv showed better emulsifying properties than sodium caseinate (Sc). Glycerol (0.5%) significantly increased the emulsifying activity index (EAI) of Pv from 19.8 to 20.9 and the emulsion stability index (ESI) from 67.6 to 75.1. The higher ESI of Pv was also obtained by 0.1% pectin and 0.5% trehalose. The results obtained from circular dichroism (CD) spectra indicated that all the tested additives displayed slight effect on the unfolded structure of Pv. Furthermore, fluorescence pattern demonstrated that glycerol and trehalose increased the hydrophobicity of Pv, while pectin displayed an opposite effect. All emulsions exhibited a shear-thinning behavior and the flow behavior was fitted to the power law model. Frequency sweeps of the emulsions illustrated that they behaved like a viscous liquid. [Copyright &y& Elsevier]

Wheat flour superheated steam treatment can improve the baking food quality by modifying the functionality of wheat flour. To reveal the underlying mechanism of improving wheat flour quality by superheated steam treatment, the gluten molecular rearrangement and polymerization behavior of wheat flour upon superheated steam were studied. Molecular size distributions of samples were analyzed using size exclusion (SE-HPLC) and electrophoresis, which illustrated that superheated steam treatment promoted the aggregation of gluten due to cross-links of disulfide (SS) bonds. Superheated steam treatment increased the SDS-insoluble proteins content from 63.07% (native wheat flour) to 93.32% (treated at 150 °C for 1 min). Infrared spectroscopy (FTIR) was used to calculate the different secondary structures percentages of gluten, suggesting that superheated steam treatment increased intermolecular β-sheet and α-helix while it decreased anti-parallel β-sheet, β-turn and β-sheet. Furthermore, thermo gravimetric analysis (TGA) and rheology suggested that superheated steam treatment enhanced gluten mass but weakened gel system due to molecular rearrangements of SS bonds and hydrogen bonds. [Display omitted] • Gluten polymerization behavior of wheat flour upon superheated steam were studied. • Superheated steam treatment induced gluten aggregation and SS bonds cross-links. • Superheated steam treatment weakened the wheat flour gel system. [ABSTRACT FROM AUTHOR]

This paper explored the impact of superheated steam (SS) treatment on the physicochemical, crystalline characteristics and in vitro digestibility of wheat starch. Upon SS treatment, treated samples showed lower swelling power, solubility, and viscosities, but had higher gelatinization temperature, which might be due to the partial gelatinization of starch granules. This agreed with micromorphology characterization, indicating the degradation of Maltese cross. In addition, SS treatment decreased the long-range crystalline and short-range order of starch, compared to native starch sample. This change of physicochemical and structural properties was responsible for the decrease of starch hydrolysis rate. Meanwhile, SS treatment obviously increased the slowly digestible starch (SDS) and resistant starch (RS) content from 10.6% to 7.9% (native starch) to 17.2% and 13.6% (150 °C, 1 min), respectively. This knowledge indicates that superheat steam technology possibly is a promising strategy in starch modification. [Display omitted] • Superheated steam (SS) treatment induced partial gelatinization of wheat starch. • SS treatment destroyed the long-range crystalline structure of wheat starch. • SS treatment increased resistant starch contents of wheat starch. [ABSTRACT FROM AUTHOR]

Wet-milled glutinous rice flour (WMF) and dry milled glutinous rice flour (DMF) have different pasting and rheological properties but the underlying mechanism has not been defined. Dry milling methods can result in glutinous rice flour (GRF) with higher residual alpha-amylase activity and damaged starch content compared to flours prepared by wet milling methods. The addition of alpha-amylase significantly increased starch hydrolysis and reduced the peak, trough, and final viscosity of GRF gels. The pasting viscosity and dynamic modules of WMF-Water gels were significantly higher than those of DMF-Water gels. Inhibiting amylase activity significantly reduced the differences in paste viscosity and dynamic modules between WMF and DMF. Scanning electron microscopy (SEM) showed that alpha-amylase affected the microstructure of the DMF. FT-IR spectra results indicated no new formation of covalent bonds in GRF-Water or GRF-Ag gels. These results suggested that endogenous alpha-amylase influenced starch hydrolysis and subsequently the viscoelastic property of GRF gels, indicating that residual endogenous alpha-amylase explains the differences in pasting and rheological properties between WMF and DMF. Image 1 • Alpha-amylase decreased the pasting viscosity of glutinous rice flour (GRF). • Damaged starch promotes hydrolysis of glutinous rice starch (GRS). • Alpha-amylase caused hydrolysis of GRS during rapid viscosity analysis test. • Alpha-amylase significantly determines the rheological properties of GRF. [ABSTRACT FROM AUTHOR]

The structural and digestive properties of wheat flour which had been treated with superheated steam were investigated. Superheated steam treatment increased the degree of gelatinization (DG) and water absorption indexes (WAI) while decreased water solubility indexes (WSI) of wheat flour samples, compared with native wheat flour. The structural properties of wheat flour were characterized using scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), particle size analyzer, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The starch granules agglomeration and denatured gluten proteins aggregation of samples were observed after treated with superheated steam. Additionally, Superheated steam treatment decreased the relative crystallinity and short-range order structure of starch. These structural changes were related to the starch digestibility. Superheated steam treatment caused the significant increase for slowly digestible starch (SDS) contents from 21.5% of native wheat flour to 35.0% of treated wheat flour (170 °C, 4 min). Additionally, the equilibrium hydrolysis concentration (C ∞) and the kinetic coefficient (k) of treated wheat flour were lower than native wheat flour, indicating that superheated steam treatment decelerated the hydrolysis rate. These results contributed to the applications of superheated steam technology in wheat flour modification. Image 1 • Structure and digestibility properties of wheat flour were studied. • Gluten aggregation of wheat flour was observed by superheated steam treatment. • Superheated steam treatment changed the structural characteristics of wheat flour. • Superheated steam treatment increased SDS and RS contents of wheat flour. [ABSTRACT FROM AUTHOR]

In this study, a starch-based nanocarrier was fabricated to allow tangeretin to avoid the disadvantages of poor aqueous solubility and weak stability. A green technique comprised of a combination of ultrasonication and recrystallization was applied, which ensured the products would be more applicable in the food, pharmaceutical, and cosmetic industries. Debranched starch (DBS) and β-cyclodextrin (β-CD) underwent ultrasonic irradiation and were self-assembled at 4 °C to form CD/DBS-nanoparticles (NPs). By developing CD/DBS-NPs with different degrees of polymerization of DBS and under varied durations of ultrasonic irradiation, the correlation between particle construction and tangeretin loading ability of CD/DBS-NPs was revealed. The maximum loading amount and loading efficiency of tangeretin in tangeretin-loaded CD/DBS-NPs (TAN@CD/DBS-NPs) were 17.91 ± 0.03 μg/mg and 83.20 ± 0.15%, respectively. Furthermore, the TAN@CD/DBS-NPs displayed a homogenous distribution and satisfying stability in a series of human microenvironments, including ionic strength (physiological saline), temperature (37 °C), and acidic stomach conditions (pH 2.1). In addition, the maximum retention index of tangeretin in TAN@CD/DBS-NPs reached 99.21 ± 0.17% after a 20-day storage period, suggesting an outstanding effectiveness of CD/DBS-NPs for tangeretin preservation. The prepared nanocarriers were demonstrated to be non-toxic to cells, showing promising potential for applications in the food, pharmaceutical, and cosmetic industries. Image 1 • β-cyclodextrin/debranched starch nanoparticles (CD/DBS-NPs) were fabricated. • Ultrasonication showed crucial impacts on physical properties of CD/DBS-NPs. • CD/DBS-NPs displayed superior loading amount and loading efficiency for tangeretin. • The crystalline structure influenced the stability of tangeretin-loaded CD/DBS-NPs. [ABSTRACT FROM AUTHOR]

Effect of pigskin gelatin and its hydrolysates on overall changes that frozen dough underwent during storage was investigated. The results showed that gelatin from pigskin could fortified the frozen dough bread quality, embodying in larger bread volume, softer and more uniform bread crumb. Impact of pigskin gelatin on changes in the structure of gluten network in frozen dough was evaluated by different techniques. SDS-polyacrylamide gel electrophoresis (SDS-PAGE) showed gelatin may inhibit the crosslinking of HMW macromolecules and entangle with SDS-soluble LMW proteins. The increased SDS-soluble proteins suggested a lower aggregation extent of glutenin macropolymer (GMP) caused by pigskin gelatin. However, the significant reduction in GMP depolymerization degree and thiol groups (-SH) content after 60-day frozen storage in presence of gelatin indicated the formation of a more resistant gluten structure against the distortion of ice crystals. There were no significant differences in the alteration of secondary structure and high-temperature stability between gelatin-depleted and gelatin-fortified groups. Nevertheless, the effect of pigskin gelatin on qualities of frozen dough was independent on its hydrolysis degree. Image 1 • Gelatin from pigskin fortified the frozen dough bread quality. • Effect of pigskin gelatin on qualities of frozen dough was independent on its hydrolysis degree. • Pigskin gelatin resulted in a lower aggregation extent of glutenin macropolymer. • Gelatin inhibited the crosslinking of HMW macromolecules and entangle with SDS-soluble LMW proteins. [ABSTRACT FROM AUTHOR]

Lactic acid fermentation is a green technology to modify functionalities of food ingredients, including proteins. In this study, the commercial lactic acid bacteria (Streptococcus thermophiles and Lactobacillus bulgaricus) were used to ferment egg white for 0 h, 3 h, 6 h, and 9 h, respectively. The microbial composition significantly changed during the process, and the abundance of B. Lactobacillus peaked at 6 h. The free sulfhydryl groups of egg white proteins (EWP) gradually decreased, and the surface hydrophobicity increased from 28.7 to 52.0 after 6 h. The rheological experiments illustrated that fermented samples exhibited a lower apparent viscosity, and the sample at 6 h possessed the highest storage modulus (G '). Correspondingly, the foaming ability of egg white significantly improved from 72.3% to 93.0% after 6 h of fermentation. This study suggested that moderate lactic acid fermentation endowed egg white with stronger foaming activities, and thus had a potential to be applied in improving texture quality of egg products. Image 1 • Fermentation treatment modified surficial and structural properties of egg white proteins. • Fermented egg white exhibited a distinct rheological behavior compared to that of native sample. • Fermentation treatment could be used to enhance foaming ability of egg white proteins. [ABSTRACT FROM AUTHOR]