Combination of enzymatically hydrolyzed potato powder with skimmed milk powder on the quality improvements of yogurt during refrigeration storage.

This study aimed to prepare a stirred type of fat-free yogurt from enzymatically hydrolyzed potato powder (EHPP) and skimmed milk powder (SMP) without changing its quality and consumer acceptance. The yogurt formulations prepared contained different amount of EHPP 0, 10, 25 and 50% and were stored for 28 days at 4 °C and observed that with increasing substitution ratio, acid production was increased while the viability of lactic acid bacteria was decreased after 28 days of storage at 4 °C. The antioxidant activities (2-Diphenyl-1-picryl-hydrazyl (DPPH) free radical scavenging activity and ferric reducing antioxidant power (FRAP) of the yogurt were increased with increasing EHPP over the storage period. The yogurt formulations having 25 to 50% EHPP has the highest DPPH free radical scavenging activity and FRAP values. Water holding capacity (WHC) was decreased over the storage period with 25% EHPP. The hardness, adhesiveness and gumminess were decreased while no significant change was found in springiness with EHPP addition over the storage period. The rheological analysis showed an elastic behavior of yogurt gels with EHPP supplementation. The sensory results of yogurt containing 25% EHPP have the highest values of taste and acceptance. Yogurt in combination with EHPP and SMP has the higher levels of WHC than non-supplemented yogurt and better stability was recorded during storage. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05737-9.

Formulation and characterization of yogurt prepared with enzymatically hydrolyzed potato powder and whole milk powder.

This study highlights the optimization of a suitable amount of enzymatically hydrolyzed potato powder (EHPP) with whole milk powder (WMP) to produce a quality yogurt. The yogurt was prepared with different levels of EHPP (0, 10, 15, 20, 25, 35 and 50% w/w) with WMP and evaluated after 24 h at 4 °C. The resulted product was analyzed on the basis of physicochemical, sensory, texture, antioxidant activity and microbiological analysis. The prepared yogurt showed a significant (p < 0.05) decrease in pH, protein and fat while acidity, moisture and ash contents were increased compared with control yogurt. In addition, textural parameters like hardness and adhesiveness were decreased while no significant (p < 0.05) change was found in springiness and cohesiveness. Moreover, color parameters such as L * and a * values decreased while b * values were increased. The current study suggested that the yogurt sample supplemented with 25% EHPP of WMP certainly improved the physicochemical, texture, microstructure, color, antioxidant and sensory properties of yogurt with EHPP. The prepared yogurt with EHPP provided an excellent flavor, satisfying sweetness, and homogeneous texture. The yogurt prepared from the EHPP presented potential industrial applications. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13197-021-05112-6.

Effects of the Mixture of Xylooligosaccharides and Egg White Protein on the Physicochemical Properties, Conformation, and Gel-Forming Ability of Culter alburnus Myofibrillar Protein during Multiple Freeze-Thaw Cycles.

This study focuses on the effect of the mixture (XO/EW) of xylooligosaccharides (XO) and egg white protein (EW) on the physicochemical properties, conformation, and gel-forming ability of Culter alburnus myofibrillar proteins (MP) during multiple freeze-thaw (FT) cycles. In our methodology, MP samples added with EW, XO, or XO/EW mixture (1%, v/v) are prepared, and after multiple FT cycles, the XO or XO/EW-treated samples show significant (p < 0.05) inhibition on the decrease of sulfhydryl content and the increase of carbonyl content of MP. Compared with EW, XO or XO/EW could delay the increase of surface hydrophobicity and the decline of secondary and tertiary structural properties of MP, indicating that XO or XO/EW could more effectively increase the stability of MP conformation. Meanwhile, XO/EW could more effectively reduce the decrease of gel strength and gel water holding capacity, and the increase in the T2 relaxation time of MP gel, confirming that XO/EW could substantially improve the MP gel-forming ability. Analysis of intermolecular interaction force proves that, compared with EW, XO/EW could reduce the content decrease of ionic and hydrogen bonds in MP gel. Overall, XO/EW could improve the stability of MP functional properties over multiple FT cycles. This study provides a new perspective for the potential commercial application of EW as a low-calorie cryoprotectant in aquatic products.

Effects of dynamic high-pressure microfluidization treatment on the functional and structural properties of potato protein isolate and its complex with chitosan.

In our previous work, dynamic high-pressure microfluidization (DHPM) treatment was shown to promote the interaction between chitosan (CS) and potato protein isolate (PPI), but the modification mechanism of DHPM treatment (6 k-12 k psi) on PPI and its complex with CS remains to be elucidated. Here, moderate DHPM treatment (≤9k psi) was found to decrease the particle size, increase the surface charge, and improve the solubility of PPI and its emulsifying and foaming properties. The PPI functional properties were further improved by CS addition followed by DHPM treatment. The ultraviolet and fluorescence spectral results showed that DHPM treatment could destroy the PPI molecularstructure, while CS addition could provide a protective mechanism against PPI damage, which was also proved by the surface hydrophobicity. The circular dichroism spectral analysis exhibited that DHPM treatment could convert different types of secondary structures by disrupting the PPI intermolecular hydrogen bonds, while CS addition could promote the formation of hydrogen bonds in the system, which was also demonstrated by infrared spectroscopy. The sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) results exhibited that DHPM treatment (≤12 k psi) was not sufficient to reduce the PPI molecular mass, while DHPM treatment (6 k-12 k psi) could destroy the structure of CS/PPI complex. The thermodynamic analysis showed that the PPI thermodynamic stability could be improved by DHPM treatment, but decreased by CS addition plus DHPM treatment. These results showed that DHPM treatment has a good potential to modify the PPI and CS/PPI complex.

Influence of the Mixture of Carrageenan Oligosaccharides and Egg White Protein on the Gelation Properties of Culter alburnus Myofibrillar Protein under Repeated Freezing-Thawing Cycles.

This study aims to investigate the influence of the mixture (CGO/EWP) of carrageenan oligosaccharide (CGO) and egg white protein (EWP) (CGO/EWP, CGO: EWP = 1:1, m/m) on the functional, structural, and gelling properties of Culter alburnus myofibrillar protein (MP) during repeated freezing-thawing cycles by treating MP samples separately with EWP, CGO, or CGO/EWP based on the wet weight (1%, m/m), using samples without any cryoprotectant as the blank group. After the second repeated freezing-thawing cycle, the sulfhydryl group content was found to be significantly (p < 0.05) higher in the CGO/EWP (30.57 nmol/mg) and CGO (36.14 nmol/mg) groups than in the EWP group (23.80 nmol/mg), indicating that CGO/EWP and CGO can more effectively delay the oxidative deterioration of functional groups. Additionally, the surface hydrophobicity was shown to be significantly lower in the CGO (25.74) and CGO/EWP (27.46) groups than in the EWP (34.66) and blank (39.32) groups. Moreover, the α-helix content was higher in the CGO (35.2%) and CGO/EWP (32.3%) groups than in the EWP (29.2%) and blank (25.0%) groups. These data indicated that CGO and CGO/EWP could more effectively increase the structural stability, thereby inhibiting the exposure of hydrophobic groups and curbing the decline of α-helix content. During the heat-induced gel-forming process, EWP and CGO/EWP could enhance the gel viscoelasticity and strength. After the second freezing-thawing cycle, when compared with the blank group, the CGO/EWP group showed significantly (p < 0.05) higher water-holding capacity (66.30% versus 53.93%) and shorter T22 relaxation time (413.56 versus 474.99 ms). The integrated results indicated that CGO/EWP could more effectively delay the decrease of protein-water molecular interaction forces in the MP gel. This study shed light on the mechanism of CGO/EWP as a cryoprotective mixture in improving the deterioration of MP gelation properties during repeated freezing-thawing cycles.

Investigating the structure and self-assembly behavior of starch-g-VAc in starch-based adhesive by combining NMR analysis and multi-scale simulation.

This work investigated the structure and self-assembly behavior of grafted starch (GS) prepared by grafting vinyl acetate (VAc) on the starch molecule. Our preliminary structure characterization, NMR, and quantum mechanical simulation demonstrated the C2 of the glucose unit as the main grafting site. The grafting frequency and chain length (starch, VAc) were calculated based on the result of gel permeation chromatography. Molecular dynamics simulation showed that, when compared with native starch, GS had less hydrogen bonding interaction, lower orderness, and higher extensibility, which were supported by the experimental results. In dissipative particle dynamics simulation, GS was shown to self-assemble into a core-shell structure (latex) and form a bridge structure with cross-linking interaction. The overall results indicate that chain entanglement and hydrogen bonding interaction of starch play a significant role in adhesive curing. This research provides a novel insight into the grafting and molecular interaction mechanism in the GS adhesive system.

Effects of oxidative modification on the functional, conformational and gelling properties of myofibrillar proteins from Culter alburnus.

Protein oxidation is a critical process in the deterioration and spoilage of fish and related commodities during processing and storage. In this study, the hydroxyl radical generation system (HRGS) was used to simulate the effect of oxidation on the functional, conformational and gelling properties of topmouth culter (Culter alburnus) myofibrillar proteins (MP). Additionally, the effects of oxidation on the gel-forming abilities of MP were also systematically analyzed from the perspective of intermolecular interaction forces. Oxidation was shown to decrease the total sulfhydryl content, increase the surface hydrophobicity, and induce conformational changes in MP. Rheological analysis showed that oxidation reduced the gel strength. Water holding capacity (WHC) and low-field nuclear magnetic resonance (LF-NMR) analyses showed that low oxidation could enhance water binding of protein matrix, while high-degree oxidation could substantially reduce the gelling properties of MP. The selective solubility of MP gel proved that oxidation could reduce the content of ionic and hydrogen bonds and increase hydrophobic interactions. All the results indicate that oxidation could alter the intermolecular interactions between protein-protein and protein-water molecules, due to irregular unfolding and inhibition of the cross-linking of amino acid side chains, leading to reduction in the quality and function of fish and related products.

An approach for compatibilization of the starch with poly(lactic acid) and ethylene-vinyl acetate-glycidyl-methacrylate.

In this study, we evaluated the possibility of dimethyldidodecylammonium bromide (DDAB)-modified graphene oxide quantum dots (DDAB-GOQDs) as a new compatibilizer to improve the compatibility of hydrophilic starch with hydrophobic polylactic acid (PLA) and ethylene-vinyl acetate-glycidylmethacrylate (EVA-GMA). The successful synthesis of DDAB-GOQDs was verified by Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and Zeta-Plus assay. The differential scanning calorimetry (DSC), polarized light optical microscopy (POM) and iso-thermal crystallization kinetics analysis showed that 0.25% DDAB-GOQDs could significantly increase the crystallization rate and nucleation density as well as reduce the spherulites size of the nanocomposites. Compared to pure composites, the nanocomposites containing 0.25% DDAB-GOQDs showed obvious enhancement in thermal stability and surface hydrophobicity, with an increase of ~22 °C and ~24.1° in the maximum decomposition temperature and contact angle, coupled with similar improvement in the storage modulus and UV-shielding capacity. Morphological analysis, FTIR and creep behavior experiments revealed that adding 0.25% DDAB-GOQDs enhanced the interface compatibility of the nanocomposites by promoting the formation of the interpenetrated network through strong polar hydrogen bond or electrostatic force within the polymeric components. Overall, (0.25%) DDAB-GOQDs can serve as an effective compatibilizer for the PLA/starch/EVA-GMA system due to improved crystallization, thermal stability, barrier properties and creep-resistance.

Cryoprotective effect of egg white proteins and xylooligosaccharides mixture on oxidative and structural changes in myofibrillar proteins of Culter alburnus during frozen storage.

The purpose of this research was to investigate the cryoprotective role of EWP-XO in the prevention of oxidative and structural changes in the myofibrillar proteins (MPs). Different concentrations of egg white protein and xylooligosaccharide (EWP-XO) mixture (0, 2, 4 and 6%) were added to the MPs of Culter alburnus fish during frozen storage (-18 °C) of 60 days. During the study, it was observed that EWP-XO significantly (P < .05) reduced the Ca-ATPase activity, which is greatly related with tertiary structural changes. Meanwhile, carbonyl contents of MPs increased in line with frozen storage (control samples). Meanwhile, samples treated with 6% EWP-XO showed less increase in carbonyl content indicating the decreased protein oxidation. The addition of EWP-XO efficiently inhibited the decline in the sulfhydryl contents. Furthermore, through circular dichroism analysis it was confirmed that the addition of EWP-XO increased the secondary structural stability by preventing the reduction in α-helix content. Microstructural analysis confirmed the preservation of a well-structured protein network that reduced the porosity and protein aggregation of MPs gel. It was concluded that 6% EWP-XO was an effective cryoprotectant mixture, which preserved the functional and structural properties of Culter alburnus during 60 days of frozen storage period.

Establishing a diagnostic scale of subacute thyroiditis without radioisotope scanning.

BACKGROUND: Radioisotope scanning is important to diagnose subacute thyroiditis (SAT), but it's not always available. So we aim to establish a diagnostic scale for SAT without radioisotope scanning. METHODS: The suspected SAT patients hospitalized in Yuebei people's Hospital from January 2012 to December 2016 were selected and divided into study group and control group according to whether they were diagnosed as SAT. The clinical indexes of two groups were collected and the diagnostic scale of SAT was established by using binary logistic regression analysis. The effectiveness of the scale was evaluated by ROC curve. RESULTS: Of 309 patients, 58.25% of patients were confirmed with SAT and the remaining 41.75% of patients were not diagnosed with SAT. After univariate analysis, variables which were considered statistically different(P < 0. 05) between the two groups were selected as independent variables and the diagnosis of SAT was taken as dependent variable in the binary logistic regression model. The logistic regression model consisted of 4 variables, each was thyroid tenderness, firm on palpation, increased ESR and elevated thyroid hormone level. The P value of Omnibus tests was≤0. 001 and the Nagelkerke R Square was 0. 915. The diagnostic scoring scale was established with these four variables according to their regression coefficient. The area under the ROC curve for this diagnostic scale was 0. 991(95% confidence interval, 0. 982-0.999). The highest Youden index was 0. 912, the corresponding cut-off point was 7. Internally validation shows a sensitivity of 92. 78% and a specificity of 98.45% of our scale. CONCLUSIONS: We established and validated a diagnostic scale for SAT without the need for radioisotope scanning for the first time. It has good application in institutions that do not have radioisotope machines or among pregnant and lactating women.

Effects of granule size on physicochemical and digestive properties of potato powder.

BACKGROUND: Potato powder, a rich source of high-quality protein and starch, plays an important role in the production of functional foods. In this study, ball-mill processed potato powders with different particle sizes (278, 208, 129, and 62 µm) were analyzed in terms of physicochemical, pasting, rheological, and digestive properties. RESULTS: Scanning electron microscopy and laser diffraction analysis of the samples revealed mono-model particle-size distributions. X-ray diffraction analysis confirmed structure destruction of starch pellets. Proximate composition and physical property analysis showed an increase in the water, ash, protein, and starch content. Meanwhile, the water solubility index and swelling power values were found to increase with decreasing grain size, and so were the brightness (L*) and redness (b*) values of the potato powders. With particle size reduced to 129 µm, large changes were observed in gelatinization properties, such as peak viscosity, trough viscosity, breakdown viscosity, and final viscosity. Oscillatory rheology results also showed that, with the decrease in particle size, the storage modulus (G') and loss modulus (G″) improved, with highest storage modulus (G') observed in the 129 µm particle size. The hydrolysis rate and glycemic index also increased in the 129 µm potato powder. CONCLUSION: The results provide information that could be useful for improving quality characteristics by using specific grain sizes in the development of potato-based products such as gluten-free products and ethnic food products with particular functional and rheological properties. © 2020 Society of Chemical Industry.

The formation mechanism and thermodynamic properties of potato protein isolate-chitosan complex under dynamic high-pressure microfluidization (DHPM) treatment.

The objective of the study was to explore the formation mechanism and thermodynamic properties of chitosan (CS)-potato protein isolate (PPI) complex under DHPM treatment. The transmission electron microscopic (TEM) results showed the formation of a complex between CS and PPI. Meanwhile, particle size and zeta-potential were shown to increase with increasing CS concentration, further confirming the formation of the complex. The surface hydrophobicity results showed CS was bound to PPI by hydrogen bond. The ultraviolet and fluorescence spectral analysis exhibited CS formed a protective mechanism against PPI destruction, preventing the exposure of tyrosine and tryptophan residues. Infrared spectrum and circular dichroism spectral analysis revealed no occurrence of chemical reaction between CS and PPI under DHPM treatment, further indicating that they are bound by hydrogen bond and hydrophobic interaction. Moreover, CS addition was shown to enhance the intermolecular interaction and promote the formation of intermolecular hydrogen bond network. Differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA) revealed that CS addition could improve the thermal stability of PPI. These results have shed light on the formation mechanism and thermodynamic properties of the CS/PPI complex and facilitate its application in food industry.

The impact of hydrophilic emulsifiers on the physico-chemical properties, microstructure, water distribution and in vitro digestibility of proteins in fried snacks based on fish meat.

The present study was aimed at investigating the effect of ionic and non-ionic emulsifiers at 3 different levels of 0.15, 0.30 and 0.45% per 100 g of flour on the physico-chemical properties, microstructure and water distribution of fish-meat based fried snacks. The results showed that the addition of distilled mono-glycerides (DMG) decreased the strength of the starch-protein network which resulted in increased expansion and decreased water holding capacity (WHC). The addition of diacetyl tartaric acid esters of mono-glycerides (DATEM) increased the WHC and the ordered structure between starch and proteins while oil uptake was decreased. Pasting properties such as breakdown, peak viscosity and pasting temperatures were increased with the addition of DATEM compared to DMG and the control indicating the strong interaction among DATEM, starch and proteins. Scanning electron microscopy (SEM) analysis showed that DATEM strengthened the starch-protein matrix and the dense and rigid microstructure with fewer voids while DMG increased the intercellular spaces between the molecules of starch and proteins. Low field nuclear magnetic resonance (LF-NMR) relaxometry analysis revealed that the amount of free water (T21) was decreased and that of bound water (T23) was increased in DATEM samples indicating the strong interaction between emulsifiers and macromolecules compared to the control and DMG. Moreover, protein in vitro digestibility was also increased with the addition of DATEM. The findings suggested that 0.30% DATEM can be used in snacks with improved physico-chemical and functional properties.

Sodium dodecyl sulfate improves the properties of bio-based wood adhesive derived from micronized starch: Microstructure and rheological behaviors.

Enhancing the performance of starch-based wood adhesive is vitally important for its practical applications. Accordingly, we designed the use of micronized starch (MS) to prepare micronized starch-based wood adhesive (MSWA) by incorporating 0, 2, 4 and 6% (w/w, dry basis starch) sodium dodecyl sulfate (SDS). The results showed that 2% SDS exhibited remarkable improvement in shear strength and viscosity of MSWA. The grafted reaction was demonstrated by 1H NMR and the steady shear results indicated that the adhesive possessed a pseudoplastic behavior under yield stress conditions. Besides, dynamic rheological measurements were applied to evaluate the structure of MSWA under varying frequencies, temperatures and constant stain. The transmission electron microscopy (TEM), Zeta potential and surface tension indicated that SDS could improve the surficial properties. Meanwhile, the microstructure of adhesive films and fracture surfaces of glued wood veneers by scanning electron microscopy (SEM) demonstrated that the migration of SDS led to the formation of surfactant layer. Furthermore, element analysis revealed the distribution of S/N in latex slices. The results of this study provide the detailed information about the influence of SDS on the rheological properties and microstructures of MSWA, which may facilitate the preparation of high performance bio-based adhesive for wood applications.

A combination of coarse-grain molecular dynamics to investigate the effects of sodium dodecyl sulfate on grafted reaction of starch-based adhesive.

Graft copolymerization is a challenging step in preparation of starch-based adhesive due to the complexity and instantaneity. A combination of both experimental and simulation methodology has been employed to investigate the process at microscopic level. Through a series of characterizations of adhesives and copolymers with different SDS (sodium dodecyl sulfate) contents, 2% (w/w, 2g SDS/100 g starch) SDS demonstrated outstanding balance between the starch grafted percentage and interfacial properties. The coarse-grain molecular dynamics (CGMD) was utilized to reveal the molecular distribution and migratory mechanisms during the reaction by calculating radius distribution function (RDF) and mean square displacement (MSD). Starch chains covering the monomers surface was found to exhibit longer radius of gyration (Rg). Furthermore, the interfacial models were constructed in this study, and interfacial tension between water and VAc beads was calculated to confirm the improvement in interfacial properties and the rationality of simulation with the addition of SDS.

Evaluation of physicochemical, textural and sensory quality characteristics of red fish meat-based fried snacks.

BACKGROUND: Red fish meat (a by-product of fillet processing from grass carp) is a rich source of good-quality protein, which makes it an important candidate for the production of functional foods. In this study, wheat flour was replaced with red fish meat (RFM) leftover from grass carp fillet frames at different levels (100-300 g kg-1 ) in fried snacks on a laboratory scale. The quality characteristics, physicochemical properties and sensory acceptability of the fried snacks were assessed. RESULTS: The addition of RFM significantly (P < 0.05) increased protein, fat, moisture and ash contents, while texture (breakage force) was improved. Expansion and water hydration capacity were decreased with increasing content of RFM. Lightness (L*) was increased whereas redness (a*) and yellowness (b*) were decreased with the addition of RFM. Scanning electron microscopy showed that the protein matrix was increased and fewer starch granules were found when RFM was added. Moreover, in vitro protein digestibility was also increased in samples prepared with RFM compared with the control. Furthermore, essential amino acids (lysine, leucine, threonine and methionine) increased (1.2-fold compared with the control) with increasing RFM content. CONCLUSION: The results suggested that red fish meat can be used to make a new snack product with improved nutritional value and textural properties. © 2019 Society of Chemical Industry.

Effects of nano-TiO2 on bonding performance, structure stability and film-forming properties of starch-g-VAc based wood adhesive.

The nano-TiO2 was utilized to improve the bonding performance, structure stability and film-forming properties of renewable starch-based wood adhesive. The results showed that 4% nano-TiO2 (nano-TiO2:starch, w;w) resulted in 6.5 MPa of shear strength and 6437 Pa.s of viscosity. The thermal stability was measured by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Additionally, low-field nuclear magnetic resonance (NMR) and rheological results exhibited the enhancement of nano-TiO2 on the pseudoplasticity and structure which determined the state and migration of water. Besides, the structural characterization of copolymer was analyzed via fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD). Furthermore, the film-forming property was evaluated by small angle X-ray scattering (SAXS) and dynamic mechanical analysis (DMA). The morphological structures of adhesive were observed by scanning electron microscopy (SEM). In conclusion, the 4% nano-TiO2 (nano-TiO2:starch, w;w) can be employed to prepare starch-based wood adhesives with superior properties for wood application.

Effects of site-specific phosphorylation on the mechanical properties of ovalbumin-based hydrogels.

An efficient one-step grafting approach was developed to modify ovalbumin (OVA) by phosphorylation through selective reaction with the hydroxyl group of Ser and Thr residues present in OVA. The site-specific phosphorylated conjugates were characterized by Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF/MS) and the results indicated that the Ser residue could be more readily phosphorylated, and the typical phosphopeptides 264LTEWTSSNVMEER276 and 340EVVGSAEAGVDAASVSEEFR359 demonstrated the formation of monophosphoester. Moreover, 13C NMR analysis showed that the ßCH2 of Ser acted as a hydroxyl donor to react with sodium tripolyphosphate (STPP), and the conjugates with variable phosphorylation sites could improve the weak network and the resulting poor mechanical properties of ovalbumin-based hydrogels. Furthermore, small-amplitude oscillatory measurements, creep recovery tests and texture profile analysis of hardness and stickiness indicated that phosphorylation can strengthen the intermolecular cross-linking of protein molecules and produce significant influence on the rheological behavior and texture properties, suggesting that a suitable conjugation site is essential for the best gelation properties at a different pH. The integrated results indicate that phosphorylation change significantly modify the viscoelastic and mechanical properties of OVA-based hydrogels by changing molecular dynamics upon heating.

Enhanced ovalbumin stability at oil-water interface by phosphorylation and identification of phosphorylation site using MALDI-TOF mass spectrometry.

To improve the interfacial properties, a phosphorylation modification of OVA was performed through dry-heating at three different pH values (5.0, 7.0 and 9.0) in the presence of sodium tripolyphosphate. X-ray photoelectron and Raman spectroscopies confirmed that phosphate groups were successfully grafted onto the ovalbumin backbone through covalent interaction to form OP bond. Additionally, 23, 21 and 18 phosphorylation sites were identified in the OVA that had been phosphorylated at pH 5.0, 7.0 and 9.0 (P-OVA5, P-OVA7 and P-OVA9) respectively by MALDI-TOF mass spectroscopy. More phosphorylated peptides and possible phosphorylation sites were found here than in previous studies with the reaction time reduced to 12h. As a result, the iso-electric point (pI) of P-OVA shifted to lower pH, improving the stability of the P-OVA-included system over a wider pH range. The dynamic interfacial tension, which depends on the phosphorylation-induced conformational change, was explored by Fourier-transform Raman and circular dichroism spectroscopies, and the equilibrium interfacial tension decreased from 17.359mNm-1 for natural OVA (N-OVA) to 15.969mNm-1 for P-OVA9. Furthermore, P-OVA was applied to O/W emulsions, resulting in a narrower size distribution with a smaller particle size in P-OVA-stabilized emulsions than in N-OVA-stabilized emulsions. The increase rate of mean particle diameter after 60-min storage decreased from 72.37% for N-OVA to 7.97% for P-OVA5, implying a significant improvement of emulsion stability by preventing aggregation and coalescence. The results from this work demonstrated that the natural biopolymer can be applied to O/W emulsions by enhancing interfacial properties with phosphorylation.

Glucagon-like peptide-1 inhibits the receptor for advanced glycation endproducts to prevent podocyte apoptosis induced by advanced oxidative protein products.

OBJECTIVE: To investigate whether and how glucagon-like peptide-1 (GLP-1) can protect podocytes from apoptosis induced by advanced oxidative protein products (AOPPs). METHODS: Murine podocytes were stimulated with 200 µg/ml AOPP for 48 h in the presence or absence of GLP-1. Cell viability was assessed using the cell counting kit-8 assay. Podocyte apoptosis was detected by flow cytometry and Hoechst 33258 staining. Superoxide radical production was assayed using lucigenin-enhanced chemiluminescence, and Western blotting was used to measure expression of RAGE, NADPH oxidase subunits p47phox and gp91phox, as well as apoptosis-associated proteins p53, Bax, Bcl-2 and caspase-3. RESULTS: Incubating podocytes with AOPPs reduced cell viability, triggered changes in cell morphology and promoted apoptosis. GLP-1 partially inhibited AOPP-induced apoptosis, O2- overproduction, and AOPP-induced expression of RAGE. GLP-1 inhibited expression of p47phox and gp91phox in AOPP-treated podocytes, and it attenuated AOPP-induced expression of p53, Bax and cleaved caspase-3, whereas it restored expression of Bcl-2. CONCLUSION: GLP-1 partially inhibits AOPP-induced apoptosis in podocytes, perhaps by interfering with the AOPP-RAGE axis, decreasing oxidative stress and inhibiting the downstream p53/Bax/caspase-3 apoptotic pathway. GLP-1 may be a useful anti-apoptotic agent for early intervention in diabetic nephropathy.