Whey protein isolate and inulin-glycosylated conjugate affect the physicochemical properties and oxidative stability of pomegranate seed oil emulsion.

Glycosylated protein was obtained by the reaction of whey protein isolate(WPI) with inulin of different polymerization degrees and was used to stabilize a pomegranate seed oil emulsion. The physicochemical and antioxidative properties of the emulsions were assessed, and the impacts of accelerated oxidation on pomegranate seed oil were examined. The interfacial tension of WPI and short-chain inulin (SCI)-glycosylated conjugate (WPI-SCI) gradually decreased with increasing glycosylation reaction time. Emulsions stabilized by WPI-SCI (72 h) were the most stable, with a thick interfacial film on the surface of the droplets. After accelerated oxidation for 72 h, WPI-SCI inhibited the oxidation of oil in the emulsion. GC-IMS results showed that the production of harmful volatile components in oil was inhibited, and the peroxide strength was less than 30 mmol/kg oil. This study contributes to understanding of stable storage of lipids.

Preparation, Characterization and Antioxidant Activity of Glycosylated Whey Protein Isolate/Proanthocyanidin Compounds.

A glycosylated protein/procyanidin complex was prepared by self-assembly of glycosylated whey protein isolate and proanthocyanidins (PCs). The complex was characterized through endogenous fluorescence spectroscopy, polyacrylamide gel electrophoresis, Fourier infrared spectroscopy, oil-water interfacial tension, and transmission electron microscopy. The results showed that the degree of protein aggregation could be regulated by controlling the added amount of procyanidin, and the main interaction force between glycosylated protein and PCs was hydrogen bonding or hydrophobic interaction. The optimal binding ratio of protein:PCs was 1:1 (w/w), and the solution pH was 6.0. The resulting glycosylated protein/PC compounds had a particle size of about 119 nm. They exhibited excellent antioxidant and free radical-scavenging abilities. Moreover, the thermal denaturation temperature rose to 113.33 °C. Confocal laser scanning microscopy (CLSM) images show that the emulsion maintains a thick interface layer and improves oxidation resistance with the addition of PCs, increasing the application potential in the functional food industry.

Two dimensional iron metal-organic framework nanosheet with peroxidase-mimicking activity for colorimetric detection of hypoxanthine related to shrimp freshness.

Two dimensional iron metal-organic framework nanosheet (2D Fe MOF) was facilely synthesized at room temperature by simple stirring of iron salts and terephthalic acid ligand in a mixed solution containing triethylamine. Its morphology and structure were fully characterized by TEM, AFM, XPS and TEM element mapping. Then, its peroxidase-mimicking activity was studied by using H2O2 and 3, 3', 5, 5'- tetramethylbenzidine as substrate. Km and Vmax of 2D Fe MOF towards H2O2 were 0.02 mM and 2.08 × 10-8 M s-1, respectively. Through the formation of cascade reaction between xanthine oxidase and 2D Fe MOF, a visual method for hypoxanthine (Hx) detection was constructed to evaluate aquatic products freshness. After effective validation, this method presented wide linear range (5.0-500.0 µM), low limit of detection (3.29 µM), satisfied accuracy (recovery of 94.78-99.85%), and good selectivity. By using this method, Hx content in shrimp samples at different storage time were determined.

Improving the physicochemical stability of Pickering emulsion stabilized by glycosylated whey protein isolate/cyanidin-3-glucoside to deliver curcumin.

Protein-polysaccharide-polyphenol delivery systems function as a promising tool to deliver bioactive ingredients aiming to improve their solubility and bioavailability. In this study, whey protein isolate (WPI), short-chain inulin (SCI), and cyanidin-3-glucoside (C3G) were first used to stabilize Pickering emulsions. The physicochemical properties and stability of curcumin encapsulated or not in Pickering emulsions were explored. Results showed that glycosylation and C3G reduced surface and interfacial tension on protein surfaces and inhibited the aggregation of emulsion droplets, thereby reducing the emulsion's particle size. WPI-SCI/C3G stabilized Pickering emulsion had the best stability. The CLSM results showed that the WPI-SCI and WPI-SCI/C3G stabilized emulsions were uniformly dispersed, suggesting that glycosylation and the interaction between protein and C3G enhanced the adsorption capacity of the interfacial protein and improved the stability of the Pickering emulsion. The retention rates of curcumin-loaded WPI-SCI- (67.34 %) and WPI-SCI/C3G- (77.07 %) stabilized Pickering emulsions on day 8 of storage were higher than those in WPI- (33.97 %) and WPI/C3G- (37.02 %) stabilized emulsions, and the degradation half-life was also extended from 7 days to >15 days. These findings provide a theoretical basis for the application of WPI Pickering emulsion and indicate a useful means for the delivery of bioactive components.

Metalloporphyrin and gold nanoparticles modified hollow zeolite imidazole Framework-8 with excellent peroxidase like activity for quick colorimetric determination of choline in infant formula milk powder.

Metalloporphyrin and gold nanoparticles (AuNPs) were fixed on the surface of hollow zeolite imidazole framework-8 (HZIF-8) by cation exchange and cross-linking reaction. The obtained hybrid nanozyme, Au/HZIF-8@TCPP(Fe), was fully characterized by TEM, HRTEM, EDS element mapping and XPS. Then, its peroxidase-like activity was explored with Km of 1.74 mM and Vmax of 9.60 × 10-8 M·S-1 towards H2O2, indicating excellent catalytic activity. Based on cascade reaction between choline oxidase and Au/HZIF-8@TCPP(Fe), a quick colorimetric method was established for choline detection in infant formula milk powder. After comprehensive verification, this method presented the merits of simple operation, satisfied detection limit (0.05 mM), wide linear range (0.05-2.0 mM), high accuracy (recovery of 92.2%-105.2%) and nice selectivity. This colorimetric method was applied to the determination of choline in milk powders of five brands. Our study could offer valuable reference for finding highly efficient nanozyme and constructing novel optical biosensors.

Colorimetric quantification of sodium benzoate in food by using d-amino acid oxidase and 2D metal organic framework nanosheets mediated cascade enzyme reactions.

A rapid colorimetric method for detecting sodium benzoate in food products was established based on the d-amino acid oxidase (DAAO) and 2D metal organic framework (2D MOF) nanosheets mediated cascade enzyme reactions. Firstly, the synthesized 2D MOF nanosheets served as high efficient nanozyme with outstanding peroxidase-like catalytic activity and catalyzed the color reaction between H2O2 and 3, 3', 5, 5'- tetramethylbenzidine. Secondly, sodium benzoate as a competitive inhibitor of DAAO, could influence the production of H2O2 in DAAO mediated oxidation reaction. After a combination of those two reactions, this colorimetric quantitative method was constructed and validated for sodium benzoate determination with wide linear range (2.0-200.0 µM), low limit of detection (2.0 µM), high accuracy (recovery rate in 95.80-108.00%) and satisfied selectivity. Lastly, this method was utilized to analyze sodium benzoate concentration in juice, wine and vinegar by naked eyes.

Ultrasmall Au nanoparticles modified 2D metalloporphyrinic metal-organic framework nanosheets with high peroxidase-like activity for colorimetric detection of organophosphorus pesticides.

Ultrasmall Au nanoparticles (UsAuNPs) in the size range of 4.0-7.0 nm was successfully immobilized on the surface of 2D metalloporphyrinic metal-organic framework nanosheets (2D MOF). Firstly, The obtained hybrid nanomaterial, UsAuNPs/2D MOF, was fully characterized by TEM, HRTEM, element mapping images and XPS. Then, the peroxidase-like activity of UsAuNPs/2D MOF was comparatively studied with other hybrid nanozyme to explore the influence of AuNPs size on peroxidase-like activity. Further, UsAuNPs/2D MOF with outstanding peroxidase-like activity was selected to form ternary cascade enzyme reaction with acetylcholinesterase (AChE) and choline oxidase (ChOx). Based on the inhibitory effect of organophosphorus pesticides on AChE, a fast and sensitive colorimetric method was established for trichlorfon detection with the advantages of simple operation, low detection limit (1.7 µM), good linear range (1.7-42.4 µM) and high accuracy (recovery rate of 96.6-105.3%). Finally, this method was applied to visual analysis of trichlorfon concentration in tomatoes, cucumbers and eggplants.

A glycated whey protein isolate-epigallocatechin gallate nanocomplex enhances the stability of emulsion delivery of ß-carotene during simulated digestion.

A glycated whey protein isolate-epigallocatechin gallate (EGCG) nanocomplex-stabilized emulsion was used to encapsulate ß-carotene. This study evaluated the stability of the emulsion in different environments and assessed its protective effect on ß-carotene. The active compound-loaded emulsion was subjected to in vitro simulated digestion. The results show that the glycated whey protein isolate-EGCG nanocomplex-stabilized emulsion has greater storage, salt ion, and thermal stability than the whey protein isolate-EGCG nanocomplex. Moreover, the emulsion exerts a considerable inhibitory effect on the degradation of the active compounds. However, the strong hydrolysis of the protein by pancreatin prevents the emulsion from surviving in the intestinal fluid, and the speed and degree of lipolysis is faster and more intense than that of naked medium-chain triglyceride (MCT). This study provides useful information for the application of natural hydrophobic active ingredients to water-soluble edible protein emulsion systems in food and drug delivery.

The Addition of α-cyclodextrin and γ-cyclodextrin Affect Quality of Dough and Prebaked Bread During Frozen Storage.

The effects of the addition of 0-3.0 wt% α-cyclodextrin (α-CD) and γ-cyclodextrin (γ-CD) on the quality of wheat flour as well as the texture and the aging of prebaked bread were evaluated. The addition of α-CD and γ-CD increased the ability of wheat flour to absorb water and shortened the times of dough formation and stabilization. Amylase activity slightly increased after using 2.0 and 3.0 wt% of α-CD and γ-CD, respectively. Moreover, the addition of α-CD and γ-CD increased the fermentation height and gas retention ability of dough. Dough samples containing 2.0 wt% α-CD and 3.0 wt% γ-CD showed the highest fermentation heights and gas retention volumes, respectively. Dough gas production increased with the addition of γ-CD. Gas production by dough samples containing more than 2.0 wt% α-CD exceeded that by samples in the control group. The results of the texture crumb of bread and specific volume tests revealed that the addition of 2.0 wt% α-CD and 3.0 wt% γ-CD reduced bread hardness and increased bread elasticity, resilience, and specific volume. The optimal α-CD and γ-CD contents were identified as 2.0 wt% and 3.0 wt%, respectively. The addition of 2.0 wt% α-CD and 3.0 wt% γ-CD delayed the aging of prebaked bread and reduced the hardness of prebaked bread during different weeks of storage, which may be due to decreasing the melting enthalpy of starch crystals. This work elucidated the mechanisms underlying the effects of CD addition on prebaked bread quality.

Maillard-Reacted Whey Protein Isolates and Epigallocatechin Gallate Complex Enhance the Thermal Stability of the Pickering Emulsion Delivery of Curcumin.

In this study, whey protein isolates (WPI), lactose (Lac) Maillard-reacted products, and epigallocatechin gallate (EGCG) complex were used to enhance the thermal stability of the Pickering emulsion delivery of curcumin. Atomic force microscopy combined with Fourier transform infrared spectroscopy were employed to study the morphological characteristics and structural changes of WPI-Lac/EGCG nanoparticles. Results proved that WPI-Lac and EGCG were combined by hydrogen bonding and hydrophobic interaction. The mechanism underlying WPI-Lac/EGCG-stabilized Pickering emulsion was further characterized by confocal laser scanning microscopy. The optimal binding ratio of WPI-Lac to EGCG was 1:1 (w/w) at pH 3.0. The particle size and zeta potential of the WPI-Lac/EGCG nanoparticles were about 110 nm and 27 mV, respectively. Analysis of microstructure and droplet size distribution revealed that the glycated WPI-Lac/EGCG-stabilized emulsions exhibited more uniform droplet distribution, stronger thermal stability, and higher curcumin percentage retention than WPI. These results indicate that the WPI-Lac/EGCG nanoparticles are potential stabilizers for Pickering emulsion requirements. This study provides a basis for the construction of Pickering emulsion systems while carrying pro-/hydrophobic bioactive components.

Maillard-Reacted Whey Protein Isolates Enhance Thermal Stability of Anthocyanins over a Wide pH Range.

The poor thermal and acid stabilities of anthocyanins greatly limit their industrial applications as functional food ingredients. This work investigated the ability of the Maillard reaction products (MRPs) of whey protein isolates and glucose to enhance the thermal stability of anthocyanins over the pH range of 2.0-7.0. Anthocyanin dispersions were subjected to up to 120 min of thermal treatment at 80 °C. The improvement in the color stability and antioxidant capacity of the anthocyanin dispersions indicated that MRP remarkably inhibited anthocyanin degradation. Fluorescence spectroscopy results suggested that anthocyanins and MRPs form complexes through hydrophobic interactions. These complexes effectively attenuated anthocyanin degradation under heat treatment at pH 6.0. The particle sizes of MRPs alone or in complex with anthocyanins remained unchanged after heating. The novel protein delivery system proposed in this study expands the applications of anthocyanins as acid- and heat-stable functional food ingredients.

Maillard-Reaction-Functionalized Egg Ovalbumin Stabilizes Oil Nanoemulsions.

Egg white proteins are an excellent source of nutrition, with high biological and technological values. However, their limited functional properties prevent their widespread industrial applications. In this study, the ovalbumin functionality was improved via glycation by Maillard reaction with d-lactose. The free amino groups and sodium dodecyl sulfate-polyacrylamide gel electrophoresis profile were determined, confirming that glycation occurred between ovalbumin and lactose. The emulsification of the conjugate was 2.69-fold higher than that of ovalbumin at pH 7.0 after glycation. The thermal stability also improved remarkably. The glycated protein products were used to form an oil-water nanoemulsion for polymethoxyflavone-rich aged orange peel oil. The resulting nanoemulsion showed good pH, thermal, and storage stabilities.

Effect of the A-Type Linkage on the Pharmacokinetics and Intestinal Metabolism of Litchi Pericarp Oligomeric Procyanidins.

The bioavailability of A-type procyanidins in vivo has been rarely investigated; as such, this study discusses the effect of A-type linkage and degree of polymerization on the metabolism of procyanidins extracted from litchi pericarp (LPOPC). Sprague-Dawley rats were gavaged with (-)-epicatechin (EC) and LPOPC and sacrificed at different time points after ingestion. A-type linkage procyanidin oligomers inhibited the absorption of EC. Analysis of urinary contents from rats administered with EC, A-type procyanidin dimer (A-2), and A-type procyanidin trimer (A-3) showed distinct native and metabolite profiles for each rat. Rats fed with A-2 and A-3 presented significantly higher levels of shikimic acid and less amount of m(p)-coumaric acid metabolites in vivo and provide insight into the quantitative structure-activity relationship of procyanidin oligomers during metabolism, indicating that procyanidins with A-type linkage could induce an altered metabolic pathway of oligomers in the gastrointestinal system.