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Green emitting copper nanoclusters (G-Cu NCs), yellow emitting Cu NCs (Y-Cu NCs), orange emitting Cu NCs (O-Cu NCs) and red emitting Cu NCs (R-Cu NCs) were prepared using chicken egg white as the stabilizer by changing the reaction conditions. This is a green, facile and cheap method to explore different color emitting CuNCs by the same precursor and stabilizers. The G-Cu NCs were employed for the detection of ethanol due to their aggregation induced emission enhancement (AIEE) effect. The fluorescence emission of Cu NCs at 526 nm under the excitation of 444 nm can be effectively enhanced in the presence of ethanol due to AIEE effect, thus realizing the quantitative determination of ethanol content in the range 5-60%. In addition, a visual dual-emission fluorescence probe with the combination of G-Cu NCs and silicon nanoparticles (Si NPs/G-Cu NCs) was designed to evaluate ethanol content conveniently and rapidly. Desirable linear relationship is observed between ratio of fluorescence intensity (I 525 /I 441 ) and ethanol content under the excitation of 383 nm. Visible color transformation of this probe is observed in the ethanol content range 2-20%. Moreover, the ethanol sensing platforms were applied to the detection and evaluation of the alcohol content of liquor, and the recoveries in liquor were in the range 99.7% to 113%, broadening the applications of Cu NCs and providing a sensitive detection method for ethanol.

This study aims to optimize the ultrasound-irradiation combined pretreatment conditions to enhance the liquid egg white (LEW) foamability and investigate the changing mechanism about the physical and structural properties of LEW during the processing. Results indicated that the foamability of the LEW was increased by ultrasound-irradiation combined pretreatment to the highest value of 92.6% (irradiation dose = 33 kGy, ultrasound time = 6 min, and ultrasound power = 300 W). Three significant proteins in LEW (ovalbumin, ovotransferrin, and lysozyme) were chosen to explore the change law on their physical and structural properties. Results indicated that ultrasound-irradiation combined pretreatment increased the solubility and reduced the pH and particle size of ovalbumin and lysozyme, thus enhancing the foamability of LEW. Furthermore, the fluorescence spectra changes implied the un-folding and destruction of ovalbumin, ovotransferrin, and lysozyme during the ultrasound-irradiation combined pretreatment. Moreover, circular dichroism spectroscopy analysis revealed that the pretreatment decreased α-helix and β-sheet of the ovalbumin, ovotransferrin, and lysozyme, which bring out the improvement of LEW foamability. The present study indicated that ultrasound-irradiation combined pretreatment had the potential to be implemented to enhance the foamability of LEW., (© 2020 Institute of Food Technologists®.)

The purpose of this study was to establish a method for determining the bacteriolytic activity after separation of lysozyme-binding proteins from egg white. Lysozyme-binding proteins such as ovotransferrin and ovalbumin were separated by non-denaturing two-dimensional electrophoresis (2DE) and transferred to a membrane. The lysozyme activity of the separated and immobilized egg white proteins was assessed directly to produce a non-denaturing 3D map of the egg white proteins by incorporating an axis that combined each spot's lysozyme-activity with the non-denaturing 2DE pattern. Lysozyme-ovotransferrin and lysozyme-ovalbumin complexes could be reconstructed in vitro after the cathode end fraction containing lysozyme was added to purified ovotransferrin and ovalbumin, respectively. These complexes retained lysozyme activity even after separation by non-denaturing 2DE. Furthermore, when the lysozyme-ovotransferrin complex from egg white was extracted after separation by isoelectric focusing by replacing the cathodic sodium hydroxide solution with phosphoric acid solution, the complex possessed bacteriolytic activity against both Bacillus subtilis and Escherichia coli. These methods can be applied to investigate protein complexes possessing bacteriolytic activity against a wide range of both Gram-positive and Gram-negative bacteria., (Copyright © 2018 Elsevier B.V. All rights reserved.)

To separate and extract the native states of lysozyme from chicken egg white, a hybrid method for the mobilization of proteins after non-denaturing gel isoelectric focusing (IEF) combined with detection of lysozyme activity was developed. When the proteins in the chicken egg white were first separated using non-denaturing gel IEF, a lysozyme was obtained at the top of the gel column at the cathode end of the IEF. And, when the IEF-separated proteins of the egg white were mobilized by replacing the cathodic sodium hydroxide solution with phosphoric acid solution, an additional active state of the lysozyme that could be bound to proteins, such as ovotransferrin, was extracted from the solution. Furthermore, it was shown that the addition of lysozyme, obtained via IEF, to pure ovotransferrin generated a complex manifesting lysozyme activity, clearly indicating a successful reconstruction of the lysozyme-ovotransferrin complex in vitro. Therefore, the obtained results demonstrated that the native states of lysozymes, such as lysozyme and the lysozyme-ovotransferrin complex, can be effectively separated and extracted using non-denaturing gel IEF. Thus, this method can be applied to separate and extract different charge states of native proteins that retain their biological activities., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The aggregation of multi-proteins is of great interest in food processing and a good understanding of the formation of aggregates during PEF processing is needed for the application of the process to pasteurize protein-based foods. The aggregates formation of a multi-protein system (containing ovalbumin, ovotransferrin and lysozyme) was studied through turbidity, size exclusion chromatography and SDS-PAGE patterns for interaction studies and binding forces. Results from size exclusion chromatography indicated that there was no soluble aggregates formed during PEF processing. The existence of lysozyme was important to form insoluble aggregates in the chosen ovalbumin solution. The results of SDS-PAGE patterns indicated that lysozyme was prone to precipitate, and was relatively the higher component of aggregates. Citric acid could be effective in inhibiting lysozyme from interacting with other proteins during PEF processing. Blocking the free sulphydryl by N-ethylmaleimide (NEM) did not affect aggregation inhibition., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The objective of this study was to determine the thermodynamic parameters (Delta(tr)G, Delta(tr)H and Delta(tr)S) associated with lysozyme and conalbumin partitioning in aqueous two-phases systems (ATPS). Influence of salt type and polyethylene glycol (PEG) concentrations on the partition coefficient of lysozyme and conalbumin from egg white was studied. The evaluated ATPS were composed of PEG 1500 and inorganic salts (sodium citrate and sodium sulfate) at a temperature of 25 degrees C and pH 7.0, with PEG 1500 g mol(-1) concentrations of 14%, 16% and 18% (mass basis). Partitioning of lysozyme in PEG-citrate ATPS was enthalpically driven, however the PEG-sulfate ATPS was entropically driven. The tested systems can be employed for the separation of these two proteins in egg white, due to the fact that lysozyme migrates toward the polymeric phase and conalbumin to the saline phase in both ATPS. A high recovery of conalbumin in the saline phase of the PEG-sulfate ATPS was determined to be enthalpically driven.

Egg proteins represent one of the most important sources evoking food allergic reactions. In order to improve allergy diagnosis, purified and well-characterized proteins are needed. Although the egg white allergens Gal d 1, 2, 3 and 4 (ovomucoid, ovalbumin, ovotransferrin, and lysozyme) are commercially available, these preparations contain impurities, which affect exact in vitro diagnosis. The aim of the present study was to set up further purification protocols and to extend the characterization of the physicochemical and immunological properties of the final batches. The egg white allergens Gal d 1-4 were purified from commercial preparations, whereas Gal d 5 (alpha-livetin) was purified from egg yolk. The final batches of Gal d 1-5 consisted of a range of isoforms with defined tertiary structure. In addition, the IgE binding capacity of the purified egg allergens was tested using allergic patients' sera. The allergen batches will be further used to set up allergen specific diagnostic assays and to screen a larger collection of patients' sera.

Hen's egg white protein is a major cause of food allergy, and a considerable number of countries have introduced labeling directions for processed food products. To control compliance with these regulations, analytical assays for the detection of egg in manufactured foods have been developed. In this study, we have tested the performance of 3 commercially available kits for quantitative egg analysis using 6 model heat-processed foods. The 3 assays worked well under standard conditions with soluble egg white proteins, but only the kit using a denaturing-reducing extraction buffer detected egg in complex heat-treated food matrixes. The differently extracted food samples were further used to evaluate the stability and allergenicity of the egg white allergens ovalbumin, ovomucoid, ovotransferrin, and lysozyme with polyclonal anti-egg antibodies and sera of 6 patients with egg allergy. It could be shown that differences in egg protein extractability have a significant impact on the interpretation of study results.

Hydrophobic adsorption equilibrium data of the hen egg white proteins albumin, conalbumin, and lysozyme were obtained in batch systems, at 25 degrees C, using the Streamline Phenyl resin as adsorbent. The influence of three types of salt, NaCl, Na(2)SO(4), or (NH(4))(2)SO(4), and their concentration on the equilibrium data were evaluated. The salt Na(2)SO(4) showed the higher interaction with the studied proteins, thus favoring the adsorption of proteins by the adsorbent, even though each type of salt interacted in a distinct manner with each protein. The isotherm models of Langmuir, Langmuir exponential, and Chen and Sun were well fitted to the equilibrium data, with no significant difference being observed at the 5% level of significance. The mass transfer model applied simulated correctly adsorption kinetics of the proteins under the studied conditions.

Structural modifications of ovalbumin, ovotransferrin, and lysozyme at the air-water interface have been investigated using SDS-PAGE, both intrinsic and ANS fluorometry, and circular dichroism experiments. Ovalbumin contact with an interface induced an exposure of aromatic residues, a slight decrease in alpha-helix structures (-1.7%), and an increase in both beta-sheet (+3.4%) and beta-turn (+7.9%) structures. Moreover, these conformational changes led to the formation of insoluble polymers of ovalbumin through intermolecular disulfide bonds. Ovotransferrin contact with an interface led to an increase in its surface hydrophobicity (+30%) and modifications of its secondary structure (-33% of alpha-helices, +96.4% of beta-sheets, +13.2% of beta-turns, and +21.2% of random coils), characteristic of major conformational changes. On the other hand, lysozyme did not undergo any structural modification. These results clearly underscore that at the air-water interface proteins are susceptible to denaturation.

This article examines the separation of lysozyme from chicken egg white by ultrafiltration with 25 kDa and 50 kDa MWCO polysulfone membranes. The effects of pH, system hydrodynamics, feed concentration, and transmembrane pressure on permeate flux, lysozyme transmission, purification factor, and productivity have been discussed. With both types of membranes, higher permeate flux and lysozyme transmission were observed at higher pH. Higher lysozyme purity was generally obtained with the 25 kDa MWCO membrane. Purity of lysozyme decreased when the feed concentration was increased. With the 50 kDa MWCO membrane permeate flux, productivity and the purity of lysozyme were found to increase with increase in transmembrane pressure. The possibility of using a two-step ultrafiltration process for achieving high productivity along with high purity of lysozyme was also investigated., (Copyright 2000 John Wiley & Sons, Inc.)

The aim of this work was to test the suitability of using recycling isotachophoresis (RITP) for the purification of ovalbumin (OVA) and/or lysozyme (LYSO) from a commercial OVA product containing LYSO and conalbumin (CAL) as major proteinaceous impurities. The search for suitable electrolyte systems and spacers was carried out by capillary isotachophoresis. RITP was performed in a recycling free-flow focusing apparatus in the batch mode with immobilization of the advancing zone structure via a controlled counterflow. Typically 700 mg of the commercial product were processed within 2 h. Enhancement of the sample load was achieved by a feed of sample under counterflow control. The collected fractions were analysed separately for conductivity, pH and ultraviolet absorption, and selected fractions were characterized by analytical capillary electrophoretic methods. All three proteins could be separated and fractionated using suitable spacers. Depending on the chosen conditions either OVA or LYSO could be purified in amounts larger than milligrams per hour (OVA 300 mg/h; LYSO 10 mg/h). The instability of CAL in solution prevented its isolation in the investigated configurations.