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The effects of storage temperature (4°C, 25°C, and 35°C) on sensory quality, physicochemical properties, texture, molecular forces, flavor, and microbial indexes of preserved eggs were studied. The results showed that the sensory quality, weight loss rate, pH, and color of preserved eggs were significantly different at different storage temperatures (P < 0.05). Compared with high temperature and normal temperature storage, low temperature storage reduced weight loss rate by 55.15 and 64.1%, respectively, improved the sensory score (P < 0.05), inhibited the reduction of pH and the increase of total volatile base nitrogen (P < 0.05), and decreased the change of color (P < 0.05). During storage, there was no difference in the springiness of preserved egg white stored at different temperatures (P > 0.05). Hardness and chewiness at 3 different temperatures increased first and then decreased, and low temperature significantly inhibited the progress of these changes to a certain extent (P < 0.05). The content of ionic bond in egg white first decreased and then increased, and content of disulfide bond increased first and then decreased. Content of ionic bond in yolk decreased all the time, and high temperature could promote this change. Whatever the temperature was, the content of free amino acids in preserved egg white and yolk increased first and then decreased, and the total content of amino acids stored at different temperatures was significantly different (P

Casein is one of the main allergens in cow's milk, accounting for 80% of cow's milk proteins. The ability of hydrolyzing proteins by bacteria is also different. In this study, the capacity of lactic acid bacteria to hydrolyze casein or β-casein and the IgG/IgE-binding capacity of hydrolysates were evaluated. The intensity of casein and β-casein degradation was analyzed by SDS-PAGE and RP-HPLC. The hydrolysates were tested for their capacity to inhibit IgG and IgE binding by ELISA. The peptides in the hydrolysate were also analyzed by LC-MS/MS. In these strains, Lactobacillus rhamnosus (CICC No. 22175) had the strongest hydrolysis of casein and β-casein. The hydrolysate of Lactobacillus rhamnosus (CICC No. 22175) showed the lowest antigenicity and potential allergenicity. It also hydrolyzed major allergen IgE epitopes and preserved T cell epitopes. Thereore Lactobacillus rhamnosus (CICC No. 22175) could be used for developing hypoallergenic dairy products and the development of tolerance. PRACTICAL APPLICATIONS: By the study, it obtained that a strain of Lactobacillus rhamnosus could effectively degrade casein and reduced the potential allergenicity of casein. At the same time, some major allergic epitopes were hydrolyzed and T cell epitopes were preserved. Therefore, it is very valuable for the application and development of lactic acid bacteria. The hydrolysate can also be used in a new hypoallergenic dairy formula with specific health benefits and promoting oral tolerance.

In this study, the mechanisms of the delay of starch digestion by luteolin were revealed by studying the luteolin-PPA (porcine pancreatic α-amylase) interaction and luteolin-starch interaction. The luteolin-PPA interaction was investigated by inhibitory kinetics analysis, fluorescence quenching, circular dichroism (CD), Fourier transform infrared (FT-IR) spectroscopy and molecular docking. The results of the inhibitory kinetics revealed that luteolin was a mixed-type inhibitor of PPA and that the inhibitory action was reversible. Fluorescence spectroscopy (including fluorescence quenching and thermodynamics) and molecular docking analyses indicated that hydrogen bonds and hydrophobic forces were the main forces between PPA and luteolin. CD and FT-IR spectroscopy analyses showed that the interaction between luteolin and PPA changed the secondary structure of PPA and induced a decline in its activity. In addition, the luteolin-starch interaction was also studied using UV-visible absorption and X-ray diffraction analyses. These indicated that luteolin could bind with PPA, and that hydrogen bonds and van der Waals forces may be present. Overall, luteolin delayed starch digestion not only by binding with PPA but also by binding with starch. Thus, luteolin has the potential to prevent and control diabetes by being added into starch-based food to delay starch digestion.

Glässer’s disease, caused by Haemophilus parasuis, is a chronic disease related to an inflammatory immune response. Baicalin exerts important biological functions. In this study, we explored the protective efficacy of treatment with baicalin and the potential mechanism of activation of the MAPK signaling pathway in porcine aortic vascular endothelial cells (PAVECs) induced by H. parasuis. H. parasuis stimulated expression of receptor for advanced glycation end products, induced a significant increase in the level of protein kinase-α and protein kinase-δ phosphorylation, and significantly up-regulated ERK, c-Jun N-terminal kinase, and p38 phosphorylation in PAVECs. H. parasuis also up-regulated the levels of apoptotic genes ( Bax, C-myc, and Fasl) and the expression levels of c-Jun and c-Fos, and induced S-phase arrest in PAVECs. However, treatment with baicalin inhibited expression of RAGE, suppressed H. parasuis-induced protein kinase-α and protein kinase-δ phosphorylation, reduced ERK, c-Jun N-terminal kinase, and p38 phosphorylation, down-regulated apoptotic genes ( Bax, C-myc, and Fasl), attenuated phospho-c-Jun production from the extracellular to the nuclei, and reversed S-phase arrest in PAVECs. In conclusion, baicalin treatment inhibited the MAPK signaling pathway, thereby achieving its anti-inflammatory responses, which provides a new strategy to control H. parasuis infection.

Preserved eggs without adding heavy metals in the pickling solution (heavy metals–free preserved eggs) have been developed, but it was found that the undesirable phenomenon such as dry shrinkage and fading occurred when they were not packaged and stored at room temperature. In this study, the effects of 5 packaging methods on the quality of heavy metals-free preserved eggs during storage were systematically studied. These methods included storage at room temperature and 4°C without packaging, wrapping with plastic bags, paraffin coating, and vacuum package. Through adopting these 5 packaging methods, the results showed that the moisture content and pH of the albumen decreased continuously, the mass loss rate increased continuously, the content of total volatile basic nitrogen increased firstly and then decreased, and the albumen hardness increased continuously. No microorganisms were detected in all samples with the 5 packaging methods during storage. Among them, the uncoated preserved eggs suffered the most serious moisture loss and mass loss, and the pH dropped at the fastest rate, followed by the preserved eggs wrapped in plastic bags. Preserved eggs stored at low temperature tended to turn yellow during storage, and the albumen showed higher hardness. The packaging method of paraffin coating performed the best in preventing the moisture loss of the albumen and the weight loss, which only decreased by 0.34 and 1.24%, respectively, after 3 mo. The best springiness, the darkest color, and the highest sensory score were found in the vacuum-packed preserved eggs after 3 mo of storage. It was concluded that paraffin coating and vacuum packing had better effect, while plastic bag packing showed the worst preservation performance for heavy metals–free preserved eggs.

The presence of Salmonella in food has been a serious threat to human health all over the world. Herein, a novel electrochemical immunosensor based on CoFe-MOFs-graphene nanocomposite was constructed to detect Salmonella in milk. The synergy of the large specific surface area and high porosity of CoFe-MOFs and the good electrical conductivity of graphene materials greatly enhanced the current signal of the nanocomposite. Gold nanoparticles were modified on CoFe-MOFs-graphene hybrids by a simple electrodeposition method. Anti-Salmonella antibody was immobilized onto the surface of the constructed electrode through the formation of a stable Au–NH2 bond. Scanning electron microscopy was employed to reveal the structure of the CoFe-MOFs-graphene nanocomposite, and the elements of the nanocomposite were observed by energy-dispersive X-ray spectroscopy. In addition, Fourier transform infrared (FT-IR) and X-ray powder diffraction (XRD) were used to analyze the structure of related materials. Under optimal experimental parameters, the constructed immunosensor detected a wide linear range of Salmonella from 2.4 × 102 CFU mL−1 to 2.4 × 108 CFU mL−1 with a detection limit of 1.2 × 102 CFU mL−1 (S/N = 3). The immunosensor showed good stability, selectivity, and reproducibility. The designed immunosensor provides a new strategy for the rapid detection of foodborne pathogens.

Gelation is one of the most important functional properties of egg yolk. High content and rich variety of protein and lipid in egg yolk are the material basis of gel formation. The natural structure of proteins in egg yolk is unfolded under treatments such as heat, alkali, salt, etc., thus causing the interactions between protein-protein and protein-lipid and forming the gel. Under different methods of induction, egg yolk is solidified to form different three-dimensional network structures. Different inducing methods exhibit different gel formation mechanisms. In this paper, the gelation behavior of egg yolk and its internal molecular agglomeration mechanism induced by heat, alkali, salt, freezing, high pressure, and salt-heating synergy were reviewed to provide a reference for further studies on the formation mechanisms and product development of egg yolk gel.

In this paper, the changes of physico-chemical characteristics, microstructures and secondary structures of duck egg white (EW) gels under the action of baijiu (Chinese liquor) were studied via the texture analyzer, environmental scanning electron microscope (ESEM) and Fourier transform infrared spectroscopy (FT-IR). Results showed that the hardness, centrifugal water holding capacity (WHC) and surface hydrophobicity of the EW gels increased gradually with the pickling time. ESEM indicated that the EW gels exhibited an increasingly compact network structure. The ionic bond and disulfide bond took the leading role in maintaining the gel network. SDS-PAGE showed that lysozyme disappeared first, and other proteins except ovomucoid disappeared gradually. The absolute value of zeta potential reached the maximum on the 8th day and then decreased slightly. The overall trend of α-helix, β-turn, β-sheet and the random coil in the secondary structure of the gel increased.

Coated with polypyrrole (Ppy)-based molecularly imprinted polymer (MIP), 3D CoFe-metal organic frameworks (CoFe-MOFs) with gold nanoparticles (AuNPs) was developed for electrochemical trace detection of norfloxacin (NOR). On one hand, the trace detection of NOR was realized with MIP/CoFe-MOFs/AuNPs/Glassy carbon electrode (GCE). The effective surface area of the imprinted cavities capable of identifying NOR on MIP/CoFe-MOFs/AuNPs/GCE increased to 0.1058 cm2 after 3D CoFe-MOFs/AuNPs was modified, which indicates that CoFe-MOFs/AuNPs could generate more imprinted cavities, thus contributing to a lower limit of detection (LOD) of 0.131 pmol L−1 (S/N = 3) with a wider linear range (5–100, 100–1000 and 1000–6000 pmol L−1). On the other hand, the recognition reaction to NOR by MIP/CoFe-MOFs/AuNPs/GCE is an irreversible electrochemical oxidation reaction involving an electron and a proton, controlled by a mixed adsorption-diffusion mechanism. Rapid and precise detection of NOR in prescription (norfloxacin capsules with the specification of 0.1 g) and pure milk with the recovery rates between 97.04 and 110.2% and the relative standard deviations (RSD) were less than 5.7%. The measured results by MIP/CoFe-MOFs/AuNPs/GCE were close to the commercial norfloxacin enzyme-linked immunosorbent assay (ELISA) kit, demonstrates its high potential to NOR trace detection in environmental and animal foods.

In this study, changes in the gel properties, microstructure, and molecular interaction force during the formation of duck egg white (EW) gel induced by ethanol were investigated. Results showed that the viscosity of the EW increased with increasing ethanol concentration and treatment time. The hardness and cohesiveness of the formed gel increased first with prolonged treatment time, then decreased slightly, and finally almost kept stable. The increase in the centrifugal water holding capacity and transformation of immobile and free water into bound water was related to the increasingly compact structure of the gel network. The force that maintained the gel network was mainly ionic bond (~45%) and disulfide bonds (~45%). The hydrogen bond and hydrophobic interaction were extremely low. SDS-PAGE results showed that the ethanol-treated EW proteins were degraded to some extent, but the bands did not significantly change with time. The negative charge content and surface hydrophobicity of the protein increased continuously. The secondary structure of the EW gel showed that the mutual transformation of β-sheet, random coil, α-helix, and β-turn resulted in the good texture characteristics of the gel. The ethanol treatment promoted the disulfide bond cross-linking of the duck EW proteins, and the network structure of the EW gel became increasingly compact, resulting in a series of changes in the water retention and binding water content of the gel. Protein aggregation also occurred, which enhanced the hardness, springiness, and cohesiveness of the duck EW gel.

Antioxidant peptides are increasingly attracting researchers in medicine and foods. In the present study, egg white hydrolysates of embryonated eggs hatched on the sixth day (EWHD) were segmented consecutively by ultrafiltration membranes with small tangential flow ultrafiltration system. Four segments with more than 30, 30 to 10 kDa, 10 to 5 kDa, and less than 5 kDa of molecular weight cut-off (MWCO) values were separated and were labeled as MWCOI, MWCOII, MWCOIII, and MWCOIV, respectively. The antioxidant activities of segments were investigated by performing DPPH•, •OH radical scavenging, ultra oxygen anion (O2−•), total antioxidant capacity, and reducing power experiments. The results indicated that MWCOI has the strongest scavenging activities on DPPH• radical. However, MWCOIV has the strongest scavenging activities on •OH, O2−•, total antioxidant capacity, and reducing power, which revealed that MWCOIV has strong antioxidant activity. MWCOIV was further separated into 14 fractions via semipreparative reverse-phased high-performance liquid chromatography (RP-HPLC), and their antioxidant activity was evaluated by different antioxidant assays in vitro. The fractions 10 and 7 had strong antioxidant activities. The purities of these 2 fractions were determined by analytical RP-HPLC. Moreover, both fractions 10 and 7 displayed high purity levels, and they were identified by quadrupole time-of-flight tandem mass spectrometry. Only fraction 10, with a molecular weight of 204 Da, can be identified to be Ser-Val. EWHD can be considered as a promising source of natural food antioxidants for the development of functional food.

Tau-fluvalinate (TFL) and flumethrin (FL), widely used in agriculture and a class of synthetic pyrethroid pesticides with a similar structure, may cause a potential security risk. Herein, the modes of binding in vitro of TFL and FL with calf thymus DNA (ctDNA) were characterized by fluorescence, UV-vis absorption, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy with the aid of viscosity measurements, melting analyses and molecular docking studies. The fluorescence titration indicated that both TFL and FL bound to ctDNA forming complexes through hydrogen bonding and van der Waals forces. The binding constants of TFL and FL with ctDNA were in the range of 10(4)Lmol(-1), and FL exhibited a higher binding propensity than TFL. The iodide quenching effect, single/double-stranded DNA effects, and ctDNA melting and viscosity measurements demonstrated that the binding of both TFL and FL to ctDNA was groove mode. The FT-IR analyses suggested the A-T region of the minor groove of ctDNA as the preferential binding for TFL and FL, which was confirmed by the displacement assays with Hoechst 33258 probe, and the molecular docking visualized the specific binding. The changes in CD spectra indicated that both FL and TFL induced the perturbation on the base stacking and helicity of B-DNA, but the disturbance caused by FL was more obvious. Gel electrophoresis analyses indicated that both TFL and FL did not cause significant DNA cleavage. This study provides novel insights into the binding properties of TFL/FL with ctDNA and its toxic mechanisms.

Resmethrin (RES) is a synthetic pyrethroid insecticide widely used to control pests in agriculture, but it may cause potential hazards to human health. The characteristics of the binding of RES with calf thymus DNA (ctDNA) were investigated in a physiological buffer (pH 7.4) by multiple spectroscopic methods combined with ctDNA melting and viscosity measurements, multivariate curve resolution-alternating least-squares (MCR-ALS) chemometrics and the molecular docking technique. The concentration profiles and the pure spectra for the reactive species (RES, ctDNA and RES–ctDNA complex), obtained through decomposing the augmented UV-vis spectral data matrix by the MCR-ALS approach, indicated that RES could bind to ctDNA and the reaction process could be quantitatively monitored. The RES molecules bound to ctDNA by groove binding, as evidenced by the negligible changes in the ctDNA melting temperature, viscosity and iodide quenching effect and the increase in the single-stranded DNA quenching effect. Fluorescence titration data indicated that the complexation of RES with ctDNA was mainly driven by hydrogen bonds and van der Waals forces, and had strong affinity. The changes in the Fourier transform infrared spectra of ctDNA suggested that RES molecules preferentially bound to the G–C region of ctDNA, which was consistent with the prediction of the molecular docking. The circular dichroism spectral analysis indicated that RES induced a decrease in the right-handed helicity of ctDNA. The DNA cleavage assay showed that RES did not cleave the pUC18 plasmid DNA. This study offers a comprehensive picture of RES–ctDNA interaction, which may provide insights into the toxicological effect of the insecticide.

In this paper, the effects of three different metal compounds, including lead oxide, copper sulfate, mixed compound of zinc sulfate and copper sulfate, on the physico-chemical properties, microstructures, molecular forces and digestion characteristics of preserved egg white were studied. The results showed that different types of metal ions had significant different effects on the penetration rate of alkali into the egg, the moisture content and the viscosity of the preserved egg white. The content of moisture and alkali in the preserved egg white pickled by copper sulfate were the largest among the three treatment groups, and the viscosity change of egg white was the slowest. L* value, a* value and b* value of preserved eggs pickled by copper method were all the largest. The eggs pickled by lead oxide possessed the optimal texture and moderate hardness and good elasticity. The eggs pickled by the mixture of copper sulfate and zinc sulfate possessed the smallest egg white gel mesh and the most compact structure, and the gel hardness was relatively high. The content of disulfide bond in preserved egg white gel pickled by lead oxide was the highest. Although there were no differences among the preserved egg whites pickled with three metal compounds on gastric digestibility, there were different at the different pickling stages. The results showed that different types of metal salts added during pickling could affect the density of the internal structure of preserved egg white gel and the molecular forces, thus changing the physico-chemical and digestive properties of the gel.

The electronic component plays an important role in the safety and operation of the maglev train. In order to reduce the uncertainties of problem with the electronic components fault diagnosis, a modified D-S evidence theory based on information fusion, which can deal with the evidence conflict well, is presented in the paper. According to the measurement results of current and voltage of circuit components, combined with the modified D-S evidence theory, the fault component will be found. Experimental results certify that the method can carry out the fault diagnosis effectively.

The binding properties of food antioxidant butylated hydroxyanisole (BHA) associated with calf thymus DNA (ctDNA) in physiological buffer (pH 7.4) were investigated. Experimental results based on fluorescence, UV–vis absorption, circular dichroism (CD), viscosity measurements and autodocking techniques confirmed the intercalation binding between BHA and ctDNA. The changes in Fourier transform infrared spectra of ctDNA induced by BHA suggested that BHA was more prone to bind to G–C rich region of ctDNA, which was further ascertained with the molecular docking studies. Analysis of the CD spectra indicated that this binding interaction led to a transformation from B-like DNA structure toward A-like conformation. The complexation of BHA with ctDNA was driven mainly by hydrogen bonds and hydrophobic forces. The binding constants of the BHA–ctDNA complex were calculated to be 2.03 × 10 4 , 1.92 × 10 4 and 1.59 × 10 4 L mol −1 at 298, 304 and 310 K, respectively. Gel electrophoresis results suggested that intercalated BHA molecules did not significantly affect plasmid DNA. Moreover, the concentration profiles and the spectra for the three reaction components (BHA, ctDNA, and BHA–ctDNA complex) of the system by resolving the augmented UV–vis spectral data matrix with the use of multivariate curve resolution-alternating least squares approach provided quantitative data to estimate the progress of BHA–ctDNA interaction. This study is expected to provide new insights into the mechanism of interaction between BHA and ctDNA.