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This study was conducted to investigate the effects of different copper salts on the physicochemical properties, microstructure and intermolecular interactions of preserved egg white (PEW) during pickling. With increased pickling time, the alkalinity of the pickling solution and the moisture of PEW pickled by three copper salts (CuSO

To determine gentamicin residues in animal tissues, a monoclonal antibody (Mab) was produced and a sensitive indirect competitive chemiluminescent enzyme immunoassay (icCLEIA) was developed. At first, gentamicin was conjugated with bovine serum albumin as immunogens which were used to immunize BALB/c mice. Then, an anti-gentamicin Mab was prepared by hybridoma technology. Finally, a sensitive icCLEIA was developed with an 50% inhibition concentration (IC

Effects of sodium ascorbate (1%, 2%, 3%) on the liquefaction of alkali-induced egg white gel (EWG) were investigated. Results showed hardness and water holding capacity (WHC) gradually decreased at 1%. However, hardness and WHC declined and then rose at 2% and 3%. Microstructural changes further confirmed the effects of sodium ascorbate on hardness and WHC. Electrophoresis showed sodium ascorbate caused the cross-linking between proteins, which was more resistant to degradation. Fourier transform infrared spectroscopy (FTIR) and surface hydrophobicity indicated sodium ascorbate significantly changed protein structure, especially at 2% and 3% resulted in protein reaggregation, increasing β-sheet, and decreasing surface hydrophobicity in the later stage. In general, sodium ascorbate didn't inhibit the liquefaction of alkali-induced EWG at 1%, but did effectively at 2% and 3%. Therefore, high concentrations of sodium ascorbate possess the potential to inhibit the "alkali injury liquefaction" of preserved egg whites without heavy metals.

Changes in the gelation behavior and mechanism were investigated in low-density lipoprotein (LDL) and high-density lipoprotein (HDL) under the treatment of alkali. Three textural parameters of two kinds of alkali-induced lipoprotein increased, especially the springiness of LDL and the hardness of HDL. Alkaline treatment contributes to the sulfhydryl (SH) oxidation and SH-disulfide bonds (SS) exchange reactions to produce SS, promoting the aggregation of proteins and the formation of lipoprotein gels. For LDL gels, the increased hydrophobic interaction improves its thermal stability. HDL underwent deep unfolding and reassemble to form a network structure with high thermal stability and uniform density. Continuously alkaline treatment destroyed less SS and exposed more buried SH. The decrease of β-structures in both lipoproteins was observed by Fourier Transform Infrared (FTIR). These results suggested that alkali-induced LDL and HDL gelation behavior highly related to the protein structure, SS and hydrophobic interactions.

In this study we investigated the changes in the physicochemical properties, microstructure, protein structure, and intermolecular forces in egg yolk, plasma, and granule gels induced with a strong alkali. The results showed that egg yolks formed a three-dimensional gel, maintained by ionic and disulfide bonds from plasma and granules, respectively. According to spin–spin relaxation time, these gel systems fixed numerous water and lipid protons. Microstructure showed that egg yolks, plasma, and granules liberated their constituents on disruption, which randomly aggregated or bonded. Under a continuous strong alkali treatment, the second-derivative spectra of egg yolks and plasma appeared as an “aggregation band”, while the ordered structure of granules decreased. The results suggested that the aggregation of alkali-induced egg yolks formed mainly due to structural changes in plasma proteins. Granules contributed to the increased hardness and the bonding of egg yolk gels via disulfide bonds induced by alkali treatment.

Changes in physico-chemical properties, microstructure, protein structures and intermolecular force of egg yolk, plasma and granule gels during salting were investigated, using low-field nuclear magnetic resonance (LF-NMR), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and chemical analysis. The results showed that the contents of soluble protein and free sulfhydryl increased and, with D2O treatment, T21 and T22 decreased in egg yolks and plasma salted for 2 d. The particles of egg yolks, plasma and granules in the later stage of salting were disrupted and they liberated their constituents (phospholipids, neutral lipids and proteins), which randomly aggregated. The treatment with NaCl changed the spatial structure of egg yolk proteins. The results suggested that the oil exudation of salted egg yolks was mainly due to structural changes in the low-density lipoproteins. Granules were shown to contribute to the higher hardness and gelation of salted egg yolks.