ɛ-(γ-Glutamyl)lysine Crosslink Formation in Sardine Myofibril Sol during Setting at 25°C

The quantitative change of ?-(y-glutamyl)lysine (EGL) crosslink and relationship between crosslink content and gel-strength were examined on salt-ground myofibril sol from sardine (Sardinops melanostictus) during incubation at 25°C. In the presence of EGTA, no EGL crosslinks were detected in myofibril sol and gelation did not occur. The EGL crosslink content and breaking strength of gels increased in proportion to incubation time. High correlation was observed between the logarithm of breaking strength and logarithm of EGL crosslink content (r=0.987). The EGL crosslinks formed by transglutaminase are important in the setting of sardine meat sol at < 30°C.     

Interaction Between Ovomucoid and Lysozyme

The interaction between ovomucoid and lysozyme was investigated by precipitation experiments, polyacrylamide gel electrophoresis and inactivation experiments on ovomucoid. The ovomucoid-lysozyme mixture produced turbidity at low salt concentrations over the pH range 6–11. Although both ovomucoid and lysozyme solutions (0.2%, pH 8.5) yielded no precipitation when heated separately at 80°C for 10 mm, about 40% of the proteins in the 0.2% solution of the ovomucoid-lysozyme mixture (2:3, in weight; 1:3, in mole) was precipitated by the same treatment. Ovomucoid was found to form complexes with lysozyme, some of which were precipitated by centrifugation (2000 ×g, 20 mm), and it was presumed that ovomucoid and lysozyme molecules were brought close together by the electrostatic attractive force, unfolded by heating, and then aggregated through intermolecular forces such as hydrophobic forces, hydrogen bonds and disulfide bonds.     

Glutathione Peroxidase of Fish

Glutathione peroxidase (GSH-Px) activity was detected in the muscle and skin tissues from several fish species. The muscle GSH-Px showed an optimum pH at 8.0 for salmon and 8.5 for carp. Stability of salmon muscle enzyme was enhanced in the presence of reduced glutathione (GSH), but considerably decreased in the presence of tert-butylhydroperoxide. When salmon fillets were stored at -50°C, the GSH-Px activity increased gradually during storage. Fish muscle GSH-Px shows potential for preventing oxidative deterioration in muscle during storage and processing.     

Measurement and correlation of supercritical CO2 and ionic liquid systems for design of advanced unit operations

Ionic liquids combined with supercritical fluid technology hold great promise as working solvents for developing compact processes. Ionic liquids, which are organic molten salts, typically have extremely low volatility and high functionality, but possess high viscosities, surface tensions and low diffusion coefficients, which can limit their applicability. CO₂, on the other hand, especially in its supercritical state, is a green solvent that can be used advantageously when combined with the ionic liquid to provide viscosity and surface tension reduction and to promote mass transfer. The solubility of CO₂ in the ionic liquid is key to estimating the important physical properties that include partition coefficients, viscosities, densities, interfacial tensions, thermal conductivities and heat capacities needed in contactor design. In this work, we examine a subset of available high pressure pure component ionic liquid PVT data and high pressure CO₂-ionic liquid solubility data and report new correlations for CO₂-ionic liquid systems with equations of state that have some industrial applications including: (1) general, (2) fuel desulfurization, (3) CO₂ capture, and (4) chiral separation. New measurements of solubility data for the CO₂ and 1-butyl-3-methylimidazolium octyl sulfate, [bmim][OcSO₄] system are reported and correlated. In the correlation of the CO₂ ionic liquid phase behavior, the Peng-Robinson and the Sanchez-Lacombe equations of state were considered and are compared. It is shown that excellent correlation of CO₂ solubility can be obtained with either equation and they share some common characteristics regarding interaction parameters. In the Sanchez-Lacombe equation, parameters that are derived from the supercritical region were found to be important for obtaining good correlation of the CO₂-ionic liquid solubility data.     

Immunoreactive Glycopeptides Separated from Peptic Hydrolysate of Chicken Egg White Ovomucoid

Chicken egg white ovomucoid was hydrolyzed with pepsin, fractionated by gel filtration, and the reactivity to anti-ovomucoid antibody was detected in the two carbohydrate-containing fractions. Immunoreactive fragments separated from these fractions by immunoaffinity chromatography were positive to both protein and carbohydrate staining, i.e., glycopeptides. Ovomucoid glycopeptides prepared by pronase-hydrolysis did not have this immunoreactivity. These results show that some glycopeptides with immunoreactivity remained after peptic hydrolysis, suggesting that the carbohydrate moieties of ovomucoid exert a protective effect against peptic hydrolysis.     

Heat-Induced Aggregation and Denaturation of Egg White Proteins in Acid Media

Heat-induced aggregation and denaturation of egg white proteins adjusted to pH 5.5, 4.5, 3.5 and 2.5 were investigated by vertical flat-sheet polyacrylamide gel electrophoretic and differential scanning calorimetric methods. The fractional and step-wise aggregation of egg white proteins was caused by heating. As the acidity was increased from pH 5.5 to 2.5, ovotransferrin, ovomacroglobulin, globulin G3A, globulins A1 and A2, and ovalbumin became much more unstable to heat. However, ovomucoid and ovoinhibitor did not aggregate in the acidified egg white under heat treatments of 3 min at 90°C or 20 min at 74°C. The heat-induced aggregation of flavoprotein was slightly greater at pH 4.5 and 3.5 than at pH 5.5 and 2.5.     

On Sodium Chloride Action in the Gelation Process of Low Density Lipoprotein (LDL) from Hen Egg Yolk

Gelation of 40% LDL solution with 1~10% NaCl was inhibited during frozen storage at ?20°C and ?25°C. Frozen storage of LDL solutions with more than 4% NaCl at ?30°C, ?40°C and ?60°C induced the gelation, whereas gelation was inhibited by addition of 1 and 2% NaCl at temperatures lower than ?30°C. Differential scanning calorimetry analyses revealed that when NaCl acts as an inhibitor of gelation, it increased the unfrozen water in the LDL solutions through formation of LDL-water-NaCl complex where the water is hardly frozen; and when it acts as an accelerator of gelation, it promoted removal of water from the complex.