Properties Of Bovine Serum Albumin Research Articles

Glucose and free radicals impair the antioxidant properties of serum albumin.

Epidemiological data consistently show that reduced levels of serum albumin, which is the most abundant protein in plasma, are associated with an increased mortality risk. Various biological properties evidenced by direct effects of the albumin molecule may explain its beneficial effects. The present work aimed to investigate in vitro whether glycation or free radicals or both factors would affect the antioxidant properties of bovine serum albumin (BSA). Glycation was performed by long-term incubations (60 days) of BSA with increasing concentrations of glucose (up to 500 mmol/l) at 37 degreesC. Minimally oxidized BSA was obtained after controlled incubations of dialyzed BSA samples with a water-soluble free radical generator [2,2' azo-bis(2-amidinopropane) HCl]. The glycation-mediated modifications and the free radical-induced conformational changes of BSA were monitored using intrinsic fluorescence measurements of the tryptophan residues and acrylamide as a quenching agent. Thiol groups, Amadori glycophore contents, and boronate binding were also measured. We found that the changes observed in the conformation of the BSA molecule were associated with modifications of its antioxidant properties. The latter were studied by the copper-mediated oxidation of human low density lipoproteins and the free radical-induced blood hemolysis test. Our data support the concept that oxidative-induced BSA modifications are important determinants in the antioxidant properties of BSA. Glycated BSA still behaved as an antioxidant but became pro-oxidant in the presence of copper, probably by generating oxygenated species. These data confirm the key role of metals ions in this process. Although these results warrant further in vivo investigations, we propose that, considering the poor glucose control found in diabetics as well as the key role of oxidative stress in vascular complications, glycation-mediated and free radical-induced impairment of the antioxidant properties of albumin might be important parameters in vascular complications encountered in diabetes.

Electrochemical Coating with Poly(phenylene oxide) Films Bearing Oligoether Groups as a Tool for Elimination of Protein Adsorption to Electrode Surfaces.

Reported herein are the adsorption properties of bovine serum albumin to glassy carbon (GC) electrodes coated with poly(phenylene oxide) (PPO) films formed by anodic polymerization of HOC6H4R in phosphate buffer (pH 7.4), where R=o-, m-, and p-MeO–or m-Me(OCH2CH2)nO–(n=1–4) group. Evaluation of the voltammetric response of caffeic acid demonstrated that a GC electrode coated with a PPO film derived from m-HOC6H4O(CH2CH2O)4Me not only shows satisfactory electrochemical performance but also resists surface fouling due to protein adsorption. Coating with the film also proved to be useful in preventing the surface of a gold electrode from being fouled by protein adsorption.

Evaluation of adsorption properties of Bovine Serum Albumin on TiO2 membrane by quartz-crystal microbalance.

Evaluation of adsorption properties of Bovine Serum Albumin on TiO2 membrane by quartz-crystal microbalance.

Diffusion of albumins in rat cortical slices and relevance to volume transmission.

The apparent diffusion coefficient, D*, was measured in rat cortical slices and compared to the free diffusion coefficient, D, for three negatively charged proteins, lactalbumin (mol. wt = 14,500), ovalbumin (45,000) and bovine serum albumin (66,000). The temporal evolution of the spatial distribution of albumin molecules labeled with the Texas Red fluorophore was determined using integrative optical imaging at intervals after a brief pressure injection from a micropipette in slices of adult rat cerebral cortex and dilute agarose gel. Diffusion coefficients were obtained by fitting appropriate equations to the data. In slices at 34 degrees C, the values of D* (10(-7) cm2/s, mean +/- S.E.M.) for lactalbumin, ovalbumin and bovine serum albumin were 2.37 +/- 0.10, 1.60 +/- 0.08 and 1.63 +/- 0.07, respectively. In agarose gel, values of D (10(-7) cm2/s) were 11.87 +/- 0.20, 10.02 +/- 0.25 and 8.29 +/- 0.17, respectively. From these data the tortuosity factors, (D/D*)0.5, were calculated, with 2.24 obtained for lactalbumin, 2.50 for ovalbumin and 2.26 for bovine serum albumin. Previous optical measurements using dextrans with mol. wts of 40,000 and 70,000 gave tortuosities of 2.16 and 2.25, but in contrast previous determinations with ion-selective microelectrodes using the small cation tetramethylammonium (mol. wt = 74.1) give tortuosities of about 1.6. The results show that proteins as large as bovine serum albumin diffuse through brain extracellular space but are more hindered than smaller molecules. A simple model compared the differences in diffusion properties of bovine serum albumin, dopamine and nitric oxide in brain tissue and discussed the implications for volume transmission of chemical information between cells. The results are also relevant to the behavior of diffusible factors in brain development and the delivery of therapeutic agents.

Interactions Involved in the Gelation of Bovine Serum Albumin

The thermal and structural properties of bovine serum albumin (BSA) were studied at different pH values, at different NaCl, lactose, sucrose, and glucose concentrations, and in the presence of cysteine, urea, NEM, and SDS. Maximum thermal stability was observed at pH 5. Glucose had a greater stabilizing effect on the thermal denaturation of BSA than sucrose. Denaturation of BSA resulted in the loss of the 1654 cm-1 band attributed to α-helical structure and the rise of two bands at 1616 and 1684 cm-1 attributed to the formation of ordered non-native β-sheet structure associated with aggregation. SDS markedly increased the thermal stability of BSA and prevented aggregate formation. The greatest unfolding on heat treatment was observed in the presence of cysteine and the least in SDS. Keywords: Bovine serum albumin; differential scanning calorimetry; Fourier transform infrared spectroscopy; denaturation; gelation

Roles of the Domain I Segment in Emulsifying Properties of Bovine Serum Albumin

Emulsifying properties of bovine serum albumin (BSA) were compared between intact BSA (molecular mass of 66 kDa) and the domain I-truncated fragment (molecular mass of 45 kDa). The particle size considerably decreased with increasing both intact BSA and the fragment concentration. The intact BSA formed a more homogeneous emulsion and smaller particle distributions than the fragment at all protein concentrations. The relative amount of protein adsorbed at an oil-water interface was much less for intact BSA than for the fragment, and the surface concentration of intact BSA per unit surface area was also much less than that of the fragment, indicating that less protein is required to form a stable film for intact BSA than for the fragment. The particle size distribution in the fragment-stabilized emulsion became more homogeneous during storage time, while that in intact BSA-stabilized BSA had no significant change. These results strongly suggested that the domain I-truncated fragment with a higher hydrophobi...

Simple method for the preparation of antigen emulsions for immunization

We have developed a rapid, safe, and reliable method to prepare emulsions of water-soluble antigens in an adjuvant oil phase for immunization purposes. The method, based on well established emulsification principles, employs a three-way ‘T’ connector to which three disposable syringes are attached. The system allows the stepwise addition of small volumes of the water phase, into the oil phase. We have compared the time required for emulsification, the rate of antigen release from the emulsion into a physiological phase, and the immunogenic properties of bovine serum albumin and transferrin contained in emulsions made by the new stepwise addition method, with those made by the widely used double-hubbed needle method. We report a significantly shorter ( P < 0.001) and a more reproducible emulsification time for the stepwise addition method (6.1 ± 2.1 min; mean ± SD) than for the double-hubbed needle method (41.1 ± 28.0 min). The stepwise addition method always yielded water-in-oil emulsions, while the double-hubbed needle method failed, about 20% of the time, to produce a water-in-oil emulsion after 120 min of mixing. Since the stepwise addition method employs a connector with a larger inner diameter (1.75 mm) than the one required for the double-hubbed needle method (0.84 mm); the pressure required for the former is markedly reduced compared with that required for the latter, thus making the new method safer and less labor-intensive. The rate of antigen release from the emulsions was significantly slower when the stepwise addition method was employed ( P < 0.01). There were no differences in viscosity and stability in the emulsions prepared by the two methods. The ability of antigen-containing emulsions to elicit an immune response was found to be identical by the two methods; no significant differences were found in antibody titers as determined by enzyme-linked immunosorbent assays. These characteristics make the stepwise addition system the method of choice.

Immunogenicity of various beta-lactam antibiotic-protein conjugates and cross-reactivity of the antibodies produced in guinea pig.

Immunogenic properties of bovine serum albumin (BSA) conjugates of various beta-lactam antibiotics (ABs) and cross-reactivity of the produced antibodies were investigated in guinea pigs. Each AB-BSA conjugate was immunized with complete Freund's adjuvant. Following the second injection, AB-specific antibodies were detected with high titers. Produced antibodies showed concentration-dependent inhibition by the corresponding AB. Cross-reactivity between the produced antibodies and ABs was evaluated with two methods, i.e. by testing for reactivity with the various AB-ovalbumin conjugates, and by assaying for inhibition of enzyme-linked immunosorbent assay (ELISA) by the various ABs. The latter method could detect minor cross-reactions more sensitively than the former one. The results suggested that similarity of the acyl side chain of a cephalosporin nucleus or a penicillin nucleus contributes to immunological cross-reactivity.

Emulsifying and oil-binding properties of bovine serum albumin and its enzymatic hydrolyzate.

Bovine serum albumin (BSA) was hydrolyzed with proteases, and the emulsifying and oil-binding properties of the hydrolyzates were then studied. By limiting hydrolysis with trypsin, the emulsifying activity index (EAI) increased about 40% above its original level. In order to find out which peptides contributed to the good emulsifying properties of the hydrolyzate, the peptides adsorbed onto the emulsified oil globule surface were extracted and analyzed. SDS-polyacrylamide gel electrophoresis showed that a peptide with a molecular weight of about 24kDa was preferentially adsorbed onto the oil surface. This 24kDa peptide was found to be fairly hydrophobic and corresponds to the third domain of BSA, residues 377-582. In spite of the preferential adsorption characteristics of the 24kDa peptide, this peptide itself had a lower EAI value than that of the whole hydrolyzate. The contribution of some small hydrophilic peptides, as well as the 24kDa peptide, to the good emulsifying properties of the BSA hydrolyzate was suggested.

Effects of Disulfide Reduction on the Emulsifying Properties of Bovine Serum Albumin

Bovine serum albumin was reduced by incubating with various concentrations (0–200 mM) of 2-mercaptoethanol, and its emulsifying properties were examined for an oil-in-water emulsion system. A particle size analysis revealed that albumin reduced at 30 mM of the thiol yielded smaller oil particles than either native protein, or the protein reduced at 70 or 200 mM of the thiol. Furthermore, the particle size was almost constant during 35 days of storage with albumin reduced at 30 mM of the thiol, while an emulsion prepared using the native protein, or the protein reduced at 70 or 200 mM of the thiol was unstable during the same storage period. Gel filtration chromatography and transmission electron micrography show that serum albumin made aggregates with high molecular size by its disulfide reduction with 70 or 200 mM, but not with 30 mM of 2-mercaptoethanol. It was, therefore, concluded that the emulsifying property of serum albumin can be improved by a mild disufide reduction.

LITERATURE ABSTRACTS

GENERAL PRINCIPLES: Viscoelastic Behavior of f3‐Lactoglobulin Gel Structures. M. Stading and A.‐M. Hermansson GENERAL PRINCIPLES: Effect of Ammonium Salts on Rheological and Thermal Properties of Kappa‐Carrageenan Gels. M. Watase GENERAL PRINCIPLES: Dough Structure, Dough Rheology and Baking Quality. A. H. Bloksma GENERAL PRINCIPLES: Correlation of Protein Sulfhydryls with the Strength of Heat‐Formed Egg White Gels White Gels (Res. Note). B. A. Margoshes GENERAL PRINCIPLES: Effects of Temperature on Viscoelastic Properties and Activation Energies of Whey Protein Gels. K. Katsuta GENERAL PRINCIPLES: Rheological Characterization of Crosslinked Waxy Maize Starch Solutions Under Low Acid Aseptic Processing Conditions Using Tube Viscometry Techniques. R. V. Dail GENERAL PRINCIPLES: Changing the Viseoelastie Properties of Cooked Rice Through Protein Disruption. B. R. Harnaker and V. K. Griffin INSTRUMENTAL MEASUREMENTS: Influence of Composition on the Resistance to Compression of Kappa Carrageenan‐Locust Bean Gum‐Guar Gum Mixed Gels: Relationship Between Instrumental and Sensorial Measurements. M. H. Damasio, S. M. Fiszman, E. Costell and L. Duran METHODOLOGY AND INSTRUMENTATION: Impact Damage to Soybean Seed as Affected by Surface Hardness and Seed Orientation. M. D. Evans and R. G. Holmes METHODOLOGY AND INSTRUMENTATION: Determining Viscosity of Fluid Foods by Continuous Lift (Res. Note). C. H. Runyon and K.L. McCarthy METHODOLOGY AND INSTRUMENTATION: A Test for Evaluation of the Serum Separation Potential of Tomato Ketchup. N. G. Stoforos and D. S. Reid METHODOLOGY AND INSTRUMENTATION: Use of a Kramer Shear Cell to Measure Cracker Dough Properties. D. W. Creighton and R. C. Hoseney METHODOLOGY AND INSTRUMENTATION: Use of a Kramer Shear Cell to Measure Cracker Flour Quality. D. W. Creighton and R. C. Hoseney METHODOLOGY AND INSTRUMENTATION: Physical and Structural Properties of Wheat Endosperm Associated with Grain Texture. G. M. Glenn and R. M. Saunders FACTORS AFFECTING TEXTURE: Instrumental and Sensory Evaluation of Textural Properties of Extrudates from Blends of High Starch/High Protein Fractions of Dry Beans. K. Skierkowski FACTORS AFFECTING TEXTURE: Effects of Salts and pH on Heating‐Related Softening of Snap Beans. J. P. Van Buren, W. P. Kean, B. K. Gavitt FACTORS AFFECTING TEXTURE: Physical Properties as Indicators of Popping Characteristics of Microwave Popcorn. L. 0. Pordesimo, R. C. Anantheswaran FACTORS AFFECTING TEXTURE: Effect of Ingredients on Physical/Structural Properties of Extrudates. D. Moore FACTORS AFFECTING TEXTURE: Effect of Surimi Addition to Fresh Pasta on Ultra‐Structure and Cooked Firmness (Res. Note). S‐H. Kim, Y‐W. Huang and J. A. Carpenterb FACTORS AFFECTING TEXTURE: Effect of Manufacturing Conditions on Rheology of Banana Gelified Milk: Optimization of the Technology. A. Hamza‐Chaffai FACTORS AFFECTING TEXTURE: Alginate Texturization of Highly Acid Fruit Pulps and Juices (Res. Note). G. Kaletunc, A. Nussinovitch and M. Peleg FACTORS AFFECTING TEXTURE: Texture Characteristics of Reheated Bread. D. E. Rogers, L. C. Doescher and R. C. Hoseney FACTORS AFFECTING TEXTURE: Thermomechanical Analysis of Gluten‐Starch‐Water Mixtures. Influence of Testing Conditions and Composition. S. Cavella, L. Piazza and P. Masib FACTORS AFFECTING TEXTURE: Effect of the Attachment of Valine Residues on the Physicochemical and Functional Properties of Bovine Serum Albumin. Margaret C. Murphy and Nazlin K. Howell FACTORS AFFECTING TEXTURE: Flour Quality Tests for Selected Wheat Cultivars and Their Relationship to Arabic Bread Quality. Ken J. Quail, Graham J. McMaster

Effect of amidation on the foaming and physico‐chemical properties of bovine serum albumin

SummaryAmidation of bovine serum albumin (BSA) was achieved by a water‐soluble carbo‐diimide, ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide (EDC)‐mediated reaction using ammonium chloride as the nucleophile. Partial and substantial amidation of 0.5% (w/v) BSA in 5.5 m ammonium chloride solution with 1 times 10‐2mmol EDC over 120 min and 1 times 10‐1mmol EDC over 10 min respectively was achieved on a large scale using diafiltration for rapid termination of the reaction and purification. Residual ammonium chloride otherwise enhanced foaming properties. The amidated proteins were characterized by isoelectric focusing, electrophoresis and hydrophobicity and disulphide‐ and sulphydryl‐group measurements. Compared with native BSA, partially amidated BSA (PA‐BSA) produced enhanced foam expansion and foam stability values. This was attributed to minimal denaturation and to the presence of both acidic and basic components (pI range 5.25–7.50) within the single protein. In contrast, substantially amidated BSA (SA‐BSA) (pI range 7–9.1) had similar foaming properties to those of the ultrafiltered BSA control which were slightly lower than those of native BSA. However SA‐BSA interacted synergistically with native BSA producing enhanced foaming properties particularly at the 1:1 ratio through electrostatic interactions, conformational changes and increased hydrophobicity.

Effects of the attachment of small molecules by carbodiimide‐mediated condensation on the physicochemical and functional properties of bovine serum albumin

AbstractThe effects of attaching three small molecules, namely N‐butylamide, putrescine and lysine, via the carboxyl groups of bovine serum albumin on its physicochemical and functional properties ere studied. To levels of attachment ere achieved by choice of reaction time. All modified samples had high isoelectric points and ere highly positive hen separated electrophoretically. Partially and extensively modified samples behaved differently in their pH titration curves, their gelation properties and the hipping properties of their lysyl derivatives, in that partially modified samples had high values compared ith the control and extensively modified samples had loer values. This as explicable by to theories: either there is increased electrostatic attraction beteen molecules hose isoelectric points are closer to neutrality, or there is a midpoint here a partial degree of conformational disruption results in superior functional properties. The level of conformational disruption in the extensively modified samples as greater than the optimum, hich resulted in impaired functional properties. An EDC control sample produced ithout added nucleophile as extensively cross‐linked intra‐ or intermolecularly and had impaired functional properties.

Freezing of Isolated Thylakoid Membranes in Complex Media. VII. The Effect of Bovine Serum Albumin

Summary THe cryoprotective properties of bovine serum albumin (BSA) were investigated with thylakoid membranes isolated from spinach leaves ( Spinacia oleracea L. cv. Monatol). The membranes were frozen in a complex salt medium containing the predominant inorganic electrolytes of the chloroplast stroma. Under mild freezing conditions, only partial stabilization of PSII-dependent photosynthetic activities but efficient cryopreservation of PSI-mediated photophosphorylation took place in the presence of BSA. The lower the freezing temperature, the less protein was necessary for optimum protection of light-induced proton uptake and ATP synthesis. At higher initial BSA concentrations or more severe freezing, i.e. when the protein concentration in the residual unfrozen fraction exceeded a critical limit, rapid inactivation of photophosphorylation occurred in parallel with the ice crystal formation. This damage was due to an increase in the proton permeability of the membranes, while the capacity of linear whole-chain electron transport remained unaffected or even rose relative to unfrozen membranes. The effects of the solutes on thylakoid activities can be explained in part by colligative action, i.e. each solute acts on different membrane sites and reduces the concentration of the others in the residual unfrozen liquid. In addition, damage and protection of the membranes was influenced by the quantity of ice formed, the final volume of the unfrozen solution, the final membrane concentration in this fraction and the duration time of exposure to a given temperature. Extremely high concentrations of BSA and thylakoids in the frozen system caused inactivation of photophosphorylation regardless of the volume of the residual liquid and the freezing temperature. When chloroplast membranes were kept at 0 °C, BSA effectively stabilized cyclic photophosphorylation but only slightly reduced the progressive inactivation of linear photosynthetic electron flow.

Effect of the attachment of valine residues on the physicochemical and functional properties of bovine serum albumin

AbstractThe effects of attaching a hydrophobic amino acid residue, valine, to the ϵ‐amino groups (lysine residues) of bovine serum albumin (BSA) on the physicochemical and functional properties were assessed. The valyl groups were attached using an N‐carboxyvaline anhydride derivative. The valine content of BSA was increased from 27 mol mol−1 protein to 47·91 or 53·72 mol mol−1. The number of lysine residues acylated was dependent on the pH of the reaction mixture as was the degree of polyvalylation. Attachment of polyvalyl chains resulted in improved whipping and gelling properties compared with a control sample of ultrafiltered BSA, and interfered with the formation of α‐helices. Hydrophobicity measurements using the fluorescent probe cis‐parinaric acid revealed increased hydrophobicity values only after the modified samples had been heat denatured.

Effect of thiolation on the physicochemical and functional properties of bovine serum albumin

AbstractThe effects of the attachment of homocysteine residues, to either 16 or 21 amino groups of bovine serum albumin (BSA), on the physicochemical and functional properties were studied. Both thiolated protein derivatives had a lower isoelectric point, hydrophobicity and α‐helix conformation compared with the native protein. Polyacrylamide gel electrophoresis indicated that modification of the proteins resulted in a mixture of products. Thiolation impaired the whipping and gelling properties of bovine serum albumin but there was little change in the emulsification properties. It was concluded that increasing the available sulphydryl groups did not promote disulphide/ sulphydryl interchange reactions leading to enhanced functional properties: on the contrary, the blocking of amino groups was instrumental in impairing the whipping and gelling properties.

Effect of succinylation on the functional and physicochemical properties of bovine serum albumin

AbstractBovine serum albumin was modijed with succinic anhydride so that 50 or 82% of lysine residues were acylated. The structural alterations caused by modification were examined by pH titration, electrophoretic patterns, circular dichroism, amino acid analysis, and the measurement of amino, sulphydryl and hydrophobic groups. Changes in these physicochemical properties were related to inferior whipping, emulsification and gelling properties of succinylated bovine serum albumin compared with the native protein.

INSTRUMENTAL MEASUREMENTS

INSTRUMENTAL MEASUREMENTS: Resistance to Tear: An Instrumental Measure of the Cohesive Properties of Muscle Food Products. (Res. Note) J. H. MacNeil and M. G. MastINSTRUMENTAL MEASUREMENTS: A Small Sample Back Extrusion Test for Measuring Texture of Cooked Rice. V. G. Reyes, Jr. and V. K. JindalINSTRUMENTAL MEASUREMENTS: The Wheat Research Institute Chomper, an Instrument that Measures Crumb Flexibility. D. W. Baruch and T. D. AtkinsINSTRUMENTAL MEASUREMENTS: Using the Wheat Research Institute Chomper to Assess Crumb Flexibility of Staling Bread. D. W. Baruch and T. D. AtkinsINSTRUMENTAL MEASUREMENTS: Rapid Testing Method for Characterizing the Rheological Behavior of Gelatinizing Corn Starch Slurries. (Note) J. F. Steffe, M. E. Castell Peres, K. J. Rose and M. E. ZabickINSTRUMENTAL MEASUREMENTS: Rheological Changes of Fortified Wheat and Corn Flour Doughs with Mixing Time. L. L. NavickisINSTRUMENTAL MEASUREMENTS: Comparison of Starch Pasting Properties in the Brabender Viscoamylograph and the Rapid Visco‐Analyzer. L. B. Deffenbaugh and C. E. WalkerINSTRUMENTAL MEASUREMENTS: Measuring Kernel Hardness Using the Tangential Abrasive Dehulling Device. J. W. Lawton and J. M. FaubionINSTRUMENTAL MEASUREMENTS: Bingham Award Lecture—1989. The Role of Instrument Inertia in Controlled‐Stress Rheometers. 1. M. KriegerINSTRUMENTAL MEASUREMENTS: Technical Note: Strain‐Measurement Error in a Constant‐Stress Rheometer. D. W. Giles and M. M. DennINSTRUMENTAL MEASUREMENTS: Technical Note: Strain‐Measurement Error in a Constant‐Stress Rheometer. D. W. Giles and M. M. DennINSTRUMENTAL MEASUREMENTS: Characteristics of a Modified Wisconsin Breakage Tester. (Technical Note) H. J. Lyon, S. G. Schmitt, C. J. Bern and C. R. Hurburgh, Jr.INSTRUMENTAL MEASUREMENTS: Impact Parameters Related to Post Harvest Brusing of Apples. G. H. Brusewitz and J. A. BartschINSTRUMENTAL MEASUREMENTS: Characterization of the Perceived Texture of Thickened Systems by Dynamic Viscosity Measurements. R. K. Richardson, E. R. Morris, S. B. Ross‐Murphy, L. J. Taylor and I.C.M. DeaGENERAL PRINCIPLES: Modelling of Flow Properties of Starch Pastes Prepared by Different Procedures. M. HarrodGENERAL PRINCIPLES: Apparent Concentration: A Method to Predict the Flow Properties of Viscous Foods for Process Applications. M. HarrodGENERAL PRINCIPLES: Time‐Dependent Flow Behavior of Starch Pastes, With Food Process Applications. M. HärrödGENERAL PRINCIPLES: Intrinsic Viscosities and Apparent Specific Volumes of Amino Acids and Sugars. ‘Effective Size’ and Taste of Sapid Molecules. S. E. Kemp and G. G. Birch, M. 0. Portmann and M. MathlouthiGENERAL PRINCIPLES: Effect of Succinylation on the Functional and Physiochemical Properties of Bovine Serum Albumin. Margaret C. Murphy and Nazlin K. HowellGENERAL PRINCIPLES: Effect of Extrusion Temperature on Physico‐Chemical Properties and Biological Value of Soybean‐Protein. E. Horváth, J. Petres, É, Gelencsér and B. CzukorSENSORY EVALUATION: Adaptation of Collaborative Methodology to the Sensory Evaluation of Foods by Scoring. P. MolnárFACTORS AFFECTING TEXTURE: Factors Related to Longissimus Tenderness Among Alternative Methods of Lean Beef Production. W. Vanderwert, P. J. Bechtel, D. L. DeVol, F. K. McKeith, L. L. Berger and R. D. ShanksFACTORS AFFECTING TEXTURE: Predicting the Effect of Drying Conditions on the Textural Properties of Roasted Peanuts. Y.‐C. HungFACTORS AFFECTING TEXTURE: Effect of Maturity and Storage Time on the Bruise Susceptibility of Peaches (cv. Red GIobe).Y.‐C. Hung and S. E. PrussiaFACTORS AFFECTING TEXTURE: Mechanical Properties of Kappa Carrageenan‐Locust Bean Gum Mixed Gels with Added Sucrose. S. M. Fiszman and L. DuranFACTORS AFFECTING TEXTURE: Effect of Hydrolysis of Lactose and Sucrose on Firmness of Ice Cream. J. B. Lindamood, D. J. Grooms and P.M.T. HansenFACTORS AFFECTING TEXTURE: Effect of Chemical Additives on Toughening of Fillets of Frozen Alaska Pollack (Therugru chulcogrumrnu). D. J. Krueger and 0. R. FennemaFACTORS AFFECTING TEXTURE: Effect of Mixing and Moisture Modification on Toughening and Dimethylamine Formation in Alaska Pollock Mince during Frozen Storage at −10°C. G. Boer and O. FennemaFACTORS AFFECTING TEXTURE: Rheological Properties of Heat‐Induced Ovalbumin Gels Prepared by Two‐step and One‐step Heating Methods. N. Kitabatake, Y. Tani and E. DoiFACTORS AFFECTING TEXTURE: Physical and Sensory Evaluation of Lean White Cakes Containing Substituted Fluffy Cellulose. E. B. Fondroy, P. J. White and K. J. Prusa

Light scattering study of solution properties of bovine serum albumin, insulin, and polystyrene under moderate pressure

Brillouin scattering experiments have been performed on very dilute solutions of bovine serum albumin (BSA) in pH=4.7,I=0.1 M NaCl; insulin in pH=7.5,I = 0.1 M NaCl and polystyrene latex suspensions in aqueous medium at room temperatureT = 201 °C. The samples were first characterized by quasi-elastic light scattering (QELS) to determine the translational diffusion coefficient (DT), hydrodynamic radius (RH), and polydispersity of each of the samples at normal pressure. Subsequently, the samples were subjected to Brillouin scattering studies where the spectrum of the scattered light was analyzed by using a piezo-electric scannend five-pass Fabry-Perot interferometer. The hydrostatic pressure (P) acting on the samples was varied in the range from 1B to 825 B in steps of 100 B each. The pressure dependence of the measured sound velocityVs (P) could be least square fitted tovs (P)=A0 +A1P +A2P2 with experimental error (± 1 %). This data has been interpreted consistent with an earlier work within the framework of modified Tait's equation of state and presumption of linear pressure dependence of the adiabatic bulk modulus in the moderate pressure regime.

Emulsifying Properties of Food Proteins: Development of a Standardized Emulsification Method

ABSTRACTA recirculating valve‐homogenizer was used to compare the emulsifying properties of bovine serum albumin and milk proteins. The energy input per unit volume was directly obtained from the mean maximum valve head pressure per stroke. The mean maximum velocity of the emulsion in the valve head was 83m sec−1 during a valve opening time of 150 × 10 −3 sec reflecting a large velocity gradient per stroke of 4.2 × 10−6 m3 The method detected changes in the emulsifying activity of proteins resulting from chemical modification, and from process or environmental factors, e.g., ionic strength. The valve‐head pressure profile was used to compare the fluidity of the emulsions at different levels of energy input per unit volume (E) and an apparent viscosity index (AVI) has been proposed.