Complex coacervation between β-lactoglobulin and acacia gum in aqueous medium

Abstract The compatibility of β-lactoglobulin (β-lg) and acacia gum in aqueous medium was investigated as a function of the pH (3.6–5.0), the protein to polysaccharide weight ratio (50:1–1:20) and the total biopolymer concentration (0.1–5 wt%). The ternary phase diagrams obtained at low ionic strengths (0.005–10.7 mM) typically accounted for phase separation through complex coacervation. Thus a drop-shaped two-phase region was anchored in the water-rich corner. The electrostatic nature of the interactions between the two biopolymers was pointed out according to the pH dependence of the two-phase region's breadth. Following the absorbance of the mixtures at 650 nm, the influence of the protein to polysaccharide ratio was also demonstrated. Electrophoretic mobility (μE) measurements and chemical analyses of separated phases revealed the formation of soluble and insoluble coacervates and complexes. A remarkable value of the protein to polysaccharide weight ratio (2:1) at pH 4.2 gave the same protein to polysaccharide (Pr:Ps) ratio in the two phases after 2 days, implying that electrostatic interactions are maximum between β-lg and acacia gum. The increase of the total biopolymer concentration reduced the influence of pH and protein to polysaccharide ratio. Also, the increase of the pH close to the β-lg IEP reduced the influence of the total biopolymer concentration and Pr:Ps ratio. As the biopolymer content was increased at pH 3.6 and 4.2, the relative β-lg solubility increased probably because of the self-suppression of complex coacervation.

[1]  G. Phillips,et al.  Fractionation and characterization of gum from Acacia senegal , 1989 .

[2]  J. Hardy,et al.  Structure and technofunctional properties of protein-polysaccharide complexes: a review. , 1998, Critical reviews in food science and nutrition.

[3]  M. Hoffmann,et al.  Molecular mass distributions of heat induced -lactoglobulin aggregates , 1997 .

[4]  P. Albertsson,et al.  Partition of Cell Particles and Macromolecules , 1986 .

[5]  V. Tolstoguzov,et al.  Thermodynamic compatibility of proteins in aqueous medium , 1986 .

[6]  W. Sawyer,et al.  Optical rotatory dispersion and sedimentation in the study of association-dissociation: Bovine β-lactoglobulins near pH5 , 1967 .

[7]  W. Horwitz.  Official Methods of Analysis , 1980 .

[8]  Peter A. Williams,et al.  Characterisation of gum from Acacia senegal trees of different age and location using multidetection gel permeation chromatography , 1998 .

[9]  G. Phillips,et al.  Hydration characteristics of the gum exudate from Acacia senegal , 1996 .

[10]  J. N. de Wit,et al.  Nutritional and Functional Characteristics of Whey Proteins in Food Products , 1998 .

[11]  I. Tucker,et al.  Characterization of Sodium Carboxymethylcellulose‐Gelatin Complex Coacervation by Viscosity, Turbidity and Coacervate Wet Weight and Volume Measurements , 1988, The Journal of pharmacy and pharmacology.

[12]  S. G. Mason,et al.  Three-phase interactions in shear and electrical fields , 1970 .

[13]  Diane J. Burgess,et al.  Microelectrophoretic studies of gelatin and acacia for the prediction of complex coacervation , 1984 .

[14]  G. Karlstroem,et al.  Phase diagram of a system of cationic surfactant and anionic polyelectrolyte: tetradecyltrimethylammonium bromide-hyaluronan-water , 1990 .

[15]  H. M. Farrell,et al.  Proton relaxation rates of water in dilute solutions of β-lactoglobulin determination of cross relaxation and correlation with structural changes by the use of two genetic variants of a self-associating globular protein , 1985 .

[16]  V. Tolstoguzov.  Structure—Property Relationships in Foods , 1996 .

[17]  A. Donald,et al.  Phase diagram of mixtures of polymers in aqueous solution using Fourier-transform infrared spectroscopy , 1993 .

[18]  S. Hansen,et al.  Detection of Intermediate Oligomers, Important for the Formation of Heat Aggregates of β-Lactoglobulin , 1998 .

[19]  A. Dash.  Determination of the physical state of drug in microcapsule and microsphere formulations. , 1997, Journal of microencapsulation.

[20]  P. Flory.  Principles of polymer chemistry , 1953 .

[21]  M. Friedman,et al.  Structures and functionalities of milk proteins. , 1996, Critical reviews in food science and nutrition.

[22]  J. C. Fenyo,et al.  Heterogeneity and homogeneity of an arabinogalactan-protein: Acacia senegal gum , 1987 .

[23]  S. N. Timasheff,et al.  Molecular Interactions in β-Lactoglobulin. III. Light Scattering Investigation of the Stoichiometry of the Association between pH 3.7 and 5.22 , 1960 .

[24]  O. Mills,et al.  A conformational change in bovine β-lactoglobulin at low pH , 1975 .

[25]  H. Klostermeyer,et al.  Polymer Science Concepts in Dairy Systems—an Overview of Milk Protein and Food Hydrocolloid Interaction , 1998 .

[26]  J. C. Fenyo,et al.  Estimation of the charge density of arabic acid by potentiometry and dye binding , 1987 .

[27]  A. Reisman.  Phase Equilibria: Basic Principles, Applications, Experimental Techniques , 1970 .

[28]  Diane J. Burgess,et al.  Practical analysis of complex coacervate systems , 1990 .

[29]  E. V. Bommel,et al.  Effect of gelatin properties in complex coacervation processes , 1992 .

[30]  T. C. Baldwin,et al.  A comparison of the physicochemical and immunological properties of the plant gum exudates of Acacia senegal (gum arabic) and Acacia seyal (gum tahla). , 1996, Food additives and contaminants.

[31]  E. Dickinson,et al.  Food Colloids, Proteins, Lipids and Polysaccharides , 1997 .

[32]  H. Mantsch,et al.  Structural and conformational changes of beta-lactoglobulin B: an infrared spectroscopic study of the effect of pH and temperature. , 1988, Biochimica et biophysica acta.

[33]  P. Dubin,et al.  Protein-Polyelectrolyte Complexes , 1994 .

[34]  A. Hermansson,et al.  Viscoelastic behaviour of β-lactoglobulin gel structures , 1990 .

[35]  F. Smith,et al.  Colorimetric Method for Determination of Sugars and Related Substances , 1956 .

[36]  Z. Haque,et al.  Association tendency of β-lactoglobulin AB purified by gel permeation chromatography as determined by dynamic light scattering under quiescent conditions* , 1996 .

[37]  S. Damodaran,et al.  Food Proteins and Their Applications , 1997 .

[38]  J. Nairm.  3 Coacervation-phase separation technology , 1995 .

[39]  D J Burgess,et al.  Spontaneous Formation of Small Sized Albumin/acacia Coacervate Particles , 1993, The Journal of pharmacy and pharmacology.

[40]  Peter A. Williams,et al.  Characterization of commercial samples of gum arabic , 1993 .

[41]  D. Anderson,et al.  Gum arabic (Acacia senegal): unambiguous identification by 13C-NMR spectroscopy as an adjunct to the Revised JECFA Specification, and the application of 13C-NMR spectra for regulatory/legislative purposes. , 1991, Food additives and contaminants.

[42]  Su-Ying Wu,et al.  β-Lactoglobulin: Structural Studies, Biological Clues , 1998 .

[43]  A. Kilara,et al.  Effects of preheating on properties of aggregates and of cold-set gels of whey protein isolate , 1998 .

[44]  G. A. Iacobucci,et al.  Functionality of gum arabic. Fractionation, characterization and evaluation of gum fractions in citrus oil emulsions and model beverages , 1995 .

[45]  G. Karlstroem,et al.  Ternary Aqueous Mixtures of a Nonionic Polymer with a Surfactant or a Second Polymer. A Theoretical and Experimental Investigation of the Phase Behavior , 1994 .

[46]  M. M. Bradford.  A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. , 1976, Analytical biochemistry.

[47]  P. Dubin,et al.  Protein Separation via Polyelectrolyte Coacervation: Selectivity and Efficiency , 1996 .

[48]  I. Tucker,et al.  Characterization of Sodium Carboxymethylcellulose‐Gelatin Complex Coacervation by Chemical Analysis of the Coacervate and Equilibrium Fluid Phases , 1988, The Journal of pharmacy and pharmacology.

[49]  J. Kinsella,et al.  Milk proteins: physicochemical and functional properties. , 1984, Critical reviews in food science and nutrition.

[50]  K. Mattison,et al.  Protein—Polyelectrolyte Phase Boundaries , 1995 .

[51]  J. C. Fenyo,et al.  Meaning of molecular weight measurements of gum arabic , 1989 .

[52]  T. Kessel,et al.  Effects of ionic strength on the solubility of whey protein products. A colloid chemical approach , 1996 .

[53]  Z. Haque,et al.  Thermal gelation of β-lactoglobulin AB purified from Cheddar whey. 1. Effect of pH on association as observed by dynamic light scattering , 1997 .