Functional, Thermal and Structural Properties of Conophor (Tetracarpidium conophorum) Albumin
Keywords:
Protein solubility, foaming properties, DSC, near-UV-CD spectra, far-UV-CD spectraAbstract
The functional, thermal and structural properties of conophor albumins under various medium conditions were investigated with a view to elucidating its behaviour under these conditions for improved utilization as functional food ingredients. Conophor albumins were isolated by dialysis of the supernatant obtained after 1.0 M NaCl extraction of the defatted flour and samples were lyophilized. Protein solubility, emulsifying activity index (EAI) and emulsion stability index (ESI), foaming capacity (FC) and foaming stability (FS) under the influence of pH and NaCl were investigated. Thermal stability and structural properties as measured by Differential Scanning Calorimetry (DSC) and Circular Dichroism (CD) respectively were also investigated under various environmental conditions. Minimum protein solubility in water (44.36%), 0.5 M (41%) NaCl and 1.0 M (38.91%) NaCl occurred at pH 6. At pH 2-6, EAI decreased with increasing pH from 34.89 ± 5.68 to 9.00 ± 1.09 (m2g-1) and thereafter, increased with increasing pH. FC and FS ranged between 7.00 - 20.00% and 40.00 - 60.71%, respectively with the maximum value obtained at pH 10 for FC and pH 6 for FS. Decreases in enthalpy (ΔH) and denaturation temperature (Td) were observed under the influence of highly acidic and alkaline pHs. The progressive increase in Td (70.95 – 77.20 °C) with increase in salt concentration (0.00M – 0.10 M) suggests a more compact conformation for conophor albumin with higher thermal stability. Far-UV-CD spectra showed that the secondary structure was stable to changes in pH (3-9), ionic strength and temperature. The tertiary structure was found to be more sensitive to change in temperature as indicated by near-UV-CD spectra.
References
A.O. Ogunsua & M.B. Adebona, Chemical composition of Tetracarpidium conophorum (Conophor Nut), Food Chemistry, 10, 1983, 173-177.
S.S. Desphande, & S. Damodaran, Structure-Digestibility Relationship of Legume 7S Proteins, Journal of Food Science, 54, 1989, 108-113
G.T Meng, & C.-Y. Ma, Thermal Properties of Phaseolus angularis (Red Bean) Globulin, Food Chemistry, 73, 2001, 453-460
S. Damodaran, Food Chemistry (O.R. Fennema, New York: Marcel Dekker, Inc., 1996).
S.K. Sathe, Solubilization and Electrophoretic Characterization of Cashew Nut (Anacardium occidentale) Proteins. Food Chemistry, 51, 1994, 319-324.
B. O. Okezie & A. B. Bello, Physicochemical and Functional Properties of Winged Bean Flour and Isolate Compared with Soy Isolate, Journal of Food Science, 53, 1988, 450- 454.
S. K. Sathe, & D. Salunke, Functional Properties of the Great Northern Bean (Phaseolus vulgaris L) Protein: Emulsion, Foaming, Viscosity, and Gelation Properties. Journal of Food Science, 46, 1981, 71-74, 81.
C. S. Lin, & J. F. Zayas, Functional of Defatted Corn Germ Proteins in a Model System: Fat Binding and Water Retention, Journal of Food Science, 63, 1987, 450-453.
P. K. J. P. D. Wanasundara & F. Shahidi, Functional Properties of Acylated Flax Protein Isolates. Journal of Agricultural and Food Chemistry, 45, 1997, 2431-2441.
R. E. Aluko, & R. Y. Yada, Relationship of Hydrophobicity and Solubility with some Functional Properties of Cowpea (Vigna unguiculata) Protein Isolate, Journal of Science of Food and Agriculture, 62, 1993. 331-335.
U. D. Chavan, D. B. Mckenzie, & F. Shahidi, Functional Properties of Protein Isolates from Beach Pea (Lathyrus Maritimus L.), Food Chemistry, 74, 2001, 177-187.
M. Naczk, L.L. Diosady, & L.J. Rubin, Functional Properties of Canola Meals Produced by Two-Phase Solvent Extraction System, Journal of Food Science, 50, 1985, 1685-1688, 1692.
M. Peleg & E.B. Bagley, Physical properties of foods (Westport, CN: AVI Pub. Co., 1983).
S. A. Odoemelam, Chemical Composition and Functional Properties of Conophor Nut (Tetracapidium Conophorum) Flour, International Journal of Food Science and Technology, 38, 2003, 729-734.
S. Y. Giami, Effect of Processing on the Proximate Composition and Functional Properties of Cowpea (Virginia unguiculata) Flour, Food Chemistry, 47, 1993, 153-158
O.S. Eke, & E.N.T. Akobundu, Functional Properties of African Yam Bean (Sphenostylis stenocarpa) Seed Flour as Affected by Processing, Food Chemistry 48, 1993, 337-340.
J. E. Kinsella, S. Damodaran, & B. German, New protein foods (A. M. Alschul, & H. L. Wilke, NY: Academic Press, 1985).
C. Myers, Characterization of proteins (F.Franks, NJ: Humana Press, 1988).
S. O. Ogunwolu, F. O. Henshaw, H. Mock, A. Santros, & S. O. Awonorin, FunctionalProperties of Protein Concentrates and Isolates Produced from Cashew (Anacardium Occidentale L.) Nut, Food Chemistry, 115, 2009, 852-858.
D. A. Sorgentini, & J. R. Wagner, Comparative Study of Foaming Properties of Whey and Isolate Soy Bean Proteins, Food Research International, 35, 2002, 721-729.
P. Retailleau, M Riès-Kautt, & A. Ducruix, No Salting-in of Lysozyme Chloride Observed at Low Ionic Strength Over A Large Range of pH. Biophysical Journal, 73, 1997, 2156-2163.
P.V. Monteiro, & V. Prakash, Functional Properties of Homogenous Protein Fractions from Peanut (Arachi hypogeal L.), Journal of Agricultural and Food Chemistry, 42, 1994, 274-278.
F.W. Sosulski, & S.E. Fleming, Chemical, Functional and Nutritional Properties of Sunflower Protein Products, Journal of American Oil Chemist Society, 54, 1977, 100.
S. Damodaran, Food Proteins and their applications (S. Damodaran & A. Paraf, New York: Marcel Dekker, 1997)
M. J. Y. Lin, E. S. Humbert, & F. W. Sosulski, Certain Functional Properties of Sunflower Meal Products, Journal of Food Science, 39, 1974, 368-370.
O. S. Lawal, K. O. Adebowale, & Y. A. Adebowale, Functional Properties of Native and Chemically Modified Protein Concentrates from Bambarra Groundnut, Food Research International, 40, 2007, 1003-1011.
E. C. Y. Li-Chan, & C.-Y. Ma, Thermal Analysis of Flaxseed (Linum Usitatissimum) Proteins by Differential Scanning Calorimetry, Food Chemistry, 77, 2002, 495-502.
P.A. Morrissey, D.M. Mulvihill, & , E.M. O`neill, Development in food proteins (B.J.F. Hudson, London: Elsevier Applied Science, 1987).
P.L. Privalov, & N.N. Khechinashviti, A Thermodynamic Approach to the Problem of Stabilization of Globular Proteins: A Calorimetric Approach, Journal of Molecular Biology, 86, 1974, 665-684
C.C. Bigelow, On the Average Hydrophobicity of Proteins and the Relationship Between it and Protein Structure, Journal of Theoretical Biology, 16, 1967, 187-211.
V. R. Harwalkar, & C.-Y. Ma, Study of Thermal Properties of Oat Globulin by Differential Scanning Calorimetry, Journal of Food Science, 52, 1987, 394-398.
P.H. Von Hippel, & T. Scheich, Structure and stability of biological macromolecule (S.N. Timesheff & G.D. Fasman, New York: Marcel Dekker, 1969).
S. Damodaran, & J.E. Kinsella, Effects of ions on protein conformation and functionality (J.P. Cherry, Washington DC: American Chemical Society, 1982).
J. Arakawa, & S.N. Timasheff, Preferential Interactions of Proteins with Salt in Concentrated Solutions, Biochemistry, 21, 1982, 6545-6552.
S. Gorinstein, M. Zemser, M. Friedman, N.L. Vasco-Mendez, & O. Paredes-Lopez, Denaturant-Induced Conformations of Globulins, Journal of Agricultural and Food Chemistry, 44, 1996, 93-99.
A. Mizuno, M. Mitsuiki, M. Motoki, K. Ebisawa, & E. Suzuki, Relationship Between The Glass Transition of Soy Protein and Molecular Structure, Journal of Agricultural and Food Chemistry, 48, 2000, 3292-3297.
F.X. Schmid, Protein structure a practical approach (T.E. Creighton Oxford: Oxford University Press, 1990).
S.M. Kelly, & N.C. Price, The Use of Circular Dichroism in the Investigation of Protein Structure and Function, Current Protein and Peptide Science, 1, 2000, 349-384.
E.H. Strickland, Aromatic Contributions to Circular Dichroism Spectra of Proteins, Critical Reviews in Biochemistry, 2, 1974, 113-175.
