Abstract
The zeta potential of a molecule is an important property in the food industry, since the electrostatic potential of a material governs its ability to interact through ionic forces with other molecules in solution. In particular, emulsions that are kept in solutions with a high magnitude of the zeta potential are shown to be more stable over time, as the electrostatic repulsive forces of protein far from its isoelectric point can help prevent oil globule coalescence over time. However, modeling the zeta potential of protein is difficult given the anisotropy of protein molecules, the shifts in amino acid side chain ionization across pH, and understanding at what distance to measure the zeta potential from the molecular surface to accurately capture the shear plane between the particle and solvent under flow. In this work, we use the Poisson-Boltzmann Equation to model the net electrostatic surface potential of pea vicilin and legumin. We then use a weighted average of these globular proteins to predict the measured zeta potential in pea protein. The R2 between the bioinformatically modeled net surface charge and the measured commercial isolate zeta potential is 0.987 between pH 2.50 and 9.50, and this equation predicted the zeta potential of a different commercial pea protein isolate with a standard error of 0.040. This shows that using the Poisson-Boltzmann Equation to solve for the net electrostatic surface potential, it is possible to accurately estimate the zeta potential of pea protein.
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We affirm that we archive shared data in a manner which it can be reasonably accessed. All models shown have appropriate accession numbers for others to find, and any manipulations are stored in our lab network.
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Acknowledgements
We thank the William R. Scholle Endowment to the Kokini laboratory to support research expenditures. We also thank Glanbia Nutrition for their donation of pea protein which was used as the comparison in zeta potential testing. This work is part of the USDA-NIFA grant 1024316.
Funding
We thank the William R. Scholle Endowment to the Kokini laboratory to support research expenditures. We also thank Glanbia Nutrition for their donation of pea protein. This work is part of the USDA-NIFA grant 1024316.
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Practical Applications
This work can be used to generate molecular models of protein for analyzing their zeta potential. The models for pea protein have been made in this paper, but the approach is generalizable to any protein for which a homology model can be generated. As such, this could be applied to model the zeta potential for many different proteins, using only the amino acid sequence information. This may help understand functionalities including gelation, complex coacervation, and emulsion stability.
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Helmick, H., Hartanto, C., Bhunia, A. et al. Validation of Bioinformatic Modeling for the Zeta Potential of Vicilin, Legumin, and Commercial Pea Protein Isolate. Food Biophysics 16, 474–483 (2021). https://doi.org/10.1007/s11483-021-09686-8
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DOI: https://doi.org/10.1007/s11483-021-09686-8