Mechanistic studies of protein fractionation by precipitation with carboxymethyl cellulose

dc.contributor.advisor Charles E. Glatz
dc.contributor.author Clark, Kathleen
dc.contributor.department Chemical and Biological Engineering
dc.date 2018-08-15T16:33:16.000
dc.date.accessioned 2020-07-02T06:15:31Z
dc.date.available 2020-07-02T06:15:31Z
dc.date.copyright Fri Jan 01 00:00:00 UTC 1988
dc.date.issued 1988
dc.description.abstract <p>The effects of pH, ionic strength, and polymer dosage level and manner of addition on the fractionation of egg white proteins by precipitation with carboxymethyl cellulose was examined. Using model solutions of egg white proteins, the behavior was quantified through a mechanistic model that accounted for both solubility and aggregation phenomena;A two stage mechanism for the formation of the protein-polymer floc has been proposed, encompassing both formation of the insoluble complex, and aggregation of these complexes into larger particles. The dual role of the polyelectrolyte in the precipitation process, precipitant and flocculant, has been identified;Only proteins of net positive charge were precipitated by the anionic polyelectrolyte and proteins of higher net charge were preferentially precipitated over those of lower net charge. Increased ionic strength levels served to reduce the maximum protein recoveries possible, increase the polymer dosage requirement, and reduce the effect of protein charge on precipitation. At lower polymer dosage levels, protein recovery increases with dosage to an optimum, then decreases with further addition of polymer. This resolubilization effect is reduced by high ionic strength levels, or the use of highly ionized polymers;The complex formation has been modeled as a multi-equilibrium binding process. The binding is the result of electrostatic interactions between the oppositely-charged protein and polyelectrolyte and is negatively cooperative. The ionic strength and charge dependence of the binding constant has been modeled using a modified Debye-Huckel expression. The resolubilization of the protein-polymer complexes is seen to occur at high net complex charge. This residual charge hinders aggregation of the complexes to form insoluble primary particles, resulting in lower protein recoveries.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/9767/
dc.identifier.articleid 10766
dc.identifier.contextkey 6366576
dc.identifier.doi https://doi.org/10.31274/rtd-180813-9349
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/9767
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/82901
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/9767/r_8825909.pdf|||Sat Jan 15 02:37:15 UTC 2022
dc.subject.disciplines Chemical Engineering
dc.subject.keywords Chemical engineering
dc.title Mechanistic studies of protein fractionation by precipitation with carboxymethyl cellulose
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication 86545861-382c-4c15-8c52-eb8e9afe6b75
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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