Fractionation of β-casein, the formation of complex coacervates between β-casein preparations and lactoferrin, and an assessment of their digestion, technofunctional and biofunctional properties

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dc.check.date9999-12-31
dc.contributor.advisorKelly, Alan
dc.contributor.advisorO'Mahony, James
dc.contributor.advisorexternalO'Regan, Jonathan
dc.contributor.advisorexternalGoulding, David A.
dc.contributor.authorvan der Schaaf, Jasper Melleen
dc.contributor.funderFondation Nestlé
dc.date.accessioned2024-06-25T11:54:40Z
dc.date.available2024-06-25T11:54:40Z
dc.date.issued2024
dc.date.submitted2024
dc.description.abstractLactoferrin (LF) and β-casein are major human milk proteins that have individually been recognized for their significant roles in infant health and nutrition. However, the impact of their complex coacervation, involving liquid-liquid phase separation, and the behavior of these structures during gastrointestinal digestion remains largely unexplored. This thesis aims to advance the fractionation and use of β-casein as a dairy ingredient and knowledge on the formation of LF:β-casein complex coacervates, their physicochemical properties, and biological functionalities within the context of infant in vitro gastrointestinal development. The commercial production of β-casein is limited, due to challenges with yield, associated costs, and industrial application of the final ingredients. Combining fractionation treatments may improve the overall composition and purity of these ingredients. A novel approach for β-casein isolation was developed in Chapter 1, that included membrane filtration combined with chymosin treatment, which removed the κ-casein fraction from the final enriched β-casein ingredient. The second chapter focused on the factors influencing the formation of complex coacervates, including pH, ionic strength, stoichiometry, temperature, protein concentration and protein profile, and demonstrated a strong interdependence of these factors. The coacervate yield varied based on the starting material, and optimal conditions at which the highest phase separation yield were identified. Understanding these factors, and their interactions, is essential for optimizing complex coacervate-based formulations for infant nutrition. The effects of spray-drying or freeze-drying on the stability and reformation of complex coacervates were also investigated. The complex coacervation of LF with β-casein increased the denaturation point of LF by 5 °C; however, this increase does not permit commercial thermal treatment of LF without anticipated denaturation and functional loss. Importantly, drying the complex coacervates and rehydrating them showed no significant impact on the rheological behavior and all complex coacervates exhibited a frequency-dependent viscoelastic behavior. Potentially, freeze-drying complexes formed under infant nutrition grade conditions and dry-blending coacervated ingredients into infant formula may avoid further thermal processing and ensure that bioactivity is retained. The final chapters investigated the stability of complex coacervates during infant in vitro digestion and their potential impact on gastrointestinal health. Complex coacervates showed altered gastric proteolysis, which resulted in different peptide profiles, and could potentially influence bioactivity. Additionally, the digested complex coacervates were studied for their anti-inflammatory properties using a cell T84 epithelial cell model. The bifidogenic properties were studied by stimulating Bifidobacterium longum ssp. infantis with digested complex coacervates; all digested samples exhibited bifidogenic effects, with undigested β-casein stimulating bifidogenesis the most. The findings of this research will further support the development of LF and β-casein complex coacervation as a potential way of producing novel ingredients, as their unique physicochemical properties, increased heat-stability, and altered peptide profiles upon digestion, potentially leading to different biological activities, make them interesting to consider for inclusion in infant nutrition.en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationvan der Schaaf, J. M. 2024. Fractionation of β-casein, the formation of complex coacervates between β-casein preparations and lactoferrin, and an assessment of their digestion, technofunctional and biofunctional properties. PhD Thesis, University College Cork.
dc.identifier.endpage409
dc.identifier.urihttps://hdl.handle.net/10468/16033
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights© 2024, Jasper Melle van der Schaaf.
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/
dc.subjectLactoferrinen
dc.subjectBeta-caseinen
dc.subjectMembrane filtrationen
dc.subjectDigestionen
dc.subjectPeptidomicsen
dc.titleFractionation of β-casein, the formation of complex coacervates between β-casein preparations and lactoferrin, and an assessment of their digestion, technofunctional and biofunctional properties
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD - Doctor of Philosophyen
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