Stabilisation of dehydrated nanoemulsions using sugar - protein matrices

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dc.contributor.advisorRoos, Yrjoen
dc.contributor.advisorFenelon, Marken
dc.contributor.authorMaher, Patrick G.
dc.contributor.funderDepartment of Agriculture, Food and the Marine, Irelanden
dc.date.accessioned2016-06-23T10:52:38Z
dc.date.available2016-06-23T10:52:38Z
dc.date.issued2015
dc.date.submitted2015
dc.description.abstractThere are numerous review papers discussing liquid nanoemulsions and how they compare to other emulsion systems. Little research is available on dried nanoemulsions. The objectives of this research were to (i) study the effect of varying the continuous phase of nanoemulsions with different carbohydrate/protein ratios on subsequent emulsion stability, and (ii) compare the physicochemical properties, lactose crystallisation properties, microstructure, and lipid oxidation of spray dried nanoemulsions compared to spray dried conventional emulsions having different water and sugar contents. Nanoemulsions containing sunflower oil (10% w/w), β-casein (2.5–10% w/w) and lactose or trehalose (10–17.5%) were produced following optimisation of the continuous phase by maximising and minimising viscosity and glass transition temperature (Tg’) using mixture design software. Increasing levels of β-casein from caused a significant increase in viscosity, particle size, and nanoemulsion stability, while resulting in a decrease in Tg’. Powders were made from spray drying emulsions/nanoemulsions consisting of lactose or a 70:30 mixture of lactose:sucrose (23.9%), sodium caseinate (5.1%) and sunflower oil (11.5%) in water. Nanoemulsions, produced by microfluidisation (100 MPa), had higher stability and lower viscosity than control emulsions (homogenization at 17 MPa) with lower solvent extractable free fat in the resulting powder. Partial replacement of lactose with sucrose decreased Tg and delayed Tcr. DVS and PLM showed that in powdered nanoemulsions, lactose crystallises faster than in powdered conventional emulsions. Microstructure of both powders (CLSM and cryo-SEM) showed different FGS in powders and different structure post lactose crystallisation. Powdered nanoemulsions had lower pentanal and hexanal (indicators of lipid oxidation) after 24 months storage due to their lower free fat and porosity, measured using a validated GC HS-SPME method, This research has shown the effect of altering the continuous phase of nanoemulsions on microstructure of spray dried nanoemulsions, which affects physical properties, sugar crystallisation, and lipid oxidation.en
dc.description.sponsorshipDepartment of Agriculture, Food and the Marine, Ireland (Food Institutional Research Measure)en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.format.mimetypeapplication/pdfen
dc.identifier.citationMaher, P.G. 2015. Stabilisation of dehydrated nanoemulsions using sugar - protein matrices. PhD Thesis, University College Cork.en
dc.identifier.endpage173en
dc.identifier.urihttps://hdl.handle.net/10468/2773
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights© 2015, Patrick G. Maher.en
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/en
dc.subjectNanoemulsionsen
dc.subjectSpray dryingen
dc.subjectLactose crystallisationen
dc.subjectGlass transition temperatureen
dc.subjectMicrostructureen
dc.subjectLipid oxidationen
dc.subjectStorage stabilityen
dc.subjectMixture designen
dc.thesis.opt-outfalse
dc.titleStabilisation of dehydrated nanoemulsions using sugar - protein matricesen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD (Food Science and Technology)en
ucc.workflow.supervisoryrjo.roos@ucc.ie
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