Novel structured emulsions for delivering of food flavours

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dc.contributor.advisor Roos, Yrjö H. en
dc.contributor.advisor Song, Miao en
dc.contributor.author Mao, Like
dc.date.accessioned 2015-10-23T09:26:56Z
dc.date.issued 2014
dc.date.submitted 2014
dc.identifier.citation Mao, L. 2014. Novel structured emulsions for delivering of food flavours. PhD Thesis, University College Cork. en
dc.identifier.endpage 240
dc.identifier.uri http://hdl.handle.net/10468/2008
dc.description.abstract Flavour release from food is determined by the binding of flavours to other food ingredients and the partition of flavour molecules among different phases. Food emulsions are used as delivery systems for food flavours, and tailored structuring in emulsions provides novel means to better control flavour release. The current study investigated four structured oil-in-water emulsions with structuring in the oil phase, oil-water interface, and water phase. Oil phase structuring was achieved by the formation of monoglyceride (MG) liquid crystals in the oil droplets (MG structured emulsions). Structured interface was created by the adsorption of a whey protein isolate (WPI)-pectin double layer at the interface (multilayer emulsion). Water phase structured emulsions referred to emulsion filled protein gels (EFP gels), where emulsion droplets were embedded in WPI gel network, and emulsions with maltodextrins (MDs) of different dextrose-equivalent (DE) values. Flavour compounds with different physicochemical properties were added into the emulsions, and flavour release (release rate, headspace concentration and air-emulsion partition coefficient) was described by GC headspace analysis. Emulsion structures, including crystalline structure, particle size, emulsion stability, rheology, texture, and microstructures, were characterized using differential scanning calorimetry and X-ray diffraction, light scattering, multisample analytical centrifuge, rheometry, texture analysis, and confocal laser scanning microscopy, respectively. In MG structured emulsions, MG self-assembled into liquid crystalline structures and stable β-form crystals were formed after 3 days of storage at 25 °C. The inclusion of MG crystals allowed tween 20 stabilized emulsions to present viscoelastic properties, and it made WPI stabilized emulsions more sensitive to the change of pH and NaCl concentrations. Flavour compounds in MG structured emulsions had lower initial headspace concentration and air-emulsion partition coefficients than those in unstructured emulsions. Flavour release can be modulated by changing MG content, oil content and oil type. WPI-pectin multilayer emulsions were stable at pH 5.0, 4.0, and 3.0, but they presented extensive creaming when subjected to salt solutions with NaCl ≥ 150 mM and mixed with artificial salivas. Increase of pH from 5.0 to 7.0 resulted in higher headspace concentration but unchanged release rate, and increase of NaCl concentration led to increased headspace concentration and release rate. The study also showed that salivas could trigger higher release of hydrophobic flavours and lower release of hydrophilic flavours. In EFP gels, increases in protein content and oil content contributed to gels with higher storage modulus and force at breaking. Flavour compounds had significantly reduced release rates and air-emulsion partition coefficients in the gels than the corresponding ungelled emulsions, and the reduction was in line with the increase of protein content. Gels with stronger gel network but lower oil content were prepared, and lower or unaffected release rates of the flavours were observed. In emulsions containing maltodextrins, water was frozen at a much lower temperature, and emulsion stability was greatly improved when subjected to freeze-thawing. Among different MDs, MD DE 6 offered the emulsion the highest stability. Flavours had lower air-emulsion partition coefficients in the emulsions with MDs than those in the emulsion without MD. Moreover, the involvement of MDs in the emulsions allowed most flavours had similar release profiles before and after freeze-thaw treatment. The present study provided information about different structured emulsions as delivery systems for flavour compounds, and on how food structure can be designed to modulate flavour release, which could be helpful in the development of functional foods with improved flavour profile. en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights © 2014, Like Mao. en
dc.rights.uri http://creativecommons.org/licenses/by-nc-nd/3.0/ en
dc.subject Emulsion en
dc.subject Structure en
dc.subject Delivery system en
dc.subject Food flavour en
dc.subject Flavour release en
dc.subject Headspace analysis en
dc.subject Emulsion stability en
dc.title Novel structured emulsions for delivering of food flavours en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral en
dc.type.qualificationname PhD (Food Science and Technology) en
dc.internal.availability Full text available en
dc.description.version Accepted Version
dc.contributor.funder Teagasc en
dc.description.status Not peer reviewed en
dc.internal.copyrightchecked Published versions of papers included. Permitted by publishers Elsevier and ACS. ACS - You may reuse all or part of the Submitted, Accepted, or Published versions of your ACS papers in your thesis or dissertation. Such reuse is permitted subject to the ACS' Ethical Guidelines to Publication of Chemical Research and you should secure confirmation from the respective ACS journal editor(s) to avoid potential conflicts with journal prior publication policies. The ACS copyright credit line should be noted on the appropriate pages and appropriate citation of any Published versions. If the thesis or dissertation to be published is in electronic format, a direct link to the Published Work must be included using the ACS Articles on Request link. Although ACS grants students automatic permission to use their ACS articles in theses, it is highly likely that the graduate school requires a statement of written permission. Students should use RightsLink to obtain permission, and provide their graduate school with the written document provided by RightsLink.
dc.internal.school Food and Nutritional Sciences en
dc.internal.school Teagasc en
dc.check.reason This thesis is due for publication or the author is actively seeking to publish this material en
dc.check.opt-out Not applicable en
dc.thesis.opt-out false
dc.check.entireThesis Entire Thesis Restricted
dc.check.embargoformat Both hard copy thesis and e-thesis en
ucc.workflow.supervisor yrjo.roos@ucc.ie
dc.internal.conferring Spring Conferring 2015


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