Effect of fat phase composition and dispersed phase crystallization on the stability of oil-in-water emulsions

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dc.contributor Helsingin yliopisto, Maatalous-metsätieteellinen tiedekunta fi
dc.contributor University of Helsinki, Faculty of Agriculture and Forestry en
dc.contributor Helsingfors universitet, Agrikultur- och forstvetenskapliga fakulteten sv
dc.contributor.author Kinnunen, Eveliina
dc.date.issued 2020
dc.identifier.uri URN:NBN:fi:hulib-202009034024
dc.identifier.uri http://hdl.handle.net/10138/319038
dc.description.abstract Infant formulas are breast milk substitutes for 0 to 12-month-old infants. Addition of milk fat to infant formulas leads to an increase in solid fat content. Infant formulas are oil-in- water emulsions in which oil is dispersed into a continuous aqueous phase. Milk fat crystallization leads to partial coalescence and creaming which are types of instability in emulsions. Partial coalescence occurs when two droplets containing crystals collide and they partially coalesce by making contact between their oil phases. The aim of this thesis was to study if milk fat crystallization leads to partial coalescence which leads to a higher rate of creaming or the increasing density of crystallizing droplets leads to a lower rate of creaming. Also, the aim was to study the effect of interfacial layer on partial coalescence. Milk fat crystallization and emulsion stability were investigated from four series of oil-in- water emulsions containing different oils in different concentrations and either whey protein or lecithin as stabilizer. The samples were stored at 5, 20 and 40 °C and measured after 0, 7 and 28 days of storage. The crystallization of bulk fat and oil in emulsions were studied with melting enthalpies measured with differential scanning calorimetry. Emulsion stability was examined with particle size distribution, instability index and creaming velocity measurements. According to the results combining vegetable oil and butter oil, and emulsifying the fat decreases the total enthalpy change and crystallization onset temperature of oils. Mixing vegetable oil and butter oil before homogenization decreased crystallization onset temperature and total enthalpy change because the oils were in same droplet, and made the emulsions behave more like vegetable oil emulsions. Mixing the oils after homogenization made the emulsions behave similarly to butter oil emulsions. Whey protein was found to be a better stabilizer of emulsions than lecithin at 5 and 20 °C, but at 40 °C some Maillard reaction was noticed. It was suspected that the concentration of lecithin in emulsions was insufficient. Based on the results it could be stated that the increasing density due to crystallizing droplets made the emulsions more stable against creaming. Best stability of emulsions containing oil mixtures would be achieved if butter oil and vegetable oil were mixed after homogenization and whey protein used as emulsifier. en
dc.language.iso eng
dc.publisher Helsingin yliopisto fi
dc.publisher University of Helsinki en
dc.publisher Helsingfors universitet sv
dc.subject fat crystallization
dc.subject emulsifiers
dc.subject emulsion
dc.subject stability
dc.title Effect of fat phase composition and dispersed phase crystallization on the stability of oil-in-water emulsions en
dc.title.alternative Rasvafaasin koostumuksen ja dispergoituneen faasin kiteytymisen vaikutus öljy-vedessä-emulsioiden stabiilisuuteen fi
dc.date.embargoedUntil 2022-06-30
dc.type.ontasot pro gradu -tutkielmat fi
dc.type.ontasot master's thesis en
dc.type.ontasot pro gradu-avhandlingar sv
dct.identifier.urn URN:NBN:fi:hulib-202009034024
dc.subject.specialization ei opintosuuntaa fi
dc.subject.specialization no specialization en
dc.subject.specialization ingen studieinriktning sv
dc.subject.degreeprogram Elintarviketieteiden maisteriohjelma fi
dc.subject.degreeprogram Master's Programme in Food Sciences en
dc.subject.degreeprogram Magisterprogrammet i livsmedelsvetenskaper sv

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