title: Optimization of β-casein stabilized nanoemulsions using experimental mixture design.
abstract: The objective of this study was to determine the effect of changing viscosity and glass transition temperature in the continuous phase of nanoemulsion systems on subsequent stability. Formulations comprising of β-casein (2.5%, 5%, 7.5%, and 10% w/w), lactose (0% to 20% w/w), and trehalose (0% to 20% w/w) were generated from Design of Experiments (DOE) software and tested for glass transition temperature and onset of ice-melting temperature in maximally freeze-concentrated state (T(g) ' & T(m) '), and viscosity (μ). Increasing β-casein content resulted in significant (P < 0.0001) increases in viscosity and T(m) ' (P= 0.0003), and significant (P < 0.0001) decreases in T(g) '. A mixture design was used to predict the optimum levels of lactose and trehalose required to attain the minimum and maximum T(g) ' and viscosity in solution at fixed protein contents. These mixtures were used to form the continuous phase of β-casein stabilized nanoemulsions (10% w/w sunflower oil) prepared by microfluidization at 70 MPa. Nanoemulsions were analyzed for T(g) ' & T(m) ', as well as viscosity, mean particle size, and stability. Increasing levels of β-casein (2.5% to 10% w/w) resulted in a significant (P < 0.0001) increase in viscosity (5 to 156 mPa.s), significant increase in particle size (P= 0.0115) from 186 to 199 nm, and significant decrease (P= 0.0001) in T(g) ' (-45 to -50 °C). Increasing the protein content resulted in a significant (P < 0.0001) increase in nanoemulsion stability. A mixture DOE was successfully used to predict glass transition and rheological properties for development of a continuous phase for use in nanoemulsions.
authors.affiliation: Teagasc Food Research Centre, Moorepark, Cork, Ireland.
authors.forename: Patrick G
authors.initials: PG
authors.lastname: Maher
authors.forename: Mark A
authors.initials: MA
authors.lastname: Fenelon
authors.forename: Yankun
authors.initials: Y
authors.lastname: Zhou
authors.forename: Md
authors.initials: M
authors.lastname: Kamrul Haque
authors.forename: Yrjö H
authors.initials: YH
authors.lastname: Roos
mesh_terms: D002364:Caseins / Q000737:chemistry*; D004355:Drug Stability; D004655:Emulsions / Q000737:chemistry*; D007785:Lactose / Q000032:analysis; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D044367:Phase Transition; D012996:Solutions; D044366:Transition Temperature; D014199:Trehalose / Q000032:analysis; D014783:Viscosity
chemical_list: D002364:Caseins; D004655:Emulsions; D012996:Solutions; D014199:Trehalose; D007785:Lactose