Microstructure considerations of new five-component Winsor IV food-grade microemulsions studied by pulsed gradient spin-echo NMR, conductivity, and viscosity

TY - JOUR

T1 - Microstructure considerations of new five-component Winsor IV food-grade microemulsions studied by pulsed gradient spin-echo NMR, conductivity, and viscosity

AU - Yaghmur, Anan

AU - Aserin, Abraham

AU - Antalek, Brian

AU - Garti, Nissim

PY - 2003/2/18

Y1 - 2003/2/18

N2 - The microstructure of an unusual Winsor IV isotropic region of five-component microemulsions based on nonionic surfactants was studied. The microemulsions are composed of R(+)-limonene, water, propylene glycol (PG), ethanol (EtOH), and polyoxyethylene sorbitan monostearate (Tween 60) with a 1:1:3 R(+)-limonene/ethanol/surfactant weight ratio. The phase diagrams of the system are characterized by an extended single continuous isotropic region starting from an oil-rich solution containing no aqueous phase (reverse micelles) to the water/propylene glycol (1/1) corner (swollen direct micelles). The microemulsions seem to be attractive for food applications. The microstructure changes gradually, smoothly, and continuously upon increasing the aqueous phase content. The microemulsion transforms from a water-in-oil (W/O) microemulsion to a bicontinuous phase and to an oil-in-water (O/W) microemulsion. The microstructure of the microemulsion along a selected dilution line, is probed using pulsed gradient spin-echo NMR, conductivity, and viscosity. The results are compared with a corresponding non-food-grade system based on C18:1E10 (Brij 96v). The hydrodynamic radius (RH) of O/W microemulsion samples based on Brij 96v and Tween 60, at 90% aqueous phase, was determined to be 5.4 ± 0.2 and 5.2 ± 0.2 nm, respectively, and the calculated values of the area of the polar headgroup (a) are 87 for Brij 96v and 160 Å2 for Tween 60-based microemulsions. The ratio of the water self-diffusion coefficient, DW, to the PG self-diffusion coefficient (DPG) (termed the L ratio) was found to be sensitive to the aqueous phase content. In the O/W microemulsions, the water/PG mixture diffuses as hydrogen bonded entity (molecular diffusion controlled), while in the W/O microemulsions, the PG partitions, in part, at the interface and the dominate diffusion process is neither aggregate nor molecular controlled.

AB - The microstructure of an unusual Winsor IV isotropic region of five-component microemulsions based on nonionic surfactants was studied. The microemulsions are composed of R(+)-limonene, water, propylene glycol (PG), ethanol (EtOH), and polyoxyethylene sorbitan monostearate (Tween 60) with a 1:1:3 R(+)-limonene/ethanol/surfactant weight ratio. The phase diagrams of the system are characterized by an extended single continuous isotropic region starting from an oil-rich solution containing no aqueous phase (reverse micelles) to the water/propylene glycol (1/1) corner (swollen direct micelles). The microemulsions seem to be attractive for food applications. The microstructure changes gradually, smoothly, and continuously upon increasing the aqueous phase content. The microemulsion transforms from a water-in-oil (W/O) microemulsion to a bicontinuous phase and to an oil-in-water (O/W) microemulsion. The microstructure of the microemulsion along a selected dilution line, is probed using pulsed gradient spin-echo NMR, conductivity, and viscosity. The results are compared with a corresponding non-food-grade system based on C18:1E10 (Brij 96v). The hydrodynamic radius (RH) of O/W microemulsion samples based on Brij 96v and Tween 60, at 90% aqueous phase, was determined to be 5.4 ± 0.2 and 5.2 ± 0.2 nm, respectively, and the calculated values of the area of the polar headgroup (a) are 87 for Brij 96v and 160 Å2 for Tween 60-based microemulsions. The ratio of the water self-diffusion coefficient, DW, to the PG self-diffusion coefficient (DPG) (termed the L ratio) was found to be sensitive to the aqueous phase content. In the O/W microemulsions, the water/PG mixture diffuses as hydrogen bonded entity (molecular diffusion controlled), while in the W/O microemulsions, the PG partitions, in part, at the interface and the dominate diffusion process is neither aggregate nor molecular controlled.

UR - http://www.scopus.com/inward/record.url?scp=0037452631&partnerID=8YFLogxK

U2 - 10.1021/la026404h

DO - 10.1021/la026404h

M3 - Journal article

AN - SCOPUS:0037452631

SN - 0743-7463

VL - 19

SP - 1063

EP - 1068

JO - Langmuir

JF - Langmuir

IS - 4

ER -