Se ha realizado un estudio de la distribución del tamaño de gotas y de las propiedades viscoelásticas lineales de emulsiones concentradas de aceite en agua, estabilizadas con diferentes proteínas (cangrejo, gluten y soja). Los sistemas estudiados siempre presentan un comportamiento típico de emulsiones altamente concentradas con un alto grado de floculación. Se ha observado que un incremento de la velocidad de agitación empleada durante la preparación o de la concentración de emulsionante dan lugar a un aumento de los módulos viscoelásticos (G' y G") y a una disminución del tamaño de gotas. Por tanto se produce un reforzamiento del entramado formado por asociación de las gotas de fase dispersa y como consecuencia, un aumento en la estabilidad de las emulsiones. | Droplet Size Distribution (DSD) and linear viscoelastic properties of concentrated o/w emulsions stabilized by different proteins (crayfish, gluten and soybean) have been studied. A typical behaviour of highly concentrated emulsions with a high degree of flocculation has been found. An increase in energy input for the emulsification process or in emulsifier concentration leads to an increase in both viscoelastic moduli (G', G") as well as to a decrease in droplet size. Thus, an enhancement of the entanglement network produced by association of protein molecules that are surrounding oil droplets or are present in the continuous phase takes place, leading to a significant improvement of emulsion stability.

The problem of the wall slip in steady-state flow measurements of oil-in-water (o/w) food emulsions has been investigated for different sensor system geometries and surface profiles. Experimental results demonstrated that slip effects are strongly dependent on the type of emulsion studied. This may be related to the emulsion microstructure. Thus, for instance, a highly structured gel-like continuous phase dampens wall slip effects, as opposed to emulsions in which creaming appears as a mechanism of instability, because of the formation of particulate flocs. The occurrence of wall slip is more clearly observed if the flow curves are obtained from stress sweep experiments. Although the recovery of the steady-state viscosity of a presheared sample is generally complete (similar values at low and high shear rates), the appearance of slip effects may be favoured by emulsion preshearing.

Food grade W/O microemulsions were developed and characterized to be used in blends with sunflower oil as replacers of palm kernel oil in whipped cream alternatives. Creams for whipping are oil-in-water (O/W) emulsions containing significant proportions of partially hydrogenated solid fat. With the addition of sunflower oil and W/O microemulsions up to 6.8% w/w in the final confectionary product we achieved the decrease of saturated fats and also the decrease of the energy required for the formulation. More specifically, by replacing 20% w/w of the oil phase by the proposed edible W/O microemulsions, the homogenization time was reduced from 7 to 5min under the same experimental conditions. In addition solid fat partial replacement permitted the modification of structural and textural characteristics. Droplet size and size distribution measurements were performed using dynamic light scattering (DLS). The existence of rather polydisperse oil droplets with diameters of approximately 1μm upon palm kernel oil partial replacement was detected. Structural characterization of the proposed alternative systems with confocal laser scanning microscopy (CLSM) showed the existence of air bubbles of diameter 6–94μm stabilized by globular oil droplets having diameters ranging from 4.2 to 5.9μm adhered to their surface. Firmness and consistency of the proposed alternative formulations were evaluated using a Stevens-texture analyzer. As a result emulsions after whipping gave products with lower density (362±9g/mL) but higher consistency (208±7g) as compared to the standard whipped cream preparation (150±5g).