Pilot-scale production process for high internal phase emulsions: Experimentation and modeling

New discovery of the coalescence kinetics of sesame oil droplets under a high internal phase: A highly efficient oil extraction technique

Traditional pressing is of low efficiency (< 80 %). A highly efficient sesame oil extraction technique was discovered via micro-hydration of sesame paste (φ = ∼ 75 %) and then agitation with a yield of ∼ 95 %. However, the extraction mechanism is still unknown. To uncover this, microscopic imaging was used, and it found that agitation progressively increased the droplet size of micro-hydrated paste (φ = 74.5 %) from an initial size of < 4 μm. As agitated for 20 min, almost 85 % (v/v) of oil was over 20 μm, which was linearly and positively correlated (R2 > 0.96) with oil yield. Increase in droplet size was due to droplet compression, film rupture, and droplet coalescence. The coalescence frequency based on agitation time followed an exponent curve (R2 > 0.97). This coalescence might be related to the decreased water relaxation time and increased paste viscosity. This study, for the first time, found the oil droplet coalescence in hydrated sesame paste (φ = 74.5 %) during agitation, thereby successfully extracting oil at room temperature. The findings of this work can be a starting point for research on micro-hydration extraction for oil-containing materials from a packing density of oil droplets point view.

Molecular Modeling of the Adsorption of an Egg Yolk Protein on a Water-Oil Interface

Egg yolk contains several molecular species with emulsifying properties, such as proteins and phospholipids. In particular, these molecules have both polar and nonpolar parts and thus can act as surfactants. One of the most surface-active proteins from egg yolk low-density lipoproteins is the so-called Apovitellenin-1. Experimental studies have been hindered by difficulties in isolating individual species from egg yolk lipoproteins. The purpose of this work was to assess the emulsifying properties of Apovitellenin-1 and any potential cooperative or competitive behavior in the presence of phospholipids. To do so, molecular simulations were carried out in a liquid-liquid interfacial system consisting of water and soybean oil, with varying concentrations of phospholipids and for different spatial configurations. To evaluate the conformational stability of the protein at the water-oil interface, the Gibbs free energy was computed from Metadynamics simulations as a function of the distance from the interface and of the radius of gyration. Moreover, a detailed analysis was also performed to determine which peptide residues were responsible for the protein adsorption at the oil-water interface as well as the lowering of the interfacial tension. Lastly, we combined the simulation results with a thermodynamic model to predict the interfacial tension behavior at increasing protein bulk concentration, which cannot be measured experimentally.

Fabrication of fat-reduced water-in-oil emulsion and the application in 3D printing

Water-in-oil (W/O) emulsion is promising to design fat-reduced foods for 3D printing. In this study, oleogel-based W/O emulsion containing 65% water fraction was prepared by sunflower wax (SW, 1.0 wt%) and soybean phosphatidylethanolamine (SP, 0.5 wt%) with stability exceeding 30 days. Besides reducing interfacial tension, from X-ray diffraction and rheological results, SP was considered co-oleogelator to change the crystal habit of SW to enhance the external SW-based oleogel structure. The strong external oleogel structure was not only good for reducing droplets movements to improve physical stability, but facilitating the molding and supporting abilities of the emulsion gel in 3D printing. Based on rheological measurements, the emulsion gels were shown improved printing performance with SP increasing: extrusion (shear-thinning behavior), recovery (excellent thixotropy), and self-supporting (sufficient storage modulus and deformation resistance). In 3D printing, the emulsion gels with growing SP were displayed better shape retention and allowed printing the designs with more delicate and vivid features. This study provided new insight for W/O emulsion formation using natural ingredients for 3D printing to create fat-reduced foods.