Montserrat Ferrando

Spray dried double emulsions containing procyanidin-rich extracts produced by premix membrane emulsification: Effect of interfacial composition

Spray drying of procyanidin-loaded W1/O/W2 emulsions produced by premix membrane emulsification (ME) enabled to produce microcapsules containing procyanidins. The interface of the emulsion droplets prior to spray drying was stabilized with several hydrophilic emulsifiers (whey protein (WPI), WPI-carboxylmethyl cellulose, WPI-gum Arabic, and WPI-chitosan). Their effect on procyanidin encapsulation efficiency, water activity, moisture and oil content, and microcapsule size distribution was investigated. Furthermore, the microstructure and droplet size distribution of redispersed microcapsules were analyzed. Although premix ME produced W1/O/W2 emulsions with a narrow droplet size distribution regardless the hydrophilic emulsifier (main peak of droplet size distribution around 9 μm), microcapsules after spray drying and double emulsions after redispersion showed profound differences in sizes depending on the interfacial composition. WPI-CMC stabilized microcapsules not only showed the highest procyanidin content (5.3 g kg(-1)) but also gave the narrowest particle size distribution with the lowest particle size for both microcapsules and the corresponding emulsions after rehydration (7.7 and 9.9 μm respectively).

Direct formulation of a solid foodstuff with phenolic-rich multicomponent solutions from grape seed: effects on composition and antioxidant properties.

The aim of our work was to supplement a solid foodstuff with grape phenolics by osmotic treatment with an aqueous solution made of osmo-active agents (NaCl and sucrose) and a commercial grape seed extract. To investigate how the composition of the osmotic solution affected phenolic infusion, experimental conditions were set by a central composite design with two factors (the molality of NaCl and sucrose in the osmotic solution). In all experiments, the total phenolic content in the osmotic solution was kept constant (6300 +/- 45 mg gallic acid equivalents/kg), and the model food (an agar-agar gel) was processed for 8 h. Throughout the response surface, the osmo-treated model food was significantly supplemented with flavan-3-ols. At the central point of the experimental design, flavan-3-ol monomers and dimers were found in concentrations of 1334 +/- 126 and 486 +/- 55 mg/kg, respectively. Their penetration into the model food was limited by sucrose to a different extent. The Trolox equivalent antioxidant capacity of the osmo-treated gel was higher than that of fruits with a very high free radical scavenging activity.

Encapsulation of grape seed phenolic-rich extract within W/O/W emulsions stabilized with complexed biopolymers: Evaluation of their stability and release

The ability of electrostatic complexes made up of sodium caseinate (NaCAS) and a polysaccharide, carboxymethyl cellulose (CMC) or gum Arabic (GA), to retain polyphenols from grape seed extract when encapsulated in W1/O/W2 emulsions was compared to that of the single NaCAS (1%). Both electrostatic complexes (0.5% NaCAS - 0.375% CMC and 0.5% NaCAS - 0.5%GA at pH 5.6) used as hydrophilic emulsifiers in W1/O/W2 were able to stabilize the O/W2 interface for 14 days, even though their protein content was reduced by a 50% regarding that of the emulsions only stabilized with NaCAS. Moreover, interfacial adsorption did not show significant differences between NaCAS-polysaccharide electrostatic complexes and the single NaCAS. In terms of interfacial barrier properties, the rate of polyphenol release during storage was not affected by the type of hydrophilic emulsifier. Since polyphenol transport in W1/O/W2 emulsions was diffusion controlled, interfacial adsorption was considered the main factor limiting polyphenol retention.

Apparent Interfacial Tension Effects in Protein Stabilized Emulsions Prepared with Microstructured Systems

Proteins are mostly used to stabilize food emulsions; however, production of protein containing emulsions is notoriously difficult to capture in scaling relations due to the complex behavior of proteins in interfaces, in combination with the dynamic nature of the emulsification process. Here, we investigate premix membrane emulsification and use the Ohnesorge number to derive a scaling relation for emulsions prepared with whey protein, bovine serum albumin (BSA), and a standard emulsifier Tween 20, at various concentrations (0.1%, 0.5%, 1.25% and 2%). In the Ohnesorge number, viscous, inertia, and interfacial tension forces are captured, and most of the parameters can be measured with great accuracy, with the exception of the interfacial tension. We used microfluidic Y-junctions to estimate the apparent interfacial tension at throughputs comparable to those in premix emulsification, and found a unifying relation. We next used this relation to plot the Ohnesorge number versus P-ratio defined as the applied pressure over the Laplace pressure of the premix droplet. The measured values all showed a decreasing Ohnesorge number at increasing P-ratio; the differences between regular surfactants and proteins being systematic. The surfactants were more efficient in droplet size reduction, and it is expected that the differences were caused by the complex behavior of proteins in the interface (visco-elastic film formation). The differences between BSA and whey protein were relatively small, and their behavior coincided with that of low Tween concentration (0.1%), which deviated from the behavior at higher concentrations.