Food Emulsions

Use Cases 

How do microgels behave at an oil-water interface and how do they respond to compression? Scaling-up to emulsions ? 

Reference: Adsorption of microgels at an oil–water interface: correlation between packing and 2D elasticity. F. Pinaud; K. Geisel; P. Massé; B. Catargi, L. Isa; W. Richtering; V. Ravaine; V. Schmitt; Soft Matter, 2014, 10, 6963.

Probing oil-water interfaces laden with microgels evidences that these soft particles adsorb quasi irreversibly and that their structure adopts different packing states when the interface is compressed.

 

Moreover, experiments with a drop tensiometer (TRACKER™ by TECLIS) show that microgels adopt spontaneously a compressed morphology at an oil-water interface. The surface elasticity deduced from these measurements exhibits a maximum corresponding to the flattened conformation. Finally, the same spontaneous adsorption coverage is observed in emulsions, thus proving the usefulness of microgels in controlling the structure and the stability of emulsions.

 

TECLIS product: TRACKER™  automatic drop tensiometer

Key words: microgels, oil-water interface, surface dilatational rheology, Langmuir trough, emulsion

How do the emulsifying properties and the stabilizing effect of plant and milk proteins in MCT oil in water emulsions depend on concentration, pH and temperature ? 

Reference: C. Amine; J. Dreher; T. Helgason; T. Tadros; Food Hydrocolloids 39 (2014) 180e186.

Through interfacial tension and interfacial elasticity measurements performed with a TRACKER™ tensiometer, the emulsifying properties and the stabilizing effect of plant (potato, soy and pea) and milk proteins (caseinate and whey) in MCT oil in water emulsions are probed under different conditions (concentration, pH and temperature). First, surface tensions are smaller at high pH values where protein molecules unfold. Second, the droplet size distribution is investigated, and a good correlation is thus found between emulsion formation and interfacial tension.  Third, using the oscillating drop technique, the authors show a correlation (although not straightforward) between emulsion stability and film elasticity. Combined all together, these results highlight two competing effects: the formation of small droplets requires small interfacial tension and hence more proteins, however, a high protein concentration results in a decreased interfacial elasticity and, ultimately leads to less stability.

TECLIS product: TRACKER™  automatic drop tensiometer

Key words: Oil in water emulsion, protein, interfacial tension, oscillating drop technique, Gibbs elasticity, stability

Incorporating Hibiscus extract microparticles in Yogurt:  what is the best ionic gelation method to generate stable systems? 

Reference: S. C. S. R. de Moura; G. N. Schettini; A. O. Garcia; D. A. Gallina; I. D. Alvim; M. D. Hubinger; Food and Bioprocess Technology; doi.org/10.1007/s11947-019-02308-9.

Encapsulation has demonstrated its value in the food and the pharmaceutical industries as it protects active components during transport and delivery. In this paper, the authors investigate the encapsulation of Hibiscus Extract (HE) by ionic gelation and the stability of these microparticles in a yogurt matrix. Two encapsulation methods are thus tested and compared: dripping and atomization.

But before looking into the final product,  an important step towards the encapsulation of HE consists in generating an HE in oil emulsion. To do that, Polyglycerol polyricinoleate (PGPR, a nonionic emulsifier) is used. Thanks to interfacial tension measurements with a drop tensiometer (TRACKER™) between HE and rapeseed oil, the surfactant concentration that best promotes emulsification is identified. The effect of surfactant concentration on the microstructure of HE in rapeseed oil emulsion is also studied as shown in the figure.

 

TECLIS product: TRACKER™  automatic drop tensiometer

Key words: Encapsulation, double emulsions, anthocyanins, hibiscus, ionic gelation, yogurt, interfacial tension, interfacial elasticity

Are the rheological properties of PolyGlycerol PolyRicinoleate at an oil/water interface obtained with the oscillating drop technique and with the transient relaxation technique equivalent?  

Reference: Relaxation Processes of PGPR at the Water/Oil Interface Inferred by Oscillatory or Transient Viscoelasticity Measurement. S. Marze; Langmuir 2009, 25(20), 12066–12072; DOI: 10.1021/la9016849.

 

The rheological properties of PolyGlycerol PolyRicinoleate (PGPR) at an oil/water are probed with two different techniques: the oscillating drop technique using a drop tensiometer (TRACKER™) and the transient relaxation technique following and area step using the TRACKER™ as well. The data collected with this latter method are fitted afterwards with different models (Lucassen-van den Tempel, Maxwell model and a mixed model where both diffusion and rearrangements are considered).

 

Similar results are obtained with the oscillating drop technique and the transient relaxation technique especially at low frequencies.

TECLIS product: TRACKER™  automatic drop tensiometer

Key words: PGPR, oil/water interface, interfacial rheology, emulsifier, oscillating drop technique, transient relaxation technique

What are the interfacial properties of

multilayered protein/pectin films ? 

Reference: Colloids and Surfaces B: Biointerfaces Corstens, M. N.; Caltenco, L. A. O.; de Vries, R.; Schroën, K.; Berton-Carabin, C. C., 2017, 153, 199-207.

The multilayer deposit on a single vegetable oil in water droplet using an automated drop tensiometer was performed at pH 3. Under theses conditions, WPI is positively charged, and pectin is negatively charged. Between each deposit, aqueous phase was replaced by a fresh solution.

Surface tension recorded during the shell/shell structure building show that there are no supplementary surface tension decrease after the pectin addition indicating that pectin did not reach the interface and is probably electrostatically adsorbed onto WPI.

In a second time, authors  study the activity of lipolytic components onto the shell/shell structure by reading the surface tension and the viscoelastic modulus of the drop model over time.

 

 

TECLIS product: TRACKER™  automatic drop tensiometer with Phase Exchange option

Key words: Multilayered emulsion, protein, pectin, drop tensiometery, bulk exchange

What are the effects of sequential absorption on the composition of oil-water interfaces in emulsions stabilized with plant-dairy protein blends ?  

Reference: Hinderink, Emma BA, et al. "Sequential adsorption and interfacial displacement in emulsions stabilized with plant-dairy protein blends." Journal of Colloid and Interface Science 583 (2020): 704-713.

Emulsions stabilized with plant-dairy protein blends exhibit complex interfacial structures. In this paper, protein displacement at oil-water interfaces is studied as a function of the sequence in which proteins are introduced. At the scale of a unique oil-water interface, surface tension and dilatational rheology experiments using a drop tensiometer with bulk-phase exchange (TRACKER™ by TECLIS) are performed. In the case of a whey-protein blend, the experiments showed that pea proteins adsorbed to pre-adsorbed whey proteins, leading to thick interfacial layers. The addition of whey proteins to a pea protein- or whey-pea protein blend-stabilized emulsion led to significant displacement of the pea proteins. The protein-protein interaction was hence identified as the driving force for this displacement.

TECLIS product: TRACKER™  automatic drop tensiometer with Phase Exchange option

Key words: emulsion, oil-water interface, pea protein, whey protein, bulk exchange, sequential adsorption