Emulsions in Life Sciences

Use Cases 

Can solid lipid nanoparticles be used as stabilizers in oil-in-water Pickering nano-emulsions ? 

Reference: Dieng, Sidy Mouhamed, et al. "Pickering nano-emulsions stabilized by solid lipid nanoparticles as a temperature sensitive drug delivery system." Soft matter 15.40 (2019): 8164-8174.

The purpose of this study was to develop Pickering O/W nano-emulsions only stabilized by solid lipid nanoparticles (SLNs), as a new generation of safe, non-toxic, biocompatible, and temperature-sensitive lipid nano-carriers. Besides a first part dedicated to understanding the stabilization mechanisms of SNLs in nano-emulsions, the second part of this study characterized the interfacial properties of an C6H6/MilliQ water interface in the presence of SNLs (in water) through surface tension and interfacial rheology measurements with an automatic drop tensiometer (TRACKER™ by TECLIS). These results highlighted the important interfacial activity of SNLs at oil/water interfaces that contributes to nano-emulsions stabilization.

TECLIS product: TRACKER™ automatic drop tensiometer

Key words: Nano-emulsions, solid lipid nanoparticles, interfacial tension, dilational rheology.

What are the mechanisms responsible of the stability of oil in water emulsions in the presence of yeast ? 

Reference: Meirelles, Aureliano Agostinho Dias, Rosiane Lopes da Cunha, and Andreas Karoly Gombert. "The role of Saccharomyces cerevisiae in stabilizing emulsions of hexadecane in aqueous media." Applied microbiology and biotechnology 102.7 (2018): 3411-3424.

Undesired emulsions may be formed during processes where microorganisms are involved. In order to find effective ways to break these unwanted emulsions, the authors investigated the stability of yeast-containing oil-in-water emulsions. In practice, different yeast-based aqueous solutions and hexadecane were used to generate emulsions that were probed in terms of phase separation, surface charge density, particle size and rheology. But prior to that, an important step consisted in characterizing the interfacial tension between the different aqueous yeast suspensions and the oil phase by the pendant dop method using an automatic drop tensiometer (TRACKER™ by TECLIS). Different yeast strains at different physiological states were used and, overall,  the results showed that the interfacial tension at the oil-water interface decreased in the presence of yeast cells.  This behavior is very likely contributing to the stabilization of yeast-containing oil-in-water emulsions.

TECLIS product: TRACKER™ automatic drop tensiometer.

Key words: Oil-in-water emulsion, yeast, biofuel, stability, interfacial tension.

What is the impact of the non-ionic surfactant Tween80 (T80) on the lipid digestion of gum Arabic (GA) stabilized oil-water emulsions ? 

Reference: Yao, Xiaolin, et al. "The influence of non-ionic surfactant on lipid digestion of gum Arabic stabilized oil-in-water emulsion." Food Hydrocolloids 74 (2018): 78-86.

In order to promote satiety and satiation from lipids, a possible approach consists in designing functional foods to delay the digestion of lipids. In this context, Tween80 (T80) was found to have an important impact on the lipid digestion of gum Arabic (GA) stabilized oil-in-water emulsions. Since digestion is an interfacial process, the authors of this paper investigated the interfacial structure of GA-T80 emulsion droplets. To do so, surface tension measurements at the oil-water interface were performed with an automatic drop tensiometer (TRACKER™ by TECLIS). Two preparation methods were used: layer by layer adsorption and mixed adsorption. The results showed that the initial presence of T80 in the solution leads to its quick adsorption while its addition to a GA monolayer produces an interfacial tension dop which suggests that the interface of GA-T80 emulsion was made of both GA and T80, while that of T80-GA emulsion and GA + T80 emulsion were dominated only by T80.

TECLIS product: TRACKER™ automatic drop tensiometer

Key words: lipid digestion, interfacial structure, interfacial tension, oil-in-water emulsions.

What is the impact of the addition of β-carotene on the structure of oil-water emulsions ? 

Reference: Gomes, A., Costa, A. L. R., Cardoso, D. D., Nathia-Neves, G., Meireles, M. A. A., & Cunha, R. L. (2021). Interactions of β-carotene with WPI/Tween 80 mixture and oil phase: Effect on the behavior of O/W emulsions during in vitro digestion. Food Chemistry, 341, 128155.

Previous studies showed that the adsorption of β-carotene is inefficient. One of the options to enhance its physicochemical stability and bio-accessibility is to incorporate it to the oil phase of oil-in-water emulsions. In this paper, the authors investigate the interaction of β-carotene with other ingredients of the emulsion: Tween 80 (T80) and Whey Protein Isolate (WPI) that were used as emulsifiers. Moreover, different oil phases were tested : sunflower oil-LCT or NEOBEE®1053-MCT. In practice, surface tension and interfacial rheology measurements were performed at the oil-water interface in  the presence of β-carotene using an automatic drop tensiometer (TRACKER™ by TECLIS). The results showed that the β-carotene reduced the interfacial tension of the LCT/MCT-water systems. The addition of β-carotene promoted an increase of viscoelasticity of LCT/MCT-T80 (0.5% WPI/0.5% T80 and 1% T80 w/w) interfaces, but an increase of WPI content reduced the viscoelasticity of interfacial layers (LCT/ MCT-1% WPI).

TECLIS product: TRACKER™ automatic drop tensiometer

Key words: oil-in-water emulsions, surface tension, dilational rheology, emulsifiers.

What are the impacts of fish oils on the digestion of β-lactoglobulin stabilized emulsions ? 

Reference: Marze, S., Meynier, A., & Anton, M. (2013). In vitro digestion of fish oils rich in n-3 polyunsaturated fatty acids studied in emulsion and at the oil–water interface. Food & function, 4(2), 231-239.

In this paper, the authors investigated the interaction between fish oils and β-lactoglobulin (β-LG) during the digestion process. One of the main steps consisted in measuring the interfacial tension with an automatic drop tensiometer (TRACKER™ by TECLIS) at the marine fish oil (f-1050)/aqueous solution in different ionic and pH conditions to mimic the environment in the three parts of the digestive tube : the month, the stomach and the small intestine. The results show that when β-LG is present, there is a sharp initial interfacial tension decrease followed by a gradual one, due to its adsorption and reorganization, respectively.  Moreover, during the mouth step, there is a sharp interfacial tension decrease in the absence of β-LG, or a small increase in the presence of β-LG. During the gastric step, there is a gradual decrease in the absence of β-LG, or a sharp initial increase followed by a small gradual one in the presence of β-LG. During the intestinal step, there is a sharp initial decrease followed by a gradual decrease. Additional experiments with a different oil: f-1812 showed that the oil type also plays an important role.

TECLIS product: TRACKER™ automatic drop tensiometer

Key words: emulsion, protein-lipid interaction, interfacial tension, digestion.

Can bilayers of fatty acid soap systems formed at high pH be used  to generate and stabilize emulsions and foams ? 

Reference: Xu, W., Zhang, H., Zhong, Y., Jiang, L., Xu, M., Zhu, X., & Hao, J. (2015). Bilayers at high pH in the fatty acid soap systems and the applications for the formation of foams and emulsions. The Journal of Physical Chemistry B, 119(33), 10760-10767.

In this paper, the authors show that bilayer structures of fatty acid soap systems can form at high pH, then they probe their ability to generate and stabilize foams and emulsions and compare their efficiency to micelles. To characterize the foaming properties of these systems, an automatic foam analyzer (FOAMSCAN™ by TECLIS) is used. The experimental protocol consisted in sparging N2 at a constant flow rate through a porous disk into a 60 mL solution. The stability of the foam was analyzed after stopping the gas flow (once the volume of the foam reached 200mL). Solutions containing micelles and bilayers of palmitic acid and Stearic acid were tested, and, in both cases, foams stabilized by bilayers were more stable than those stabilized with micelles. Similar results were observed in emulsions.

TECLIS product: FOAMSCAN™ foam analyzer

Key words: fatty acid, bilayer, micelles, foam stability, emulsification.