A double emulsion with leaf extract

Larissa Tessaro, Andresa Gomes, Paulo José Do Amaral Sobral

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Larissa Tessaro, Andresa Gomes, Paulo José Do Amaral Sobral. A double emulsion with leaf extract. International Journal of Molecular and Physical Gastronomy, 2025, 11 (1), pp.1-4. 10.17180/ijmpg-2025-art01.. hal-04912123v2

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Inrae-AgroParisTech
International Centre for Molecular and Physical Gastronomy

International Journal
of
Molecular and Physical Gastronomy

**Authors**

Larissa Tessaro, Andresa Gomes, Paulo José do Amaral Sobral

**Title of the work**

A double emulsion with leaf extracts

Year 2025, Volume 11 (1), Number 1, pp. 1-4

**Published online:**

27 January 2025

https://icmpg.hub.inrae.fr/international-activities-of-the-international-centre-of-molecular-gastronomy/international-journal-of-molecular-and-physical-gastronomy/2-scientific-part/image-for-thought/double-emulsion

A double emulsion with leaf extracts © 2025 by Larissa Tessaro, Andresa Gomes, Paulo José do Amaral Sobral is licensed under Attribution 4.0 International

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# A double emulsion with leaf extract?

Larissa Tessaro ¹, Andresa Gomes ¹,², Paulo José do Amaral Sobral ¹,²*

1. Department of Food Engineering, Faculty of Animal Science and Food Engineering, University of São Paulo, Av. Duque de Caxias, 225, 13635-900, Pirassununga, SP, Brazil.

2. Food Research Center (FoRC), University of São Paulo, Rua do Lago, 250, Semi-industrial building, block C, 05508-080, São Paulo, SP, Brazil.

*Correspondence: pjsobral@usp.br

<figure><img src="image_4.png" /><figcaption>Figure 1. Photomicrograph of a double emulsion encapsulating “Pitanga” (Eugenia uniflora L.) leaf hydroethanolic extract obtained by a fluorescence microscope (BX51, Olympus, Tokyo, Japan).</figcaption></figure>
**Abstract**

The polydispersity of a water-in-oil-in-water (W/O/W) double emulsion is discussed from a photomicrograph picture captured by fluorescence microscopy with Nile Red dye to color the oil phase of the W/O/W emulsion. Large drops of soybean oil are dispersed in the external aqueous phase, with small droplets of water containing Pitanga (*Eugenia uniflora* L.) leaf hydroethanolic extract inside. W/O/W emulsions have great relevance in several industries, including food, due to their ability to encapsulate aqueous and polar bioactive compounds, promoting controlled release and protection of bioactive properties, and ability to create multi-layered flavors and textures. However, the stability and formation of monodisperse W/O/W emulsions still represent significant challenges, especially due to droplet size polydispersity, which affects the stability and functionality of the system.

**Keywords**

emulsion, double emulsion, picture

The photomicrograph of a water-in-oil-in-water (W/O/W) double emulsion (Figure 1) was obtained using Nile red dye (0.25 mg/mL DMSO) added in the double emulsion at 1:10 ratio (dye:sample, v/v) to coloring the oil phase (Tessaro et al., 2022). The sample was placed on a microscope slide and the photomicrograph was captured using a fluorescence microscope (BX51, Olympus, Tokyo, Japan) with a 100 x oil immersion objective lens (Tessaro et al., 2022). Large droplets of soybean oil (red) dispersed in an external aqueous phase and containing small droplets of water (black) inside containing "Pitanga" leaf hydroethanolic extract (*Eugenia uniflora* L.) can be observed in this Figure. Double emulsions are a type of colloidal system where a primary emulsion is dispersed within a secondary one, forming a complex structure with three distinct phases (Dickinson, 2011). The most studied type is the water-in-oil-in-water ($W_1/O/W_2$)

emulsion, where an inner water-in-oil emulsion ($W_1/O$) is dispersed in an outer aqueous phase ($W_2$).

These emulsions are valuable across industries like food, cosmetics, and pharmaceuticals due to their ability to encapsulate both hydrophilic and hydrophobic compounds, offering versatile properties for controlled release and enhanced product sensory characteristics. The lipidic and external aqueous phases protect the encapsulated bioactive compounds, preserving their stability and functionality in different applications (Heidari et al., 2022).

$W_1/O/W_2$ emulsions are interesting in gastronomy for creating unique textures, controlling flavor release, protecting sensitive ingredients, increasing bioaccessibility (Tessaro et al., 2024), and producing foods low in fat, salt, or sugar (Buyukkestelli and EI, 2021). They encapsulate both hydrophobic and hydrophilic compounds, offering a creamy, smooth consistency while preserving the nutritional properties of ingredients like essential oils, probiotics, vitamins, and antioxidants (Øye et al., 2023).

$W_1/O/W_2$ emulsions also provide an alternative for extending shelf life and adding functional benefits to foods, meeting consumer demands (Øye et al., 2023). With their ability to create multi-layered flavors and textures, $W_1/O/W_2$ emulsions are an alternative tool in the developing of healthier and functional dishes, such as sauces, yogurts, ice cream, and beverages (Zhang et al., 2024). For example, a low-fat meat batter was produced with a $W_1/O/W_2$ emulsion encapsulating *Murraya koenigii* berries extract and showed better oxidative stability, without affecting the other attributes of the food product (Kumar and Kumar, 2020).

Despite their potential, the formation and stabilization of $W_1/O/W_2$ emulsions present challenges. Achieving high kinetic stability requires careful selection of emulsifiers and emulsification methods (McClements, 2004). Emulsifiers, which reduce interfacial tension between aqueous and lipidic phases, are key to
stabilizing the emulsion and preventing droplet coalescence. Mechanical energy during emulsification is crucial for reducing droplet size and ensuring uniform distribution. The size and polydispersity of droplets—the variation in their size distribution—are significant factors influencing the emulsion's stability and functionality (McClements, 2004).

Polydispersity in W₁/O/W₂ emulsions, where droplet sizes vary widely, can negatively affect the system's properties, such as stability, texture, and functionality. Large droplets may lead to coalescence, where droplets merge, and Ostwald ripening, where smaller droplets dissolve into larger ones due to pressure differences, potentially causing the breakdown of the emulsion (Dickinson, 2011). These destabilizing processes limit the practical applications of W₁/O/W₂ emulsions, particularly in food and cosmetics, where consistent texture and visual stability are critical (McClements, 2004). For example, polydisperse emulsions may appear grainy or have uneven texture, which detracts from the sensory appeal of products (Chen et al., 2022). High polydispersity also leads to phase separation over time, as larger droplets settle more quickly than smaller ones (McClements, 2004).

The formation of monodisperse double emulsions —where droplet sizes are uniform—remains a major challenge. Various strategies, such as optimizing the selection of emulsifiers, emulsification techniques, and processing conditions, are employed to minimize polydispersity and enhance emulsion stability and performance. These include adjusting factors like viscosity, phase ratios, temperature, pH, and ionic strength, all of which affect droplet formation and stability (McClements and Jafari, 2018).

The authors acknowledge the São Paulo Research Foundation-FAPESP (grant 2013/07914-8) and the Brazilian National Council for Scientific and Technological Development-CNPq (grant 40.3746/2021-3). P.J.A.S. thanks

CNPq (30.2482/2022-9) for his research fellowship and A.G. thanks FAPESP (2019/26348-0) for her post-doc fellowship. This study was financed in part by the "Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil" (CAPES) - Finance Code 001 (PhD fellowship of L.T.).

## References

Buyukkestelli HI, El SN. 2021. Enhancing sweetness using double emulsion technology to reduce sugar content in food formulations, *Innovative Food Science and Emerging Technologies Journal*, 74, 102809.
https://doi.org/10.1016/j.ifset.2021.102809

Chen M, Abdullah, Wang W, Xiao J. 2022. Regulation effects of beeswax in the intermediate oil phase of the stability, oral sensation and flavor release properties of Pickering double emulsions, *Foods*, 11(7), 1039.
https://doi.org/10.3390/foods11071039

Dickinson E. 2011. Double emulsions stabilized by food biopolymers, *Food Biophysics*, 6(1), 1-11.
https://doi.org/10.1007/s11483-010-9188-6

Heidari F, Jafari SM, Ziaiifar AM, Malekjani N. 2022. Stability and release mechanisms of double emulsions loaded with bioactive compounds: a critical review, *Advanced Colloid Interface Science*, 299, 102567.
https://doi.org/10.1016/j.cis.2021.102567

Kumar Y, Kumar V. 2020. Effects of double emulsion (W₁/O/W₂) containing encapsulated Murraya koenigii berries extract on quality characteristics of reduced-fat meat batter with high oxidative stability, *Lebensmittel und Technologie Wissenschaft*, 127, 109365.
https://doi.org/10.1016/j.lwt.2020.109365

McClements DJ, Jafari SM. 2018. Improving emulsion formation, stability and performance
International Journal of Molecular and Physical Gastronomy

Image for thought

using mixed emulsifiers: A review, *Advanced Colloid Interface Science*, 251, 55–79.
https://doi.org/10.1016/j.cis.2017.12.001.

McClements DJ. 2004. *Food Emulsions*. 2. ed. Boca Raton: CRC Press.

Øye G, Simon S, Rustad T, Paso K. 2023. Trends in food emulsion technology: Pickering, nano-, and double emulsions, *Current Opinions in Food Science*, 50, 101003.
https://doi.org/10.1016/j.cofs.2023.101003.

Tessaro L, Luciano CG, Martins MFL, Ramos AP, Martelli, M.R., Sobral PJA. 2022 Stable and bioactive W/O/W emulsion loaded with “Pitanga” (Eugenia uniflora L.) leaf hydroethanolic extract, *Journal of Dispersion Science and Technology*, 43, 1890-1900.
http://dx.doi.org/10.1080/01932691.2021.1949339

Tessaro L, Gonçalves RF, Martins JT, Pinheiro, AC, Vicente AA, Sobral PJ. 2024. Gelatin-based nanocomposite films activated by double emulsion loaded with “Pitanga” leaf extract: Bioaccessibility and cytotoxicity of emulsions and films after in vitro digestion, *Food Hydrocolloids*, 154, 110136.
https://doi.org/10.1016/j.foodhyd.2024.110136

Zhang L, Hu Y, Jiang L, Huang H. 2024. Microbial encapsulation and targeted delivery mechanisms of double emulsion loaded with probiotics—a state-of-art review, *Food Review International*, 40, 1731-1755.
https://doi.org/10.1080/87559129.2023.2230268

**Edited by:**

Pr José Miguel Aguilera

**Reviewers:**

1. Anonymous

2. Anonymous

**Received:**

4 June 2024

**Accepted :**

10 December 2024

**Published:**

20 January 2025.

**Section:**

This article was published in the “Image for Thought” section of the International Journal of Molecular and Physical Gastronomy

**Citation:**

Larissa Tessaro, Andresa Gomes, Paulo José do Amaral Sobral. 2025. Can polydispersity affect the properties of a double emulsion?, *International Journal of Molecular and Physical Gastronomy*, 11(1), 1, 1-4. DOI: https://doi.org/10.17180/ijmpg-2025-art01.