Edible gas marbles stabilized with cocoa particles: understanding their behavior by tuning the edible liquid phase

Introduction: Gas marbles have recently emerged as a new class of particle-stabilized gas–liquid systems. A gas marble consists of a single air bubble suspended in air and encapsulated by a thin liquid shell stabilized by solid particles, forming an air-in-liquid-in-air structure. Gas marbles can be generated using various edible particles, but their formation has so far been demonstrated almost exclusively in water, where only particles with intermediate wettability (moderately hydrophilic contact angles) lead to stable structures. Because liquid surface tension strongly influences the three-phase contact angle, expanding gas-marble formation beyond water requires understanding how the liquid phase governs gas marbles formation and stability.

Methods: In this work, we investigate the formation of gas marbles using cocoa particles and a wide range of edible liquids differing in surface tension and composition. We also systematically varied a model liquid phase from water/ethanol mixtures. Unlike previous studies that focused primarily on particle wettability in water-based systems, this work explicitly isolates and elucidates the role of the liquid phase in governing gas-marble formation.

Results and discussion: We demonstrate that the three-phase contact angle can be tuned through liquid surface tension, enabling or inhibiting gas-marble formation. We show, for the first time, that stable cocoa-based gas marbles can be produced in a broad set of edible liquids, provided that the liquid surface tension remains sufficiently high (above 34 mN/m). These gas marbles exhibit notable robustness, including heat resistance and long-term stability. Overall, this study establishes clear criteria linking liquid surface tension, particle wettability, and gas-marble formation. These findings provide new physical insight into particle-stabilized gas–liquid interfaces beyond water systems and offer general formulation guidelines applicable across a wide range of edible and non-aqueous liquids.

1 Introduction

Liquid foams consist of gas bubbles dispersed in a continuous liquid phase (Cantat et al., 2013). This liquid phase may be water or oils (Fameau and Saint-Jalmes, 2017). Liquid foams play a central role in many food applications (Dickinson, 2020; Murray, 2020). Most aqueous foams are generated and stabilized using surface-active molecules, including surfactants, proteins, and polymers. In addition, foams can also be stabilized by solid particles, giving rise to the so-called Ramsden/Pickering foams (Hunter et al., 2008; Lam et al., 2014; Murray, 2019; Iwashita, 2020; Fujii, 2024), showing advantages in terms of higher stability and tunable interfacial properties (Lam et al., 2014; Xiao et al., 2016; Dickinson, 2020; Jiang et al., 2020; Murray, 2020). In such systems, solid particles irreversibly adsorb at the gas–liquid surface, forming a mechanical barrier that prevents bubble coalescence (Binks, 2002; 2017; Subramaniam et al., 2006; Abkarian et al., 2007; Nakayama et al., 2015; Fujii and Nakamura, 2017). This irreversible adsorption is a key distinction from surfactant-based stabilization: while surfactants can desorb or re-equilibrate when conditions change, particles remain strongly anchored at the interface, imparting structural rigidity and long-term stability (Binks, 2002). Particle interfacial behavior is primarily governed by their wettability, quantified by the three-phase contact angle (θ) they adopt at the fluid interface. Hydrophilic particles (θ < 90°) tend to stabilize aqueous foams by residing mainly in the water phase, whereas hydrophobic particles (θ > 90°) are more effective at stabilizing non-aqueous foams (Binks and Horozov, 2006; Fameau and Salonen, 2014). Stabilization efficiency can also be tuned by modifying particle morphology, surface roughness, surface charge, or the presence of surface-active chemical groups (Binks, 2002; 2017).

In recent years, novel solid particle-stabilized gas bubble system, “gas marble”, has been developed (Timounay et al., 2017; Yasui et al., 2024). The gas marbles are single air bubbles suspended in air and encapsulated by a thin liquid shell stabilized by solid particles (an air-in-water-in-air configuration). Recently, we demonstrated that gas marbles can be produced using a variety of edible particles, with water serving as the liquid phase (Mukai et al., 2025; Yagishita et al., 2026). The key parameter governing gas-marble formation is the three-phase water contact angle of the particles. Highly hydrophilic particles (low contact angle) fail to remain at the air–liquid surface, preventing marble formation, whereas highly hydrophobic particles (high contact angle) destabilize the liquid shell and lead to bubble rupture. Only particles with intermediate wettability form stable gas marbles. Moreover, gas marbles made from cinnamon particles, for example, are known to exhibit remarkable resistance to drying, heating, freezing, and even mechanical deformation (Mukai et al., 2025).

To date, however, edible gas marbles have only been produced using mainly water as the liquid phase, despite the well-established role of liquid surface tension in tuning the three-phase contact angle (Lam et al., 2014; Binks, 2017), although there is only one report demonstrating various other edible liquid phases could be used to produce gas marbles as shown by using cinnamon as particles: coffee, milk, soy milk, vinegar and soy sauce (Mukai et al., 2025). As a result, it remains unclear whether the contact-angle criterion identified in water is universal, or how it is modified when the liquid phase itself is varied. In particular, a systematic and quantitative understanding of how liquid surface tension governs particle wettability and gas-marble formation across chemically distinct edible liquids is still lacking. In this work, we address this gap by fixing the particle (cocoa particles) and systematically varying the liquid phase across a wide range of edible liquids, thereby decoupling particle effects from liquid-phase effects. This approach allows us to identify liquid-dependent thresholds for gas-marble formation and to generalize the underlying physical principles beyond water-based systems. In particular, we investigate how the nature and surface tension of the liquid phase influence the formation and stability of gas marbles produced using cocoa particles, which are known to yield highly stable marbles using water and therefore constitute an excellent model particle system. We examined gas-marble formation using 34 different edible liquids varying in composition and surface tension. First, we show that with water as the liquid phase, gas marbles can be formed across an unprecedented range of initial bubble volumes, from 5 to 2000 μL, a range not previously reported for gas marbles systems. We found that when the surface tension of the liquid phase was below 34 mN m^-1, the resulting three-phase contact angle dropped below 60°, which was insufficient to produce gas marbles. Only liquids with higher surface tension allowed successful formation. No gas marble could be obtained using edible oils as the liquid phase. Furthermore, gas marbles formed using water–ethanol mixtures only when the ethanol content remained below 30%; at higher ethanol concentrations, the surface tension became too low to sustain marble formation. These findings provide fundamental insight into how the liquid phase controls gas-marble formation and offer practical formulation guidelines for their fabrication, particularly regarding the minimum surface-tension requirements. The use of fully edible materials opens new possibilities for applying gas-marble technology in food science and molecular gastronomy.

2 Materials and methods

2.1 Materials and samples preparation

The cocoa powder was bought in the supermarket (Van Houten Cocoa, manufacturer Kataoka & Co., Ltd.). All the edible liquids were bought in the supermarket and were used as received (Supplementary Table S1; Supplementary Figure S1). Doubly distilled water prepared using a deionized water system (Advantec MFS RFD240NA: GA25A-0715) was used. The ethanol (purity, 94.8–95.8 v/v%) was from Sigma-Aldrich Japan G.K.

The gas marbles were produced by following the protocol developed by Roux et al. (2022). Cocoa particles were sprinkled onto a flat air-liquid surface to create a dense particle raft. A precise volume of air was then injected beneath the surface using a U-shaped needle (4982 PD 18G, Kyowa Interface Science Co., Ltd.: inner diameter, 0.90 mm) connected to a syringe. The bubble trapped beneath the particles raft was then scooped up and gently rolled on the particle layer using a spatula to ensure full coverage. As the bubble rolled, the particles raft formed a closed air bubble structure. The gas marbles could then be easily removed using two spatulas and placed onto a solid surface for characterization.

2.2 Characterization of cocoa particles

The cocoa particles were characterized using first an optical microscope (BX53, Olympus Co.) equipped with a digital imaging system (Moticam 5.0 MP, Shimadzu Co. Ltd.). Then, scanning electron microscopy (SEM) studies were performed on the edible particles coated with a thin layer of gold using a TM4000II miniscope (Hitachi High-Tech Corporation). The volume-average diameter (D_v) of the edible particles dispersed in water was measured using a laser diffraction particle size analyzer (Mastersizer 2000, Malvern). The circularity was also estimated using the ImageJ software by enclosing the outer circle of the particle using freehand selections as described in reference (Schneider et al., 2012). From the cocoa particles characteristics, we calculated the dimensionless Bond number (B_o) defined using Equation 1.

$B_o=\frac{\Delta \rho g{L}^2}{\gamma }(1)$

where Δρ is the difference in density of the two phases (liquid and particle (density = 1.32 g.cm^-3) (Yagishita et al., 2026); g is the gravitational acceleration; L is the particle diameter and γ is the surface tension of the liquid.

2.3 Surface tension of the edible liquids

The surface tensions of the liquids were measured using the Wilhelmy plate method with a precision surface tension analyzer (DY-300, Kyowa Interface Science Co., Ltd.). The obtained force-displacement profiles were processed and evaluated using the dedicated analysis software (Dynalyzer, Kyowa Interface Science Co., Ltd.), ensuring reliable and reproducible determination of the interfacial properties.

2.4 Three-phase liquid contact angle of cocoa particles

To measure the static three-phase liquid contact angle, 5 µL droplets were placed on pressed pellets prepared from dried cocoa particles. Measurements were recorded immediately after droplet deposition and again after 10 s (the typical timescale for gas-marble formation), at 25 °C, using a DropMaster DMs-401 system (Kyowa Interface Science Co., Ltd.) and the θ/2 (height–width) method. Error bars represent the standard deviation from three independent replicate measurements performed on separately prepared pellets for each powder.

3 Results and discussion

3.1 Gas marbles formation and properties with water as liquid phase

The cocoa particles used in this study were commercially edible particles, and we first characterized their properties to gain insight into the gas marbles stabilization mechanisms. The D_v in water medium was measured to be 32 ± 20 µm (Figure 1a). The shape of the particles was determined by calculating the circularity value, which was around of 0.78 ± 0.08, using stereomicroscopy images (Figure 1b). Scanning electron microscopy (SEM) observation revealed that the particles had surface roughness with a few micrometer sizes (Figure 1c). The density was measured to be 1.32 ± 0.01 g cm^-3 using a helium pycnometer.

Figure 1

Figure 1. (a) Size distribution of the cocoa particles determined by laser diffraction particle size analysis, (b) stereomicroscopy and (c) scanning electron microscopy images of the cocoa particles.

First, we investigated the maximum air-bubble volume that could be stabilized by cocoa particles to produce gas marbles using water (Figure 2). The initial air-bubble volume was varied from 5 μL to 5000 µL. Stable gas marbles were successfully formed for bubbles ranging from 5 µL to 2000 μL, corresponding to diameters of approximately 2.5–15 mm. To our knowledge, this is the first-time gas marbles of such large size have been obtained. Gas marbles exhibited spherical shape for low air-bubble volume from 5 to 500 μL, however for larger initial bubbles (1000–2000 µL), gas marbles were a little bit flattened. Moreover, for even larger initial air bubbles (between 3000–5000 µL) gas marbles could still be formed, but they broke during removal from the particle rafts at the air–water surface (Supplementary Figure S2). Gas marbles exhibited the high water loading for initial bubble volumes between 5 and 10 μL, with values of 67.2% ± 4.4% and 63.0% ± 4.5%, respectively. Water loading then decreased gradually as the initial bubble volume increased from 100 to 500 μL, and eventually reached an approximately stable regime around 54%–58% (Supplementary Figure S3). The observed increase in the water weight fraction for smaller gas marbles can be rationalized by considering the role of gravity during the formation process. For gas marbles with small diameters, gravitational effects are negligible compared with capillary forces, allowing the water film formed around the gas core to retain a relatively large thickness throughout fabrication. In contrast, for larger gas marbles, gravitational drainage becomes significant during formation, causing the liquid initially present at the upper region of the marble to flow downward toward the lower hemisphere. This gravity-induced redistribution of the liquid phase effectively reduces the average thickness of the water film in the resulting gas marble. Consequently, gas marbles of smaller size preserve a thicker water shell and therefore exhibit a higher water weight fraction than their larger counterparts.

Figure 2

Figure 2. Optical photographs of gas marbles based on cocoa particles and water varying in diameter due to an initial air bubble ranging from 5 μL to 2,000 µL before and after drying at room temperature for 24 h. Initial air bubble volume of: (a) 5 μL, (b) 20 μL, (c) 100 μL, (d) 500 μL, (e) 1000 μL, and (f) 2000 µL.

All gas marbles, regardless of diameter, were relatively spherical immediately after formation, prior to drying (Figure 2). However, after 1 day of drying at room temperature, gas marbles produced from initial bubble volumes of 1,000 µL and above began to collapse and adopted a non-spherical shape. This result highlights that controlling the initial bubble volume is essential for maintaining the spherical shape of gas marbles during aging. We suppose that the water evaporation plays a key role in the stability of the gas marbles and the decrease in size, and initial water loading is important. The smallest gas marbles contained higher water loading than the larger ones, and they were less sensitive to drying. This contraction of the gas marbles is likely attributable to evaporation of the liquid phase from the particle shell surrounding the enclosed air, which progressively compacts the granular film, reduces the overall marble size, and ultimately leads to jamming at the surface (Stratford et al., 2005). But it is important to note that evaporation and water loading are not the only parameters playing a role here. If evaporation were the only mechanism driving morphological changes, one would expect the height and width of the marbles to decrease equally, since the shell surface was initially widely exposed (with only a small contact area between the shell and the supporting support). However, the photographs clearly demonstrate a significant influence of gravity playing a non-negligible role in these gas marbles systems. There was a vertical collapse of the biggest gas marbles leading to a change from spherical gas marbles to flattened ones after 1 day of drying, highlighting the effect of gravity on their external morphology. Consequently, the larger the gas marble, the more sensitive it is to gravitational deformation due to the greater mass of stabilizing particles comprising the shell.

3.2 Gas marbles formation and properties with various edible liquid phase

Building on the results obtained with water, we next investigated the production of gas marbles using various edible liquids while keeping the initial air-bubble volume fixed at 20 µL. We selected five broad categories of edible liquids: seasoning liquids, dairy products, edible beverages (non-alcoholic), alcoholic beverages with different ethanol contents, and vegetable oils. This classification is arbitrary and is used solely to facilitate interpretation of the results (Figure 3; Table 1).

Figure 3

Figure 3. Optical photographs of gas marbles based on cocoa particles just after production using various edible liquids. The pink color corresponds to seasoning liquid. The yellow color to dairy products. The green color to various edible drink. The blue color to alcoholic beverage. It is important to note that this classification is arbitrary and is presented here only to facilitate understanding. It is based on the typical ways these liquids are used in culinary applications. The scale bar is the same for all photographs.

Table 1

Table 1. Gas marbles formation test using cocoa particles and various edible liquids: √-gas marble formation, X-no gas marble formation. The surface tension is given for each edible liquid. Edible liquids that produce gas marbles are shown in blue, while those that fail to form gas marbles are shown in pink. The surface tension of the honey was unmeasurable due to too high viscosity.

We successfully produced gas marbles for a wide range of edible liquids across these categories. Gas marbles were obtained with all the seasoning liquids, dairy products liquids, drink and alcoholic beverages with low ethanol content such as wine. However, no gas marbles could be formed with vegetable oils, and alcoholic beverages with a high ethanol content (specifically whisky at 37% ethanol and gin at 47.3%). All the gas marbles formed were spherical. Only the gas marbles produced with honey were relatively flattened, adopting a so-called “pancake” shape. This can be explained by the high viscosity of honey compared to the other edible liquids, which are mainly composed of water. The shape of gas marble changed from near-sphere to pancake by mechanical stress applied using a spatula during rolling on the particle raft. Due to the high viscosity, the pancake shape could not be near-sphere to decrease interfacial energy. Once the cocoa particles fully covered the pancake marble surface, the shape could be retained due to interfacial jamming effect (Bala Subramaniam et al., 2005; Stratford et al., 2005; Cui et al., 2013).

To understand why gas-marble formation was or was not possible depending on the edible liquid phase, we first measured the air–liquid surface tension of all liquids. We found that gas marbles could only be formed for liquids with a surface tension above 34 mN/m. Next, we examined the evolution of the three-phase liquid contact angle over time for each liquid. We focused on static contact-angle measurements to ensure consistent comparison across the diverse set of edible liquids, which exhibit a broad range of viscosities. This method provides a general indication of cocoa-particle wettability and their ability to stabilize an air–liquid surface under comparable conditions (Figure 4; Table 1). It is important to note that the reported values represent apparent, time-dependent contact angles measured on porous powder pellets. These values are used as a consistent and comparative metric of wettability, rather than as strictly defined advancing or receding contact angles. Vegetable oils such as canola oil and olive oil showed low initial contact angles (<60°), which decreased rapidly over time, reaching 20°–30° within a few tens of seconds. These liquids did not lead to gas-marble formation. Similarly, alcoholic beverages with high ethanol content (≥30%), such as whisky (37%) and gin (47.3%), also exhibited initial contact angles below 60° that quickly dropped to 20°–30°. These two liquids failed to produce gas marbles. In contrast, more favorable behavior was observed for all other edible liquids. Their initial three-phase contact angles ranged from 70° to 100°, decreasing more moderately to 60°–80° after 40 s. For example, coffee exhibited relatively stable contact angles, starting near 100° at t = 0 s and decreasing only slightly to ∼90° after 40 s. For these liquids, cocoa particles displayed intermediate wettability, which was sufficient to stabilize the air–liquid surface and allow gas-marble formation. A particular case was honey, which showed very high and time-stable contact angles (>140°) due to its high viscosity. Despite the impossibility of measuring its surface tension for the same reason, honey nonetheless supported gas-marble formation.

Figure 4

Figure 4. Evolution of the three-phase contact angle with time for cocoa particles with different edible liquids. The blue color corresponds to the contact angle values zone leading to gas marbles formation (○) (Group I), and the pink color corresponds to contact angle values zone where no gas marbles could be produced (▲) (Group II). Error bars represent the standard deviation calculated from three independent replicate measurements performed on separately prepared pellets for each liquid.

Overall, these results allow us to classify the edible liquids into two groups. The first group was composed with liquids forming gas marbles, characterized by surface tensions between 34 and 68 mN/m and three-phase contact angles between 60° and 140°. The second group was composed with liquids that do not form gas marbles, characterized by low surface tensions (<34 mN/m) and three-phase contact angles below 60°, which prevent stable particle adsorption and thus inhibit gas-marble formation.

The key parameter that predicts whether gas marbles can form is the three-phase liquid contact angle, which governs particle wetting behavior (Figure 4). This angle determines whether particles remain adsorbed at the air–liquid surface, where they can effectively encapsulate air bubbles or whether they become fully dispersed in the liquid phase, which makes gas-marble formation impossible. An intermediate wettability regime is therefore essential: only when particles are partially wetted, they become energetically trapped at the surface and self-assemble into stable granular films capable of stabilizing gas marbles (Timounay et al., 2015; Timounay, 2016; Timounay and Rouyer, 2017). Our results confirm previous findings obtained with various edible particles in water, which already demonstrated the central role of the three-phase liquid contact angle in determining gas-marble stability. Here, we further show that this parameter can be tuned by the surface tension of the continuous liquid phase, providing a direct link between liquid physicochemical properties and the ability to form gas marbles.

For food applications, a key prerequisite is stability under elevated temperatures. We therefore followed the thermal stability of all successfully produced gas marbles by subjecting them to a heat treatment at 80 °C for 1 week (Figure 5). Photographs taken before and after heating were compared to evaluate morphological changes. All gas marbles remained intact throughout the heat treatment, demonstrating excellent thermal resistance across all edible liquid phases tested. However, a systematic decrease in diameter was observed for every gas marble, regardless of the liquid used for their preparation. For instance, gas marbles produced with water showed a reduction in diameter from approximately 3.7 mm–2.5 mm, corresponding to a 33% decrease after 1 week at 80 °C. The shrinkage was even more pronounced for gas marbles made from alcoholic beverages. For example, Shochu (20% ethanol) produced gas marbles with an initial diameter of ∼3.45 mm, which decreased to ∼1.95 mm after 1 week, representing a 43% reduction. This contraction of the gas marbles is likely attributable to evaporation of the liquid phase from the particle shell surrounding the enclosed air, which gradually compacts the granular film and reduces the overall marble size, leading to jamming at the surface (Stratford et al., 2005). Despite this shrinkage, all gas marbles preserved their structural integrity during heating, indicating robust stability against high-temperature drying, independent of the liquid phase used. We also observed for few gas marbles a darkening after heating (e.g., honey or soy sauce). This darkening effect could be attributed to thermal or oxidative browning of the complex food-based liquids upon exposure to heat and air, and while it does not directly reflect a loss of marble integrity, it may indirectly influence long-term stability through changes in liquid composition and viscosity.

Figure 5

Figure 5. Stability of gas marbles against heat. Optical photographs of gas marbles stabilized with cocoa particles, before and after heat treatment at 80 °C for 1 week. The initial air bubble volume was 20 µL. The pink color corresponds to seasoning liquid. The yellow color to dairy products. The green color to various edible drink. The blue color to alcoholic beverage. The scale bar is the same for all photographs.

3.3 Effect of water/ethanol weight ratio on gas marbles formation and properties

To better understand the peculiar behavior of gas marbles obtained from alcoholic beverages, we investigated a model system consisting of water–ethanol mixtures with ethanol contents ranging from 0 to 100 wt%. The water–ethanol system serves as a model liquid platform that validates the generality of the liquid-dependent criterion identified from the broader set of edible liquids. Gas marbles were successfully formed only for ethanol concentrations between 0 and 20 wt%, confirming the trends previously observed for alcoholic beverages of varying ethanol content (Figure 6). Above 20 wt% ethanol, gas-marble formation was no longer possible. We measured the surface tension and the three-phase liquid contact angle for each mixture. Gas marbles were obtained only when the liquid phase exhibited a surface tension above 34 mN/m and a three-phase contact angle greater than 60° at 0 s (Table 2; Supplementary Figure S4). These observations reinforce the conclusions drawn from the full set of edible liquids: surface tension–controlled wettability is the dominant physical parameter governing gas-marble formation. It is also important to note that ethanol evaporation can induce interfacial instabilities driven by surface tension gradients (Marangoni effects), which may affect the trapping and retention of particles at the surface. That is why we also closely examined the behavior of cocoa particles when spread at the air–liquid surface to form particle rafts (Figure 6). For ethanol concentrations between 30 wt% and 100 wt%, cocoa particles immediately sank into the liquid phase upon deposition at the air–liquid surface. As no particles remained at the surface, none were available to wrap around and stabilize the air bubble, making gas-marble formation impossible under these conditions. This sinking behavior became increasingly pronounced with higher ethanol content, consistent with the progressive decrease in surface tension. In contrast, at low ethanol content (≤20 wt%), the liquids displayed intermediate wettability. When cocoa particles were spread onto these air–liquid surfaces, the particles remained trapped at the surface and formed a stable granular layer. Air bubbles could then be effectively encapsulated by rolling them across this interfacial particle raft, leading to successful gas-marble formation. It is important to note that the Bond number (B_o) was calculated for all liquid phases, and in all cases we obtained B_o ≪ 1 (Table 2) (Protière, 2023). A B_o much smaller than unity normally implies that surface tension should dominate over gravitational forces, and therefore cocoa particles would be expected to remain at the air–liquid surface. However, this was not what we observed experimentally for ethanol-rich liquids. This discrepancy most likely arises from the polydispersity of the cocoa particles in size, shape, and density, making accurate quantitative determination of the B_o challenging (Vella et al., 2006; Vella, 2015).

Figure 6

Figure 6. Gas marbles formation as a function of the water/ethanol weight ratio. (a–c) Optical photographs of gas marbles based on 0 wt%, 10 wt% and 20 wt% of ethanol just after formation at room temperature. Gas marbles formation occurred due to the relatively high surface tension of the liquids, leading to adequate three-phase contact angle. The cocoa particles can effectively stabilize the air bubble introduced beneath the particle raft on the water surface. Rolling the air bubble on the particle raft can coat it, leading to efficient gas marbles formation. (d–f) At and above 30 wt% ethanol in water, the surface tensions of the liquids were too low and the three-phase contact angles were also too low, leading to high wetting of the cocoa particles by the solvent resulting to the sinking of the particles inside the liquid.

Table 2

Table 2. Gas marbles formation test using various ethanol-water mixtures: √-gas marble formation, X-no gas marble formation. The surface tension is given for each ethanol content (wt%). The calculated Bond number are given. Ethanol contents (wt%) that produce gas marbles are shown in blue, while those that fail to form gas marbles are shown in pink.

4 Conclusion

In this study, we used as model system cocoa particles to improve the understanding of gas marbles stabilized by edible particles. First, we demonstrated that cocoa particles can stabilize unusually large gas marbles with water as liquid phase, with air-bubble volumes up to 2000 μL, significantly larger than those previously reported. Then, we observed that gas-marble formation was possible for a wide range of edible liquids (seasoning, dairy products, drink and alcoholic beverages). The formation of the gas marbles was found to depend strongly on the surface tension of the liquid phase and the resulting three-phase liquid contact angle, which together govern particle wettability at the air–liquid surface. Thus, liquids with low surface tension, such as vegetable oils or ethanol-rich beverages (>20% ethanol), produced contact angles below 60° and caused cocoa particles to sink into the liquid phase, preventing the formation of a particle raft and eliminating the possibility of gas-marble formation. Model water–ethanol mixtures confirmed these thresholds and highlighted the role of solvent composition in tuning particle wettability. We demonstrate that the three-phase liquid contact angle can be tuned through liquid surface tension, enabling or inhibiting gas-marble formation. Once formed, we showed that the various gas marbles produced here exhibited robust stability, even under thermal treatment of 80 °C for 1 week showing their high robustness, although all marbles shrank in diameter due to evaporation-driven contraction of the particle shell. Overall, our results identify intermediate wettability, sufficient surface tension, and control of solvent composition as the key parameters governing the formation and long-term stability of edible gas marbles. Beyond extending previous water-based studies, this work establishes a quantitative, liquid-dependent framework for gas-marble formation that is applicable across chemically diverse liquid phases. These findings advance the fundamental understanding of particle-stabilized gas–liquid interfaces and demonstrate that gas-marble physics is not restricted to water systems. The present study establishes a framework for designing gas-filled edible structures using food-grade particles and opens new opportunities for applications in food engineering, encapsulation, and molecular gastronomy.

Data availability statement

The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding authors.

Author contributions

TY: Data curation, Investigation, Writing – review and editing. A-LF: Conceptualization, Data curation, Writing – original draft, Writing – review and editing. SF: Conceptualization, Funding acquisition, Project administration, Supervision, Validation, Writing – original draft, Writing – review and editing.

Funding

The author(s) declared that financial support was received for this work and/or its publication. This research was funded by Grant-in-Aid for Scientific Research (B) (JSPS KAKENHI Grant Numbers JP24K01562) and Osaka Institute of Technology research project grant.

Conflict of interest

The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

The authors A-LF, SF declared that they were an editorial board member of Frontiers at the time of submission. This had no impact on the peer review process and the final decision.

Generative AI statement

The author(s) declared that generative AI was not used in the creation of this manuscript.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Supplementary material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/frsfm.2026.1772355/full#supplementary-material

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