# Bibliometric mapping analysis of Pickering emulsion applied in 3D food printing

Patrícia Marques de Farias, Julia Rabelo Vaz Matheus, Bianca Chieregato

Maniglia, Patricia Le-Bail, Alain Le-Bail, Markus Schmid, Ana Elizabeth

Cavalcante Fai

► To cite this version:

Patrícia Marques de Farias, Julia Rabelo Vaz Matheus, Bianca Chieregato Maniglia, Patricia Le-Bail, Alain Le-Bail, et al.. Bibliometric mapping analysis of Pickering emulsion applied in 3D food printing. International Journal of Food Science and Technology, 2024, 59 (4), pp.2186-2196. 10.1111/ijfs.17040 .
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<figure><img src="image_1.png" /></figure>
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Review

Bibliometric mapping analysis of Pickering emulsion applied in 3D
food printing

Patrícia Marques de Farias,<fnref n="1" />,<fnref n="2" /> ID Julia Rabelo Vaz Matheus,<fnref n="1" /> ID Bianca Chieregato Maniglia,<fnref n="3" /> ID Patricia Le-Bail,<fnref n="4" />,<fnref n="5" /> ID Alain Le-Bail,<fnref n="5" />,<fnref n="6" /> ID Markus Schmid<fnref n="7" />* ID & Ana Elizabeth Cavalcante Fai<fnref n="1" />,<fnref n="2" />* ID

(Received 23 December 2023; Accepted in revised form 19 February 2024)

**Summary** Three-dimensional food printing (3DFP) can produce foods with tailored nutritional content, complex shapes and textures. This technology requires food formulations (food inks) with specific rheological properties. Pickering emulsions (PE) have gained attention due to their long-term stability and desirable printable properties, making them an excellent candidate for 3DFP. The purpose of this study is to use bibliometric analysis to identify the most important scientific research on PE used in 3DFP. This includes identifying key authors, countries and universities or institutions where the research was conducted, as well as the primary journals that provide information on this topic. Our study provides insight into the relevance of food ink properties for next-generation 3DFP and the main raw materials used for the development of PE. Out of the 28 original research articles analysed, only 10 countries have studied the application of PE for 3DFP. China and the United Kingdom have been the primary leaders in researching this topic. The Food Hydrocolloids Journal has been the main source of scientific information. The studies cited Pickering stabiliser particles, including soy protein isolate, microcrystalline cellulose and acetylated microcrystalline cellulose, as well as oil phases based on sunflower, canola, olive and soybean oils. High internal phase Pickering emulsions (HIPPEs) have shown great thermal and conductive stability, making them a promising choice for 3DFP post-processing. Further studies should assess the bioavailability and bioaccessibility of the bioactive compounds that are encapsulated. It is also important to explore their potential use in real food systems and to integrate innovative packaging solutions.

**Keywords** Additive manufacturing, biopolymers, high internal phase emulsion, ink formulation, rheological properties, tailored food.

Introduction

Three-dimensional food Printing (3DFP), also known
as food layered manufacturing (FLM) is an additive
manufacturing process digitalised via computer-aided
design (CAD) of modelling, building and fabrication
of complex solid geometries layer by layer, which is
used with edible materials such as starch and proteins

and also with seaweed, chocolate, meat puree, fruits
and vegetable juices and powders and the layers are
connected by chemical reactions or phase transitions
(Wegrzyn et al., 2012; Mantihal et al., 2020; Hussain
et al., 2022; Zhao et al., 2021). The extrusion-based
3D Food Printer has emerged as a revolutionary and
promising equipment in the food industry (Hussain
et al., 2022) since it allows the manufacture of various
shapes of food products, meeting several nutritional
requirements and physical conditions of patients with
diabetes, stroke, dysphagia, paralysis and Parkinson's

<footnote n="1">1 Food and Nutrition Graduate Program, Federal University of the State of Rio de Janeiro - UNIRIO, Av. Pasteur, 296, Urca, Rio de Janeiro 22290-240, Brazil</footnote>

<footnote n="2">2 Laboratory of Multidisciplinary Practices for Sustainability (LAMPS), Institute of Nutrition, State University of Rio de Janeiro - UERJ, R. São Francisco Xavier, 524, Maracanã, Rio de Janeiro 20550-013, Brazil</footnote>

<footnote n="3">3 São Carlos Institute of Chemistry, University of São Paulo – USP, Av. Trabalhador São-Carlense 400, Parque Arnold Schimidt, São Carlos 13566-590, Brazil</footnote>

<footnote n="4">4 INRAe, UR BIA 1268, Rue de la Géraudière, CEDEX 03, 44316 Nantes, France</footnote>

<footnote n="5">5 USC 1498 INRAE-TRANSFORM Department and GEPEA UMR CNRS 6144, Rue de la Géraudière, 44316 Nantes, France</footnote>

<footnote n="6">6 ONIRIS, UMR GEPEA CNRS 6144, Rue de la Géraudière, CS 82225, 44322 Nantes, France</footnote>

<footnote n="7">7 Sustainable Packaging Institute SPI, Faculty of Life Sciences, Albstadt-Sigmaringen University, Anton-Günther-Str. 51, Sigmaringen 72488, Germany</footnote>

<footnote>*Correspondent: E-mail: schmid@hs-albsig.de; bethfai@yahoo.com.
br</footnote>
<figure><img src="image_2.png" /></figure>

Review

**Bibliometric mapping analysis of Pickering emulsion applied in 3D food printing**

Patrícia Marques de Farias,<fnref n="1" />,<fnref n="2" /> ID Julia Rabelo Vaz Matheus,<fnref n="1" /> ID Bianca Chieregato Maniglia,<fnref n="3" /> ID Patricia Le-Bail,<fnref n="4" />,<fnref n="5" /> ID Alain Le-Bail,<fnref n="5" />,<fnref n="6" /> ID Markus Schmid<fnref n="7" />* ID & Ana Elizabeth Cavalcante Fai<fnref n="1" />,<fnref n="2" />* ID

*(Received 23 December 2023; Accepted in revised form 19 February 2024)*

**Summary** Three-dimensional food printing (3DFP) can produce foods with tailored nutritional content, complex shapes and textures. This technology requires food formulations (food inks) with specific rheological properties. Pickering emulsions (PE) have gained attention due to their long-term stability and desirable printable properties, making them an excellent candidate for 3DFP. The purpose of this study is to use bibliometric analysis to identify the most important scientific research on PE used in 3DFP. This includes identifying key authors, countries and universities or institutions where the research was conducted, as well as the primary journals that provide information on this topic. Our study provides insight into the relevance of food ink properties for next-generation 3DFP and the main raw materials used for the development of PE. Out of the 28 original research articles analysed, only 10 countries have studied the application of PE for 3DFP. China and the United Kingdom have been the primary leaders in researching this topic. The Food Hydrocolloids Journal has been the main source of scientific information. The studies cited Pickering stabiliser particles, including soy protein isolate, microcrystalline cellulose and acetylated microcrystalline cellulose, as well as oil phases based on sunflower, canola, olive and soybean oils. High internal phase Pickering emulsions (HIPPEs) have shown great thermal and conductive stability, making them a promising choice for 3DFP post-processing. Further studies should assess the bioavailability and bioaccessibility of the bioactive compounds that are encapsulated. It is also important to explore their potential use in real food systems and to integrate innovative packaging solutions.

**Keywords** Additive manufacturing, biopolymers, high internal phase emulsion, ink formulation, rheological properties, tailored food.

**Introduction**

Three-dimensional food Printing (3DFP), also known as food layered manufacturing (FLM) is an additive manufacturing process digitalised via computer-aided design (CAD) of modelling, building and fabrication of complex solid geometries layer by layer, which is used with edible materials such as starch and proteins

and also with seaweed, chocolate, meat puree, fruits and vegetable juices and powders and the layers are connected by chemical reactions or phase transitions (Wegrzyn et al., 2012; Mantihal et al., 2020; Hussain et al., 2022; Zhao et al., 2021). The extrusion-based 3D Food Printer has emerged as a revolutionary and promising equipment in the food industry (Hussain et al., 2022) since it allows the manufacture of various shapes of food products, meeting several nutritional requirements and physical conditions of patients with diabetes, stroke, dysphagia, paralysis and Parkinson's

<footnote n="1">1 Food and Nutrition Graduate Program, Federal University of the State of Rio de Janeiro - UNIRIO, Av. Pasteur, 296, Urca, Rio de Janeiro 22290-240, Brazil</footnote>

<footnote n="2">2 Laboratory of Multidisciplinary Practices for Sustainability (LAMPS), Institute of Nutrition, State University of Rio de Janeiro - UERJ, R. São Francisco Xavier, 524, Maracanã, Rio de Janeiro 20550-013, Brazil</footnote>

<footnote n="3">3 São Carlos Institute of Chemistry, University of São Paulo – USP, Av. Trabalhador São-Carlense 400, Parque Arnold Schimidt, São Carlos 13566-590, Brazil</footnote>

<footnote n="4">4 INRAe, UR BIA 1268, Rue de la Géraudière, CEDEX 03, 44316 Nantes, France</footnote>

<footnote n="5">5 USC 1498 INRAE-TRANSFORM Department and GEPEA UMR CNRS 6144, Rue de la Géraudière, 44316 Nantes, France</footnote>

<footnote n="6">6 ONIRIS, UMR GEPEA CNRS 6144, Rue de la Géraudière, CS 82225, 44322 Nantes, France</footnote>

<footnote n="7">7 Sustainable Packaging Institute SPI, Faculty of Life Sciences, Albstadt-Sigmaringen University, Anton-Günther-Str. 51, Sigmaringen 72488, Germany</footnote>

<footnote>*Correspondent: E-mail: schmid@hs-albsig.de; bethfai@yahoo.com.br</footnote>
disease. It also enables the design of foods for specific consumer groups including infants, elderly people, pregnant women and bodybuilders, for example (Feng et al., 2019). However, the rheological and textural properties of printable matrix inks used in the 3D equipment, depend on the ingredients used in the formulation. To create a desired 3D-printed food product successfully, the printable ink must have a gel-like structure that offers a well-defined pseudoplastic behaviour, when the shear rate increases as the viscosity decreases providing low resistance to flow through nozzles and satisfactory yield stress, which is the least force necessary to start the flow during the extrusion process (Shahbazi & Jäger, 2020; Shahbazi et al., 2021a).

Emulsions have been utilised in 3D printing formulations due to their unique rheological behaviour. To achieve a shear-thinning, viscoelastic and thixotropic character, diversified ingredients and additives have been employed as inks. This allows for the maintenance of the printed structure and adherence to previously deposited layers. For effective 3D printing, printing inks in the form of colloidal emulsions is a recommended processing method (Shahbazi et al., 2022b). A traditional emulsion is a stable system of small droplets of two immiscible liquids, typically oil and water, dispersed in each other with the aid of surfactants, such as emulsifiers and stabilisers (Santamaria-Echart et al., 2021). However, many of the surfactants used in traditional emulsions are synthetic and toxic, which can adversely affect human health.

The demand for clean-label and naturally prepared materials is rapidly increasing due to the need for more sustainable food systems (Rawal et al., 2023). This supports the recent growing interest in the application of the Pickering emulsion (PE) technique in the 3DFP process. PE is an emulsion stabilised by solid particles instead of surfactants, which can adsorb strongly at the water/oil interface, exhibiting an amphiphilic property. Additionally, PE has many unique advantages, including high resistance to coalescence, long-term stability, good biocompatibility and desirable printable properties (Sun et al., 2022). It can be used as a multifunctional biopolymeric-based ink and a fat replacer in food processing. Moreover, PE helps endure repeated mechanical deformation during the printing process, achieving enhanced functionality and printability (Wang et al., 2023b). In addition, high internal phase Pickering emulsions (HIPPEs) also have been investigated for 3D printing processes. These emulsions are based on oil/water high-internal-phase and are novel printable materials. They have the potential for application in the food, medical and cosmetic industries due to their ability to maintain the stability of the shape and structure of printable products (Wan et al., 2021; Bi et al., 2022).

Bibliometric analysis has been considered an attractive instrument for quantitative analysis to evaluate the growth and development of a particular matter or research field. It helps to identify emerging subjects and measure output (Sridhar et al., 2022). This review uses bibliometric methodology to identify performance research streams from journals, co-authors and universities/institutions on the specific subject of PE applied to 3D food printing. Therefore, this study comprehensively maps, quantifies and analyses the use of PE inks in 3DFP as a new and sustainable trend in the field of food science and technology.

## Bibliometric search strategy and data selection criteria

Data collection for this research was done on January 25, 2023, from the Web of Science (WoS), Scopus and PubMed electronic databases. The searches were conducted by using the following descriptors: ('Pickering emulsion') AND ('3D' OR 'Additive manufacturing') AND ('Food') AND ('Printing').

Initially, the articles were screened by title and abstract. Thereafter, they were screened by a full-text review to identify which studies we should include here. For this review, were included research articles that: (a) focus on PE and 3DFP; (b) are original research articles; (c) were published in journals with impact factor (IF); (d) have the full text available in English; (e) have been published in paid or open access journals; and (f) have been published to January 25, 2023, following the methodology proposed by de Farias et al. (2023) and Matheus et al. (2023). To identify the earliest article investigating 3DFP using PE, no time limit was established during the search. Figure 1 presents a flowchart outlining the process of identifying, screening and including articles in this review. The exclusion criteria for this study were as follows: undergraduate works, dissertations, theses, abstracts and works presented in congresses or symposia, as well as those included in Annals. Additionally, studies in languages other than English, studies published in journals without an IF, studies focusing solely on 3D printing or only on PE and reviews and case studies, such as economic assessments, were excluded. To facilitate data management, the articles that met the inclusion criteria were organised in a spreadsheet – data are not shown.

## Bibliometric analysis and scientific performance

### Database and quantitative analysis

The analysis shows that the subject has gained researchers' attention in specific countries, such as China and the United Kingdom, with the first
disease. It also enables the design of foods for specific consumer groups including infants, elderly people, pregnant women and bodybuilders, for example (Feng et al., 2019). However, the rheological and textural properties of printable matrix inks used in the 3D equipment, depend on the ingredients used in the formulation. To create a desired 3D-printed food product successfully, the printable ink must have a gel-like structure that offers a well-defined pseudoplastic behaviour, when the shear rate increases as the viscosity decreases providing low resistance to flow through nozzles and satisfactory yield stress, which is the least force necessary to start the flow during the extrusion process (Shahbazi & Jäger, 2020; Shahbazi et al., 2021a).

Emulsions have been utilised in 3D printing formulations due to their unique rheological behaviour. To achieve a shear-thinning, viscoelastic and thixotropic character, diversified ingredients and additives have been employed as inks. This allows for the maintenance of the printed structure and adherence to previously deposited layers. For effective 3D printing, printing inks in the form of colloidal emulsions is a recommended processing method (Shahbazi et al., 2022b). A traditional emulsion is a stable system of small droplets of two immiscible liquids, typically oil and water, dispersed in each other with the aid of surfactants, such as emulsifiers and stabilisers (Santamaria-Echart et al., 2021). However, many of the surfactants used in traditional emulsions are synthetic and toxic, which can adversely affect human health.

The demand for clean-label and naturally prepared materials is rapidly increasing due to the need for more sustainable food systems (Rawal et al., 2023). This supports the recent growing interest in the application of the Pickering emulsion (PE) technique in the 3DFP process. PE is an emulsion stabilised by solid particles instead of surfactants, which can adsorb strongly at the water/oil interface, exhibiting an amphiphilic property. Additionally, PE has many unique advantages, including high resistance to coalescence, long-term stability, good biocompatibility and desirable printable properties (Sun et al., 2022). It can be used as a multifunctional biopolymeric-based ink and a fat replacer in food processing. Moreover, PE helps endure repeated mechanical deformation during the printing process, achieving enhanced functionality and printability (Wang et al., 2023b). In addition, high internal phase Pickering emulsions (HIPPEs) also have been investigated for 3D printing processes. These emulsions are based on oil/water high-internal-phase and are novel printable materials. They have the potential for application in the food, medical and cosmetic industries due to their ability to maintain the stability of the shape and structure of printable products (Wan et al., 2021; Bi et al., 2022).

Bibliometric analysis has been considered an attractive instrument for quantitative analysis to evaluate the growth and development of a particular matter or research field. It helps to identify emerging subjects and measure output (Sridhar et al., 2022). This review uses bibliometric methodology to identify performance research streams from journals, co-authors and universities/institutions on the specific subject of PE applied to 3D food printing. Therefore, this study comprehensively maps, quantifies and analyses the use of PE inks in 3DFP as a new and sustainable trend in the field of food science and technology.

## Bibliometric search strategy and data selection criteria

Data collection for this research was done on January 25, 2023, from the Web of Science (WoS), Scopus and PubMed electronic databases. The searches were conducted by using the following descriptors: ('Pickering emulsion') AND ('3D' OR 'Additive manufacturing') AND ('Food') AND ('Printing').

Initially, the articles were screened by title and abstract. Thereafter, they were screened by a full-text review to identify which studies we should include here. For this review, were included research articles that: (a) focus on PE and 3DFP; (b) are original research articles; (c) were published in journals with impact factor (IF); (d) have the full text available in English; (e) have been published in paid or open access journals; and (f) have been published to January 25, 2023, following the methodology proposed by de Farias et al. (2023) and Matheus et al. (2023). To identify the earliest article investigating 3DFP using PE, no time limit was established during the search. Figure 1 presents a flowchart outlining the process of identifying, screening and including articles in this review. The exclusion criteria for this study were as follows: undergraduate works, dissertations, theses, abstracts and works presented in congresses or symposia, as well as those included in Annals. Additionally, studies in languages other than English, studies published in journals without an IF, studies focusing solely on 3D printing or only on PE and reviews and case studies, such as economic assessments, were excluded. To facilitate data management, the articles that met the inclusion criteria were organised in a spreadsheet – data are not shown.

## Bibliometric analysis and scientific performance

### Database and quantitative analysis

The analysis shows that the subject has gained researchers' attention in specific countries, such as China and the United Kingdom, with the first
<figure><img src="image_2.png" /><figcaption>**Figure 1** Flow chart of the process of identification, screening and the inclusion of papers.</figcaption></figure>

publication on the subject dating back to 2019. A total of 28 articles were identified on the WoS database from 2019 to January 25, 2023 and published in various scientific journals. After screening based on the selection criteria, 24 articles were selected. Similarly, the Scopus database identified 30 articles, of which 28 were selected. In the same way, 11 articles were identified from the PubMed database and 8 were selected after screening. In total, the preliminary search yielded 69 records from the three databases; after screening, we included 28 articles (Fig. 1) in this review portfolio (excluding repeated articles) in agreement with the selection criteria.

Figure 2 depicts the number of articles based on the year of publication. Since 2019, there has been an increasing trend in the use of PE inks for 3DFP. In 2019, 1 original research article was published, followed by 2 in 2020, 6 in 2021 and 10 in 2022. As of January 25, 2023, nine original research articles were

published, indicating that this subject will likely receive increased attention and development in the coming years.

## Journal performance and the scientific impact of publications

To analyse the scientific impact of the research conducted on PE applied in 3DFP, this bibliometric review identified 13 scientific journals that published the 28 original research articles included in this review. Among the identified journals, Food Hydrocolloids stands out with 11 published articles on the subject, followed by Journal of Food Engineering with 3 articles and ACS Applied Materials & Interfaces, Food Chemistry and Colloids and Surfaces A: Physicochemical and Engineering Aspects with 2 articles each. Eight other journals have one publication each. Figure 3 shows the list of these journals, highlighting their IF.

## Countries, universities/institutions' performance and the collaboration index

The network mapping of countries and their publications was based solely on the nationality of the authors of the 28 articles selected for this review. Figure 4 displays the geographical distribution, revealing that only 10 countries have studied the application of PE in 3DFP. The concept of single-country publications (SCP) and multiple-country publications (MCP), respectively focus on scientific articles from one country and demonstrate interaction among authors of different nationalities and realities (de Farias et al., 2023). The study identified 13 SCPs and 15 MCPs. The collaboration network analysis revealed three research hubs: China, Europe and North America. The analysis of the cluster data revealed that China has the highest number of publications on this topic, with 20 publications (11 SCPs and 9 MCPs). The United Kingdom follows with 8 publications (1 SCP and 7 MCPs), while Austria and the United States of America both have 5 MCP publications.

To identify the academic interest in the application of PE in 3DFP worldwide, this review found 31

<figure><img src="image_3.png" /><figcaption>**Figure 2** Scientific production about PE applied in 3D food printing. Legend: \*Data for the number of publications in 2023 are up to January 25.</figcaption></figure>
<figure><img src="image_3.png" /><figcaption>**Figure 1** Flow chart of the process of identification, screening and the inclusion of papers.</figcaption></figure>

publication on the subject dating back to 2019. A total of 28 articles were identified on the WoS database from 2019 to January 25, 2023 and published in various scientific journals. After screening based on the selection criteria, 24 articles were selected. Similarly, the Scopus database identified 30 articles, of which 28 were selected. In the same way, 11 articles were identified from the PubMed database and 8 were selected after screening. In total, the preliminary search yielded 69 records from the three databases; after screening, we included 28 articles (Fig. 1) in this review portfolio (excluding repeated articles) in agreement with the selection criteria.

Figure 2 depicts the number of articles based on the year of publication. Since 2019, there has been an increasing trend in the use of PE inks for 3DFP. In 2019, 1 original research article was published, followed by 2 in 2020, 6 in 2021 and 10 in 2022. As of January 25, 2023, nine original research articles were

published, indicating that this subject will likely receive increased attention and development in the coming years.

## Journal performance and the scientific impact of publications

To analyse the scientific impact of the research conducted on PE applied in 3DFP, this bibliometric review identified 13 scientific journals that published the 28 original research articles included in this review. Among the identified journals, Food Hydrocolloids stands out with 11 published articles on the subject, followed by Journal of Food Engineering with 3 articles and ACS Applied Materials & Interfaces, Food Chemistry and Colloids and Surfaces A: Physicochemical and Engineering Aspects with 2 articles each. Eight other journals have one publication each. Figure 3 shows the list of these journals, highlighting their IF.

## Countries, universities/institutions' performance and the collaboration index

The network mapping of countries and their publications was based solely on the nationality of the authors of the 28 articles selected for this review. Figure 4 displays the geographical distribution, revealing that only 10 countries have studied the application of PE in 3DFP. The concept of single-country publications (SCP) and multiple-country publications (MCP), respectively focus on scientific articles from one country and demonstrate interaction among authors of different nationalities and realities (de Farias et al., 2023). The study identified 13 SCPs and 15 MCPs. The collaboration network analysis revealed three research hubs: China, Europe and North America. The analysis of the cluster data revealed that China has the highest number of publications on this topic, with 20 publications (11 SCPs and 9 MCPs). The United Kingdom follows with 8 publications (1 SCP and 7 MCPs), while Austria and the United States of America both have 5 MCP publications.

To identify the academic interest in the application of PE in 3DFP worldwide, this review found 31

<figure><img src="image_4.png" /><figcaption>**Figure 2** Scientific production about PE applied in 3D food printing. Legend: \*Data for the number of publications in 2023 are up to January 25.</figcaption></figure>
<table><caption>**Figure 3** Journals' performance (number of articles published) and the scientific impact of the journals (the impact factors were obtained from the official website of each journal in January 2023).</caption><thead><tr><th>11 Articles</th><th>3 Articles</th><th>1 Article</th></tr></thead><tbody><tr><td>Food Hydrocolloids (IF: 11.504)</td><td>Journal of Food Engineering (IF: 6.203)</td><td>Chemical Engineering Journal (IF: 16.477)<br>Additive Manufacturing (IF: 11.362)<br>Carbohydrate Polymers (IF: 10.723)<br>Ultrasonics Sonochemistry (IF: 9.336)</td></tr><tr><td><strong>2 Articles</strong></td><td>ACS Applied Materials & Interfaces (IF: 10.383)<br>Food Chemistry (IF: 9.231)<br>Colloids and Surfaces A: Physicochemical and Engineering Aspects (IF: 5.518)</td><td>Biomacromolecules (IF: 6.978)<br>Journal of Agricultural and Food Chemistry (IF: 5.895)<br>Food and Bioprocess Technology (IF: 5.581)<br>Chemical Engineering Science (IF: 4.889)</td></tr></tbody></table>

universities/institutions researching this topic. Jiangnan University (China) ranks first among the universities/institutions with 10 published articles, followed by the University of Leeds (UK) with 6 published articles, the University of Natural Resources and Life Sciences (BOKU) (Austria) with 5 published articles and the Dalian Polytechnic University (China). Figure 5 presents the performance of all universities and institutes that participated in publishing the 28 articles included in this review, along with their respective nationalities.

The collaboration index (CI) was calculated by dividing the total number of authors of multiple-authored articles by the total number of multiple-authored articles (Koseoglu et al., 2016). The CI for the papers selected for this review was 5.79. The CI remained relatively constant over the years, with an average of 6: 2019 (CI = 6), 2020 (CI = 7), 2021 (CI = 5.5), 2022 (CI = 5.3) and up to January 25, 2023 (CI = 6.22). These results suggest an increasing emphasis on collaboration among universities, institutions and countries conducting research on using PE as 3DFP inks.

## Most productive authors and most cited papers

Table 1 summarises all papers included in this review, highlighting the most productive authors and the most cited papers. The author with the highest productivity

is Mahdiyar Shahbazi from the University of Natural Resources and Life Sciences (BOKU), Austria, with six original research papers published on the use of PE in 3DFP. Therefore, Mahdiyar Shahbazi and his collaborators are the authors who are most actively contributing to this research topic. The most cited paper is the article titled 'High Internal Phase Oil-in-Water Pickering Emulsions Stabilized by Chitin Nanofibrils: 3D Structuring and Solid Foam' by Zhu et al. (2020), which has been listed in all three databases: WoS, Scopus and PubMed and cited 146 times.

Additionally, Fig. 6 presents a Sankey diagram that illustrates the relationship between the first author, journals and publication years of the 28 articles on the subject.

## The use of PE inks in 3DFP: Trends, challenges and perspectives

Emulsion gels can be used to regulate the rheological properties of 3D printing formulations, allowing for changes in yield stress, modulus of elasticity and fluidity. This makes them a viable alternative for 3D printing applications. Under certain conditions, such as high droplet concentrations and strong attractive interactions, oil droplets can aggregate and form fractal clusters and three-dimensional particle networks, resulting in elastic-like properties (Hashemnejad
<table><caption>**Figure 3** Journals' performance (number of articles published) and the scientific impact of the journals (the impact factors were obtained from the official website of each journal in January 2023).</caption><thead><tr><th>11 Articles</th><th>3 Articles</th><th>1 Article</th></tr></thead><tbody><tr><td>Food Hydrocolloids (IF: 11.504)</td><td>Journal of Food Engineering (IF: 6.203)</td><td>Chemical Engineering Journal (IF: 16.477)<br>Additive Manufacturing (IF: 11.362)<br>Carbohydrate Polymers (IF: 10.723)<br>Ultrasonics Sonochemistry (IF: 9.336)</td></tr><tr><td><strong>2 Articles</strong></td><td>ACS Applied Materials & Interfaces (IF: 10.383)<br>Food Chemistry (IF: 9.231)<br>Colloids and Surfaces A: Physicochemical and Engineering Aspects (IF: 5.518)</td><td>Biomacromolecules (IF: 6.978)<br>Journal of Agricultural and Food Chemistry (IF: 5.895)<br>Food and Bioprocess Technology (IF: 5.581)<br>Chemical Engineering Science (IF: 4.889)</td></tr></tbody></table>

universities/institutions researching this topic. Jiangnan University (China) ranks first among the universities/institutions with 10 published articles, followed by the University of Leeds (UK) with 6 published articles, the University of Natural Resources and Life Sciences (BOKU) (Austria) with 5 published articles and the Dalian Polytechnic University (China). Figure 5 presents the performance of all universities and institutes that participated in publishing the 28 articles included in this review, along with their respective nationalities.

The collaboration index (CI) was calculated by dividing the total number of authors of multiple-authored articles by the total number of multiple-authored articles (Koseoglu et al., 2016). The CI for the papers selected for this review was 5.79. The CI remained relatively constant over the years, with an average of 6: 2019 (CI = 6), 2020 (CI = 7), 2021 (CI = 5.5), 2022 (CI = 5.3) and up to January 25, 2023 (CI = 6.22). These results suggest an increasing emphasis on collaboration among universities, institutions and countries conducting research on using PE as 3DFP inks.

## Most productive authors and most cited papers

Table 1 summarises all papers included in this review, highlighting the most productive authors and the most cited papers. The author with the highest productivity

is Mahdiyar Shahbazi from the University of Natural Resources and Life Sciences (BOKU), Austria, with six original research papers published on the use of PE in 3DFP. Therefore, Mahdiyar Shahbazi and his collaborators are the authors who are most actively contributing to this research topic. The most cited paper is the article titled 'High Internal Phase Oil-in-Water Pickering Emulsions Stabilized by Chitin Nanofibrils: 3D Structuring and Solid Foam' by Zhu et al. (2020), which has been listed in all three databases: WoS, Scopus and PubMed and cited 146 times.

Additionally, Fig. 6 presents a Sankey diagram that illustrates the relationship between the first author, journals and publication years of the 28 articles on the subject.

## The use of PE inks in 3DFP: Trends, challenges and perspectives

Emulsion gels can be used to regulate the rheological properties of 3D printing formulations, allowing for changes in yield stress, modulus of elasticity and fluidity. This makes them a viable alternative for 3D printing applications. Under certain conditions, such as high droplet concentrations and strong attractive interactions, oil droplets can aggregate and form fractal clusters and three-dimensional particle networks, resulting in elastic-like properties (Hashemnejad
<figure><img src="image_4.png" /><figcaption>**Figure 4** Geographic distribution of researchers in this thematic area and research collaborations (represented by the blue lines).</figcaption></figure>

et al., 2019). Therefore, controlling droplet concentration and colloidal interactions in emulsion gels can modulate the functional performance of edible inks. However, research on 3D-printed emulsions is limited because the instability and poor self-support behaviour of emulsions make shape control difficult (Riesco et al., 2019). Most emulsions deform easily, do not readily maintain designed shapes, especially when slender structures are included and are prone to phase separation in the extrusion process during 3D printing (Riesco et al., 2019).

At the beginning of the 20th century, Pickering discovered that emulsions stabilised by solid particles such as nano- and microparticles, known as PE, have several advantages over traditional emulsions. These include the ability to resist droplet coalescence and particle dispersion in the dispersed phase, as well as the ability to be more easily tailored to specific applications due to their unique properties, exhibiting distinctive viscoelasticity (Shi et al., 2020; Jiang et al., 2022). However, for 3D printing, highly concentrated PE, or HIPPEs, are usually required. In emulsion systems, changing the volume of the internal phase will affect the melting and plastification behaviour of the

emulsion (Wang et al., 2018). When the proportion of the internal phase of an emulsion exceeds 74% ($\varphi > 0.74$), it is possible to obtain HIPPEs (Lis-sant, 1966). These emulsions exhibit high stability and have a self-supporting texture due to highly concentrated emulsion droplets that are flocculated (Yang et al., 2017). Thus, HIPPEs are considered effective inks for 3DFP.

Food-grade HIPPEs tend to have high viscosity and stability with a stable 3D network and can be used as suitable inks to print food in complex shapes through nozzle extrusion (Du et al., 2021). 3D-printed foods include both ready-to-eat and semi-finished products. The raw materials of ready-to-eat products must be sterilised beforehand, while semi-finished products often require additional processing, such as frying and baking. The presence of HIPPEs increases thermal and conductive stability and preserves texture during thermal and sterilisation processes, confirming their suitability for 3D printing (Yang et al., 2017; Li et al., 2020).

In the last few years, HIPPEs have been used in the 3D printing of porous materials. However, it is not enough to only investigate whether HIPPEs can be
<figure><img src="image_5.png" /><figcaption>**Figure 4** Geographic distribution of researchers in this thematic area and research collaborations (represented by the blue lines).</figcaption></figure>

et al., 2019). Therefore, controlling droplet concentration and colloidal interactions in emulsion gels can modulate the functional performance of edible inks. However, research on 3D-printed emulsions is limited because the instability and poor self-support behaviour of emulsions make shape control difficult (Riesco et al., 2019). Most emulsions deform easily, do not readily maintain designed shapes, especially when slender structures are included and are prone to phase separation in the extrusion process during 3D printing (Riesco et al., 2019).

At the beginning of the 20th century, Pickering discovered that emulsions stabilised by solid particles such as nano- and microparticles, known as PE, have several advantages over traditional emulsions. These include the ability to resist droplet coalescence and particle dispersion in the dispersed phase, as well as the ability to be more easily tailored to specific applications due to their unique properties, exhibiting distinctive viscoelasticity (Shi et al., 2020; Jiang et al., 2022). However, for 3D printing, highly concentrated PE, or HIPPEs, are usually required. In emulsion systems, changing the volume of the internal phase will affect the melting and plastification behaviour of the

emulsion (Wang et al., 2018). When the proportion of the internal phase of an emulsion exceeds 74% ($\varphi > 0.74$), it is possible to obtain HIPPEs (Lis-sant, 1966). These emulsions exhibit high stability and have a self-supporting texture due to highly concentrated emulsion droplets that are flocculated (Yang et al., 2017). Thus, HIPPEs are considered effective inks for 3DFP.

Food-grade HIPPEs tend to have high viscosity and stability with a stable 3D network and can be used as suitable inks to print food in complex shapes through nozzle extrusion (Du et al., 2021). 3D-printed foods include both ready-to-eat and semi-finished products. The raw materials of ready-to-eat products must be sterilised beforehand, while semi-finished products often require additional processing, such as frying and baking. The presence of HIPPEs increases thermal and conductive stability and preserves texture during thermal and sterilisation processes, confirming their suitability for 3D printing (Yang et al., 2017; Li et al., 2020).

In the last few years, HIPPEs have been used in the 3D printing of porous materials. However, it is not enough to only investigate whether HIPPEs can be
<figure><img src="image_5.png" /><figcaption>**Figure 5** Performance of all universities/institutes that participated in the publication of the 28 articles included in this bibliometric review.</figcaption></figure>

successfully extruded through the spout, appearance and nutrition factors. The shelf life of the printed product must also be considered (Zhang *et al.*, 2022). When it comes to 3D printing food products, it is crucial to be mindful of potential microbial contamination at every stage of the process. This includes the preparation of the food formula and the contact with various materials like steel pistons, plastic tubes and extruders (Severini *et al.*, 2018). During the extrusion process, materials are typically heated and cooled to create a pliable mass that can be extruded through a nozzle. However, this process can increase the risk of bacterial or fungal growth, which can shorten the product's shelf life (Dankar *et al.*, 2018). Therefore, depending on the food's composition and the level of processing required, the printed food may need to undergo immediate post-processing, such as cooking, frying, or roasting, to ensure that it is safe for consumption.

The HIPPEs have a high-energy storage modulus as a non-Newtonian shear fluid, which allows it to pass smoothly through the nozzle and maintain its shape. It has broad application prospects in 3DFP. Nevertheless, some problems still need to be solved. Firstly, HIPPEs mainly focus on vegetable proteins and there are few reports on emulsions stabilised with meat proteins. Most of the selection of composite particles is

carried out on proteins-polysaccharides. It is not clear whether other composite particles can stabilise HIPPEs effectively. At the same time, particle modification is usually by chemical modification, which does not meet the requirements of green food. Second, the traditional diffusion adsorption rearrangement theory cannot perfectly explain the formation and stability of the HIPPEs oil-water interface, so there is an urgent need to enrich and refine the theory. In addition, research on 3DFP based on HIPPEs is lacking. At present, it mainly focuses on the rheological properties of the emulsion and the printing effect of the HIPPEs. There are few reports on the application of HIPPEs in real food systems and there is a lack of HIPPEs-based 3D printing research, particularly in the use of plant proteins as solid particle stabilisers. Future investigations should focus on developing 3D-printed food-grade HIPPEs using widely available and cost-effective plant proteins as stabilisers.

Forthcoming research on food-grade HIPPEs can focus on the following aspects: (1) Compose additional types of biomacromolecule particles, such as protein-protein and polysaccharide-polysaccharide composite particles, to determine their potential for stabilising high internal phase emulsions; (2) Investigate the multiscale structure of the oil-water interface, develop a theory for the dynamic formation of emulsion
<figure><img src="image_6.png" /><figcaption>**Figure 5** Performance of all universities/institutes that participated in the publication of the 28 articles included in this bibliometric review.</figcaption></figure>

successfully extruded through the spout, appearance and nutrition factors. The shelf life of the printed product must also be considered (Zhang *et al.*, 2022). When it comes to 3D printing food products, it is crucial to be mindful of potential microbial contamination at every stage of the process. This includes the preparation of the food formula and the contact with various materials like steel pistons, plastic tubes and extruders (Severini *et al.*, 2018). During the extrusion process, materials are typically heated and cooled to create a pliable mass that can be extruded through a nozzle. However, this process can increase the risk of bacterial or fungal growth, which can shorten the product's shelf life (Dankar *et al.*, 2018). Therefore, depending on the food's composition and the level of processing required, the printed food may need to undergo immediate post-processing, such as cooking, frying, or roasting, to ensure that it is safe for consumption.

The HIPPEs have a high-energy storage modulus as a non-Newtonian shear fluid, which allows it to pass smoothly through the nozzle and maintain its shape. It has broad application prospects in 3DFP. Nevertheless, some problems still need to be solved. Firstly, HIPPEs mainly focus on vegetable proteins and there are few reports on emulsions stabilised with meat proteins. Most of the selection of composite particles is

carried out on proteins-polysaccharides. It is not clear whether other composite particles can stabilise HIPPEs effectively. At the same time, particle modification is usually by chemical modification, which does not meet the requirements of green food. Second, the traditional diffusion adsorption rearrangement theory cannot perfectly explain the formation and stability of the HIPPEs oil-water interface, so there is an urgent need to enrich and refine the theory. In addition, research on 3DFP based on HIPPEs is lacking. At present, it mainly focuses on the rheological properties of the emulsion and the printing effect of the HIPPEs. There are few reports on the application of HIPPEs in real food systems and there is a lack of HIPPEs-based 3D printing research, particularly in the use of plant proteins as solid particle stabilisers. Future investigations should focus on developing 3D-printed food-grade HIPPEs using widely available and cost-effective plant proteins as stabilisers.

Forthcoming research on food-grade HIPPEs can focus on the following aspects: (1) Compose additional types of biomacromolecule particles, such as protein-protein and polysaccharide-polysaccharide composite particles, to determine their potential for stabilising high internal phase emulsions; (2) Investigate the multiscale structure of the oil-water interface, develop a theory for the dynamic formation of emulsion
<table><caption>**Table 1** Studies are ordered by the number of papers by the first author followed by information about databases, total number of citations of the study, year, Pickering stabiliser particle and oil phase used in the study and reference</caption><thead><tr><th>First author</th><th>Database</th><th>Total citation number</th><th>Year</th><th>Pickering stabiliser particle (concentration)†</th><th>Oily phase (concentration)†</th><th>Ref.</th></tr></thead><tbody><tr><td rowspan="5">Mahdiyar Shahbazi</td><td>Multiple databases</td><td>26</td><td>2022</td><td>Soy protein isolate (25%, w/w) and microcrystalline cellulose (5.6%, w/w)</td><td>Sunflower oil (2%, w/w)</td><td>Shahbazi et al. (2022a)</td></tr><tr><td>Multiple databases</td><td>26</td><td>2022</td><td>Soy protein isolate (25%, w/w) and microcrystalline cellulose (4.2%, w/w)</td><td>Sunflower oil (4%, w/w)</td><td>Shahbazi et al. (2022b)</td></tr><tr><td>WoS and Scopus</td><td>39</td><td>2021</td><td>Sodium caseinate (18%, w/w) and acetylated microcrystalline cellulose (4.2%, w/w)</td><td>Canola oil (4%, w/w)</td><td>Shahbazi et al. (2021a)</td></tr><tr><td>WoS and Scopus</td><td>36</td><td>2021</td><td>Sodium caseinate (18%, w/w) and acetylated microcrystalline cellulose (4.2%, w/w)</td><td>Canola oil (4%, w/w)</td><td>Shahbazi et al. (2021b)</td></tr><tr><td>Multiple databases</td><td>22</td><td>2021</td><td>Soy protein isolate (25%, w/w) and microcrystalline cellulose (4.2%, w/w)</td><td>Canola oil (4%, w/w)</td><td>Shahbazi et al. (2021c)</td></tr><tr><td rowspan="2">An-Qi Bi</td><td>Multiple databases</td><td>17</td><td>2022</td><td>Casein (3%, w/v) and pectin (1–5%, w/v)</td><td>Soybean oil (66.7%, w/v)</td><td>Bi et al. (2022)</td></tr><tr><td>Multiple databases</td><td>42</td><td>2020</td><td>Casein (3%, w/v)</td><td>Edible oil (80%, w/v)</td><td>Bi et al. (2020)</td></tr><tr><td>Chao Qiu</td><td>WoS and Scopus</td><td>1</td><td>2023</td><td>Glycyrrhizic acid-zein composite nanoparticles (2%, w/v)</td><td>Soybean oil (50%, w/v)</td><td>Qiu et al. (2023)</td></tr><tr><td>Chao Wu</td><td>WoS and Scopus</td><td>45</td><td>2021</td><td>Cod myofibers (0.25–5%, w/v)</td><td>Soybean oil (75–90%, w/v)</td><td>Wu et al. (2021)</td></tr><tr><td>Chenxi Wang</td><td>Scopus</td><td>0</td><td>2023</td><td>Glycyrrhizic acid (2%, w/w)-zein (2%, w/w) composite nanoparticle and chitosan (1–3%, w/w)</td><td>Soybean oil (10–70%, v/v)</td><td>Wang et al. (2023a)</td></tr><tr><td>Dan Xu</td><td>Scopus and Pubmed</td><td>0</td><td>2023</td><td>Tea protein (3%, w/v) and xanthan gum (0–2.5%, w/v)</td><td>Olive oil</td><td>Xu et al. (2023)</td></tr><tr><td>Ekanem E. Ekanem</td><td>Scopus</td><td>2</td><td>2022</td><td>Keratin (1%, w/w) and oxidised cellulose nanofibril (0.5–1%, w/w)</td><td>Sunflower oil</td><td>Ekanem et al. (2022)</td></tr><tr><td>Jiaxin Guo</td><td>WoS and Scopus</td><td>2</td><td>2023</td><td>Spirulina platensis protein nanoparticles (1%, w/w) and xanthan gums (1%, w/w)</td><td>Sunflower waxes (5%, w/w) and soybean oil</td><td>Guo et al. (2023a)</td></tr><tr><td>Jie Du</td><td>WoS and Scopus</td><td>104</td><td>2021</td><td>Gelatin (20%, w/v) cross-linked by transglutaminase (0.002%, w/w)</td><td>Soybean oil (10–90%, v/v)</td><td>Du et al. (2021)</td></tr><tr><td>Lijuan Zhang</td><td>WoS and Scopus</td><td>25</td><td>2022</td><td>Sea bass protein (0.5–4%, w/w)</td><td>Corn oil (74–90%, v/v)</td><td>Zhang et al. (2022)</td></tr><tr><td>Mengwei Wang</td><td>Scopus</td><td>0</td><td>2023</td><td>Fibre polysaccharide-protein from H. pluvialis residues (2%, w/v)-gelatin (0.5–3%, w/w) complexes</td><td>Soybean oil</td><td>Wang et al. (2023b)</td></tr><tr><td>Qiaoli Zhao</td><td>WoS and Scopus</td><td>1</td><td>2023</td><td>Perilla protein isolate-chitosan composite nanoparticles (0.1–0.6%, w/w)</td><td>Rapeseed oil (80%, w/w)</td><td>Zhao et al. (2023)</td></tr><tr><td>Qinbo Jiang</td><td>WoS and Scopus</td><td>0</td><td>2022</td><td>Phytosterol nanoparticles (2%, w/w) and κ-carrageenan (0.3%, w/w)</td><td>Mixture of soybean oil and palm kernel stearin (25–100%, v/v)</td><td>Jiang et al. (2022)</td></tr><tr><td>Shaoyi Cen</td><td>WoS and Scopus</td><td>10</td><td>2022</td><td>Citrus pectin-β-Cyclodextrin complex (0.5–2%, w/w)</td><td>Sunflower seed oil (50–75%, w/w)</td><td>Cen et al. (2022)</td></tr><tr><td>Sun Min Kim</td><td>WoS and Scopus</td><td>10</td><td>2022</td><td>Cocoa powder (0–30%, w/w)</td><td>Whipped cream (30%, w/w)</td><td>Kim et al. (2022)</td></tr></tbody></table>
<table><caption>**Table 1** Studies are ordered by the number of papers by the first author followed by information about databases, total number of citations of the study, year, Pickering stabiliser particle and oil phase used in the study and reference</caption><thead><tr><th>First author</th><th>Database</th><th>Total citation number</th><th>Year</th><th>Pickering stabiliser particle (concentration)†</th><th>Oily phase (concentration)†</th><th>Ref.</th></tr></thead><tbody><tr><td rowspan="5">Mahdiyar Shahbazi</td><td>Multiple databases</td><td>26</td><td>2022</td><td>Soy protein isolate (25%, w/w) and microcrystalline cellulose (5.6%, w/w)</td><td>Sunflower oil (2%, w/w)</td><td>Shahbazi et al. (2022a)</td></tr><tr><td>Multiple databases</td><td>26</td><td>2022</td><td>Soy protein isolate (25%, w/w) and microcrystalline cellulose (4.2%, w/w)</td><td>Sunflower oil (4%, w/w)</td><td>Shahbazi et al. (2022b)</td></tr><tr><td>WoS and Scopus</td><td>39</td><td>2021</td><td>Sodium caseinate (18%, w/w) and acetylated microcrystalline cellulose (4.2%, w/w)</td><td>Canola oil (4%, w/w)</td><td>Shahbazi et al. (2021a)</td></tr><tr><td>WoS and Scopus</td><td>36</td><td>2021</td><td>Sodium caseinate (18%, w/w) and acetylated microcrystalline cellulose (4.2%, w/w)</td><td>Canola oil (4%, w/w)</td><td>Shahbazi et al. (2021b)</td></tr><tr><td>Multiple databases</td><td>22</td><td>2021</td><td>Soy protein isolate (25%, w/w) and microcrystalline cellulose (4.2%, w/w)</td><td>Canola oil (4%, w/w)</td><td>Shahbazi et al. (2021c)</td></tr><tr><td rowspan="2">An-Qi Bi</td><td>Multiple databases</td><td>17</td><td>2022</td><td>Casein (3%, w/v) and pectin (1–5%, w/v)</td><td>Soybean oil (66.7%, w/v)</td><td>Bi et al. (2022)</td></tr><tr><td>Multiple databases</td><td>42</td><td>2020</td><td>Casein (3%, w/v)</td><td>Edible oil (80%, w/v)</td><td>Bi et al. (2020)</td></tr><tr><td>Chao Qiu</td><td>WoS and Scopus</td><td>1</td><td>2023</td><td>Glycyrrhizic acid-zein composite nanoparticles (2%, w/v)</td><td>Soybean oil (50%, w/v)</td><td>Qiu et al. (2023)</td></tr><tr><td>Chao Wu</td><td>WoS and Scopus</td><td>45</td><td>2021</td><td>Cod myofibers (0.25–5%, w/v)</td><td>Soybean oil (75–90%, w/v)</td><td>Wu et al. (2021)</td></tr><tr><td>Chenxi Wang</td><td>Scopus</td><td>0</td><td>2023</td><td>Glycyrrhizic acid (2%, w/w)-zein (2%, w/w) composite nanoparticle and chitosan (1–3%, w/w)</td><td>Soybean oil (10–70%, v/v)</td><td>Wang et al. (2023a)</td></tr><tr><td>Dan Xu</td><td>Scopus and Pubmed</td><td>0</td><td>2023</td><td>Tea protein (3%, w/v) and xanthan gum (0–2.5%, w/v)</td><td>Olive oil</td><td>Xu et al. (2023)</td></tr><tr><td>Ekanem E. Ekanem</td><td>Scopus</td><td>2</td><td>2022</td><td>Keratin (1%, w/w) and oxidised cellulose nanofibril (0.5–1%, w/w)</td><td>Sunflower oil</td><td>Ekanem et al. (2022)</td></tr><tr><td>Jiaxin Guo</td><td>WoS and Scopus</td><td>2</td><td>2023</td><td>Spirulina platensis protein nanoparticles (1%, w/w) and xanthan gums (1%, w/w)</td><td>Sunflower waxes (5%, w/w) and soybean oil</td><td>Guo et al. (2023a)</td></tr><tr><td>Jie Du</td><td>WoS and Scopus</td><td>104</td><td>2021</td><td>Gelatin (20%, w/v) cross-linked by transglutaminase (0.002%, w/w)</td><td>Soybean oil (10–90%, v/v)</td><td>Du et al. (2021)</td></tr><tr><td>Lijuan Zhang</td><td>WoS and Scopus</td><td>25</td><td>2022</td><td>Sea bass protein (0.5–4%, w/w)</td><td>Corn oil (74–90%, v/v)</td><td>Zhang et al. (2022)</td></tr><tr><td>Mengwei Wang</td><td>Scopus</td><td>0</td><td>2023</td><td>Fibre polysaccharide-protein from H. pluvialis residues (2%, w/v)-gelatin (0.5–3%, w/w) complexes</td><td>Soybean oil</td><td>Wang et al. (2023b)</td></tr><tr><td>Qiaoli Zhao</td><td>WoS and Scopus</td><td>1</td><td>2023</td><td>Perilla protein isolate-chitosan composite nanoparticles (0.1–0.6%, w/w)</td><td>Rapeseed oil (80%, w/w)</td><td>Zhao et al. (2023)</td></tr><tr><td>Qinbo Jiang</td><td>WoS and Scopus</td><td>0</td><td>2022</td><td>Phytosterol nanoparticles (2%, w/w) and κ-carrageenan (0.3%, w/w)</td><td>Mixture of soybean oil and palm kernel stearin (25–100%, v/v)</td><td>Jiang et al. (2022)</td></tr><tr><td>Shaoyi Cen</td><td>WoS and Scopus</td><td>10</td><td>2022</td><td>Citrus pectin-β-Cyclodextrin complex (0.5–2%, w/w)</td><td>Sunflower seed oil (50–75%, w/w)</td><td>Cen et al. (2022)</td></tr><tr><td>Sun Min Kim</td><td>WoS and Scopus</td><td>10</td><td>2022</td><td>Cocoa powder (0–30%, w/w)</td><td>Whipped cream (30%, w/w)</td><td>Kim et al. (2022)</td></tr></tbody></table>
<table><caption>**Table 1 (Continued)**</caption><thead><tr><th>First author</th><th>Database</th><th>Total citation number</th><th>Year</th><th>Pickering stabiliser particle (concentration)<sup>†</sup></th><th>Oily phase (concentration)<sup>†</sup></th><th>Ref.</th></tr></thead><tbody><tr><td>Tao Ma</td><td>WoS and Scopus</td><td>32</td><td>2022</td><td>Cellulose nanocrystals (0.25–1.25% w/w)</td><td>Corn oil (33%, v/v)</td><td>Ma et al. (2022)</td></tr><tr><td>Tingting Feng</td><td>WoS and Scopus</td><td>40</td><td>2022</td><td>Pea protein isolate-high methoxyl pectin-epigallocatechin gallate complexes (1%, w/v)</td><td>Tea camellia seed oil blend (52%, w/w)</td><td>Feng et al. (2022)</td></tr><tr><td>Xueqing Li</td><td>WoS and Scopus</td><td>1</td><td>2023</td><td>β-cyclodextrin-chitosan complexes (0.1–5% w/v)</td><td>Sunflower seed oil (76–92%, w/w)</td><td>Li et al. (2023)</td></tr><tr><td>Ya Zhu</td><td>Multiple databases</td><td>146</td><td>2020</td><td>Chitin nanofibrils (0.064% w/w)</td><td>Sunflower oil (88%, w/v)</td><td>Zhu et al. (2020)</td></tr><tr><td>Yaowei Liu</td><td>WoS and Scopus</td><td>72</td><td>2019</td><td>Whey protein isolate (10%, w/v)</td><td>Soybean oil (30–60%, v/v)</td><td>Liu et al. (2019)</td></tr><tr><td>Ying Wan</td><td>Multiple databases</td><td>66</td><td>2021</td><td>Cellulose-rice proteins complex (1–3%, w/v)</td><td>Soybean oil (80%, v/v)</td><td>Wan et al. (2021)</td></tr><tr><td>Ziang Guo</td><td>WoS and Scopus</td><td>0</td><td>2023</td><td>Basa fish protein (20 mg/mL)</td><td>Sunflower oil (60% w/w)</td><td>Guo et al. (2023b)</td></tr><tr><td>Zinuo An</td><td>WoS and Scopus</td><td>1</td><td>2023</td><td>Tea residue protein–xanthan gum particles complex (0–2.5%, w/v)</td><td>Olive oil (70%, v/v)</td><td>An et al. (2023)</td></tr></tbody></table>

Multiple databases represent articles found in the three databases: WoS, Scopus and PubMed.

<figure><img src="image_6.png" /><figcaption>**Figure 6** Sankey diagram (first author – journals – years linkages).</figcaption></figure>

structure from a microscopic to macroscopic view and explore the advanced mechanism of HIPPEs stabilisation; (3) The rheological properties and stability of

high internal phase emulsions will be studied and considering factors such as nutrition, taste, colour and shape and (3) Inspect the rheological properties

<footnote>†Based on the paper that was referenced.</footnote>
<table><caption>**Table 1 (Continued)**</caption><thead><tr><th>First author</th><th>Database</th><th>Total citation number</th><th>Year</th><th>Pickering stabiliser particle (concentration)†</th><th>Oily phase (concentration)†</th><th>Ref.</th></tr></thead><tbody><tr><td>Tao Ma</td><td>WoS and Scopus</td><td>32</td><td>2022</td><td>Cellulose nanocrystals (0.25–1.25% w/w)</td><td>Corn oil (33%, v/v)</td><td>Ma et al. (2022)</td></tr><tr><td>Tingting Feng</td><td>WoS and Scopus</td><td>40</td><td>2022</td><td>Pea protein isolate-high methoxyl pectin-epigallocatechin gallate complexes (1%, w/v)</td><td>Tea camellia seed oil blend (52%, w/w)</td><td>Feng et al. (2022)</td></tr><tr><td>Xueqing Li</td><td>WoS and Scopus</td><td>1</td><td>2023</td><td>β-cyclodextrin-chitosan complexes (0.1–5% w/v)</td><td>Sunflower seed oil (76–92%, w/w)</td><td>Li et al. (2023)</td></tr><tr><td>Ya Zhu</td><td>Multiple databases</td><td>146</td><td>2020</td><td>Chitin nanofibrils (0.064% w/w)</td><td>Sunflower oil (88%, w/v)</td><td>Zhu et al. (2020)</td></tr><tr><td>Yaowei Liu</td><td>WoS and Scopus</td><td>72</td><td>2019</td><td>Whey protein isolate (10%, w/v)</td><td>Soybean oil (30–60%, v/v)</td><td>Liu et al. (2019)</td></tr><tr><td>Ying Wan</td><td>Multiple databases</td><td>66</td><td>2021</td><td>Cellulose-rice proteins complex (1–3%, w/v)</td><td>Soybean oil (80%, v/v)</td><td>Wan et al. (2021)</td></tr><tr><td>Ziang Guo</td><td>WoS and Scopus</td><td>0</td><td>2023</td><td>Basa fish protein (20 mg/mL)</td><td>Sunflower oil (60% w/w)</td><td>Guo et al. (2023b)</td></tr><tr><td>Zinuo An</td><td>WoS and Scopus</td><td>1</td><td>2023</td><td>Tea residue protein–xanthan gum particles complex (0–2.5%, w/v)</td><td>Olive oil (70%, v/v)</td><td>An et al. (2023)</td></tr></tbody></table>

Multiple databases represent articles found in the three databases: WoS, Scopus and PubMed.

<figure><img src="image_7.png" /><figcaption>**Figure 6** Sankey diagram (first author – journals – years linkages).</figcaption></figure>

structure from a microscopic to macroscopic view and explore the advanced mechanism of HIPPEs stabilisation; (3) The rheological properties and stability of

high internal phase emulsions will be studied and considering factors such as nutrition, taste, colour and shape and (3) Inspect the rheological properties

<footnote>†Based on the paper that was referenced.</footnote>
and stability of HIPPEs and, taking into account fac-
tors such as nutrition, taste, colour and shape, develop
3D printing of easy-to-swallow foods with special
shapes, thus expanding the prospects of application of
HIPPEs in the food industry (Wu *et al.*, 2022).

Furthermore, in terms of real applications in the food industry, further research is needed to explore fat replacement, in vitro and in vivo digestibility, as well as further understanding of encapsulation and release of bioactive compounds. It is also necessary to optimise PE production by considering production conditions and studying the stabilisation and behaviour of PE in various food matrices under different conditions of temperature, pH and ionic strength. The evaluation should focus on the cooking and digestion conditions, as well as the food's shelf life. Additionally, it is important to conduct bioavailability and bioaccessibility studies of bioactive compounds encapsulated in PE, as this is a significant potential application for these emulsions.

As an additional challenge in the growing realm of
3D-printed food, a critical and frequently neglected
consideration is the adjustment of packaging ideas to
facilitate these inventive food products. Unlike regular
foodstuffs, 3D-printed culinary creations frequently
showcase distinctive shapes, textures and compositions
that typical packaging solutions may not sufficiently
shield or maintain. Innovative packaging designs are
needed, which must not only cater to the unique char-
acteristics of 3D-printed foods but also meet the
increased consumer demands for sustainability and
safety. A research by Sun et al. (2015) highlights the
significance of using biodegradable and eco-friendly
packaging materials, which align with the sustainable
values driving much of the innovation in 3D food
printing. Godoi et al. (2016) highlight the significance
of packaging that preserves the nutritional quality and
structural integrity of 3D-printed food, which can be
vulnerable to environmental factors. The advancement
of materials and technologies is necessary; this includes
active and intelligent packaging systems, according to
Realini & Marcos (2014), which can respond to envi-
ronmental changes and ensure the longevity and safety
of sensitive food products and therefore also for many
3D-printed foods. To fully realise the potential of
3DFP technology, it is essential to integrate novel
packaging solutions. This will ensure that innovative
products are delivered to the consumer in optimal
condition.

Conclusion

Given the advantages of operability and convenience,
it is very likely that 3D printing of food will become
an indispensable process in our daily lives. However,

food formulations to be printed often do not have the
rheological properties necessary for their processabil-
ity. The use of emulsions has been reported as an
alternative for regulating the rheological properties of
food formulations for 3D printing. The bibliometric
analysis of this paper revealed that the first article on
this topic was published in 2019, indicating its current
relevance. Subsequently, there has been a growing
trend in research on this subject. Out of the 28 original
research articles, only 10 countries have studied the
application of PE in 3DFP. China has been at
the forefront of this research, followed by the United
Kingdom. The *Food Hydrocolloids Journal* has been
the primary source of scientific information.

The cited studies mention Pickering stabiliser parti-
cles, including soy protein isolate, microcrystalline cel-
lulose and acetylated microcrystalline cellulose, as well
as oil phases based on sunflower, canola, olive and
soybean oils.

HIPPEs have been primarily used in the 3D printing of porous materials, demonstrating high thermal and conductive stability, which is advantageous for post-processing. Further research is required to explore additional types of formulations for the particles and oil phase. It should also investigate the stability of these emulsions and the bioavailability and bioaccessibility of the encapsulated bioactive compounds. These studies must also be carried out on real food systems.

Moreover, to fully utilise the potential of 3D food
printing technology, it is essential to integrate novel
packaging solutions that preserve the nutritional qual-
ity and structural integrity of 3D-printed food.

**Acknowledgments**

The authors would like to thank the staff and facili-
ties of the Rio de Janeiro State University (UERJ),
the Federal University of the State of Rio de
Janeiro (UNIRIO) and the University of São Paulo
(USP). Open Access funding enabled and organized
by Projekt DEAL.

**Author contributions**

**Patrícia Marques de Farias:** Conceptualization; methodology; validation; investigation; data curation; writing – review and editing. **Julia Rabelo Vaz Matheus:** Methodology; data curation; writing – original draft; validation. **Bianca Chieregato Maniglia:** Writing – review and editing. **Patricia Le-Bail:** Writing – review and editing. **Alain Le-Bail:** Writing – review and editing. **Markus Schmid:** Writing – review and editing; supervision. **Ana Elizabeth Cavalcante Fai:** Validation; resources; writing – review and editing; supervision; project administration; funding acquisition.
and stability of HIPPEs and, taking into account factors such as nutrition, taste, colour and shape, develop 3D printing of easy-to-swallow foods with special shapes, thus expanding the prospects of application of HIPPEs in the food industry (Wu *et al.*, 2022).

Furthermore, in terms of real applications in the food industry, further research is needed to explore fat replacement, in vitro and in vivo digestibility, as well as further understanding of encapsulation and release of bioactive compounds. It is also necessary to optimise PE production by considering production conditions and studying the stabilisation and behaviour of PE in various food matrices under different conditions of temperature, pH and ionic strength. The evaluation should focus on the cooking and digestion conditions, as well as the food's shelf life. Additionally, it is important to conduct bioavailability and bioaccessibility studies of bioactive compounds encapsulated in PE, as this is a significant potential application for these emulsions.

As an additional challenge in the growing realm of 3D-printed food, a critical and frequently neglected consideration is the adjustment of packaging ideas to facilitate these inventive food products. Unlike regular foodstuffs, 3D-printed culinary creations frequently showcase distinctive shapes, textures and compositions that typical packaging solutions may not sufficiently shield or maintain. Innovative packaging designs are needed, which must not only cater to the unique characteristics of 3D-printed foods but also meet the increased consumer demands for sustainability and safety. A research by Sun *et al.* (2015) highlights the significance of using biodegradable and eco-friendly packaging materials, which align with the sustainable values driving much of the innovation in 3D food printing. Godoi *et al.* (2016) highlight the significance of packaging that preserves the nutritional quality and structural integrity of 3D-printed food, which can be vulnerable to environmental factors. The advancement of materials and technologies is necessary; this includes active and intelligent packaging systems, according to Realini & Marcos (2014), which can respond to environmental changes and ensure the longevity and safety of sensitive food products and therefore also for many 3D-printed foods. To fully realise the potential of 3DFP technology, it is essential to integrate novel packaging solutions. This will ensure that innovative products are delivered to the consumer in optimal condition.

## Conclusion

Given the advantages of operability and convenience, it is very likely that 3D printing of food will become an indispensable process in our daily lives. However,

food formulations to be printed often do not have the rheological properties necessary for their processability. The use of emulsions has been reported as an alternative for regulating the rheological properties of food formulations for 3D printing. The bibliometric analysis of this paper revealed that the first article on this topic was published in 2019, indicating its current relevance. Subsequently, there has been a growing trend in research on this subject. Out of the 28 original research articles, only 10 countries have studied the application of PE in 3DFP. China has been at the forefront of this research, followed by the United Kingdom. The *Food Hydrocolloids Journal* has been the primary source of scientific information.

The cited studies mention Pickering stabiliser particles, including soy protein isolate, microcrystalline cellulose and acetylated microcrystalline cellulose, as well as oil phases based on sunflower, canola, olive and soybean oils.

HIPPEs have been primarily used in the 3D printing of porous materials, demonstrating high thermal and conductive stability, which is advantageous for post-processing. Further research is required to explore additional types of formulations for the particles and oil phase. It should also investigate the stability of these emulsions and the bioavailability and bioaccessibility of the encapsulated bioactive compounds. These studies must also be carried out on real food systems.

Moreover, to fully utilise the potential of 3D food printing technology, it is essential to integrate novel packaging solutions that preserve the nutritional quality and structural integrity of 3D-printed food.

## Acknowledgments

The authors would like to thank the staff and facilities of the Rio de Janeiro State University (UERJ), the Federal University of the State of Rio de Janeiro (UNIRIO) and the University of São Paulo (USP). Open Access funding enabled and organized by Projekt DEAL.

## Author contributions

**Patrícia Marques de Farias:** Conceptualization; methodology; validation; investigation; data curation; writing – review and editing. **Julia Rabelo Vaz Matheus:** Methodology; data curation; writing – original draft; validation. **Bianca Chieregato Maniglia:** Writing – review and editing. **Patricia Le-Bail:** Writing – review and editing. **Alain Le-Bail:** Writing – review and editing. **Markus Schmid:** Writing – review and editing; supervision. **Ana Elizabeth Cavalcante Fai:** Validation; resources; writing – review and editing; supervision; project administration; funding acquisition.
**Conflict of interest**

There are none to declare.

**Ethical approval**

Ethics approval was not required for this research.

**Funding information**

This research work was funded and supported by the Research Support Foundation of the State of Rio de Janeiro (FAPERJ) (code E-26/010/002738/2019; code E-26/211.985/2021; code E-26/201.428/2022), the São Paulo Research Foundation (FAPESP, Brazil) for the Young Investigator grant (2020/08727-0 and 2021/05947-2) and the Pays de la Loire Region, as well as the European Union, as part of the European H2020 SWEET project.

**Data availability statement**

Research data are not shared.

**References**

An, Z., Liu, Z., Mo, H. et al. (2023). Preparation of Pickering emulsion gel stabilized by tea residue protein/xanthan gum particles and its application in 3D printing. *Journal of Food Engineering*, **343**, 111378.

Bi, A.-Q., Xu, X.-B., Guo, Y., Du, M., Yu, C.-P. & Wu, C. (2020). Ultrasound pre-fractured casein and in-situ formation of high internal phase emulsions. *Ultrasonics Sonochemistry*, **64**, 104916.

Bi, A.-Q., Xu, X.-B., Guo, Y., Du, M., Yu, C.-P. & Wu, C. (2022). Fabrication of flavour oil high internal phase emulsions by casein/pectin hybrid particles: 3D printing performance. *Food Chemistry*, **371**, 131349.

The 3D printing properties of Pickering HIPEs fabricated by casein/pectin hybrid particles with flavour oil showed excellent 3D printing properties and have potential applications in the food, medical and cosmetic industries.

Cen, S., Li, Z., Guo, Z. et al. (2022). 4D printing of a citrus pectin/β-CD Pickering emulsion: a study on temperature induced color transformation. *Additive Manufacturing*, **56**, 102925.

Dankar, I., Haddarah, A., Omar, F.E.L., Sepulcre, F. & Pujolà, M. (2018). 3D printing technology: the new era for food customization and elaboration. *Trends in Food Science & Technology*, **75**, 231-242.

de Farias, P.M., Matheus, J.R.V., Fai, A.E.C., de Vasconcelos, L.B. & Tapia-Blácido, D.R. (2023). Global research trends on the utilization of nopal (opuntia Sp) cladodes as a functional ingredient for industrial use. *Plant Foods for Human Nutrition*, **78**, 621-629.

Du, J., Dai, H., Wang, H. et al. (2021). Preparation of high thermal stability gelatin emulsion and its application in 3D printing. *Food Hydrocolloids*, **113**, 106536.

Ekanem, E.E., Wilson, A., Scott, J.L., Edler, K.J. & Mattia, D. (2022). Continuous rotary membrane emulsification for the production of sustainable Pickering emulsions. *Chemical Engineering Science*, **249**, 117328.

Feng, C., Zhang, M. & Bhandari, B. (2019). Materials properties of printable edible inks and printing parameters optimization during 3D printing: a review. *Critical Reviews in Food Science and Nutrition*, **59**, 3074-3081.

Feng, T., Fan, C., Wang, X., Wang, X., Xia, S. & Huang, Q. (2022). Food-grade Pickering emulsions and high internal phase Pickering emulsions encapsulating cinnamaldehyde based on pea protein-pectin-EGCG complexes for extrusion 3D printing. *Food Hydrocolloids*, **124**, 107265.

Godoi, F.C., Prakash, S. & Bhandari, B.R. (2016). 3D printing technologies applied for food design: status and prospects. *Journal of Food Engineering*, **179**, 44-54.

Guo, J., Gu, X., Du, L. & Meng, Z. (2023a). Spirulina platensis protein nanoparticle-based bigels: dual stabilization, phase inversion, and 3D printing. *Food Hydrocolloids*, **135**, 108160.

Guo, Z., Li, Z., Cen, S. et al. (2023b). Preparation of pangasius hypophthalmus protein-stabilized Pickering emulsions and 3D printing application. *Journal of Food Engineering*, **341**, 111333.

Hashemnejad, S.M., Badruddoza, A.Z.M., Zarket, B., Ricardo Castaneda, C. & Doyle, P.S. (2019). Thermoresponsive nanoemulsion-based gel synthesized through a low-energy process. *Nature Communications*, **10**, 2749.

Hussain, S., Malakar, S. & Arora, V.K. (2022). Extrusion-based 3D food printing: technological approaches, material characteristics, printing stability, and post-processing. *Food Engineering Reviews*, **14**, 100-119.

Jiang, Q., Binks, B.P. & Meng, Z. (2022). Double scaffold networks regulate edible Pickering emulsion gel for designing thermally actuated 4D printing. *Food Hydrocolloids*, **133**, 107969.

Kim, S.M., Woo, J.H., Kim, H.W. & Park, H.J. (2022). Formulation and evaluation of cold-extruded chocolate ganache for three-dimensional food printing. *Journal of Food Engineering*, **314**, 110785.

Koseoglu, M.A., Rahimi, R., Okumus, F. & Liu, J. (2016). Bibliometric studies in tourism. *Annals of Tourism Research*, **61**, 180-198.

Li, X., Fan, L. & Li, J. (2023). Extrusion-based 3D printing of high internal phase emulsions stabilized by co-assembled β-cyclodextrin and chitosan. *Food Hydrocolloids*, **134**, 108036.

Li, X., Xu, X., Song, L. et al. (2020). High internal phase emulsion for food-grade 3D printing materials. *ACS Applied Materials & Interfaces*, **12**, 45493-45503.

Lissant, K.J. (1966). The geometry of high-internal-phase-ratio emulsions. *Journal of Colloid and Interface Science*, **22**, 462-468.

Liu, Y., Zhang, W., Wang, K., Bao, Y., Regenstein, J.M. & Zhou, P. (2019). Fabrication of gel-like emulsions with whey protein isolate using microfluidization: rheological properties and 3D printing performance. *Food and Bioprocess Technology*, **12**, 1967-1979.

Ma, T., Cui, R., Lu, S. et al. (2022). High internal phase Pickering emulsions stabilized by cellulose nanocrystals for 3D printing. *Food Hydrocolloids*, **125**, 107418.

Mantihal, S., Kobun, R. & Lee, B.-B. (2020). 3D food printing of as the new way of preparing food: a review. *International Journal of Gastronomy and Food Science*, **22**, 100260.

Matheus, J.R.V., de Farias, P.M., Satoriva, J.M., de Andrade, C.J. & Fai, A.E.C. (2023). Cassava starch films for food packaging: trends over the last decade and future research. *International Journal of Biological Macromolecules*, **225**, 658-672.

Qiu, C., Wang, C., Li, X. et al. (2023). Preparation of high internal phase Pickering emulsion gels stabilized by Glycyrrhizic acid-Zein composite nanoparticles: gelation mechanism and 3D printing performance. *Food Hydrocolloids*, **135**, 108128.

Rawal, K., Annamalai, P.K., Bhandari, B. & Prakash, S. (2023). Oat flour as a novel stabiliser for designing plant-based Pickering emulsion. *Journal of Food Engineering*, **340**, 111300.

Realini, C.E. & Marcos, B. (2014). Active and intelligent packaging systems for a modern society. *Meat Science*, **98**, 404-419.

Riesco, R., Boyer, L., Blosse, S. et al. (2019). Water-in-PDMS emulsion templating of highly interconnected porous architectures for 3D cell culture. *ACS Applied Materials & Interfaces*, **11**, 28631-28640.

Santamaria-Echart, A., Fernandes, I.P., Silva, S.C. et al. (2021). New trends in natural emulsifiers and emulsion technology for the
**Conflict of interest**

There are none to declare.

**Ethical approval**

Ethics approval was not required for this research.

**Funding information**

This research work was funded and supported by the Research Support Foundation of the State of Rio de Janeiro (FAPERJ) (code E-26/010/002738/2019; code E-26/211.985/2021; code E-26/201.428/2022), the São Paulo Research Foundation (FAPESP, Brazil) for the Young Investigator grant (2020/08727-0 and 2021/05947-2) and the Pays de la Loire Region, as well as the European Union, as part of the European H2020 SWEET project.

**Data availability statement**

Research data are not shared.

**References**

An, Z., Liu, Z., Mo, H. et al. (2023). Preparation of Pickering emulsion gel stabilized by tea residue protein/xanthan gum particles and its application in 3D printing. *Journal of Food Engineering*, **343**, 111378.

Bi, A.-Q., Xu, X.-B., Guo, Y., Du, M., Yu, C.-P. & Wu, C. (2020). Ultrasound pre-fractured casein and in-situ formation of high internal phase emulsions. *Ultrasonics Sonochemistry*, **64**, 104916.

Bi, A.-Q., Xu, X.-B., Guo, Y., Du, M., Yu, C.-P. & Wu, C. (2022). Fabrication of flavour oil high internal phase emulsions by casein/pectin hybrid particles: 3D printing performance. *Food Chemistry*, **371**, 131349.

The 3D printing properties of Pickering HIPEs fabricated by casein/pectin hybrid particles with flavour oil showed excellent 3D printing properties and have potential applications in the food, medical and cosmetic industries.

Cen, S., Li, Z., Guo, Z. et al. (2022). 4D printing of a citrus pectin/β-CD Pickering emulsion: a study on temperature induced color transformation. *Additive Manufacturing*, **56**, 102925.

Dankar, I., Haddarah, A., Omar, F.E.L., Sepulcre, F. & Pujolà, M. (2018). 3D printing technology: the new era for food customization and elaboration. *Trends in Food Science & Technology*, **75**, 231-242.

de Farias, P.M., Matheus, J.R.V., Fai, A.E.C., de Vasconcelos, L.B. & Tapia-Blácido, D.R. (2023). Global research trends on the utilization of nopal (opuntia Sp) cladodes as a functional ingredient for industrial use. *Plant Foods for Human Nutrition*, **78**, 621-629.

Du, J., Dai, H., Wang, H. et al. (2021). Preparation of high thermal stability gelatin emulsion and its application in 3D printing. *Food Hydrocolloids*, **113**, 106536.

Ekanem, E.E., Wilson, A., Scott, J.L., Edler, K.J. & Mattia, D. (2022). Continuous rotary membrane emulsification for the production of sustainable Pickering emulsions. *Chemical Engineering Science*, **249**, 117328.

Feng, C., Zhang, M. & Bhandari, B. (2019). Materials properties of printable edible inks and printing parameters optimization during 3D printing: a review. *Critical Reviews in Food Science and Nutrition*, **59**, 3074-3081.

Feng, T., Fan, C., Wang, X., Wang, X., Xia, S. & Huang, Q. (2022). Food-grade Pickering emulsions and high internal phase Pickering emulsions encapsulating cinnamaldehyde based on pea protein-pectin-EGCG complexes for extrusion 3D printing. *Food Hydrocolloids*, **124**, 107265.

Godoi, F.C., Prakash, S. & Bhandari, B.R. (2016). 3D printing technologies applied for food design: status and prospects. *Journal of Food Engineering*, **179**, 44-54.

Guo, J., Gu, X., Du, L. & Meng, Z. (2023a). Spirulina platensis protein nanoparticle-based bigels: dual stabilization, phase inversion, and 3D printing. *Food Hydrocolloids*, **135**, 108160.

Guo, Z., Li, Z., Cen, S. et al. (2023b). Preparation of pangasius hypophthalmus protein-stabilized Pickering emulsions and 3D printing application. *Journal of Food Engineering*, **341**, 111333.

Hashemnejad, S.M., Badruddoza, A.Z.M., Zarket, B., Ricardo Castaneda, C. & Doyle, P.S. (2019). Thermoresponsive nanoemulsion-based gel synthesized through a low-energy process. *Nature Communications*, **10**, 2749.

Hussain, S., Malakar, S. & Arora, V.K. (2022). Extrusion-based 3D food printing: technological approaches, material characteristics, printing stability, and post-processing. *Food Engineering Reviews*, **14**, 100-119.

Jiang, Q., Binks, B.P. & Meng, Z. (2022). Double scaffold networks regulate edible Pickering emulsion gel for designing thermally actuated 4D printing. *Food Hydrocolloids*, **133**, 107969.

Kim, S.M., Woo, J.H., Kim, H.W. & Park, H.J. (2022). Formulation and evaluation of cold-extruded chocolate ganache for three-dimensional food printing. *Journal of Food Engineering*, **314**, 110785.

Koseoglu, M.A., Rahimi, R., Okumus, F. & Liu, J. (2016). Bibliometric studies in tourism. *Annals of Tourism Research*, **61**, 180-198.

Li, X., Fan, L. & Li, J. (2023). Extrusion-based 3D printing of high internal phase emulsions stabilized by co-assembled β-cyclodextrin and chitosan. *Food Hydrocolloids*, **134**, 108036.

Li, X., Xu, X., Song, L. et al. (2020). High internal phase emulsion for food-grade 3D printing materials. *ACS Applied Materials & Interfaces*, **12**, 45493-45503.

Lissant, K.J. (1966). The geometry of high-internal-phase-ratio emulsions. *Journal of Colloid and Interface Science*, **22**, 462-468.

Liu, Y., Zhang, W., Wang, K., Bao, Y., Regenstein, J.M. & Zhou, P. (2019). Fabrication of gel-like emulsions with whey protein isolate using microfluidization: rheological properties and 3D printing performance. *Food and Bioprocess Technology*, **12**, 1967-1979.

Ma, T., Cui, R., Lu, S. et al. (2022). High internal phase Pickering emulsions stabilized by cellulose nanocrystals for 3D printing. *Food Hydrocolloids*, **125**, 107418.

Mantihal, S., Kobun, R. & Lee, B.-B. (2020). 3D food printing of as the new way of preparing food: a review. *International Journal of Gastronomy and Food Science*, **22**, 100260.

Matheus, J.R.V., de Farias, P.M., Satoriva, J.M., de Andrade, C.J. & Fai, A.E.C. (2023). Cassava starch films for food packaging: trends over the last decade and future research. *International Journal of Biological Macromolecules*, **225**, 658-672.

Qiu, C., Wang, C., Li, X. et al. (2023). Preparation of high internal phase Pickering emulsion gels stabilized by Glycyrrhizic acid-Zein composite nanoparticles: gelation mechanism and 3D printing performance. *Food Hydrocolloids*, **135**, 108128.

Rawal, K., Annamalai, P.K., Bhandari, B. & Prakash, S. (2023). Oat flour as a novel stabiliser for designing plant-based Pickering emulsion. *Journal of Food Engineering*, **340**, 111300.

Realini, C.E. & Marcos, B. (2014). Active and intelligent packaging systems for a modern society. *Meat Science*, **98**, 404-419.

Riesco, R., Boyer, L., Blosse, S. et al. (2019). Water-in-PDMS emulsion templating of highly interconnected porous architectures for 3D cell culture. *ACS Applied Materials & Interfaces*, **11**, 28631-28640.

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Zhu, Y., Huan, S., Bai, L. et al. (2020). High internal phase oil-in-water Pickering emulsions stabilized by chitin nanofibrils: 3D structuring and solid foam. *ACS Applied Materials & Interfaces, 12*, 11240–11251.
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The experiments on three-dimensional printing have confirmed that HIPPEs stabilised by SBP microgel particles are extrudable, have good printing performance, and self-supporting properties.

Yang, T., Hu, Y., Wang, C. & Binks, B.P. (2017). Fabrication of hierarchical macroporous biocompatible scaffolds by combining Pickering high internal phase emulsion templates with three-dimensional printing. *ACS Applied Materials & Interfaces, 9*, 22950–22958.

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Zhao, Q., Fan, L., Liu, Y. & Li, J. (2023). Mayonnaise-like high internal phase Pickering emulsions stabilized by co-assembled phosphorylated perilla protein isolate and chitosan for extrusion 3D printing application. *Food Hydrocolloids, 135*, 108133.

Zhu, Y., Huan, S., Bai, L. et al. (2020). High internal phase oil-in-water Pickering emulsions stabilized by chitin nanofibrils: 3D structuring and solid foam. *ACS Applied Materials & Interfaces, 12*, 11240–11251.