A Bibliometric Analysis of Global Research Trends on Virgin Coconut Oil as a Functional Food

This bibliometric analysis covers the period 2007–2024, with 190 documents published across 130 sources, including journals, books, and conference proceedings (Table 1). The average document age of 4.74 years indicates that this topic remains relevant and has seen significant growth in recent years, driven by increasing interest in functional foods. A total of 812 authors contributed to this research, highlighting global collaboration and widespread attention to the bioactive potential of VCO, such as its antioxidant, antibacterial, and antiviral properties.

Table 1. Summary statistic of the articles collected

Source: biblioshiny

Regarding publication types, 145 articles dominate the contributions, followed by 20 conference papers, 18 review articles, and a few books and book chapters. The prevalence of original research and reviews underscores a strong focus on experimental studies and the synthesis of existing knowledge. Overall, the data reflect a dynamic and multidisciplinary research landscape. Future studies can focus on clinical applications, bioactive mechanisms, and optimizing extraction methods to enhance VCO’s functional potential.

The analysis of the annual scientific production on VCO reveals a clear trajectory of growth and increasing interest in this area of research. From its modest beginnings, VCO research has evolved into a significant field, with peaks in publication output reflecting broader trends in health and wellness. Various factors, including funding availability, research trends, and public interest, may influence the fluctuation in annual production. Overall, the data underscores the importance of VCO in contemporary scientific research and its potential implications for health and nutrition.

3.1 Annual scientific production

The effort to examine Annual Scientific Production poses a challenge, as authors and publishers must comply with minimum acceptable standards within each discipline. Within this aim, the overall research productivity and its fluctuations over time are important as they show the context and evolution of a specific area. This analysis also helps stakeholders such as researchers, policymakers, and funders to determine the phases of concentrated research, prioritize changes in research targets, and predict new pathways in research. In addition, it marks the starting point for better distribution of limited resources and for promoting collaboration to address or alleviate existing anticipated problems.

Figure 2 shows VCO research scientific publications between 2007 and 2024. It indicates significant growth starting from 2007, when only two articles were published, and culminating in his astonishing 30 articles in 2023. The rapid increase in publications from 2009 to 2023 indicates a growing awareness and recognition of VCO's health benefits and industrial applications. Interestingly, in 2008, there were no publications reflecting a possible lack of interest or knowledge related to VCO. However, in 2009, four publications marked the start of the upward trend.

Figure 2. Trend of publications on virgin coconut oil (VCO) as a functional food (2007–2024)

The X-axis represents the years of publication, while the Y-axis indicates the number of articles.

Even further scholarly output was recorded in 2017 and 2018. Together, 27 articles were published in these two years, 13 and 14, respectively, showing sustained scholarly interest in HPVA. Widening use of VCO in the food and drug industry due to new technologies such as nanoemulsion, new microencapsulation methods [25, 26], or even new global perceptions of natural food and functional nutrition being 'better' likely increased academic and consumer interest [4], explaining the jump in publications during these years. It is attested by VCO's increasing recognition in the context of global health, as well as today's innovations. These trends further highlight the importance of VCO as an object of study. It is also the case that VCO research is more actively being undertaken, as indicated by the publication of 19 articles in 2024. That said, there is still considerable scepticism about these oscillations. This is mainly because there is a strong conviction in the importance and changing aspects of the field, as well as the need for further interdisciplinary work. If the stakeholders understood these behaviours, it would be easier for them to endorse non-cooking VCO ideas and aid in resolving contemporary health and industrial dilemmas.

3.2 Average citations per year

Examination of average citations per year is important when determining the effect and academic productivity of the research work done in a specific area. This metric sheds light on the acceptance of research output over time, revealing the most important contributions to the field and how well these contributions have been accepted in the community. In the case of VCO research, citation data serve to identify significant studies in the context of their respective fields, periods of increased attention, and disciplines in which innovations and discoveries are recognized. This also helps the stakeholders to identify barriers or saturation levels that inhibit further progress and to make sure that research activities are active and geared towards the future.

The upward trend between 2014 and 2020, as illustrated in Figure 3, depicts the increased scholarly attention and acknowledgement towards VCO research from this period onwards. The peak in 2021 averaged 8 citations per paper, clearly indicating the benefit of earlier studies, especially the ones on VCO’s antimicrobial, antioxidant, and functional food properties [4]. The increase in citations can also result from the development of new technologies, such as nanoemulsion and microencapsulation, which expanded the scope of VCO’s use in medicine and industry [10, 27] Also, the increased global interest in the use of natural health products and sustainable foods most probably gave rise to this attention.

However, there has been a significant drop in citations following 2021, with forecasted numbers dipping dramatically in 2024. This drop may be a result of diminished research novelty, possible overexploitation of research topics, or the limited window for citations of newly published works. The spike in 2021 indicates the potential of prior works to influence VCO research. Their relevance is established, while the dip indicates work that requires fresh perspectives to stimulate academic interest. Future research can aim to assess cross-disciplinary applications for VCO’s impact to be relevant and address new global needs, for example, in advanced medicine, nanotechnology, or environmental conservation. Considering these developments and their consequences will help researchers and other VCO constituents to adapt to changes in VCO research and promote intelligent innovation.

Figure 3. Average citations per year illustrate the trend in average annual citations received by publications related to virgin coconut oil (VCO) research from 2014 to 2024

3.3 Author contributions

Table 2 highlights the overall author contribution, productivity, and bibliometric impact within the research area, which follows the trends of authorship and impact. The top contributors, Illam S.P., Manikantan M.R., and Raghavamenon A.C., have published five articles, each with scores between 1.13 and 1.14, with high collaborative work in multidisciplinary fields. On the other hand, authors Koh S.P. and LONG K, with their scores of 0.99, show discrete contributions within the range of co-authored works. Highly fractionalized scorer Benjakul S, who has 1.83 out of four articles, demonstrates high leadership due to being the main author of a lot of impactful research.

Table 2. Author contributions to research on virgin coconut oil (VCO) as a functional food: Total and fractionalized articles

These authors greatly contributed because they highly specialize in areas within VCO research, such as food technology, biochemistry, and health sciences. They emphasize the need to explore the application of VCO in functional foods, anti-microbial agents, and more advanced technologies like nanoemulsions. Researchers such as Benjakul S. are the most excellent among many in terms of leadership, as they take the initiative to conduct cutting-edge studies to improve the methods of extraction and new applications of VCO.

Table 3 complements this by illustrating the distribution of authors based on the number of documents written. A vast majority (90.6%) of authors contributed to only one document, highlighting the prevalence of single-time contributors in the field. A much smaller proportion of authors (6.5%) produced two documents, and only a minuscule fraction (0.6%) contributed five documents, emphasizing the significance of consistent contributors like Illam S.P. and Benjakul S., who are also prominent in the first table. This small group of core authors demonstrates sustained productivity and leadership within the research domain.

Table 3. Lotka’s law distribution

Table 4 examines the bibliometric impact of authors through metrics such as the h-index, g-index, m-index, total citations (TC), and year of first publication (PY_start). Authors such as Benjakul S., Chaijan M., Panpipat W., and Sungpud C. show strong bibliometric performance, with an h-index of 4, g-index of 4, m-index of 0.667, and citation counts ranging from 63 to 89, indicating a balanced combination of productivity and impact. Illam S.P. and Raghavamenon A.C. also show strong performance, with an h-index of 4, g-index of 5, NP of 5, and TC of 97, reflecting both sustained output and strong scholarly influence. Similarly, Narayanankutty A. records an h-index of 4, g-index of 4, and TC of 97, suggesting notable research visibility.

In contrast, authors such as Che man Y.B. and Famurewa A.C. have relatively lower h-index values (3), although their citation performance remains notable. Che man Y.B. stands out in particular with the highest total citations (460) and the earliest publication start year (2009), indicating a long-standing influence in the field despite a smaller publication count (NP = 3). Rohman A. also shows moderate impact, with an h-index of 4, g-index of 4, and TC of 190, although the lower m-index (0.286) suggests a longer publication timespan rather than a weaker influence.

Overall, the data suggest that a core group of authors—particularly Illam S.P., Raghavamenon A.C., Benjakul S., Chaijan M., Panpipat W., and Sungpud C.—contribute substantially to the development of this research area through consistent publication output and solid citation performance. At the same time, authors such as Che man Y.B., Rohman A., and Famurewa A.C. highlight that strong citation impact may also be achieved through longer-term scholarly contributions. These findings underline the importance of both sustained productivity and collaborative research in enhancing scientific visibility and impact.

Table 4. Bibliometric indicators of authors' local impact contributing to research on virgin coconut oil (VCO)

3.4 Most productive journals

The treemap above visualizes the number of articles published by various scientific journals related to research on VCO as a functional food, can be seen in Figure 4. The journal with the highest contribution is the IOP Conference Series: Earth and Environmental Science, which has published 8 articles. This is followed by the Journal of Food Science and Technology and the AIP Conference Proceedings, each contributing 7 articles. Other notable journals, such as the International Food Research Journal and the Journal of Food Science, have also made significant contributions, each publishing 5 articles. Additionally, journals like the International Journal of Food Science and Technology, Journal of Food Biochemistry, and others play an important role in disseminating research findings, although their article counts are relatively lower. This visualization highlights the focus of scientific journals on VCO research as a functional food and identifies the key platforms for publications in this field.

Figure 4. Treemap visualization of journals publishing research on virgin coconut oil (VCO) as a functional food

Each block corresponds to a journal, and its size reflects the number of articles published, as indicated by the numerical value within each block.

This distribution indicates a well-rounded research focus spanning food technology, biochemical analysis, medicinal properties, and engineering applications of VCO. The prominence of interdisciplinary and international journals further signifies the global recognition of VCO’s potential as a functional food. These journals play a critical role in advancing knowledge, fostering collaborations, and disseminating findings that validate VCO’s health benefits, nutritional properties, and technological applications. Collectively, this analysis underscores the growing importance of VCO research in diverse scientific fields and its increasing relevance in both food science and environmental studies.

3.5 Most relevant affiliations and affiliations

The view of the relevant organizations participating in the production of research on VCO confirms a strong global and local interest in the area (Table 5). Marine institutions did best in this area, with Universiti Putra Malaysia (UPM) leading the pack with 29 articles (4% of total publications). UPM’s considerable number of publications is a characteristic feature of Malaysia’s national health and industrial strategy, with an emphasis on agriculture and food science development, of which coconuts are one of the most beneficial resources. Other tertiary institutions from Malaysia have also performed reasonably well, such as Universiti Kebangsaan Malaysia (16 articles) and Universiti Teknologi Malaysia (14 articles). These data suggest a well-established and well-funded research culture that encourages collaboration. These institutions will contribute further to understanding VCO’s functional and biochemical properties from the perspective of food science and bioactive compounds.

Table 5. Affiliations with the highest number of articles on virgin coconut oil (VCO) research

Amala University’s Cancer Research Centre in India ranks second with 17 articles (2%) outside Malaysia. This may indicate concentration on VCO’s medicinal uses, such as its anticancer and other therapeutic properties. More Brazilian institutions like the Federal University of Paraíba (13 articles), the Federal University of Viçosa (12), and even the University of Belgrade (16 articles) show this growing trend of international collaboration in VCO studies. These institutions underscore the increasing interest in tapping VCO’s potential benefits in sustainable food systems. Moreover, Gadjah Mada University in Indonesia and the University of Delhi are regular contributors to the field, demonstrating the regional commitment to increasing VCO research and development in Southeast Asia and the Indian continent.

The graph of affiliations' production over time (Figure 5) showcases the growth in article production from leading affiliations between 2007 and 2024. Universiti Putra Malaysia demonstrates a clear and consistent upward trajectory, beginning its contributions in 2008 and experiencing significant growth post-2015, reaching its peak in 2017 and maintaining this high output. This sustained production underscores its central role in advancing research. In contrast, Amala Cancer Research Centre only began contributing significantly in 2019 but has shown steady growth since then, reflecting a more recent but impactful participation. Universiti Kebangsaan Malaysia shows notable growth starting in 2014 and has steadily increased its contributions over time. Similarly, the University of Belgrade and Universiti Teknologi Malaysia display a gradual rise in production, particularly between 2018 and 2021, marking periods of active research engagement.

Figure 5. The affiliations' production over time graph illustrates the number of articles published by five different affiliations from 2007 to 2024

The y-axis represents the number of articles, while the x-axis shows the years.

When analyzed together, the data reveal that those Malaysian institutions—Universiti Putra Malaysia, Universiti Kebangsaan Malaysia, and Universiti Teknologi Malaysia—are dominant contributors in this research field, likely due to Malaysia's emphasis on functional food studies and its role as a major coconut producer. The recent and growing contributions from international affiliations such as Amala Cancer Research Centre (India) and University of Belgrade (Serbia) highlight expanding global collaborations and interest in the research topic. This pattern indicates a shift from localized research efforts to a broader international network, fostering interdisciplinary partnerships and advancing knowledge dissemination. Collectively, the data emphasize the importance of institutional leadership, sustained research productivity, and emerging collaborations in shaping the field's development over time.

3.6 Worldwide publications

The data offered here give a further breakdown of the country’s contributions to the science of Corresponding Author’s Countries (Figure 6), country Scientific Production (Table 6), Production Over Duration (Figure 7), and Most Cited countries (Table 7). All these visualizations provide information on the geographical locations, patterns of collaboration, volume, and productivity of research output, and the effectiveness of the scholarly output.

Figure 6. Corresponding author's countries

SCP: Single country publications, MCP: Multiple country publications.

Figure 7. Country production over time

Table 6. The top ten most productive countries on VCO research

According to Figure 6, India seems to take the lead with the highest amount of documents published and, as such, makes a very strong contribution to its research output. This is closely followed by Indonesia and Malaysia, which also make large contributions, showing the concentration and focus that seem to be exhibited by most of the Southeast Asian countries on relevant research areas. Countries such as Thailand, Brazil, China, and Nigeria have moderate contributions, while the USA and Iran, together with some smaller countries, make the least number of publications. What is quite striking is the mix of Single Country Publications (SCP) and Multiple Country Publications (MCP). India and Malaysia show strong domestic contributions (SCP), while countries such as Brazil, China, and the USA engage in collaborative research (MCP), which signals that such nations are internationally inclined.

Table 7. The most cited documents globally

TC: total citation, TCPY: total citation per year, NTC: normalized total citation

The focus on the countries’ contributions is crucial for examining the global research framework for VCO. It reveals regions with specialization competencies, gaps of geographic representation, and the collaboration patterns that stimulate innovations. India and Malaysia are dominant because of their agricultural linkages to coconut and existing research infrastructure. The foreign partnerships in MCPs from the USA and Brazil tell how appealing and multifaceted VCO research is. This analysis is significant for balancing the global resource allocation, building international relations, and motivating the lesser countries to embrace this new area of study.

Table 6 depicts the volume and contribution of research work done on VCO per country in terms of the frequency of publications, TC of these articles, and average citations per article published. These data are critical in understanding the contributions and academic impacts of different nations regarding VCO research.

Following India is Malaysia, focusing broadly on publications (more than 140 articles). Despite both countries having a high number of articles, Malaysia leads with a TC of over 500 and an average of 18 citations per article, demonstrating the quality of the work being published. As previously stated, this follows Malaysia's heavy agricultural and food science investment and has strong research institutions such as Universiti Putra Malaysia and Universiti Kebangsaan Malaysia. Furthermore, Malaysians prove to be superior researchers. Brazil and Nigeria rank highly due to the impact of their research on citations. With a focus on sustainable foods and bioactive ingredients in VCO, they achieved an impressive per-article average of 20 and 25 citations, respectively. Indonesia, though having low citations per article, averaging 10.6, is mid-ranked globally with 317 citations. This suggests that Indonesians conduct impactful studies. However, they are still struggling to get global recognition. They conducted a total of 142 highly impactful studies, but were still mid-ranked.

With an admirable average per article citation of 34.5 and ranking at mid-position globally, the USA contributed only 50 articles, with a total of 207 citations. This suggests that the USA is highly impactful and issues quality publications. On the other hand, the Philippines conducted 20 studies with the highest average per article citations of 44.3; this suggests they focus on specialized studies. Thailand and China contribute moderately, with 13.5 and 13.8 average citations from 48 and 52 articles, respectively.

Serbia possesses 29 patents that earn an average of 21.3 citations each, demonstrating an increasing interest from Eastern European nations in VCO research, focusing on interdisciplinary works like health and sustainability. The grouping of contributions from these countries highlights the relevance of VCO research for areas of focus on regions and the VCO research shaping those collaborations.

The country production over time graph reveals dynamic trends in scientific productivity. India shows consistent growth, experiencing a rapid increase after 2016, firmly establishing its leadership. Malaysia and Indonesia also show notable upward trends, particularly after 2018, indicating their growing focus on VCO and related fields. Countries like Brazil, China, and Nigeria display slower but steady growth, suggesting increasing involvement in research activities. This temporal analysis highlights the expanding global interest in the research domain, particularly among emerging economies.

3.7 Three-field plot (authors, affiliations and countries)

The three-field plot in the VCO research highlights the intricate relationships between authors, their affiliations, and contributing countries, which collectively drive the production of scientific publications (Figure 8). Authors, as key knowledge contributors, play a central role in advancing VCO research as a functional food. Prominent researchers like Koh S.P., Manikantan M.R., and Pandiselvam R represent a diverse pool of expertise across food science, nutrition, and agricultural research. These authors are supported by their affiliations, such as Universiti Putra Malaysia, University of Delhi, and ICAR-Central Plantation Crops Research Institute, which serve as hubs for scientific activity by providing infrastructure, funding, and collaborative networks. The strong presence of Malaysian institutions reflects the country's commitment to leveraging its abundant coconut resources for functional food research. In contrast, Indian institutions demonstrate significant contributions, particularly in exploring VCO's nutritional and medicinal benefits.

Figure 8. The three-field plot depicts the connections between institutions (AU_UN), authors (AU), and their respective countries (AU_CO)

At a broader level, the countries involved—Malaysia, India, Thailand, Nigeria, Indonesia, and Japan—showcase the global scale of collaboration in this research domain. Malaysia emerges as a leading contributor, driven by its major coconut producer role and strategic investment in functional food innovation. India follows closely, with its institutions and researchers focusing on VCO's health applications. Other countries, such as Thailand and Indonesia, utilize their coconut production industries to contribute meaningfully to the research. At the same time, nations like Nigeria and Japan underscore the growing international interest in functional foods beyond traditional coconut-growing regions. This interconnected framework demonstrates how authors, institutions, and countries collaborate to advance scientific knowledge on VCO, combining expertise, resources, and geographic advantages to produce impactful publications. Such collaboration not only fosters innovation but also enhances the global understanding of VCO’s potential as a functional food, contributing to its recognition as a valuable solution for nutrition and health.

3.8 Most globally cited documents

The top ten globally cited papers on VCO as a functional food have significantly contributed to advancing the understanding of its health benefits, chemical properties, and therapeutic applications (Table 8). Marina et al. [28] in Trends in Food Science and Technology provided a comprehensive review of VCO's physicochemical properties, antioxidant activity, and its potential as an emerging functional food oil. In another study published in the International Journal of Food Science and Nutrition, Marina et al. [29] further explored VCO's chemical composition, demonstrating its higher antioxidant capacity compared to refined coconut oil. Similarly, Khaw et al. [30] in BMJ Open conducted a randomized trial comparing VCO, olive oil, and butter, concluding that VCO does not adversely affect lipid profiles, thus supporting its inclusion in a balanced diet.

Villarino et al. [31] in LWT - Food Science and Technology focused on the sensory characteristics of VCO, highlighting its distinct flavor profile, which may influence consumer preference. Shilling et al. [32] in Journal of Medicinal Food investigated the antimicrobial effects of VCO and its fatty acids against Clostridium difficile, revealing significant antimicrobial activity that positions VCO as a potential therapeutic gent. Ghani et al. [33] in Food Science & Nutrition compared VCO produced through wet and dry extraction methods, emphasizing how production processes impact antioxidant properties and quality, which are critical for functional food applications. Ogbolu et al. [34] in Journal of Medicinal Food examined VCO's antifungal effects against Candida species, demonstrating its efficacy in combating drug-resistant strains, thus offering potential as a natural antifungal agent. Rohman [35] in International Journal of Food Properties discussed the application of Fourier Transform Infrared (FTIR) spectroscopy for authenticating functional oils, including VCO, underscoring its role in ensuring quality and detecting adulteration. Illam et al. [36] in Toxicology Mechanisms and Methods explored the protective effects of VCO polyphenols against oxidative stress-induced cell death, attributing VCO's functional benefits to its antioxidant properties. Lastly, Carpiné et al. [37] in Food and Bioprocess Technology assessed the quality of VCO produced using various extraction methods, emphasizing the importance of extraction techniques in maintaining its physicochemical integrity and functional properties.

Collectively, these studies highlight VCO's chemical composition, antioxidant activity, antimicrobial properties, and therapeutic potential, reinforcing its role as a functional food [38, 39]. The findings have laid a strong foundation for future research. They focus on its applications in nutrition, disease prevention, and food quality enhancement, solidifying VCO's global recognition in the functional food industry [40, 41].

3.9 Most locally cited documents

The most locally cited papers on VCO as a functional food provide a comprehensive understanding of its health benefits, chemical composition, and practical applications, contributing significantly to scientific advancements in this area (Table 8). Marina et al. [28] in Trends in Food Science & Technology conducted a literature-based review on VCO as an emerging functional food oil. They highlighted its unique physicochemical properties, antioxidant activity, and medium-chain fatty acid (MCFA) content, positioning VCO as a promising functional food to combat oxidative stress-related diseases. In another study published in the International Journal of Food Science and Nutrition [29], the chemical properties of VCO were analyzed using gas chromatography, revealing higher levels of phenolic compounds and antioxidants compared to refined coconut oil, reinforcing its superior health-promoting potential. Villarino et al. [31] in LWT – Food Science and Technology explored the sensory attributes of VCO compared to refined coconut oil through descriptive sensory evaluation, showing that VCO’s distinct aroma and flavor enhance its consumer acceptance and marketability. The physicochemical properties, antioxidant capacities, and metal content of VCO are produced via wet and dry processing methods [42]. Their findings indicated that wet-processed VCO retains superior antioxidant capacity and lower metal content, emphasizing the impact of extraction methods on VCO quality. Famurewa et al. [43] in Experimental and Therapeutic Medicine explored VCO's immunomodulatory effects using in vivo models, demonstrating its potential to enhance immune function and reduce inflammation, further solidifying its functional food status. Similarly, Illam et al. [36] in Toxicology Mechanisms and Methods investigated the antioxidant effects of VCO polyphenols on oxidative stress-induced cell death in vitro. The results confirmed that VCO polyphenols effectively inhibit reactive oxygen species (ROS) production, providing cellular protection against oxidative damage [44].

Rohman et al. [5] in Food Reviews International focused on the application of Fourier Transform Infrared (FTIR) spectroscopy for authenticating functional oils, including VCO. This study demonstrated FTIR’s accuracy and reliability in detecting adulteration, offering an essential tool for quality assurance. Yeap et al. [42] in Journal of Medicinal Food tested the antifungal properties of VCO against Candida species using in vitro methods. They found that VCO effectively inhibits Candida, including drug-resistant strains, positioning it as a natural antifungal alternative. Dayrit et al. [45] in Journal of Dietary Supplements evaluated VCO's antioxidant and anti-inflammatory properties in animal models, showing that it reduces oxidative stress and inflammation, supporting its role in preventing chronic diseases. Finally, Ahmad and Ayub [46] in Pure and Applied Chemistry analyzed the quality of VCO compared to refined coconut oil, confirming that VCO retains natural bioactive components like polyphenols and MCFAs, which are often lost in refining processes. This finding underscores VCO's superior quality and position as a premium health oil.

These studies demonstrate VCO's diverse health benefits, ranging from its antioxidant, anti-microbial, and immunomodulatory effects to its superior chemical composition and sensory properties. These papers provide a strong foundation for further research and reinforce VCO's status as a functional food with significant potential for human health by addressing key aspects such as production methods, quality assurance, and therapeutic applications.

Table 8. Top locally cited documents on virgin coconut oil

Y: year, LC: local citation, GC: global citation, NLC: normalized local citation.

3.10 Reference spectroscopy

Figure 9, the reference publication year spectroscopy, has been used to demonstrate the focus on the distribution of citation references concerning the publication years. The black line depicts the total number of cited references. In contrast, the red line depicts the deviations from the five-year median, giving a more dynamic perspective on referencing VCO studies. The number of cited references grew considerably during 2008 - 2015, with the highest level around 2013 – 2015. It was a period of intense research activity. During this period, spectroscopy techniques such as Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) were widely used to examine VCO and estimate its chemical composition, purity, and bioactive compounds. The peak also reflects the active years when a standard method was developed to characterize VCO and its functional properties, including medium-chain fatty acids (MCFAs) and antioxidants.

Figure 9. Reference publication year spectroscopy

The black line represents the number of cited references for each publication year. The red line shows the deviation from the 5-year median, highlighting significant shifts or trends in citation patterns. The x-axis indicates the publication year of cited references, while the y-axis shows the count of cited references.

The period after 2016 has seen a decline in cited references, which has deepened since 2020. This development could be symptomatic of a particular research emphasis, where new techniques or cross-disciplinary VCO approaches have supplemented spectroscopy. The drop such applications suffered could equally account for the citation decline, given how many years it has been since this field matured. Also, the recent publication’s reference quota will likely suffer because of the ever-expanding timeframe for citation accumulation.

The red line, which denotes deviations concerning five-year medians, demonstrates a robust peak around 2009. This corroborates claims regarding introducing whole new realms of applied spectroscopy or bold new studies and initiatives. In 2015, only minimal deviations were noticed after such activities, which indicates a steady state in the introduction of references to papers for VCO. Citation decline notwithstanding, spectroscopy remains a vital technique in studying VCO, albeit more often than not in conjunction with other newer methods, like those employing nanoemulsions and bioinformatics.

The development of the VCO goes hand in hand with the development of physicochemical characterization tools and techniques such as spectroscopy. VCO had a peak referencing period, and advances in VCO research were significantly aided by FTIR and NMR. These techniques served as vital approaches and laid a strategic foundation for further research. With the integration of complementary scientific disciplines with spectroscopy, the method continues to be a centrepiece in expanding research and innovation. Supporting this analysis, studies [46, 47] emphasize the continued relevance of spectroscopy in truly functional food research on quality control and bioactive VCO.

3.11 The three-field plot

Figure 10 presents three field plots illustrating the connection structure among Sources (SO), Authors (AU), and Keywords/Research Themes (DE) involved in the scientific publishing of VCO. This visualization depicts the scholarly ecosystem in which research on the functional and medicinal properties of VCO is conducted and developed. The leftmost column highlights the primary SO journals where VCO-related studies have been published, including Food Analytical Methods, Journal of Medicinal Food, Journal of Food Biochemistry, and the International Food Research Journal. These journals focus on food science, biochemistry, and toxicology, reflecting the multidisciplinary nature of VCO research and its relevance to both food and health sciences.

Figure 10. The three-field plot depicts the connections between source (SO), authors (AU), and their respective descriptors (DE)

For instance, the journal Food Analytical Methods has some notable interests in VCO, such as its uses and benefits, specifically towards the verification methods using sophisticated analytical techniques, including the FTIR Spectroscopy, which establishes the genuineness, purity, and quality of VCO [48-50]. Besides that, VCO has also been reported in the Journal of Medicinal Food, paying attention to its health-promoting factors, such as antioxidants and anti-inflammatories, which are essential in functional food [28, 51, 52]. In addition, the International Food Research Journal has also looked at VCO for its physicochemical properties and recent use in various food and pharmaceutical preparations [53, 54]. This diverse set of publications confirms the nutritional qualities of VCO and its technological uses, demonstrating the multidisciplinary focus of these journals – VCO connects food science with medicine and technology.

The first column shows key authors related to VCO research, such as Illam S.P., Koh S.P., Rohman A., Raghavamenon A.C., and Pandiselvam R., who work in the area of food chemistry, bioactive compounds, and analysis. The authors [54] established a practice in the industry by using FTIR spectroscopy alongside chemometric analysis to verify the quality of VCO. The authors [32] have also discussed how MCFAs can help lipid metabolism and oxidative stress, while Raghavamenon AC worked on VCO’s anti-inflammatory properties and oxidative damage. The therapeutic scope of VCO has also increased because of the research done by the authors [55, 56] on nanoemulsions, improving the bioavailability and stability of the VCO.

The right column illustrates major scientific issues, such as VCO, antioxidants, MCFAs, oxidative stress, anti-inflammatory properties, and nanoemulsions. The studies VCO’s multidimensional role as a functional food are further proven by advanced analytical methods and bioactive-focused innovations.

The strong connections between authors and themes like antioxidants, oxidative stress, and anti-inflammatory activities highlight VCO's growing recognition as a functional food with significant health benefits, particularly in combating inflammation, lipid imbalances, and oxidative damage. Additionally, emerging research themes such as nanoemulsions and FTIR Spectroscopy underscore the application of advanced technologies in analyzing and improving VCO's efficacy and bioavailability. This visualization also highlights the critical role of journals in disseminating findings across scientific communities, as leading publications like the Journal of Food Science and Technology and the International Journal of Food Science and Technology are central platforms for researchers.

In summary, the Three-Field Plot illustrates how scholarly publications on VCO are shaped by the interplay between specialized journals, contributing authors, and targeted research themes. The concentration of studies around VCO’s antioxidant and anti-inflammatory properties, coupled with technological advancements such as nanoemulsions, signifies the multifaceted nature of VCO research. This interconnected system reflects the global effort to validate VCO as a functional food and its applications in improving human health and nutrition.

3.12 The trend topics graph

The trend topics in Figure 11 showcase the evolving landscape of research on VCO, revealing how the focus has shifted over time to address both its analytical properties and its growing role as a functional food. The period from 2014 to 2018 witnessed an emphasis on technology and composition analysis of VCO for research with keywords such as “FTIR spectroscopy, “chemometrics,” and “physicochemical properties.” These studies focused on corroborating and certifying VCO quality, purity, and chemical composition to make claims about “VCO” as a natural product. For instance, in 2020, Amit et al. [54] used Fourier Transform Infrared (FTIR) spectroscopy to check for adulteration in VCO, which illustrated its use during quality control processes. In the same vein, Mulia et al. [55] used FTIR and chemometrics to study VCO’s physicochemical properties and proved its applicability for VCO quality control in the industry. In parallel to this, Mousa et al. [50], who had studied the fatty acid profile and antioxidant activity of VCO, confirmed the existence of MCFAs and phenolic compounds, which serve as functional food components. Such findings were of vital importance for bringing VCO quality to international standards and enhancing its credibility for it to be a tradeable and functional food-grade product.

The word ‘antioxidant’ has become more and more prominent after 2018 as scientists shifted their attention toward the capacity of VCO to reduce oxidative stress, which leads to chronic conditions such as heart disease, diabetes, and inflammatory conditions [57-60]. This change in research focus indicates heightened attention to the bioactive components of VCO, such as the phenolic MCFAs that are active at low concentrations and possess powerful antioxidant functions. For example, the studies [61, 62] showed that free radical neutralization and oxidative damage mitigation by VCO are possible due to its rich antioxidant content. These findings solidified VCO’s role in promoting health and preventing chronic diseases by exploiting its therapeutic potential. Likewise, the studies [29, 63] focused on VCO’s high-phenolic content and antioxidant activity and suggested its use in Functional Foods and Nutraceuticals.

Further research was conducted on VCO's traceability and oil processing methods in addition to quality validation. Studies [62, 63] were able to establish a primitive methodology for tracing the origin of VCO through the use of FTIR Spectroscopy and Principal Component Analysis (PCA), which helped in the formulation of traceability systems that increased VCO’s integrity as a natural product. At the same time, Amit et al. [54] investigated how various methods of extraction changed the VCO’s physiochemical properties, which can serve as a guide for producers to refine the processing methods without affecting the active ingredients. Their contribution assisted these researchers in defining the quality requirements for VCO and pointing out the importance of certain technological and compositional features for it to be accepted in the international markets. The application of FTIR Spectroscopy, coupled with chemometrics and PCA, lays the foundation for much more advanced studies integrating the chemistry of VCO with medicine, cosmetics, and nutritional science, thereby increasing the range and scope of the global marketplace for VCO.

As the field progressed, the spotlight began to shift toward the health and nutritional benefits of VCO. Starting around 2016, terms such as "lipid profile," "cholesterol," and "MCFAs" emerged prominently, signaling a growing interest in VCO's impact on cardiovascular health, lipid metabolism, and obesity. Researchers increasingly explored the role of MCFAs, particularly "lauric acid," in modulating lipid profiles and reducing cholesterol levels. By 2020, these topics reached their peak, reflecting VCO’s rising popularity as a natural solution to combat metabolic disorders and lifestyle-related diseases.

The growing attention to bioactivity is accentuated even further as the term “antibacterial” has emerged in recent years, testimony to the increasing studies on the antimicrobial character of VCO. Most of the claimed antibacterial activity of VCO is believed to be due to the presence of lauric acid, which has been well-documented to possess potent antibacterial and antifungal features [64, 65]. The study [8] and other studies showed that VCO is effective against pathogens like Staphylococcus aureus and Candida albicans, supporting its traditional application in medicine. Additionally, the studies [66, 67] discussed the importance of monolaurin, a lauric acid derivative, which disintegrates microbial cell membranes, further supporting the usage of VCO against infections and increased immune defence.

The graph further demonstrates cross-comparison analysis, including the early availability of the benchmark ‘olive oil’ along with VCO, which depicts attempts to benchmark VCO's health advantage against the other popular oils. Comparative studies on VCO and olive oil have concerned lipid and cardiovascular profiles, showing that VCO helps lower cholesterol and improve lipid metabolism [68]. For instance, the study [69] reported that both VCO and olive oils caused a decrease in LDL cholesterol and an increase in HDL cholesterol in animals, which suggests each may have some benefit to heart health.

Figure 11. Trend Topics illustrates the evolution of research terms related to coconut oil and associated topics over time