1 Introduction

Cassava (Manihot esculenta Crantz) is a globally significant crop, particularly important for smallholder farmers in sub-Saharan Africa (SSA) [1,2,3,4]. Introduced to Africa in the sixteenth and seventeenth centuries by Portuguese explorers, cassava has become a vital food security crop for millions [5, 6]. While its exact origin is debated, with multiple theories suggesting its roots in the southern edge of the Brazilian Amazon, one thing is clear: cassava is a resilient crop, thriving in drought-prone regions with less fertile soils [1, 2, 4, 5, 7, 8].

Cassava is the third most important food staple in Africa (after maize and rice) consumed by hundreds of millions daily [9]. Cassava is drought tolerant, and can easily survive in less fertile soil, with uncertain rainfall patterns. Globally, production reached 315 million tonnes in 2021, marking a 9% increase from 2017 [10]. Nigeria, the leading producer, accounted for approximately 63 million tonnes, representing 31% of African production and 20% of global production. Notably, the top three producers—Nigeria, the Democratic Republic of Congo, and Thailand—contribute a combined 44% share of global cassava production [10].

Sub-Saharan Africa (SSA) plays a dominant role in global cassava production. In 2020, SSA exceeded a 2005 prediction [5] by contributing 63.3% to global cassava production, up from the projected 60%. The latest estimate for 2021 shows SSA as the world's leading cassava producer, accounting for 65% of global production with 204 million tonnes [10]. Despite this significant production, non-food uses of cassava in SSA remain limited. In 2019, only 3,000 tonnes were reportedly committed to non-food applications [11, 12].

Globally, cassava utilisation is largely focused on food consumption, primarily as fresh roots and processed products like flour and fermented meals. Thailand is the leading exporter of cassava, mainly in the form of cassava flour, starch, and chips, generating an export value of $1.29 billion in 2021, representing approximately 35% of the global export value. China, on the other hand, leads in cassava imports, with a total import value of $1.48 billion, accounting for 40.5% of the global import value in 2021 [13].

Cassava (Manihot esculenta Crantz) is a vital global food staple, yet comprehensive bibliometric analyses exploring its production, trade, and research landscape are scarce. While studies have examined fermented foods like Kimchi [14] and Yerba-mate [15], a thorough understanding of cassava research trends and gaps is critical. This study addresses this need by conducting a bibliometric analysis of cassava research publications from 2000 to 2023. The objectives of this study include:

  1. (i)

    examining global cassava production and trade trends,

  2. (ii)

    analysing the quantity and evolution of research publications,

  3. (iii)

    exploring key research topics through keyword analysis

  4. (iv)

    identifying the geographical trends in terms of research institutions and countries based on publication output.

To accomplish these objectives, the study utilised data from the Food and Agriculture Organisation Statistical Database (FAOSTAT), The Observatory of Economic Complexity (OEC), and a bibliometric database, mapping, and visualization software package. This study will provide valuable insights into the global research landscape of cassava, highlighting areas for future research and collaboration.

2 Methods

2.1 Securing data (search strategy)

Global cassava production and trade trends were analysed using data from FAOSTAT and OEC. A bibliometric analysis of cassava research was conducted using the Scopus database, considered a highly reliable source for scholarly publications [16, 17]. The search was conducted on August 31th, 2023, retrieving publications from 2000 to 2023, focusing on peer-reviewed articles and reviews. The search strategy for cassava publications was conducted based on the search term query of Scopus database given as: (TITLE-ABS-KEY ("Cassava") AND PUBYEAR > 1999 AND PUBYEAR < 2024 (LIMIT-TO (DOCTYPE, "ar") OR LIMIT-TO (DOCTYPE, "re")).

The initial search yielded 15,513 documents, of which 13,238 were articles and reviews. All accompanying metadata, including abstracts, keywords, funding sources, author information, publication year, thematic areas, and document source, were extracted and downloaded as a CSV file. For visualization and analysis of the bibliometric data, VOSviewer 1.6.19 was employed due to its exceptional visualization capabilities and free availability [18, 19].

2.2 Data analysis

To understand the evolution of cassava (Manihot esculenta Crantz) research, we conducted a bibliometric analysis of the 13,238 extracted publications using VOSviewer. This software is widely used for visualizing and analysing networks of authors, institutions, and countries through techniques like co-authorship, co-occurrence, and co-citation. VOSviewer's advanced visualization capabilities allow us to identify clusters within the research landscape, highlighting key trends and collaborations [18, 19].

3 Results

3.1 Global cassava production quantity, area harvested, and total yield

Global cassava production has steadily increased, reaching 315 million tonnes (t) in 2021 from 286 million tonnes in 2017 (Table 1). Nigeria remains the top producer worldwide, contributing 20% of global production with 63 million tonnes in 2021 [10]. Other leading producers include the Democratic Republic of Congo (DR Congo), Thailand, Ghana, and Brazil (Fig. 1).

Table 1 Global cassava production quantity (2017–2021)
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Fig. 1
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Source: Author’s graph using FAOSTAT data 2023

Top 10 cassava (in tonnes) producing countries in 2021.

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Africa is the largest cassava-producing region, accounting for approximately 204 million tonnes in 2021, up from 177 million tonnes in 2017. However, Oceania remains the lowest producer, with 266,362 tonnes in 2021.

In terms of harvested area, global cassava production in 2021 covered 29.7 million hectares (Table 2). Nigeria has the largest harvested area, with 9.1 million hectares (30.6% of the global share), followed by DR Congo with 5.6 million hectares (18.9%). While Nigeria leads in production quantity, its total yield has declined significantly, falling from 11.2 tonnes per hectare in 2011 to 6.9 tonnes per hectare (t/ha) in 2021. This decline contrasts with Cambodia, which, despite ranking ninth in production quantity, has the highest total yield at 27.4 t/ha in 2021 [4, 10].

Table 2 Top 10 cassava producers, production quantity, area harvested, and total yield in 2021
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3.2 Global cassava trade outlook

Africa remains the leading region for cassava production, but its role in global trade is less prominent. In 2021, cassava was the 614th most traded product globally, with a total trade value of $3.65 billion. This represents a 40% increase in global cassava exports from 2020 to 2021 (from $2.6 to $3.65 billion) [13]. While only two African countries, Ethiopia and Egypt, made the top 10 exporting countries in 2021, Thailand retained its top spot as the leading exporter. Thailand's export value has grown from $1.19 billion in 2017 to $1.29 billion in 2021, accounting for 35.4% of the global share (see Table 3) [4, 13].

Table 3 Top 15 cassava exporting countries in 2021
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Nigeria, despite being the world's largest producer, ranks 59th globally for cassava exports, with a trade value of only $1.02 million, representing 0.03% of the global share. This reflects the fact that Nigeria processes the vast majority of its cassava production domestically, with less than 1% exported [4, 20,21,22]. Other leading cassava exporters include Cambodia, Laos, Vietnam, and the United States, ranking second, third, fourth, and fifth, respectively.

In addition, China is the leading importer of cassava globally, with a total import value of $1.48 billion, accounting for 40.5% of the global share in 2021. Across continents, Djibouti led in Africa ($68 million), the Netherlands in Europe ($178 million), the United States in the Americas ($112 million), and Australia in Oceania ($4.9 million) [13].

Among the top 15 cassava importing countries in 2021 (Table 4), Vietnam ($524 million), Thailand ($454 million), the Netherlands ($176 million), and the United Kingdom ($120 million) followed China as the top importers.

Table 4 Top 15 cassava importing countries in 2021
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3.3 Overview of cassava research publications (2000-2023)

A Scopus database search yielded 13,238 cassava-related publications from 2000 to August 31, 2023. The dataset focused on original research (n = 12,661) and review articles (n = 577), excluding other publication types.

Cassava publications have increased significantly over the past two decades, reaching 13,238 by 2023 (Fig. 2). The dataset comprises a total of 245,020 citations, with an average of 18.51 citations per document. The average document age is 8.06 years, indicating a steady growth rate of 6.38% per year.

Fig. 2
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Cassava-related publication trend (2000–2023)

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The dataset includes contributions from 35,237 authors, with 449 single-authored documents. The international co-authorship rate is 27.5%, and the average number of co-authors per document is 4.82. The dataset's h-index is 41, indicating that 41 publications have been cited at least 41 times.

The publications primarily use English (n = 12,179; 92%), with Portuguese (n = 508), Spanish (n = 175), and Chinese (n = 291) among the other languages used. The dataset covers 27 subject areas, with Agricultural and Biological Sciences (n = 7,713; 32%) being the most prevalent, followed by Biochemistry, Genetics and Molecular Biology (n = 2,698; 11.2%), Environmental Science (n = 1,890; 7.8%), and Chemistry (n = 1,490; 6.2%) (Fig. 3).

Fig. 3
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Cassava-related publications by subject areas (2015–2023)

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3.4 Publication sources

To identify significant journal outlets for cassava research, the study analysed the top journals based on document count and citations (Table 5). Livestock Research for Rural Development had the highest number of publications (n = 250), followed by Starch—Staerke and Carbohydrate Polymers with 178 and 147 documents, respectively. Carbohydrate Polymers had the highest total citations (11,710), while Bioresources Technology had the highest average citation per document (AC/D) of 80.06. Notably, Bioresources Technology also had the highest impact factor (IF) of 11.4 and h-index of 341. Livestock Research for Rural Development had the highest total link strength (TLS) of 4,826.

Table 5 Top 10 Journals that published cassava-related articles (2000–2023)
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Figure 4 visualizes the network of journal co-citation relationships, considering journals with at least 30 documents. This analysis reveals four clusters with 1,528 links and a total link strength (TLS) of 24,369. The colour of an item (journal) is determined by the cluster to which the item belongs while lines between items represent links. The African Journal of Biotechnology had the highest TLS of 61, followed by Food Chemistry, Journal of the Science of Food and Agriculture, and International Journal of Food Science and Technology, each with 60 links. Livestock Research for Rural Development, with its high TLS of 4,828, demonstrates strong co-citation connections with other journals.

Fig. 4
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Network visualization of bibliographic coupling of sources, VOSviewer 1.6.19

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The network analysis highlights the varying degrees of connectedness between journals. Journals like the Journal of Applied Polymer Science exhibit lower co-citation connections, while journals in the red cluster, such as Frontiers in Plant Science, PLOS ONE, and Euphytica, show higher co-citation links, indicating stronger research connections.

3.5 Publications (Documents) related to cassava

To identify the most influential cassava publications, the study analysed the top 15 papers with at least 370 citations (Table 6). The most cited publication [23], focused on plant viruses and was published in Molecular Plant Biology (IF 4.9, h-index 121). Another highly cited publication [24], examined the structure and properties of cassava starches and was published in Carbohydrate Polymers (IF 11.2, h-index 251). Other notable publications include [25], which investigated cassava starch films, and [26], which explored deep learning for cassava disease detection.

Table 6 Top 15 cassava-related publications
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Interestingly, this analysis revealed a significant representation of authors from developed countries, particularly the United States (5 papers, 33.3%) and Brazil (3 papers, 20%). Only one publication featured a lead author from a lower- and middle-income country (LMIC), specifically India. No publications with African lead authors were identified within this top 15 list.

The network analysis of bibliographic coupling of documents receiving high citations is presented in Fig. 5. We selected documents with at least 135 citations, resulting in 200 top-cited documents. Of these, 103 formed 10 distinct clusters based on their connections, with a total of 244 links (TL) and 585 total link strength (TLS). Figure 5 uses coloured circles to represent the number of citations for each document, with larger circles indicating higher citation counts. Lines connecting the documents illustrate their relatedness, with closer proximity indicating stronger co-citation links.

Fig. 5
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Network visualization of bibliographic coupling of documents, VOSviewer 1.6.19

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Cluster 1, for instance, included 16 items, with document [38] having the highest citation count (347) but relatively few links (3) and low link strength (3). Conversely, document [39] within the same cluster, despite having fewer citations (174), exhibited higher relatedness with 8 links and 24 TLS. This suggests that higher citation counts do not always correspond to greater connectedness within the network.

In cluster 2, [40] had the highest citation count (615) with 4 links and 5 TLS. Notably, the paper with the highest overall citations (842) belonged to cluster 3 ([41]). Interestingly, while documents [23] and [24] in clusters 7 and 4 respectively, had high citation counts (783 and 689), they had relatively low link strength. Finally, document [42] in cluster 10 exhibited the highest number of links (18) among all clusters, despite having a moderate citation count (175) and 70 TLS.

3.6 Country summary of cassava-related publications

From the extracted 13,238 articles on cassava, the corresponding author's affiliations captured a total of 274 countries. Analysing the data revealed each country's position in terms of scientific research production, as presented in Table 7. This table shows countries with at least 30 cassava-related publications, along with their total citations (TC), average citations per document (AC/D), total links (TL), and total link strength (TLS).

Table 7 Top 20 countries of authors publishing cassava-related articles (2000–2023)
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Brazil emerged as the most productive country with 2,534 publications, 44,584 citations, and an AC/D of 17.6. Nigeria followed closely with 2001 publications and 24,124 citations. Rounding out the top 5 were China (1,549 publications, 28,548 citations), Thailand (1,367 publications, 24,091 citations), and the United States (1,142 publications, 38,795 citations). While the United States had the highest TLS (169) and total links (59), the United Kingdom demonstrated the highest AC/D (36.6).

Significantly, two LMICs, Nigeria (2nd) and India (7th), ranked within the top 10. Other African countries appearing in the top 20 included South Africa (12th, 374 articles), Kenya (14th, 315 articles), Ghana (15th, 301 articles), Uganda (17th, 280 articles), and Tanzania (18th, 276 articles).

To gain deeper insights into international collaborations, we mapped the co-authorship of countries based on author institutions. This analysis is presented in Fig. 6, which includes 60 countries meeting the threshold of 30 documents per country, resulting in 2,104 links and 16,294 TLS.

Fig. 6
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Network visualization map of international research collaboration among countries with cassava-related publications, VOSviewer 1.6.19

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In cluster 1 (25 countries), Nigeria had the highest number of documents (2001), citations (24,124), links (57), and TLS (1,169). However, Switzerland had the highest AC/D (47.03) in this cluster and across all five clusters. In cluster 2 (17 countries), China had the most documents (1,549) with 49 total links, while Australia had the largest number of links (52) and Thailand received the highest TLS (531). In cluster 3 (11 countries), Brazil had the highest number of documents (2,534) and citations (44,584), but France received the largest number of links (55) and TLS (619).

Table 8 provides additional information about each cluster. Cluster 1 had a total of 133,617 citations and 7,914 TLS. Nigeria, the United Kingdom, and Kenya had the highest TLS in this cluster, indicating strong co-citation links between these countries. Cluster 2 (17 countries) had a total of 110,590 citations and 3,036 TLS. While China had the highest number of publications (1,549), Thailand and Australia had higher TLS, suggesting stronger collaborations within the cluster. In cluster 3, Brazil had the highest number of publications (2,534) and citations (44,584), but France had the highest TLS (619), indicating stronger co-citation links between countries within this cluster.

Table 8 Citation features of co-authorship clusters according to countries
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Cluster 4 (5 countries) had 27,820 citations and 1,821 TLS, with Colombia receiving the highest number of publications (807), citations (17,130), and TLS (855). Overall, countries like Brazil, Nigeria, China, and Colombia exhibited stronger co-citation links (research collaborations) in Fig. 6. These countries received more citations, publications, and TLS compared to other countries across all five clusters, indicating significant collaborations in cassava-related research.

3.7 Organisations, authors and funding sponsors of cassava-related publications

Authors (corresponding authors) from 274 countries contributed to the pool of 13,238 retrieved cassava-related publications from 2000 to August 31, 2023. Table 9 showcases the geographic distribution of institutions (organisations) whose contributions to the cassava literature have been significant. This study identified 160 organisations/affiliations of authors from the Scopus database.

Table 9 Top Affiliations/Organisations of authors of the cassava publications
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The Brazilian Agricultural Research Corporation led in cassava publications (n = 419). This was followed by the International Institute of Tropical Agriculture (IITA) in Ibadan, Nigeria (n = 380), the International Centre for Tropical Agriculture (CIAT) in Colombia (n = 343), and the University of Ibadan in Nigeria (n = 294), ranking 2nd, 3rd, and 4th respectively (see Table 9). Notably, only three Nigerian organisations (IITA, Ibadan; University of Ibadan; Federal University of Agriculture, Abeokuta) were among the top 20 institutions, contributing 902 cassava-related articles from 2000 to 2023. In contrast, institutions from China (5) and Brazil (5) contributed 956 and 1,090 cassava-related publications respectively. This suggests that the most productive organisations are located in developed countries, with China and Brazil taking the lead. (Table 9). Table 10 presents the top 15 funding sponsors with the highest number of cassava-related publications. Interestingly, all top funding sponsors were from developed countries, led by the National Council for Scientific and Technological Development (732 publications), the National Natural Science Foundation of China (587), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) (553 publications), which ranked 1st, 2nd, and 3rd respectively. Notably, no African-based funding sponsors or those from developing countries made the top 15 list. This highlights the significant gap in research funding between developed and developing countries, particularly in Africa, despite the region being the highest producer of cassava. While Nigeria, as the global leader in cassava production, ranked among the top institutions publishing cassava-related articles, it was absent from the top funding sponsor list (see Table 10). This disparity underscores the need for increased research funding in developing countries, particularly in Africa, to support advancements in cassava research and development.

Table 10 Top 15 Funding sponsors of cassava publications
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Table 11 presents the top influential authors of cassava-related publications from 2000 to 2023. Sixteen authors contributed a total of 731 papers, representing 5.5% of all cassava publications. The table includes each author's total citations (TC), country of affiliation, and h-index, as provided by the Scopus database.

Table 11 Top 10 Authors of cassava-related publications
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The author with the highest number of publications (118), total citations (14,038), and h-index (55) was Preston, Tom R [43]. According to his Scopus profile, he is affiliated with the Scottish Universities Environmental Research Centre in East Kilbride, United Kingdom [43]. Preston has published extensively in the field of Agronomy, including a recent paper titled “Methane production in rumen in vitro incubations of ensiled cassava (Manihot esculenta) root supplemented with urea and protein-rich leaves from grasses, legumes and shrubs,” published in Livestock Research for Rural Development.

Following Preston are:

Wanapat (TC: 6,582; h-index: 40) [44]

Ceballos (TC: 3,755; h-index: 35) [45]

Dixon, A.G.O (TC: 3,755; h-index: 35) [46]

Maziya-Dixon, B (TC: 3,755; h-index: 35) [47]

These authors rank 2nd, 3rd, 4th, and 5th, respectively. It is notable that African authors represent 50% of this category. Three authors are from Nigeria [46,47,48], and two are from Tanzania [49] and Uganda [51], collectively contributing about 43% (31 papers) of the total articles published in this category. This indicates that African scientists are at the forefront of global cassava research since 2000.

In contrast, the remaining five authors are from developed countries—namely the United Kingdom, Thailand, Colombia, China, and the United States—contributing a total of 417 publications.

Keywords analysis

Evaluating the relationship between keywords is crucial for unveiling and recognizing scholarly content across various fields of endeavour [53, 54]. Keyword analysis is often conducted via co-occurrence mapping, which shows the links between specialised terminologies used in scholarly publications. Typically, research publications have five or more keywords that are linked to the content [55].

In this study, 51,599 keywords were investigated, with 138 keywords appearing at least 150 times across 13,238 scholarly publications. The co-occurrence analysis of these keywords is presented in Fig. 7 and Tables 12 and 13.

Fig. 7
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Network visualization map of keywords (5 clusters). The size of the circle revealed the research trends in cassava research, VOSviewer 1.6.19

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Table 12 Top 10 occurring keywords in the cassava publications
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Table 13 Features of publications’ keyword clusters according to co-occurrence of all keywords
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Table 12 reveals the top 10 keywords of cassava-related articles, each with a minimum of 150 occurrences. The co-occurrence map shows the 138 selected keywords distributed across 5 clusters, with a total of 8,141 links (TL) and 222,717 total link strength (TLS), indicating the inter-relatedness of the keywords. The size and boldness of the circles and text in the map represent the strength of co-occurrence (weights) of each keyword with others in the dataset. The clusters are colour-coded in red, green, blue, yellow, and purple. The distance between items and lines indicates the proximity and relatedness of the keywords.

In all 5 clusters, "Manihot esculenta" was the most frequently occurring keyword, with 4,940 occurrences, 137 links, and a TLS of 22,952, accounting for 37.3% of all publications. Cluster 1 (red) featured the keyword "Manihot" with 2,000 occurrences, 137 links, and a TLS of 18,173, accounting for 15.1% of all publications. Other keywords in Cluster 1 include "genetics" (792 occurrences; 130 links; 7,671 TLS), "metabolism" (777 occurrences; 137 links; 8,124 TLS), "plant leaf" (364 occurrences; 128 links; 3,670 TLS), and "Manihot esculenta Crantz" (331 occurrences; 127 links; 1,238 TLS). Cluster 1, associated with themes like "cassava, genetics, and plant diseases," comprises 31 items, with a total of 11,689 keyword occurrences and a total link strength of 111,969.

Cluster 2 (green), containing 30 items, focuses on global cassava production and food security. "Manihot esculenta" again had the highest number of occurrences (4,940), links (137), and TLS (22,952), making it the most significant keyword in all 13,238 documents (Fig. 7). Other notable keywords in this cluster include "cassava" (4,875 occurrences; 137 links; 29,899 TLS), "Nigeria" (450 occurrences; 129 links; 2,566 TLS), "agriculture" (357 occurrences; 135 links; 2,578 TLS), "Africa" (338 occurrences; 120 links; 2,320 TLS), and "food security" (250 occurrences; 113 links; 1,325 TLS). Cluster 2 has a total of 17,171 keyword occurrences and a total link strength of 104,832. The inclusion of keywords such as Africa, Nigeria, Brazil, and Thailand in Cluster 2 underscores the central theme of "cassava production in developing and developed nations".

Cluster 3 (blue) consists of 28 items, with the keyword “controlled study” having the highest number of occurrences (1,223), links (137), and a total link strength (TLS) of 12,354. This cluster focuses on issues related to "humans, animals, and cassava," with key terms including “human,” “female,” “male,” “animals,” and “cassava flour.” Other significant keywords in Cluster 3 are “humans” (483 occurrences; 128 links; 4,595 TLS), “animal feed” (156 occurrences; 101 links; 1,653 TLS), “food processing” (198 occurrences; 122 links; 1,603 TLS), and “nutritional value” (160 occurrences; 116 links; 1,513 TLS). Overall, Cluster 3 has a total keyword occurrence (TO) of 11,237 and a TLS of 102,088 (see Table 13).

Cluster 4 (yellow) also comprises 28 items and includes important keywords related to cassava processing products. The keyword “starch” has the highest TO (2,386), with 136 links and a TLS of 13,625. Other prominent keywords in this cluster are “plant (botany)” (1,962 occurrences; 137 links; 9,662 TLS), “Fourier transform infrared spectroscopy” (259 occurrences; 96 links; 1,662 TLS), “chemical composition” (178 occurrences; 119 links; 1,442 TLS), “chemical properties” (191 occurrences; 60 links; 798 TLS), and “biodegradation” (166 occurrences; 108 links; 1,144 TLS). Cluster 4 has a total keyword occurrence of 11,461 and a TLS of 73,495.

Cluster 5 (purple), which includes 23 items, centres on the "biochemical processes of cassava". The keyword “fermentation” is the most frequent in this cluster, with 845 occurrences and a TLS of 6,477. Other key terms in Cluster 5 include “ethanol,” “hydrolysis,” “enzyme activity,” “bioethanol,” and “biofuel.”

4 Discussion

To evaluate the impact and dissemination of cassava-related publications between 2000 and 2023, a review of the global cassava production and trade outlook was conducted, along with a bibliometric analysis of 13,238 publications retrieved from the Scopus database. These documents involved contributions from 274 countries, 29,684 organisations, and 35,237 authors were published across 2,665 journal outlets.

The study revealed an upward trajectory in cassava research, with publications increasing from 180 articles in 2000 to 3,823 in 2011, 11,382 in 2021, and 12,491 in 2022 (Fig. 2). Analysis of the top 10 journal outlets publishing cassava-related articles from 2000 to 2023 showed that Livestock Research for Rural Development had the highest number of publications (250). Notably, the African Journal of Biotechnology (ranked 5th with 124 articles) was the only journal of African origin (Kenya) among the top 10 outlets, although its indexing in Scopus was discontinued in 2011. Most top publishing outlets were based in developed countries, including Livestock Research for Rural Development (Colombia), Starch—Staerke (Germany), Carbohydrate Polymers (United Kingdom), International Journal of Biological Macromolecules (Netherlands), and Frontiers in Plant Science (Switzerland).

Regarding journal impact factor (JIF), the study found that not all top ten journals had very high JIFs (Table 5). Four journals in this category had JIFs less than 3.0, and two had no JIF. This indicates that both high and not-too-high impact factor journals have published cassava-related articles.

However, more than 90% of the leading authors were from developed countries, and no African authors were among the top 15 leading authors in this category (Table 6). Furthermore, no African publishers were among the top publishers. The study suggests that researchers and publishing outlets in low-and middle-income countries (LMICs) should prioritise establishing reputable and credible journal platforms to facilitate the publication of significant research originating from these regions as well as other parts of the world.

In addition, Brazil was the most productive country in terms of cassava research publications. African countries accounted for 25% of the top 20 productive countries, with Nigeria being the only African country ranked among the top 10 (Table 7). Regarding authors’ affiliations, the Brazilian Agricultural Research Corporation, International Institute of Tropical Agriculture (IITA) in Ibadan, Nigeria, and the International Center for Tropical Agriculture (CIAT) were ranked 1st, 2nd, and 3rd respectively. Notably, only three institutions from Nigeria were among the top 20 institutions of authors of cassava-related publications.

Furthermore, in terms of funding sponsors for cassava research, 100% of the top 15 sponsors were from developed countries, highlighting a significant research funding and collaboration gap in low-and middle-income countries (LMICs), particularly in Africa. Insufficient research funding allocated to universities and other institutions in many developing nations could potentially explain the low research funding observed [56,57,58,59].

To form distinct themes for each of the five identified cassava research clusters in this study, keywords were used. Cluster 2 had the highest occurrences (17,171) and total link strength (TLS) of 104,832, with "sustainable development" being the highest occurring keyword (4,940) in this cluster (Table 10). Other important keywords in this cluster include cassava, Nigeria, agriculture, Africa, and food security. Cluster 1 focused on themes such as “Cassava research: understanding genetics, metabolism, physiology, and phylogeny.” Cluster 3 included keywords related to human gender and age-groups, suggesting themes like "Cassava: nutrition and human health." Clusters 4 and 5 had keywords focused on the chemical and industrial utilisation of cassava, including terms like cassava starch, chemistry, cellulose, temperature, water, Fourier transform infrared spectroscopy, fermentation, and ethanol.

Additionally, in terms of global cassava production, this study revealed that Africa remained the highest producing region with a total of 203.5 million tonnes in 2021. Nigeria was the highest producing country with 63 million tonnes, representing 20% of the global production in 2021 [10]. However, Nigeria ranked 59th globally with a trade value of 1.02 million and had a 0.03% share of global exports in 2021 [13]. It was reported that despite being the highest producer, Nigeria has not fully exploited the trade potential of cassava in the international market [4, 20,21,22]. In 2021, China and Thailand were the top importer and exporter of cassava, respectively [13]. Djibouti (9th, $68.3 million import value) was the only African country among the top 10 cassava importing countries, while Ethiopia (7th, $130 million export value) and Egypt (10th, $81.8 million export value) were the only African countries among the top 10 cassava exporting nations in 2021 [4]. Notably, most of the top cassava importing and exporting countries are currently found within developed nations [4, 13].

4.1 Limitations of the study

The bibliometric analysis of cassava publications had some limitations worth mentioning. First, this study is limited to documents found in the Scopus database and does not consider publications in other databases. Second, only original and review articles were included, excluding other publication types such as conference papers, book chapters, and grey literature. Despite these limitations, the study provided a comprehensive exploration of the development of cassava research efforts and the areas of knowledge significant to the global community.

5 Conclusion

The study conducted a bibliometric analysis of cassava research using data from the Scopus database, covering the period from 2000 to 2023. Research on cassava in Scopus has increased since 2000. According to FAOSTAT 2023 data, Nigeria maintained its position as the foremost producer of cassava until 2021. According to OEC 2023 data, China continued to be the primary importer of cassava, while Thailand remained the principal exporter in 2021. The most cited articles focused on the production, health benefits, biological activity, and chemical composition of cassava, as well as its industrial applications. However, 80% of the top journals publishing cassava research were based in developed nations, with only one African-based journal, the African Journal of Biotechnology, among the top 10.

Brazil ranked first among the most productive countries for cassava publications with 2,534 documents. Funding sponsors from Brazil and China provided the highest financial support for cassava research. No sponsors from Africa were ranked among the top funding sponsors, highlighting a research funding gap in the region. Notably, 50% of the top 10 prolific authors of cassava publications were from Africa. Keyword analysis of cassava-related publications highlighted key areas of study such as Manihot esculenta, cassava starch, fermentation, genetics, hydrolysis, ethanol, cassava flour, and food security. Institutions in Brazil and Nigeria made the most influential contributions to cassava research.